NATCAT Manual

8/11/2019 NATCAT Manual

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CourseParticipant

Notes


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Preface

These notes have been written to try and approximate the NATCAT course as close aspossible and are not intended to be another airway text book. It is hoped that thesenotes, combined with the course, will provide a useful source of practical airway

management information that trainees and critical care practitioners will use throughouttheir careers.

We would like to thank Drs Andrew Heard and Keith Greenland for allowing us toincorporate their publications and ideas into the notes. Large sections of these notes havebeen taken from unpublished material prepared for Anaesthetic Trainees at the AustinHospital by Dr Jon Graham. We thank him for permission to use his work.

We would welcome any feedback regarding these notes and the NATCAT course ingeneral. Please send through your comments/ideas to:

[email protected]

[email protected]

NATCAT November 2013

This work is copyright. Apart from any use permitted under the Copyright Act 1968, no partmay be reproduced by any process, nor may any other exclusive right be exercised,without the permission of A. Cocciante & co-authors, Melbourne 2010


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Contents

Introduction ....................................................................................... 5

MODULE 1Airway Equipment & Usage .............................................................. 6Supraglottic Approach ................................................................................................ 7

Equipment for bag-mask airway management ............................................................. 7Bag and Mask Ventilation Techniques ......................................................................... 8Supraglottic airway devices ........................................................................................ 10LMA insertion .............................................................................................................. 13

Infraglottic Approach ................................................................................................. 15Equipment for intubation ............................................................................................. 15

Laryngoscope Blades ............................................................................................. 15Endotracheal tubes (ETT) ....................................................................................... 19

Aides in tracheal intubation ..................................................................................... 23Endotracheal Intubation Techniques .......................................................................... 25

Intubating using a laryngoscope ............................................................................. 25Intubating through a LMA ........................................................................................ 31Fibrescope assisted intubation through a LMA ....................................................... 32

Surgical Airway Devices ............................................................................................. 35Cricothyroidotomy devices ...................................................................................... 35Emergency Cricothyroidotomy ................................................................................ 35Cannula Cricothyroidotomy ..................................................................................... 37Oxygenation via a transtracheal cannula ................................................................ 39Inserting a surgical airway via the Seldinger technique .......................................... 42

Scalpel Bougie Technique ...................................................................................... 43Scalpel Finger Cannula Technique ......................................................................... 44Tracheostomy devices ........................................................................................... 45

Equipment Reference Sheet................................................................................... 50

MODULE 2Fibreoptic Intubation ....................................................................... 52

Introduction to the fibreoptic endoscope.............................................................. 53The basic movements of the fibreoptic endoscope .................................................... 55

Performing an awake fibreoptic intubation.......................................................... 57Practical hints for successful awake fibreoptic intubation ........................................... 71

MODULE 3Airway Assessment & Practical Airway Management .................... 72

The Focused Airway Examination ......................................................................... 73Predictors of difficult bag-mask ventilation .............................................................. 75Predictors of a difficult intubation ............................................................................ 76Predictors of difficult LMA ventilation ...................................................................... 80Predictors of difficult cricothyroidotomy .................................................................. 81

The Predicted Difficult Airway................................................................................ 82


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Troubleshooting Common Technical Airway Issues ................................................... 83An Example of a Systematic Airway Exam ................................................................. 86

Practical Airway Management ................................................................................ 89The Unanticipated Difficult Intubation ......................................................................... 89The Anticipated Difficult Airway .................................................................................. 96

An approach to the problem of difficult or impossible ventilation through an ETT or

tracheostomy tube .................................................................................................... 104


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Introduction

Airway management can be divided into 2 broad approaches:

A. Supraglottic approachconsisting of:

i. Bag mask ventilation:either supporting the patients ownspontaneous breathing or using intermittent positive pressureventilation (IPPV)

ii. Supraglottic device insertione.g. LMA insertion

B. Infraglottic approachconsisting of:

i. Endotracheal intubationii. Surgical airway insertione.g. cricothyroidotomy or tracheostomy

Although there is often more then one way to manage a patients airway for a particularsituation or procedure, the chosen method of airway management will be influenced by:

1. The presence of patient factors including the predictors of a difficult airway.2. Surgical factors.3. The experience of the person managing the airway.4. The equipment available.

Successful airway management thus hinges on being able to integrate the above 4 factorsto develop an airway management strategy which should include an initial airway

plan as well as a back up plan(s)in the event of the first plan failing.

As far as possible, we have tried to keep the format of these notes simple by keeping tothe supraglottic and infraglottic approaches to airway management. All equipment andissues pertaining to each approach will be discussed together in Module 1. Module 2 willfocus on the technical issues related to performing an awake fibreoptic intubation and inmodule 3, we will review where each technique fits into the overall airway strategy.


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MODULE 1

Airway Equipment & Usage


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Supraglottic Approach

Equipment for bag-mask airway management

Mask

A correct fitting mask-covers the nose and mouth and should form an airtight seal on theface. Care must be taken not to make contact with the eyes.It is important to correctly size the mask on patients face before commencing airwaymanagement.

Breathing circuit:

This can be an air viva bag e.g. ambubag (ideally with reservoir bag attached) oranaesthetic circuit e.g. Mapleson, circleIt must be checked to ensure the ability to generate positive pressure and ideally shouldbe connected to an oxygen source.

Aids in successful bag-mask airway management

Oropharyngeal airways (Guedel airways):These are curved plastic devices with a central lumen which, when inserted properly overthe tongue, will create an air passage between the tongue and posterior pharyngeal wall.

They come in a variety of sizes: size 3 (8cm long, greenrim)(Only adult sizes shown) size 4 (9 cm long, yellowrim)

size 5 (10 cm long, redrim)size 6 (11cm long, orangerim)

Ensure the correct size: Distance from the corner of the patients mouth to angle of jawshould correlate to length of airway. The flange should lie flush with lips when correctlyinserted and should not interfere with bag-mask ventilation.

Nasopharyngeal airwaysThese are long, cylindrical shaped devices made of flexible material which need to be

lubricated before insertion.


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In the awake/semiconscious patient, they are better tolerated then oropharyngeal airways.Their size is measured by their internal diameter in mm (as for endotracheal tubes).The correct size can be determined by the size of the patients nostril but generally a size6 for a female and a 7 for a male.The end should lie flush with the nostril and should not cause gagging. If so, pull theairway back slightly.

They are contraindicated in a suspected base of skull fracture.

Bag and Mask Ventilation Techniques5

The ability to bag-mask a patient is the most important airway skillto possess.Airway patency during bag-mask ventilation is maintained by:

1. A correct fitting mask.

2. Optimal head position.

3. Manipulation of the head and neck.4. The use of oral or nasopharyngeal airways.

If any difficulty is experienced during bag-mask ventilation, it is important to ensure that theabove 4 factors are optimised. Two hands and even two people may be required tooptimise the airway for bag-mask ventilation.

1. Mask

A correct fitting mask covers the nose and mouth and should form an airtight seal onthe face. It should sit in the palm of the left hand with the hypothenar eminence extendingbelow the left side of mask. The IPJ of the thumb should hold the collar of the mask,closest to you in the midline with the index finger reaching around the other side of thecollar with the PIPJ in the midline. The middle finger should rest on the mask or under thechin. The ring and little finger should be applying jaw thrust (upward pressure) at the angleof the jaw.Before applying the mask, the mouth should be opened slightly and the mask first appliedto the area below the bottom lip and then down onto the face.

Achieving a seal

It is important to be able to achieve a good seal to enable adequate bag mask ventilation.There are 3 areas where leaks commonly occur:

I. Nose: To achieve a seal at the nose, apply downward pressure with the thumb.

II. Chin:To seal at the chin, the index and middle finger should apply downward

pressure to the mask whilst the ring and little fingers should simultaneously apply

jaw thrust (upward pressure) at the angle of the jaw.

III. Sides:To seal the left side, the skin of the cheek is gathered against the side of the

mask by the hypothenar eminence. At the right side of the mask, the ends of the

thumb and index /middle finger apply downward pressure to the right side of the

mask or an assistant can lift the right check up to form a seal.


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Generally one should imagine trying to pull the face up to meet the mask, not pushingthe mask down to meet the face.

2. Positioning6

There is limited research as to whether the sniffing position (neck flexion with headextension) is better than simple neck extension for bag and mask ventilation but it probablyis and is also convenient if intubation is to follow.

3. Manipulation of head and neck

This can be achieved in the following 3 ways:

Head tilt and chin lift: lengthens the anterior neck which elevates the

tongue and epiglottis away from the posterior pharyngeal wall.

Jaw thrust: achieved by elevating the angle of the mandible. Because the

tongue is attached to the mandible, it elevates the tongue from the posterior

pharyngeal wall.

Opening the mouth: an oral airway may assist with this.

4. The use of oral or nasopharyngeal airways

An oral airway (Guedel airway) should be inserted with the curvature facing upwards andthen rotated 180as it is advanced (this insert and rotate maneuver is applicable in adultpatients but potentially hazardous in infants). It is important to ensure that the correct sizeof airway is used. The length of the oral airway should be equal to the distance from thecorner of the patients mouth to the patients ear lobe/ angle of the jaw and the flangeshould lie flush with the lips once fully inserted.

