The Difficult Airway

The clinical scenario when safe oxygenation and ventilation cannot be achieved in the desired way with the use of an individual’s usual practice

Difficult Intubation

Difficult Mask Ventilation

Difficult Intubation

Difficult Mask Ventilation

Difficult Supraglottic Airway

1:50Intubation

1:25Supraglottic

1:20MaskDifficult

Incidence in general population

1:20001:50Intubation

1:3001:25Supraglottic

1:6001:20MaskFailedDifficult

Incidence in general population

1:2000

1:50

1:50

1:6

Intubation

Pre-Hospital

1:3001:25Supraglottic

1:6001:20MaskFailedDifficult

Incidence in general population

Timmermann et al., 2006 Resuscitation 70:179-85 (1106 patients)

Trauma patients had highest incidence of difficult and failed

intubation

Difficult Mask Ventilation(DMV)

Degrees of Difficulty

1 Single person BVM with chin lift+/-jaw thrust

2 Above + OP or NP airway or both

3 Above plus assistant to squeeze bag or provide jaw thrust/face mask seal

4 Anaesthetist plus 2 assistants; one to squeeze bag and other to provide jaw thrust/face mask seal

Obese (BMI>26)BeardedElderly (>55)SnorersEndentulous

Male‘n’eckMallampati (grade 3 or 4)

Difficult Supraglottic Airway

Inability to open mouth more than 2.5cm(impossible if <2.0cm)

Intraoral/pharyngeal masses

Difficult Intubation

Look externally

Evaluate 3-3-2

Mallampati

Obstruction

Neck mobility

Look externally - trauma, limited mouth opening

Look externally

Evaluate 3-3-2 3 fingers between the teeth

3 fingers between the tip of the jaw and start of neck

2 fingers between the thyroid notchand floor of mandible

Look externally

Evaluate 3-3-2

Mallampati assessmentClass 1 - soft palate, fauces, uvula, & both anterior and

posterior pillars Class 2 - soft palate, fauces, and uvula Class 3 - soft palate and the base of the uvula Class 4 - soft palate is not visible

1 2

3 4

Look externally

Evaluate 3-3-2

Mallampati assessment

Obstruction - epiglottitis, peritonsillar abscess, trauma

Look externally

Evaluate 3-3-2

Mallampati assessment

Obstruction

Neck mobility - limited movement, cervical collar

Is LEMON useful?

Look externally Large incisors

Evaluate 3-3-2 Reduced mouth opening & reduced thyroid to floor of mouth distance

Mallampati assessmentObstruction Neck mobility

114 grade 1 29 grade 211 grade 3 2 grade 4

Reed et al., 2005 EMJ 22:99-102

2509 patientsUpper front teethPrevious Hx of difficult intubationMallampati >1Mouth opening <4cm

Diff intub (%) 0 2 4 8 17Risk factors 0 1 2 3 4

Eberhart et al., EJA March 2010

But does it all really matter?

When do we intubate?

Are all of our intubations ‘difficult’?

Blood/vomitus in airway

Limited mouth opening

Facial/neck trauma

C-Spine precautions

Preoxygenation

Preoxygenation with Non-Invasive Ventilation in critically ill patients is better than BVM preoxygenation

Baillard et al., 2006 Am J Respir Crit Care Med 174:171-7

Baillard et al., 2006 Am J Respir Crit Care Med 174:171-7

NIV - pressure support to obtain an expired tidal volume of 7–10 ml/kg with a PEEP of 5 cm H2O for 3 minutes

Control – BVM with 15 L/min oxygen. Patients were allowed to breath spontaneously with occasional assistance

Preoxygenation of morbidly obese patients at 25° head up is better

than supine

Dixon et al., 2005 Anesthesiology 102:1110-5

Time to reach an SpO2 of 92% in morbidly obese patients

Head up 25° = 201 ± 56 s

Supine = 155 ± 70 s (p=0.02)

Dixon et al., 2005 Anesthesiology 102:1110-5

Better gas exchange by

reducing atelectasis

reducing V/Q mismatch

less reduced FRC

Dixon et al., 2005 Anesthesiology 102:1110-5

You have a look and can’t see anything

30 second drills Change operator position Change patient position (small pad under head with

neck in neutral position) Release cricoid and use bi-manual laryngoscopy Use better suction where secretions or blood block

view Laryngoscope can be inserted deeply and slowly

withdrawn until identifiable anatomy is seen Consider changing laryngoscope blade size or type Consider changing operator

Six variables to correct

Experienced practitioner No significant muscle tone Optimal position Blade length Blade type Use of laryngeal manipulation

Benumof 1994 Canadian Journal of Anaesthesia 41:361-5

Posture

The novices tended to crouch, head closer to the mouth, elbow more flexed and forearm further from the horizontal.