Nasopharyngeal airways are better tolerated than oral airways, however they do have thedisadvantage of potentially causing epistaxis and a potential bloody airway. They arecontraindicated in facial fractures and base of skull fractures. The correct sizednasopharyngeal airway should reach from the nostril to the ear lobe/ angle of jaw. If they

induce a cough, withdraw slightly.


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Two-person bag-mask ventilation

Sometimes despite optimising all of the above, 2 people are required to enable successfulbag-mask ventilation. This is commonly achieved by one person using both hands to apply

jaw thrust with the fingers whilst holding the mask with the thumbs and the second personapplying positive pressure ventilation.

Muscle relaxants7

Administration of muscle relaxants generally improves the conditions for bag and maskventilation and intubation. However, the concern is that one is burning bridges bydelaying the possibility of a return of spontaneous ventilation for a more prolongedperiod. As a general rule, in the setting of difficult bag-mask ventilation, muscle relaxantsshould not be used.

Supraglottic airway devices

Supraglottic devices establish a direct conduit for air to flow when placed in thesupraglottic area. They come in a variety of sizes and shapes and most have balloons orcuffs that once inflated, provide a reasonably tight seal in the upper airway.

A large variety of such airways exist, however we will limit our review to the variety oflaryngeal masks commonly available.

Classic laryngeal mask (cLMA)

This device has wide bore tubing connected to an oval inflatable cuff that seals around thelarynx.It is currently available in eight different sizes for use in patients ranging in size fromneonates to adults.Typical adult sizes are:

Size 3 patient 30-50kg




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cLMAs were initially designed to help provide an airway in a spontaneously breathingpatient. However, current evidence suggests that the cLMA appears to be effective andprobably safe for positive pressure ventilation in patients with normal airway resistance,compliance and normal tidal volumes.14

The cLMA does notprotect the airway from aspiration and does not easily allow for the

removal of pulmonary secretions and therefore should not be used in an elective settingfor patients at a high risk of aspiration.

The cLMA, as with all the various types of LMAs, plays a major role as a rescue device inan unexpected difficult airway.

Flexible LMA (fLMA)

The fLMA is similar in design to the cLMA but incorporates a non-kinkable, wire-reinforcedtube.It was designed specifically for use in ENT, head and neck and dental surgery.The long flexible, narrow bore tube provides better surgical access to the oropharyngealcavity compared with the cLMA.

Proseal LMA (pLMA)

The pLMA is a variant of the cLMA with the following design modifications:

The airway tube is reinforced, similar to the fLMA, to improve flexibility and avoidkinking.

The airway tube is shorter than in the cLMA.

The drainage tube runs parallel to the airway tube exiting at the mask tip. This isdesigned to vent gas and gastric contents from the stomach and allow the passageof an orogastric tube. The drainage tube can accommodate any standard gastrictube (


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It is designed to improve performance and safety during controlled ventilation by:

Improved airway seal compared with the cLMA.

Theoretically providing improved protection against aspiration compared with thecLMA. When the pLMA is correctly placed, the drainage tube lies in continuity withthe oesophagus and the airway tube in continuity with the trachea, providingeffective separation of the respiratory and GI tract.

It is available in the same sizes as the cLMA.

Supreme LMA (sLMA)

The sLMA is marketed as a disposable pLMA but has its own particular design features

It is precurved It has moulded fins within the bowl to protect the airway from epiglottic obstruction,

performing a similar role to the epiglottic elevating bar in the ILMA.

It has bite block and oesophageal tube.

Ventilation is via the airway tube, which incorporates a drain tube within itslumento shorten and straighten its path.

Intubating LMA (ILMA)-Also known as the Fastrach LMA

Although it is possible to intubate blindly through any LMA, the success is variable and it is

generally unreliable. The ILMA was therefore specifically designed to facilitate intubation ofthe trachea through the LMA with greater success and ease.

The device consists of:

A rigid metal curved airway tube with a manipulating handle.

An epiglottic elevating bar

A deeper bowel

A ramp that directs an ETT up and into the larynx enhancing the success rate ofblind intubation.

The ILMA comes with its own dedicated wire-reinforced, silicone bullet tipped ETT, whichhas been shown to have the highest intubation success rate.


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The ILMA is available in sizes 3, 4 and 5 and the dedicated ILMA endotracheal tubes areavailable in sizes 7, 7.5 and 8. All 3 sizes of ILMA are able to accommodate all 3 sizesof tube.

The ILMA endotracheal tube contains a low volume-high pressure cuff, which is notsuitable for prolonged intubation.

The ILMA endotracheal tube has been found to be easier to use for awake nasalintubations19and this will be discussed further in module 2.

LMA insertion

Inserting a cLMA

Many different techniques have been described to insert a cLMA. The method describedhere is the one developed by the designer of the LMA, Dr Brain. It also applies to theflexible LMA and supreme LMA.

Preparation:

Ensure that the LMA has a properly functioning cuff and valve.

Ensure that cuff of the LMA is properly lubricated, taking care to avoid gettinglubricant into the bowel of the cuff as this may potentially obstruct the airway.

Ensure that the cuff is fully deflated

Insertion

Position the patients head and neck as you would for a normal intubation.

Open the patients mouth and insert the LMA.

Press the tip of the LMA up against the hard palate and slide the LMA over the hardpalate and soft palate into the hypopharynx until definite resistance is felt.

Inflate the LMA without holding the tube. (short outward movement is normal)

Ensure the ability to ventilate and then secure the LMA.

Sometimes the LMA can be obstructed by the back of the tongue on insertion. If this is thecase, it is often helpful to gently turn the LMA vertical, slide the LMA along the paraglossalgutter and then turn it horizontal again once the posterior tongue has been bypassed.


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For inserting a flexible LMA, it is necessary to place the index and middle finger on the cuffof the LMA, either side of the tube and guide it into position. This is because the flexibletubing does not have enough rigidity to advance the cuff when the tubing is advanced.

Inserting a proseal LMA (pLMA)

Three insertion techniques are commonly used to insert the pLMA:

1. Use of an introducerThe introducer is a removable metal device, which sits at the base of the cuff, runs onthe underside the tubing and connects to the proximal plastic circuit connecter. Whenapplied correctly, it allows for the pLMA to be inserted like a cLMA and once sittingcorrectly, the introducer can be removed.

2. Digital insertionThe pLMA can also be inserted without an introducer. Like the flexible LMA, the cuffthen has to be guided directly by the fingers to ensure correct placement.

3. Gum elastic bougie (GEB) guided insertion

The drain tube of the pLMA is primed with the straight end of a lubricated GEB. Undergentle laryngoscopy, 5-10cm of the straight end of the GEB is placed into theoesophagus while an assistant holds the distal GEB and pLMA. The laryngoscope isthen removed and the pLMA advanced using the digital insertion technique. The GEBis then removed while holding the pLMA in position.

Once the pLMA is inserted, it should be possible to pass a gastric tube down the draintube of the pLMA. If this is not possible, this suggests that the tip of the pLMA is eitherfolded over or not sitting over the oesophageal inlet and thus cannot reduce the risk of

aspiration or gastric insufflation.

Inserting an Intubating LMA (Fastrach LMA)

The ILMA should be inserted deflated and flattened. Often no head or neck manipulation isrequired. As with other LMA insertions, the mask tip should be slid backwards along thehard palate, following the curve of the soft palate and posterior pharyngeal wall to preventunfolding. The LMA should not be held while the cuff is inflated.To achieve optimal ventilation, it may often be required to tip the handle slightly forwardand back in the sagittal plane to ensure a better position of the internal aperture withrelation to the glottic opening. Once this position is achieved, the chances of successful

intubation can be increased by applying slight anterior lift of the ILMA handle in order tomove the ILMA away from the posterior pharyngeal wall during intubation11(Chandymanoeuvre). You should only proceed to intubation once an adequate airway isobtained through the ILMA.Intubating through the ILMA is covered in Practical Airway Management - Infraglottic

Approach


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Infraglottic Approach

Equipment for intubation

In this section, we will review the equipment required to undertake tracheal intubation with

an endotracheal tube.

Laryngoscope Blades

Many different types of blades exist, each with their own particular advantages.All blades consist of a:

Base for attachment to the handle

Tongue which can be straight or curved

Web which forms a shelf along one edge of the tongue, connecting the tongue tothe Flange and incorporating electric connections and bulb or fibreoptic bundle

Flange which runs parallel to the tongue and is usually only present for the proximal

1/3-2/3 of the blade

1. Curved blades

The Macintosch blade is the most commonly used curved blade in Australia and theUK. The long axis of the blade is curved and the tongue, web and flange form a right-angled, reverse Z shape in cross section. The web and flange are bulky, the tip isatraumatic and the light source is shielded by the web.This blade can be difficult to use in patients with limited mouth opening or prominentincisors.The two adult sizes most commonly used are sizes 3 or 4

2. Straight blades

The Miller blade is the most popular straight blade used in paediatric anaesthesia andin adult practice, especially in the USA. The Miller blade differs from the Macintosh


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blade in that the tongue is straight with a slight upward curve near the tip and theflange, web and tongue form a C with the top flattened in cross-section.

The Straight blade is thought to be particularly useful in patients where intubation witha Macintosh blade may be difficult due to the following patient features:

Limited mouth opening A short thyromental distance

A large tongue

Prominent upper incisors

A long floppy posteriorly directed epiglottis

A precise technique with the straight blade is essential and there is a significantlearning curve in its correct use to obtain a view of the larynx.

Like the Macintosh blade, the two most commonly used adult sizes are sizes 3 and 4.

3. McCoy blade

The McCoy blade is a modified Macintosh blade, which has a hinged tip controlled by aleaver on the handle. It can improve the view of some grade 2-3 patients by lifting theepiglottis when the leaver is pulled, thereby bringing the larynx into view.

It is useful in patients with limited or no neck movement or in patients where neckmovement is undesirable e.g. c-spine injury.It is much less useful in patients with a grade 4 view.


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4. Kessel blade

The Kessel blade is similar to the Macintosh blade but with an altered angle of theblade with the handle. The increased angle of the Kessel blade of about 110 degreeswith the handle may allow for easier insertion of the laryngoscope blade in patients withantesternal space restriction e.g. pregnant patients, morbidly obese patients

This can be used in conjunction with a short laryngoscope handle, also designed forsuch patients.

5. Non-standard laryngoscopes and rigid fibreoptic intubation aids

Rigid fibreoptic intubation systems can be classified into 3 groups15:

i. Videolaryngoscopes which allow indirect laryngoscopy and then requireindependent endotracheal tube +/- stylet for intubation e.g. Glidescope, McGrathand C-MAC (pictured in that order below):

ii. Devices for indirect laryngoscopy with an optical blade and a conduit for theendotracheal tube e.g. Airtraq and Pentax-AWS (pictured below)


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The videolaryngoscopes in i and ii can also be divided into those based on a standardMacintosh blade design e.g. C-Mac, McGrath Mac and those with a hyperangulatedblade e.g. Glidescope, Airtraq, C-Mac D-blade. This is more of a functionalclassification, as the shape of the blade will influence the technique employed whenusing the device. This is covered later in the notes.

iii. Fibreoptic optical stylets placed within the endotracheal tube e.g. Levitan andBonfils (pictured below)

The techniques required to use these devices differ from one device to the next andthere does appear to be a learning curve associated with their use initially.Evidence is still lacking to support the replacement of standard laryngoscopes withnon-standard devices for routine or difficult intubations and the results of large

multicentre trials of new devices are required

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Endotracheal tubes (ETT)

Modern endotracheal tubes are made of PVC and consist of a cylindrical tube, aninflatable cuff at the distal end and a side vent near the distal end of tube known as aMurphy eye. This was created to prevent complete respiratory obstruction in the event thatthe open end of the ETT were to become sealed by contact with the tracheal wall or

occluded by a mass or mucus.

ETTs can be inserted orally or nasally and can be cuffed or non-cuffed, the latter normallybeing used in paediatrics. Endotracheal tube sizes are based on their internal diameter inmm and range from 2mm to 10.5mm. Common adult sizes are 7-8mm

Cuffed ETTs

Various types of cuffed endotracheal tubes exist but they all have essentially 2 functions:1. To create a seal against the tracheal mucosa to prevent aspiration2. To facilitate positive pressure ventilation by preventing air leakage around the tube.

Care must be taken not to over inflate the cuff as this may cause mucosal injury.Clinically, the cuff should be inflated until such time as a leak ceases to be presentwhen positive pressure is being applied to the ventilatory circuit.

We will briefly review some of the more commonly used cuffed endotracheal tubes inanaesthesia today:

1. RAE tubes (after their inventors Ring, Adair and Elwyn, also called polartubes)

These are endotracheal tubes that are manufactured with preformed bends and aredesigned to facilitate surgery of the head and neck. They come in a variety of sizes andare either shaped for nasal (north facing) or oral (south facing) intubation. When insertedcorrectly, the preformed bend should sit either at the chin (oral) or external nares (nasal).Their advantage in head and neck surgery over standard ETTs is that:

They are less likely to kink when positioned correctly

The tube connector is situated further away from the surgical field

The tube fits the contours of the face so it can be secured well with a reduced riskof moving

When used, the following points need to be remembered:

Due to the bend, suctioning of these tubes is more difficult

The location of the bend and hence the intra-airway length, is based on the tubediameter, which may result in either endobronchial placement or the tube not beingadvanced sufficiently into the trachea.

Flexion or extension of the head once the tube is secured may result in accidentalendobronchial intubation or extubation


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2. Reinforced or armoured tubes

These are tubes that contain a spiral of metal in the wall to allow for greater flexibility of thetube. This helps to reduce the risk of kinking or occlusion of the tube if it were to be twistedor compressed, such as can occur when a patient is placed prone for surgery.

There are a few important differences between reinforced and normal cuffed tubes whichshould be remembered:

The tubes are longer than standard tubes so they can be used orally or nasally. Ifused orally, care must be taken to avoid endotracheal intubation

If the patient bites the tube it may stay compressed. Always insert a bite block orequivalent if an oral tube is inserted.

The connector is welded to the tube and cant be removed as with standard tubes.As a result, these tubes cant be cut and shortened.

3. Microlaryngoscopy Tubes (MLT)

These were designed for use in patients undergoing laryngeal surgery to optimise thesurgical field by allowing the use of a smaller sized tube in an adult patient. They come ininternal diameter sizes 4-6mm but with adult cuff sizes and are slightly longer thanstandard adult endotracheal tubes. Because of the narrowed internal diameter, they arenot optimal for prolonged spontaneous ventilation.

4. Double Lumen Tubes (DLT)

A DLT is a single endotracheal tube, consisting of two individual lumens, side by side,each lumen having their own connecter and cuff. The two lumens are not the same lengthand are designed to sit in different parts of the lower airway.The shorter lumen is known as the tracheal lumen and when the DLT is inserted correctly,its cuff (the proximal cuff) should lie in the trachea. The other longer lumen is known as theendobronchial lumen and when the DLT is positioned properly, its cuff (the distal cuff)should lie in the desired mainstem bronchus.

Examples of various endotracheal

tubes (from left to right):

Oral RAE

Nasal RAE

Size 4 MLT (note length)

Size 6 reinforced tube


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DLTs are classified as either right or left sided and this refers to the longerendobronchial portion of the DLTi.e. in left sided DLTs, the longer lumen should extendinto the left main bronchus and shorter lumen into the trachea. The situation is reversedwith right sided DLTs.

The most common DLTs used in Australia are the disposable, plastic PVC

Bronchocath/Mallinkrodt DLTs (pictured below). With these DLTs, the lumens are colourcoded with the shorter tracheal lumen having a clear cuff and the longer bronchial lumenhaving a blue cuff.

DLTs are usually used in thoracic surgery because:

They protect the dependent lung from blood and secretions.

They allow independent control of ventilation to each lung.

They improve surgical access.

The sizes of these tubes are given in Charriere (CH) gauge which is equivalent to French(Fr) gauge and relate to the external diameter of the tube. One Fr is equal to approx.

0.33mm hence a 39Fr has an external diameter of roughly 13mm.

The sizes of Bronchocath/Mallinkrodt tubes which are commonly used are:

41 and 39Fr for men

37 and 35Fr for women

Apart from the differences between right and left sided DLTs, which have already beendescribed, a further difference exists and this is best understood while actually examininga left and right-sided Bronchocath/Mallinkrodt DLT simultaneously. Due to the early takeoffof the right upper lobe from the right main bronchus, it is often easier to correctly position aleft sided tube. For this anatomical reason, right-sided Mallinkrodt tubes have a right upper

lobe opening and a doughnut shaped cuff around the bronchial lumen which pushes thetube away from bronchial wall. The cuff does not extend between the right upper lobeopening and the distal end of the tube. This allows the right upper lobe to be ventilatedfrom the distal end of the tube as well as through the upper lobe opening.

The correct positioning of DLTs in the airway should always be assessed usingclinical means and confirmed using a fibrescope, as incorrect positioning can bepotentially catastrophic.


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5. Bronchial Blockers (BB)

Although bronchial blockers are not endotracheal tubes per se, now is a good time todiscuss them briefly.BBs are balloon tipped catheters, which are maneuvered through a single lumen tube into

the appropriate main or lobar bronchus. This is normally achieved with the aid of afibrescope. The balloon is then inflated to isolate the lung or lobe from ventilation at whichtime the isolated lung/lobe will slowly collapse.