Matthews et al., 1998 Anaesthesia 53:331-4

The novices tended to crouch, head closer to the mouth, elbow more flexed and forearm further from the horizontal.

The trained subjects tended to stand back, elbow less flexed and forearm close to or even below the horizontal.

Matthews et al., 1998 Anaesthesia 53:331-4

The more experienced group levered less,with signifcantly lower laryngoscope handle angles (C)

Eye-to- laryngoscope distances (D) were greater in the more experienced group

Walker 2002 Br J Anaesth 89:772-4

Tesler et al., 2003 Resuscitation 56:83-9

Tesler et al., 2003 Resuscitation 56:83-9

Tesler et al., 2003 Resuscitation 56:83-9

Robinson et al., 2004 Air Med Journal 23:40-3

Position

Brodsky et al., 2003 Anesthesia and Analgesia 96:1841-2

Manual In-Line Stabilisation

MILS Does not limit cervical movement with

jaw thrust and laryngoscopy Worsens laryngeal view which prolongs

intubation attempt1

Increases pressures applied by the laryngoscope blade during laryngoscopy2

1 Thiboutot et al., 2009 Can J Anaesth 56:412-82 Santoni et al., 2009 Anesthesiology 110:6-7

It is prudent for clinicians to use manual in-line stabilization

when it does not hinder intubation attempts

Manoach and Paladino 2007 Ann Emerg Medicine 50:236-45

Cricoid Pressure

An Essay on the Recovery of the Apparently Drowned

"the restoring of the action of the lungs to be of the very first importance in all our attempts to recover the apparently dead." In addition, a description of pressure on the front of the neck as follows to "prevent the air passing into the stomach instead of entering the lungs."

Royal Humane Society, London: Silver Medal Winner (1788) Charles Kite of Gravesend

Sellick 1961 The Lancet 278 7199:404-6

Cricoid Pressure

Fails to prevent aspiration Reduces lower oesophageal sphincter pressure May prevent gastric insufflation during mask

ventilation Makes ventilation more difficult Causes lateral displacement and/or incomplete

obstruction of oesophagus Makes LMA insertion and ventilation more difficult May worsen laryngeal view May cause significant movements of cervical spine Is often applied incorrectly

Ellis et al., 2007 Annals Emerg Med 50:653-5

Cricoid pressure entered medical practice on a limited evidence base but with common sense supporting its use.

Ellis et al., 2007 Annals Emerg Med 50:653-5

Given that the risks of cricoid pressure worsening laryngeal view and reducing airway patency have been well described, we recommend that the removal of cricoid pressure be an immediate consideration if there is any difficulty either intubating or ventilating the ED patient.

Ellis et al., 2007 Annals Emerg Med 50:653-5

Given that the risks of cricoid pressure worsening laryngeal view and reducing airway patency have been well described, we recommend that the removal of cricoid pressure be an immediate consideration if there is any difficulty either intubating or ventilating the ED patient.

BURP?

Anaes Analgesia 1997:84:419-21

OELM or Bimanual Laryngoscopy

Percentage ofcases withimproved view

Cricoid 52%

BURP 54%

Bimanual 89%

Annals Emerg Med 2006:47;548-55

Prospective observational study Effects of cricoid pressure and laryngeal manipulation on laryngeal view in London HEMS

402 patients 98.8% patients intubated on the first or second attempt. In 61 intubations the larynx required manipulation.

Cricoid pressure removed in 22 - view improved in 50%.Bimanual manipulation used in 25 – view improved in 60%. BURP used in 14 - view improved in 64%.

Two patients regurgitated when cricoid pressure was released.

Harris et al., Resuscitation epub 2010

Cook 2000 Anaesthesia 55:274-9

Cook 2000 Anaesthesia 55:274-9

Bougie

Fibreoptic

Levitan et al., 1998 Acad Emerg Med 5:919-23

Bougie or stylet?

The gum elastic bougie is superior to the stylet for a simulated difficult intubation

Gataure et al, Anaesthesia 1996 51:935-8

Gataure et al, Anaesthesia 1996 51:935-8

Stylet - intubation was difficult and needed more time, especially when glottic opening was not

visible

Bougie - duration and ease of intubation was not influenced by

laryngeal view Noguchi et al., 2003 Can J Anaesth 50:712-7

When is a bougie not a bougie?

When it’s a tracheal tube introducer

BMJ 1949; 1:28

How do I know the bougie is in the trachea?