There are 2 main types of BBs available:

1. Cook blockers either Arndt (wire guided) or Cohen (tip-deflecting) endobronchialblockers

2. Univent tube

Have a look at the following websites for more information on BBs and on their insertion:

http://www.youtube.com/watch?v=Tru-vVO6s3w&feature=related

http://cucrash.com/Handouts05/MillerH%20Bronchial%20Blockers.pdf

BBs should be considered in the following situations:

Patients requiring lung isolation who have difficult airways. In such cases,intubating with a DLT could be very difficult.

Patients with a permanent tracheostomy.

Patients who are already intubated with a single lumen tube and in whomremoving the ETT is potentially hazardous e.g. trauma patients & ICU

patients. When only isolation of a lobar bronchus is required.

Generally, they are more difficult to place correctly when compared to DLTs. It is alsomore difficult to intermittently ventilate the collapsed lung if required and if done, this willresult in the loss of lung isolation as the cuff has to be deflated to achieve this.It is also very important to be aware that a BB, which is fully inflated and then migratesproximally into the trachea, may cause complete tracheal obstruction, which if notidentified early, may be catastrophic. Simply deflating the balloon can relieve this.


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Aides in tracheal intubation

There are numerous devices that can aide our ability to intubate the trachea. The majorityof them are cheap, portable and fairly easy to use and a good knowledge of them is

important when managing airways.

Intubating stylet

The intubating stylet comprises a malleable metal rod, which is able to fit into an ETT. Itsdistal end should sit just within the distal tip of the ETT (cuffed end) and its proximal endshould protrude out the proximal end of the ETT. Once placed, the ETT and stylet can bebent into the desired shaped simultaneously. Once bent, the ETT should keep the shapeuntil such time as the stylet is removed.The stylet is useful in patients with an anterior larynx as an anterior bend at the tip canfacilitate intubation. Once the tip of the ETT is through the cords, the stylet should be

removed.Care must be taken to ensure the distal end does not protrude beyond the distal tip of theETT as this may cause mucosal injury.

Bougies

A bougie is a 60-70cm long malleable device, which is inserted through the vocal cordsinto the trachea and over which an ETT can be railroaded.The distal 2.5 cm is angulated and this facilitates insertion through the vocal cords whenonly the epiglottis (Grade III view) or tip of the arytenoids (Grade II view) can be visualised.

A 2nd operator then threads the tube over the bougie.

Numerous types of bougies are available. Some of the more common ones available inAustralia are:

Eschmann gum elastic bougie - a beige coloured bougie. Standard lengthis 60cm with a15Fr (5mm) external diameter. Suitable for ETT sizes 6-11. Apaediatric bougie is also available 70cm long, 10Fr (3.3mm) externaldiameter and is suitable for adult DLT insertion

Cook Frova bougie - a blue 65cm long bougie with 14Fr (4.7mm) externaldiameter. It is essentially a hollow tube with a distal opening and comes witha Rapi-fit leur lock connector, which allows for jet ventilation in an

emergency. A yellow 8 Fr (2.6cm) , 35 cm long paediatric bougie is alsoavailable for ETT sizes> 3mm

Cook exchange catheters

These are long, hollow semi rigid tubes that allow for an exchange of an ETT i.e. prior toextubation, an exchange catheter is inserted down the airway, the ETT is then removedand the new ETT railroaded over the exchange catheter into the airway. Being hollow, theyalso enable the operator to oxygenate the patient. This can be done via:


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i. A detachable 15 mm adaptor for connection to an anaesthetic circuit or air viva.This adaptor comes with the catheter

ii. A leur lock connection, which is suitable for jet ventilation. This also comes with thecatheter

iii. Oxygen tubing which is able to be connected directly onto the catheter

There are a few sizes available, each with differing external diameters but of similar length(83-100cm long). The most common size used in adult anaesthesia is the 19 Fr with anexternal diameter of 6.3mm which is suitable for a size 7 ETT or greater.

For exchange of a DLT, smaller sizes are required:

11F external diameter 3.7mm (appropriate for DLT size 35& 37)

14F external diameter 4.7mm (appropriate for DLT size 39& 41)

Aintree Intubating catheter (AIC)

This is a very similar device to the Cook airway exchange catheter but is specificallydesigned to fit snugly ontothe length of an adult 4mm fibrescopeleaving the flexible 3cmtip of the scope unsheathed. It was initially designed to facilitate intubation using afibrescope through a LMA by:

Loading an AIC over a fibrescope

Passing the fibrescope through a correctly positioned LMA, down through the cordsto the carina and then sliding the AIC off the fibrescope

Removing the fibrescope and LMA whilst holding the AIC in place

Railroading an ETT over the AIC.

It is 56cm long with an internal diameter of 4.8mm and an external diameter of 19Fr(6.3cm), which allows its use with size 7 and greater ETTs.It too comes with a detachable rapi-fit leur lock device which allows for ventilation ifrequired.

Left:

Intubating stylet, Frova intubating

bougie and Aintree catheter

Below:

Aintree Catheter and Frova bougiewith their 15mm Rapi-fit

connectors attached


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Endotracheal Intubation Techniques

Endotracheal intubation can be performed in a variety of ways and to assist with intubationwe can use a variety of devices on their own or in combination:

1. Laryngoscopes with a variety of blades with or without the use of a bougie.2. An intubating conduit e.g. ILMA, cLMA3. A fibreoptic endoscope4. Nothing, as for a blind nasal intubation

In this section, we will review intubation via direct and indirect laryngoscopy using as wellas intubation through a LMA. Awake fibreoptic intubations will be covered in module 2.

Intubating using a laryngoscope

Optimal positioning

Before a laryngoscope is picked up, it is imperative to optimise the chances of asuccessful first time intubation by positioning the patient appropriately.Optimum positioning involves achieving a line of sight from the maxillary teeth to the larynxand this has classically been described in the 3 axis alignment theory which involveslining up the oral, pharyngeal and laryngeal axes as best as possible.More recently however, Greenland et al 4have attempted to describe the optimum positionon the basis of a two-curve theory and we encourage you to review the article.

The sniffing position is the time honored best position and this involves 350neck flexion

and 150face plane extension4. Practically this can be achieved by placing the patientshead on a pillow to achieve neck flexion and then once induced, the head can be gentlyextended before intubation. Sometimes further flexion i.e. another pillow or lifting the headoff the pillow can improve the view.

In obese or pregnant patients, elevation of the shoulders and head may be necessary andcan be achieved by using multiple pillows or blankets positioned under the shoulders.Ideally, the sternum of the patient should be at the same horizontal level as thetragus or angle of the jaw.This is illustrated below using the 3 axis alignment theorywhere the oropharyngeal axis (OA), laryngeal axis (LA) and pharyngeal axis (PA) shouldalign as close as possible.


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Using the laryngoscope

Macintosh blade

The Macintosh blade is introduced from the right side of the patients mouth and is used tosweep the tongue to the left while introducing the blade into the vallecula. Thelaryngoscope is then lifted upwards to expose the vocal cords which lie behind theepiglottis. It is important to be conscious of lifting the laryngoscope upwards and notlevering it at the wrist - this levering action will not enhance your view and willincrease the chance of damaging the patients teeth.

Straight blade8

The paraglossal technique12described to use a straight blade successfully is vastlydifferent to that of a Macintosh blade and there is a significant initial learning curve in itscorrect usage. It is not a blade that you want to use for the first time in an emergencysituation.

The patients head should be fully extended (remove the pillow) and turned to the left. Themouth should be opened as wide as possible and the laryngoscope positioned as farlateral in the mouth as possible. The blade should be advanced over the paraglossal gutterto the right of the tongue. The tip of laryngoscope is passed posterior to epiglottis and a


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sufficient lifting force is applied to achieve maximum elevation of the epiglottis. Anassistant retracting the corner of the mouth often helps.

An alternative technique is to advance the laryngoscope into the oesophagus and thenelevate and withdraw slowlyuntil the glottis is seen.

Often the view can be lost when intubation with the ETT is attempted. This problem can be

overcome be initially intubating with a bougie and then railroading an ETT over it.

McCoy blade

As for the Macintosch blade, the exception being that once the tip has been placed in thevallecula and the laryngoscope lifted, further elevation of the epiglottis can be achieved bypulling the leaver on the handle, which moves the tip of the blade anteriorly.

Videolaryngoscopes

Reviewing the technique associated with every device is beyond the scope of these noteshowever anecdotally; a few general principles do apply depending on the type ofvideolaryngoscope used.

For those scopes based on the standard Macintosh blade e.g. C-Mac, McGrath Mac,direct laryngoscopy should be performed as usual and the epiglottis identified if possible.Only then should the image on the monitor be viewed, laryngeal position optimised andintubation attempted. Keeping the image of the larynx in the middle of the monitor appearsto be helpful with these devices. Tube delivery with these devices is very similar tostandard Macintosh blades.

For those scopes with hyperangulated blades e.g. Glidescope, AirTraq, C-Mac D-Blade,

direct laryngoscopy is generally not attempted and locating the epiglottis (epiglottoscopy)is done on the monitor or in the viewer. The blade is then elevated to expose the larynx.With these blades, optimising the view of the larynx to the center of the monitor mayparadoxically make intubation more difficult due to the angle of the blade. Rather,intubation may be easier if the tip of the blade is not advanced too close to the larynx andthe image of the larynx is kept in the top half of the monitor. This will help with visualisingthe tube as it is advanced towards the larynx. Depending on whether the device has adedicated channel through which the tube is advanced, a stylet may be required. Acommon problem with this is that the styletted tube catches on the cricoid cartilage or hightracheal rings anteriorly, preventing tube insertion. One solution is to remove the styletonce the tip of the tube is through the cords. Another option is to rotate the hyperangulated

stylet to the right 90 degrees clockwise. This will help better align the tip of the rotated tubewith the tracheal axis instead of pointing upwards. The tube and can be further advancedbefore the stylet is withdrawn.

A recent article Observations on the assessment and optimal use of videolaryngoscopesby Greenland, Segal, Bradley et al, Anaesthesia Intensive Care 2012; 40: 622-630 reviewsthe specific techniques associated with the more common videolaryngoscopes on themarket today.


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Describing the view of the larynx achieved during laryngoscopy

Traditionally, the best laryngeal view achieved during direct laryngoscopy is describedusing the Cormack and Lehane grading system(see below). This is a grading systembased on how much of the laryngeal inlet is visible following direct laryngoscopy. This isimportant in order to facilitate communication of this information to other relevant medical

personnel.

With the advent of videolaryngoscopes and indirect laryngoscopy, it has become apparentthat a grade 1 view of the larynx on the monitor does not necessarily translate intopassing a tube through the cords easily. As a result, there is a push for the formation of anindirect laryngoscopy grading system to account for this. Although a few classificationshave been suggested, none have met with universal acceptance. Until such aclassification is agreed upon, whenever intubation has been successful via indirectlaryngoscopy it would be prudent to note:

1. The device used

2. The view obtained on the monitor (using the Cormack and Lehane grading system)3. Mechanism used to pass the tube e.g. bougie, pre-shaped stylet

4. Difficulties in passing the tube

For those scopes based on the standard Macintosh blade e.g. C-Mac, McGrath Mac, itwould also be useful to perform and note the best view on direct laryngoscopy.

The Cormack and Lehane grading system

Grade I: most of glottis is seen

Grade II: only posterior portionof glottis can be seen

Grade III: only epiglottis may beseen (none of glottis seen)

Grade IV: neither epiglottis norglottis can be seen


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Strategies to improve the view of the larynx when using a laryngoscope:

1. Ensure position isoptimised(as discussed earlier)2. External laryngeal manipulation (ELM)

This can be backward pressure or BURP (backward upward rightward pressure)applied directly on the thyroid cartilage

Practically it is best achieved by asking your assistant to manipulate the larynx withtheir right hand whilst you perform laryngoscopy and asking them to hold theposition when a best view is obtained.

3. Consider an alternate blade4. Assess if the patient is adequately relaxed or if a further dose of relaxant/

propofol is required

Ideally, the ability to achieve at least a grade 3 laryngeal view is desirable as this mayallow intubation with the help of a bougie.

Use of a bougie to facilitate/assist intubation

The majority of patients with a grade 1, 2 or 3 laryngoscopic view of the larynx can beintubated with a laryngoscope and a bougie. Patients with a grade 4 view are much lesslikely to be intubated simply with a laryngoscope and bougie and if successful, it is likely totake significantly longer.

When using a bougie:

The view of the larynx should be optimised and maintained as discussed above.When using a Macintosch blade, the larynx should lie in the midline behind the

epiglottis. The tip of the bougie should be manually bent to the desired angle to improve

success. Sometimes curving the entire bougie may also help. It should then begently passed behind the epiglottis and then anteriorly between the cords. It isoften beneficial to gently run the tip of the bougie along the underside of theepiglottis.

Sometimes the tip will meet resistance once under the epiglottis. If this is the case,gently rotate and remove/advance the bougie until through the cords.

Successful placement through the cords should be accompanied by the feeling ofthe bougie passing over the tracheal rings (clicks) and potential resistance whenthe carina is abutted

Once through the cords, a previously prepared ETT can be railroaded over thebougie while the laryngoscopic view is maintained. It is important thatsomeone is continually holding the bougie while the railroading takes place.

If resistance is met when trying to pass the ETT through the cords:

Rotate the ETT 90 anticlockwiseas you advance. Consider a smaller ETT, a reinforced ETT or ILMA ETT. Consider releasing cricoid pressure if applied.


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It is important to remember that:

1. Second attempts at intubation should not be performed withoutevery effort being made to improve the probability of success.This should be done by assessing where the difficulty lay in the

first attempt and making the appropriate changes for the secondattempt i.e. changing the blade, optimising position, use of abougie. Repeated attempts at intubation without making changeswill lead to ongoing failure and airway trauma.

2. Repeated attempts beyond the second attempt increases the riskof airway trauma and hence the risk of losing the ability toventilate the patient.

3. Always revert back to bag-mask ventilation when a difficult

intubation scenario is encountered.


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Intubating through a LMA

Intubating through a LMA can be performed: Blind Using a fibrescope with or without an Aintree Intubating Catheter

Blind

Blind intubation through any LMA besides the ILMA is often unsuccessful. The ILMA hasbeen designed for this specific role and should be used whenever possible if a blindintubation is envisaged.However, if another type of LMA is used to perform this manoeuvre e.g. cLMA, pLMA theuser needs to be aware of the following potential problems:

The LMA used may often be too long in that when a standard ETTis fully insertedinto a LMA, the cuff may sit in the cords and not be able to inserted further into theairway. Methods to overcome this problem include using an ILMA ETT, a

reinforced ETT, a warm nasal RAE ETT or a MLT as these ETTs are oftenlonger than standard ETTs.

Only smaller diameter tubes are able to be passed through the cLMA/pLMA i.e. asize 3 and 4 LMA will accommodate a size 6 ETT with difficulty and a size 5ETT easily. A size 5 LMA will accommodate a size 7 ETT

If a cLMA is used, the bars at the glottis opening may cause obstruction whenattempting to pass the ETT down the LMA. This can be overcome by either slightlywithdrawing the ETT and then rotating the ETT as you advance it or cutting the barsbefore the LMA is inserted.

If the ILMA ETT is used with the ILMA, the issue of the ETT being too short does notoccur. As well as this, all 3 sizes of the ILMA are able to accommodate a size 6, 7 or8 ETT.

Blind intubation through the ILMA

This should ideally only be attempted once an adequate airway is obtained throughthe LMA

Choose the correct sized tube and ensure that lubricant is applied onto the tip oftube and then pass it in and out of ILMA to lubricate the shaft of the ILMA(important).

Ensure the longitudinal line on the tube is facing the operator i.e. facing upwards.

Insert the tube into the ILMA until the horizontal black line is in line with the proximalend of the ILMA. This indicates that the distal end of the tube is at the level of theepiglottic elevator bars.

At this point, the ILMA handle should be elevated a few millimeters to lift the ILMAaway from the post pharyngeal wall and align the opening better with the glottis.Resistance will be felt as the tube is advanced through the cords. The cuff shouldbe inflated and confirmation of tracheal placement obtained. If unsuccessful, the


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cuff should be deflated, the tube removed and ventilation re-established through theILMA.

Redirection and re-manipulation of the ILMA handle may enhance successful passage ofthe tube during future intubation attempts

Fibrescope assisted intubation through a LMA

A fibrescope can be used to guide an ETT through the cords, using the LMA as a conduit.Once again, the ILMA is the optimal device to use in this setting and if another type of LMAis used, the problems that were described in the blind intubation through a LMA sectionwill also be encountered (see above).

In the majority of cases, the larynx can be seen from within the bowl of the LMA when afibrescope is passed down a LMA. The view may also be improved by using head andneck movements e.g. chin lift, jaw thrust or cricoid pressure under direct vision.

Anecdotally, using a fibrescope through a pLMA often results in a better view of the glottiscompared with the ILMA or cLMA. This is due to the presence of the EEB in the ILMA andaperture bars in the cLMA.Intubation through a LMA can be performed with or without the use of an AintreeIntubating catheter. Both techniques will be described:

Using only a fibrescope

Prepare an appropriately sized LMA and ETT.Prepare a 4 mm fibrescope - using a bigger scope will result in difficulty in passingit through a size 6 or 6.5 ETT.

Insert a LMA and confirm the ability to ventilate.Insert the fibrescope through the ETT so that the distal end of the fibrescope lies

just within the distal end of the ETT.Ensure the outside of the ETT is lubricated.Insert both into the LMA and advance together.If ILMA used: advance so that the ETT elevates the EEB after which the fibrescopeis advanced through the cords and the ETT railroaded over it into the tracheaIf cLMA/pLMA used:once the glottis is visualized, advance the fibrescope throughthe vocal cords (first through the aperture bars in the cLMA) and railroad the ETTinto the trachea. The aperture bars should be flexible enough to allow the ETTthrough when using a cLMA otherwise they can be cut before insertion of the

LMA.Advance the ETT over the fibrescope until its adaptor is flush against the adaptor ofthe LMA and then remove the fibrescope.Ensure the ability to ventilate through ETT.The LMA may be deflated and left in situ or may be removed. Removal may riskaccidental extubation.