Clicks

Distal hold-up

Coughing

ClicksTip of bougie touches the tracheal

cartilages

Distal hold-upTip is touching the carina (approx 40cm)

CoughingMuscle relaxation is incomplete

Clicks – 90%

Distal hold-up – 100%

Kidd et al., 1988 Anaesthesia 43:437-8

Hodzovic et al., Anaesthesia 2004 59:811-6

Hodzovic et al., Anaesthesia 2004 59:811-6

Pre-hospital use of bougie

1442 pre-hospital intubations over 30 months

41 patients (3%) required a bougie

Bougie successful in 33 cases (78%)

8 patients required a second technique

Jabre et al., 2005 Am J Emerg Med 23:552-5

Laryngoscope Blades

Best results for intubation were obtained with the Macintosh and

the McCoy

A good laryngeal view does not equate with ease of intubation

Arino et al., 2003 Can J Anaesth 50:501-6

Size 4 English Macintosh performed the best at all insertion

depths

Yardeni et al., 2002 Acta Anaes Scand 46:1003-9

Other tricks

Left Molar Approach

Yamamoto et al., 2000 Anesthesiology 92:70-4

The left molar approach reduces the distance from the patient's teeth to larynx

and prevents intrusion of maxillary structures into the line of view.

Although it may offer advantages in terms of laryngoscopic view, there can be

difficulty in the insertion of the tracheal tube.

Cuvas et al., 2009 J Anesth 23:36-40

Failed intubation

3-4 attempts with some of the manoeuvres described

Declare a failed intubation Maintain cricoid Insert oral airway and ventilate with 100% O2 If ventilation difficult, try LMA; if still no ventilation,

and if laryngospasm excluded use crico-thyroid puncture

insanity (n) [in-san-i-tee] : doing the same thing over and

over again and expecting different results

Albert Einstein, (attributed) US (German-born) physicist (1879 - 1955)

LMA and Cricoid Pressure

The LMA is indicated in the known or difficult airway situation

The clinical record of the LMA in the CICV situation is excellent

Prehospital use of the ProSeal LMA

Successful use in 3 cases of failed intubation

PolytraumaBurns

Maxillofacial Trauma

Grier at al., 2009 Resuscitation 80:138-41

Insertion technique

Bougie inserted under direct vision into oesophagus

ProSeal railroaded over bougie

Howarth et al., 2002 Anaes Int Care 30:624-7

Intubating LMA (Fastrach) also been used successfully in

prehospital difficult-to-manage airways

Timmermann 2007 BJA 99:286-91

Pre-hospital resuscitation using the iGEL.

Thomas M, Benger J.

Resuscitation. 2009 80(12) 1437

Rapid sequence airway (RSA) with a LMA Supreme is quicker to

‘secure’ the airway (with less hypoxia) compared to a RSI in a simulated difficult trauma airway.

Southard et al., 2010 Resuscitation 81(5) 576-8

Confirmation of correct tube placement

Direct visualisation Auscultation for breath sounds Chest movement Feel of reservoir bag

CO2 detectors

Oesophageal detectors: withdraw air freely from trachea but the oesophagus will collapse

False negative

Equipment failure Disconnection Kinked gas sampling tube Kinked tracheal tube Severe airway obstruction Poor pulmonary perfusion

False positive

Tube in oesophagus after exhaled gases forced into stomach

Tube in oesophagus after fizzy drinks

Distal end of tube in pharynx

Gadgets

Video Laryngoscopes(VLEs)

Van Zundert et al., 2009 Anesthesia and Analgesia109: 825-31

Van Zundert et al., 2009 Anesthesia and Analgesia109: 825-31

Van Zundert et al., 2009 Anesthesia and Analgesia109: 825-31

Although VLSs offer several advantages........a good laryngeal view does not guarantee easy or successful tracheal tube insertion.

We recommend that the geometry of VLSs, including blade design, should be studied in more detail.

Van Zundert et al., 2009 Anesthesia and Analgesia109: 825-31

Indirect Laryngoscopes with tracheal tube conduit

Airtraq2006 – 4

2007 – 192008 – 182009 – 22

2010 – 20+

Airway Scope2006 – 1

2007 – 202008 – 222009 – 18

2010 – 13+

54 paramedics used each device (Macintosh laryngoscope, Airtraq and Airway Scope) in a random

order on three manikins

standard airway - no manipulation of the manikin’s airway

difficult airway - set to simulate grade 3 laryngoscopy view

sitting manikin - no manipulation of the airway

In the difficult airway manikin.....

Tracheal intubation with the AWS was more successful and faster than the Airtraq

and Macintosh laryngoscopes

Dogma is the established belief or doctrine held by a religion, ideology or any kind of organization: it is authoritative and not to be disputed, doubted or diverged from