If ventilation is required during intubation, then a fibrescope adaptor can be inserted intothe circuit attached to the ETT (see picture below). The tight fit of the ETT into the LMA willallow for the application of IPPV during intubation.


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Using a fibrescope and Aintree Intubating Catheter (AIC)

The AIC is a very similar device to a Cook airway exchange catheter but is

specifically designed to assist intubating through a LMA by fitting snugly onto thelength of an adult 4mm fibrescopeleaving the flexible 3cm tip of the scopeunsheathed.The AIC is loaded onto the fibrescope, which is then passed down the LMA and intothe trachea as described above.The fibrescope and then the LMA are withdrawn leaving the AIC in the trachea.

A standard ETT can then be railroaded over the AIC whilst performinglaryngoscopy.Thesmallest ETT that can be used is a size 7mm as the AIC is 19F i.e. it hasan external diameter of 6.5mm

It is important to note that the Supreme LMA, the disposable version of thepLMA, is NOT reliably compatible with the Aintree catheter

If there is any difficulty in railroading the ETT over the AIC, it may be used as aoxygenation device in the same way as the Cook catheter, as it comes with 2 detachable15mm Rapi-fit connectors that connect to standard anaesthetic circuits/ air vivas


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Removing the ILMA once the patient is intubated

The manufacturers advise that prolonged placement of the ILMA in situ may lead to animpairment of mucosal perfusion of the posterior hypopharyngeal wall. As a result, theyadvise that the ILMA be removed once the patient is intubated. This process cansometimes be difficult and there is always the risk of accidental extubation while trying to

remove the ILMA. As a result, the risk of mucosal injury should be weighed up againstthe risk of accidental extubation in the particular case before commencing theremoval of the ILMA, once the patient is intubated.

The technique of removing the ILMA is as follows:

Disconnect the circuit with the ETT connector attached to the circuit i.e. notattached to the ETT. This prevents misplacement of the ETT connector!!

Fully deflate the ILMA.

Ease out the ILMA by reversing the insertion procedure, while applying counterpressure to the tip of the tube with index finger.

When the proximal end of ETT is flush with proximal end of the ILMA, insert thestabilising rod and slide the ILMA out over the rod. Ensure that the ETT does notmove with the ILMA i.e. ensure the stabilising rod is held stable!

Remove the stabilising rod when the ILMA is clear of the mouth and the ETT is ableto be held at its most distal point (closest to the patients mouth)

Hold the ETT tightly while the inflation line and pilot balloon are unthreaded from theILMA. Some airway practitioners advocate deflating the ETT pilot balloon inorder to make this step easier to perform and to decrease the risk of shearingthe pilot balloon off the ETT as the ILMA is removed.

Reattach the circuit to the ETT, re-inflate the ETT and ensure the ability to ventilate.


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Surgical Airway Devices

Surgical airway management takes the form of either a cricothyroidotomy or tracheostomy.From an anaesthetic viewpoint, a cricothyroidotomy is easier, safer and quicker to performand as a result, it forms the final step in the DAS algorithm. It is however, important toknow a little about tracheostomy tubes, as you may be faced with a patient with one in situ

who may be experiencing respiratory difficulties.

Cricothyroidotomy devices

A cricothyroidotomy can be performed quickly using a:

14g cannula inserted through the cricothyroid membrane or

A surgical scalpel, bougie and size 6 ETT or

A Melker Emergency Cricothyrotomy Catheter Set, which contains components forinserting a cricothyroid catheter via a Seldinger technique.

We will now review each of the techniques individually:

Emergency Cricothyroidotomy

Many different techniques have been described to perform an emergencycricothyroidotomy but there is very little evidence to support one technique over another.With this in mind, Dr. Andrew Heard, an anesthetist, published the following paper:

Heard AMB, Green RJ, Eakins P. The formulation and introduction of a cant

intubate, cant ventilate algorithm into clinical practice. Anaesthesia 2009;64:601-

608

In it, he attempts to set out an algorithm that anaesthetists could follow if ever faced with acant intubate, cant oxygenate (CICO) situation. He has based his algorithm on 4 yearsof observing wet labs where junior and senior anaesthetic staff practice performingemergency cricothyroidotomies. Due to the rarity of a CICO situation, this paper iscurrently the best evidence we have available and as such, we will use the algorithm as aguide in reviewing the potential techniques available when performing an emergencycricothyroidotomy.

We acknowledge that the algorithm set out below is just a guideline and not the definitiveanswer to which technique to use. It has been written with anaesthetists in mind, themajority of whom are NOT surgically trained and relies on the fact that anaesthetists are

more familiar with using a needle and syringe than with making an incision with a scalpel.We are aware that this may not be the case with airway practitioners who work in thecritical care and emergency setting.

We will review the advantages and disadvantages of each method but theimportantpoint to make is that, after consideration of all factors involved, you decide on atechnique or algorithm that you would use in a CICO situation, practice thetechnique or algorithm and be prepared to carry it out should you find yourself in aCICO situation.The decision to proceed to an emergency cricothyroidotomy is already apsychologically difficult one and it is one that can potentially be made more difficult if youare unclear about which method to employ when faced with the stress of a potentially

catastrophic situation.


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The algorithm advocates 4 techniques to perform a cricothyroidotomy namely:

1. Cannula cricothyroidotomy

2. Melker tube insertion

3. Scalpel bougie technique

4. Scalpel finger technique

Dr. Heard discusses the following techniques and the CICO algorithm on You Tube.Search: DrAMBHeard

We will now consider each one in turn:

Heard AMB, Green RJ, Eakins P. The formulation and introduction of a cant intubate, cant

ventilate algorithm into clinical practice. Anaesthesia2009; 64:601-608


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Cannula Cricothyroidotomy

The initial priority in a CICV situation is to achieve a safe, simple and fast methodof oxygenation (SSFO). Oxygenation is the important consideration; elevations inCO2 are of little concern in this setting. Sometimes a cannula cricothyroidotomy and

oxygenation is all that is needed until the patient resumes spontaneous ventilation or untilthe airway can be secured in a more timely fashion. Otherwise cannula cricothyroidotomyallows SSFO and acts as a bridge to a definitive airway with a Melker tube via theSeldinger technique.

As can be seen from the algorithm, it is suggested that needle or cannulacricothyroidotomy be the initial technique employed when attempting to perform anemergency cricothyroidotomy.

Some of the advantages to this technique include:

It is a safe, simple and quick procedure to perform The ability to provide oxygenation quickly

Non-surgically trained practitioners are more familiar with the equipment used

Minimal blood loss

Enables stabilisation of the situation to facilitate further planning

Facilitates insertion of a Melker tube

Once transtracheal oxygenation is established, it may facilitate further intubation

attempts from above, as air from below may escape though the glottis, potentially

making identification of the glottis on laryngoscopy easier

More options are available if this technique fails

Some of the disadvantages included:

It is nota definitive airway

The cannula may kink or block with secretions or blood

An unrecognised improperly positioned cannula through which jet ventilation has

commenced may result in surgical emphysema

Transtracheal oxygenation provides oxygenation, not effective ventilation. The

patient will become hypercapnoeic if a definitive airway is not established

A time lag of potentially 60 secs may occur before the patients oxygen saturations

improve after commencing transtracheal oxygenation

Performing a cannula cricothyroidotomy13

The cricothyroid membrane is located 1.5 - 2 cm below the thyroid notch. This membraneand not the lower trachea is generally preferred for the immediate surgical airway.However, if it cant be located, dont delay; use the lower trachea or failing that,cannulate in the midline.


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1. Identify the cricothyroid membrane and stabilize it with the non-dominant hand.Theindex fingerof the non-dominant hand should palpate the membraneand the thumband middle fingersshould stabilise the trachea.

2.Hold a 5 ml syringe (containing 1 - 2 ml saline) connected to a 14G cannula in thedominant hand, with fingers between the flange and the plunger. A 5ml syringeis

preferred because with 10 or 20 ml syringes, the hand is too far from cricothyroidmembrane and with the 3ml syringe the barrel aspiration volume is too small. Filling the5ml syringe with 1-2 ml of saline best demonstrates the endpoint of bubbles when theairway is entered.

3.Insert the needle through the skin at approximately 450caudally.In patients withdeep airway anatomyyou may need to insert to cannula perpendicularly or there may notbe enough cannula length to reach the airway.

4.Aspirate as you advance into the airway. Stop advancing immediately once air isaspirated.Only aspirate on the way inas false flashbacks of air can occur on withdrawingif the cannula and trochar are slightly separated.

5. The endpoint is free aspiration of airup the full barrel of syringe.Aspirate all theway up the barrel.

6. Stabilise the cannula hub with the non dominant hand and then release the plunger ofthe syringe held by your dominant hand. If tip of the cannula is incorrectly placed, you willsee the plunger being sucked back into the syringe barrel by the vacuum created byaspirating outside of the airway. NO VACUUM INDICATES CORRECT PLACEMENT.

7.Place the dominant hand underneath the syringe, holding the needle in a pencil gripwith the hand resting against the chin or neck to immobilise the cannula.

8.Advance the cannula over the needle into trachea with non dominant hand andremove trochar. It should advance as easily as an IV. Do not remove the needlebefore you advance the cannula otherwise the cannula will kink.

9. HOLD THE CANNULA SECURE.

10. Using a syringe with saline, repeat the full free aspiration of air from cannula. Thelack of recoil of plunger confirms airway placement.If the initial aspiration fails then theslight withdrawal of the cannula while aspirating will correct thisas the cannula maybe against posterior tracheal wall. AGAIN, NO VACUUM INDICATES CORRECTPLACEMENT.

11. Attach an appropriate oxygen supply source and begin oxygenation. It is important toconcentrate on oxygenation and not trying to achieve ventilation at this point.

Oxygenation through the cannula can be achieved either via a jet ventilator or via oxygentubing connected to an oxygen flowmeter.


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Oxygenation via a transtracheal cannula

1. Jet oxygenation: via the Sanders injector or Manujet jet ventilator

Safe jet oxygenation is crucial to achieving SSFO via a cannula (or bougie).The jetting devices can deliver wall pressure which is 400 kPa = 4 bar (58 psi). When

jetting through a 14G cannula, this provides flow rates that are sufficient to achieve normaloxygenation and normocarbia (if patent upper airway) for prolonged periods if required. Itis important to start at low pressure around 1 bar and slowly increase. Normally 2.5 bar issufficient.

During jet ventilation, exhalation relies on the elastic recoil of the lungs through a patentupper airway. It is crucial that the patient achieves full expiration before a new jetinspiration is delivered. Stacked jet ventilator breaths in which there is insufficient time forthe expiration can result in bilateral pneumothoraces and cardiovascular collapse.

Attempts should be made to maximise upper airway patency e.g. by use of chin lift and jawthrust, the use of airways or LMAs. Complete upper airway obstruction is considered

a contraindication to jet ventilation.It is also very important that the cannula being used for jet ventilation is correctly placed.Jet ventilating into a cannula incorrectly placed insubcutaneous tissues or a vessel canbe rapidly fatal, hence the importance of aspirating the full barrel of the syringe andensuring no vacuum effect on placement.

With all jets, the operator needs to watch for chest rising and also for chest falling.

A failure of chest risemeans that the cannula position needs to be adjusted. This

usually is due to a kink introduced where the cannula comes out of the skin and can

be rectified by relaxing your hold of the cannula and withdrawing a millimeter at a

time whilst aspirating on syringe, until air flows freely up the syringe barrel again.

A failure of chest fallingmeans that no further jet ventilation should be delivered

to avoid pneumothorax and cardiovascular collapse. Frequency of jet ventilation

may be as low as one per minute, which will still deliver 1000ml of oxygen in that

minute.

Manujet jet

ventilator attachedto a 14 G cannula


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2. High flow oxygen delivery

Numerous systems can provide transtracheal oxygenation by delivering high flow oxygenfrom a high-pressure source (e.g. wall oxygen outlet, oxygen cylinder) through a cannulacricothyroidotomy.These methods may provide oxygenation but they quickly result in hypercarbia and

should not be regarded as a long-term airway solution, but merely as a bridge toestablishing a definitive airway.

We will review 2 such systems:

I. ENK flow modulator

The ENK flow modulator device consists of a short, noncompliant tube with 5 openingslocated at opposite sites in front of a syringe connecter, which is connected between atranstracheal needle or intravenous catheter and an oxygen delivery system flowing at a

rate of at least 15 l/min. It allows manually controlled oxygen flow by performingintermittent occlusion of the openings. Occlusion of all 5 holes is required for effectiveinsufflation. The frequency of opening occlusions should be guided by the patientschest rise & fall as well as by their oxygen saturations.

II. Oxygen tubing connected to a flowmeter9

Many different methods of performing percutaneous transtracheal oxygenation, usingsystems that deliver high flow oxygen and that can be quickly and easily assembled, havebeen described.

One such method is described below:

Equipment required:1. High pressure source of oxygen e.g. hospital piped oxygen, oxygen cylinder

2. Oxygen flow meter that can be attached to the high pressure source

3. A normal length of normal oxygen tubing


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4. A 3 way tap

5. A 14G cannula

Attach the one end of a normal length of oxygen tubing to an oxygen flowmeter and

the other end onto a 3-way tap. This may require some force.

Once the transtracheal cannula has been inserted, the 3-way tap is then attached

to the cannula. All of the 3-way taps should be in the open position.

The oxygen flowmeter is then opened to between 12-15l/min. In children, the

oxygen flow in liters/min is equal to the childs age. If the chest does not rise, then

increase the oxygen flow in increments of 1 L/min.

The tap that is open to air is occluded in inspiration and then un-occluded when

the patient is being allowed to exhale via their patent upper airway. Occluding the

open to air tap for 4 secondsat flow rates of between 12-15l/min through a 14G

cannula should deliver between 800-1000ml of oxygen.

The risk of barotrauma is high in an airway that is fully occluded, as air is

unable to escape. Watch for chest fall.If the chest does not fall, it would be

prudent to turn the oxygen flow off to allow for venting of air from out of the chest

through the open tap. Once chest fall is observed, the oxygen may be turned back

on and the open tap occluded.

The frequency and duration of tap occlusion should be guided by the

patients chest rise & fall as well as by their oxygen saturations.

Another method describes excluding the 3-way-tap from the system completely and

merely opposing the end of the oxygen tubing, with oxygen flow at 15l/min, to thetranstracheal cannula during oxygenation. Un-opposing the oxygen tubing from thecannula would allow for venting of air from within the chest, out, through the cannula.

Again, the frequency of inspiration should be guided by the patients chest rise& fall as well as by their oxygen saturations


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Inserting a surgical airway via the Seldinger technique

Melker Tube Insertion13

The Melker tube kit (Cook) contains all the equipment required to insert acricothyroidotomy or tracheotomy tube via the Seldinger technique. Melker tubes areavailable as either 5mm cuffed tubes or 6mm, 4mm or 3,5mm uncuffed tubes. It isrecommended that you insert a cannula and achieve SSFO, as described above,prior to embarking on the second part of the Seldinger technique i.e. insertingthe wire etc.

1. Pass the cannula through the cricothyroid membrane as for the CannulaCricothyroidotomy Technique described above. Oxygenation should becommenced via jet or oxygen flowmeter.

2. Once the patients saturations have stabilised, insert the wire through the

cannula. Pass a generous length of wire to prevent accidental wire removal. Ifunable to pass the wire, reconfirm cannula position using a syringe with saline.

3. Remove the cannula and HOLD ONTO THE WIRE.

4. Make a 2 cm stab incision caudally with a scalpel. Ensure that the wire is able tomove within the incision with no skin tags to stop the insertion of the Melker tubeand dilator.

5. Pass the Melker tube-dilator device over the wire. Hold the device in thedominant hand making sure that the dilator is fully advanced in the tube .

6. Advance into the airway - moderate to heavy force may be required. If unable toadvance, ensure the dilator is fully advanced in the tubeand considerlengthening the incision. If the wire becomes kinked then readvancecannula over wire, jet oxygenate and then replace with a CVC wire and re-attempt Melker insertion.

7. Remove the wire and introducer, inflate cuff and attach tube to circuit or self-inflating bag.


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Scalpel Bougie Technique13

(Consider when palpableneck airway anatomy present)

According to Heard, the scalpel bougie technique should be considered if there hasbeen failure of cannula cricothyroidotomy and the patients neck anatomy is palpable.

Anecdotally however, many practitioners favour this technique as their preferred

approach to performing a cricothyroidotomy. We will consider the advantages anddisadvantages of this technique:

Advantages:

Quick to perform

A definitive airway can be achieved quickly with the ability to ventilate

Minimum equipment is required

Disadvantages:

Blood!. Potentially lots of blood!!

Making an incision with a scalpel may be an unfamiliar act for non surgically

trained personnel

Psychologically a bigger step than cannula cricothyroidotomy

Possible to create a false track

Difficult to perform another technique if this fails

For this technique all that is needed is a:

Scalpel and blade A bougie (ideally one that will permit insufflation of oxygen if required)

A size 6mm ETT

A method of oxygenating down the bougie if available

1. Identify the cricothyroid membrane and stabilise it with the non-dominant hand.

2. With the scalpel in the dominant hand, make a horizontal stabincision throughthe cricothyroid membrane.

3. Rotate the blade through 900so that the blade points caudallyand then pull thescalpel towards you, thereby creating a triangular hole.

4. Swap hands so that the non-dominant hand holds the blade.

5. With the dominant hand, hold the Cook Frova bougie near the bent tip so that thestraight end is pointing away from you and is parallel to the floor. Insert the tipinto the trachea, using the blade face as a guide to the hole.


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4. Identify the airway structures and hold them with the left hand.

5. Insert a14 G cannula as in the cannula cricothyroidotomy technique, then jetoxygenate and proceed to placing a Melker tube.

Tracheostomy devices (17,18)

Tracheostomy tubes are small rigid, curved tubes that are normally cuffed at their distalend. They are inserted into a tracheostomy stoma such that the distal end lies abovethe carina and the proximal flange lies flush with the skin. They can then be connectedto a breathing circuit or the patient can breathe room air. They are usually gradedaccording to their internal diameter (as for ETTs) and when inflated, the cuff protectsagainst aspiration.

They normally come with an introducer, which fits, into the lumen of the tracheostomytube. The introducer provides a smooth rounded tip to assist with the passage of thetube and is removed once the tube is positioned.

Some tracheostomy tubes have an outer cannula, which is the main tube that sits inthe trachea, and an inner cannula, which is a removable tube that fits inside the outercannula. The inner cannula is regularly removed and cleaned to try and prevent thebuildup of secretions.

A cuffed tracheostomytube with purpleinsertion trochar in situ.The insertion trochar isremoved once thetracheostomy isinserted.

A cuffed tracheostomytube with innercannula removed


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Fenestrated and uncuffed flange tubes

Fenestrated tubes have single or multiple holes on the outer curvature of the tube andare used as a weaning tool and to facilitate speech. As a result of the consequent airleak, they cant be used for positive pressure ventilation. The air leak may be overcome

by placement of a non-fenestrated inner cannula

Uncuffed tubes are similarly inserted for weaning and to facilitate speech and like thefenestrated tubes, are ineffective for positive pressure ventilation.

Above the Cuff Suction Tracheostomy Tubes

Some cuffed tubes can have an additional suction port to remove secretions above thecuff. The additional lumen terminates above the cuff in a rectangular opening, allowing

subglottic drainage. Reports suggest that aspiration of subglottic secretions can preventor delay the onset of ventilator-associated pneumonia. Aspiration of subglotticsecretions is performed intermittently using a syringe attached to the proximal end ofthe suction lumen or continuously using suction pressure of 15-20cmH20

Fenestratedtracheostomytube with innercannula removed

Above the cuff suctiontracheostomy tube.

Note the opening above thecuff


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Tracheostomy tubes are commonly secured with tracheostomy ties, to facilitate promptremoval of the tube in an emergency. They can also be sutured in place.

Sometimes tracheostomy tubes may have one of the following devices attached:

Speaking valvesare one-way valves that allow inspiration through thetracheostomy tube but not expiration. Expiration must therefore occur around the

tube and as a result, air passes through the vocal cords to achieve phonation.

Occlusion capsare weaning devices that stop all airflow through the

tracheostomy. Clearly, to use either of these devices, the cuff must be

deflated.

Heat & moisture exchanges can be connected to the tracheostomy tube to act

as a surrogate nose and assist in humidification. They should not be used if

there are significant secretions as they can easily be occluded.

If there is any concern about any of these devices causing obstruction of thepatients airway, they should be able to be easily removed from the tracheostomytube.

Passy-Muirspeakingvalves


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References

1. Kheterpal et al. Prediction and outcomes of impossible mask ventilation: A

review of 50000 anesthetics.Anesthesiology 2009; 110:8917

2. Heard AMB, Green RJ, Eakins P. The formulation and introduction of a cant

intubate, cant ventilate algorithm into clinical practice. Anaesthesia

2009;64:601-608

3. Campos J. Which device should be considered the best for lung isolation:

double-lumen endotracheal tube versus bronchial blockers. Current Opinion in

Anaesthesiology Feb 2007; volume 20(1),27-31

4. Greenland KB, Edwards MJ, Hutton NJ, Challis VJ, Irwin MG, Sleigh JW.

Changes in airway configuration with different head and neck positions using

magnetic resonance imaging of normal airways: a new concept with possible

clinical applications Br. J. Anaesth. (2010) 105(5): 683-690

5. McGee JP,Vender JS. Nonintubation management of the airway: mask

ventilation. Benumofs Airway Management, Hagberg CA, pg 345-370, Mosby

2007

6. Kovacs G, Law JA. Airway management in emergencies McGraw Hill 2008

7. Calder I, Yentis SM. Could safe practice be compromising safe practice? Should

anaesthetists have to demonstrate that face mask ventilation is possible before

giving a neuromuscular blocker? Anaesthesia 2008;63:113-115

8. Henderson JJ. The use of paraglossal straight blade laryngoscopy in difficult

tracheal intubation. Anaesthesia. 1997;52:552-60.

9. Ryder IG, Paoloni CC, Harley CC. Emergency transtracheal ventilation:assessment of breathing systems chosen by anaesthetists. Anaesthesia 1996;

51: 7648.

10. Bould MD, Bearfield P.Anaesthesia. 2008 May;63(5) Techniques for emergency

ventilationthrough a needle cricothyroidotomy.:535-9.

11. Ferson DZ,Rosenblatt WH, Johansen MJ, Osborn I, Ovassapian A. Use of the

intubating LMA-Fastrach in 254 patients with difficult-to-manage airways.

Anesthesiology 2001; 95:1175-1181

12. Henderson JJ. The use of paraglossal straight blade laryngoscopy in difficult

tracheal intubation. Anaesthesia 1997;52:552-56013. Heard AMB, Green RJ, Eakins P. The formulation and introduction of a cant

intubate, cant ventilate algorithm into clinical practice. Anaesthesia

2009;64:601-608

14. Devit JH et al The LMA and PPV, Anesthesiology 1994;80:550-555


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15. Mihai R,Blair E, Kay H, Cook TM. A quantitative review and meat-analysis ofperformance of non-standard laryngoscopes and rigid fibreoptic intubation aids.

Anaesthesia 2008;63:745-76016. Frerk CM, Lee G. Laryngoscopy: Time to change our view. Anaesthesia

2009;64:351-35417. Cameron T ed. Tracheostomy Care Resources: A Guide to the Creation of Site

Specific Tracheostomy Procedures and Education. Austin Health 200618. Russell C, Matta B eds. Tracheostomy, a multiprofessional handbook.Greenwich medical 2004

19. Barker KF, Bolton P, Cole S, Coe PA. Ease of laryngeal passage duringfibreoptic intubation: a comparison of three endotracheal tubes.Acta

Anaesthesiol Scand2001; 45: 6246


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Equipment Reference Sheet

Endotracheal tubes

All endotracheal tubes (except DLT): size is of the internal diameter in mm

Double Lumen Tubes (DLT): size is of the external diameterin French gauge (Fr).1Fr = 0.33mm

Sizes of the internal lumens of DLT(as a guide to fibrescope/bougie use)3:

Size 35Fr = 4.3 - 4.5mm internal diameter (tracheal>bronchial)

Size 37Fr = 4.5 - 4.7mm internal diameter (tracheal>bronchial)

Size 39Fr = 4.9mm internal diameter

Size 41Fr = 5.4mm internal diameter

Arndt endobronchial blockers:

7Fr blocker needs >= size 7.5 ETT using a 4mm scope

9Fr blocker needs >= size 8 ETT using a 4mm scope

Laryngeal Masks

cLMA sizes:

Size 3 able to accommodate a size 5.5 ETT easily or 6 with difficulty

Size 4 able to accommodate a size 5.5 ETT easily or 6 with difficulty

Size 5 able to accommodate a size 7 ETT

ILMA sizes

Sizes 3,4,5 all able to accommodate up to size 8 ILMA ETT

Fibrescopes

Fibrescope sizes: Sizes based on the external diameter of the scope

4mm scope suitable for placing DLT and intubating through a LMA

5.2mm scope invariably requires a 7.5mm ETT for successful intubation

Bougies/intubating catheters

Sizes based on external diameter

Cook Frova bougie: a blue 65cm long bougie with 4.7mm external diameter.Suitable for ETT sizes 5.5+


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Eschmanngum elastic bougie (adult): a beige colored bougie. Standardlength is 60cm with a15Fr (5mm) external diameter. Suitable for ETT sizes 6-11. Not suitable for DLT insertion

Eschmann gum elastic bougie (paed): a paediatric bougie is also available.70cm long, 10Fr (3.3mm) external diameter and is suitable for DLT insertion

Cook exchange catheters: 83 - 100cm long, common adult size has 19Fr

(6.3mm) external diameter: suitable for size 7+ ETTs.For exchange of a DLT, smaller sizes are required:11F (3.7mm) external diameter: appropriate for DLT size 35 & 37Fr14F (4.7mm) external diameter: appropriate for DLT size 39 & 41Fr

Aintree Intubating catheter:56cm long, internal diameter of 4.8mm and anexternal diameter of 6.5mm. Suitable with size 7+ ETTs.Fits onto a 4mm scope

All of the above are suitable for oxygenation through a central lumen via a rapi-fitconnector.


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MODULE 2

Fibreoptic Intubation


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Introduction to the fibreoptic endoscope

A fibreoptic endoscope is a hand-held device consisting of tiny glass fibres, arranged inbundles, to carry light source illumination to the distal end of the scope and reflect li

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