Thursday Cme Presentation
Transcript of Thursday Cme Presentation
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ANG CHIA MIN
Laryngoscopy and TrachealIntubation in the Head-
Elevated Position in ObesePatients: A Randomized,Controlled, Equivalence Trial
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2008; 107:1912-1918
Laryngoscopy and Tracheal Intubation in theHead-Elevated Position in Obese Patients: A
Randomized, Controlled, Equivalence Trial
Srikantha L. Rao, MBBS, MS*, Allen R. Kunselman,
MA, H. Gregg Schuler, MS, CCRC, and Susan
DesHarnais, PhDFrom the *Department of Anesthesiology, Office of the Vice
Dean for Research and Graduate Studies, andDepartment of Public Health Sciences, PennsylvaniaState University, College of Medicine, M.S. Hershey
Medical Center, Pennsylvania.
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INTRODUCTION
Excellent intubating conditions are imperative fordirect laryngoscopy and the efficient placementof a tracheal tube.
The proper positioning of a patient beforeinduction is a key step.
Classic teaching has been to position the patientin the "sniffing" position, or supine with moderate
head elevation and atlanto-occipital extension.
Bannister FB, Macbeth RG. Direct laryngoscopy and tracheal intubation. Lancet1944;244, 6325:6514
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OBESE vs NORMAL WT PT
some studies have reported that trachealintubation is more difficult in obese as comparedto normal weight patientsLinksJuvin P, Lavaut E, Dupont H, Lefevre P, Demetriou M, Dumoulin JL, Desmonts JM. Difficulttracheal intubation is more common in obese than in lean patients. Anesth Analg 2003;97:595600
Shiga T, Wajima Z, Inoue T, Sakamoto A. Predicting difficult intubation in apparently normalpatients: a meta-analysis of bedside screening test performance. Anesthesiology 2005; 103:42937
Other studies have reported no differencebetween the two groups, attributed it to a rampedposition with the patient's head clearly elevated
above their shoulders to improve laryngealexposure in obese patients.
Levitan RM, Ochroch AE. Airway management and direct laryngoscopy: a review and update. CritCare Clin North Am 2000;16:37388
Brodsky JB, Lemmens HJ, Brock-Utne JG, Vierra M, Saidman LJ. Morbid obesity and trachealintubation. Anesth Analg 2002; 94:7326
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Head up vs supine sniff position
In a randomized study with a crossover design of 40 non-obese patients, significantly improved laryngeal view was
demonstrated by performing laryngoscopy in the 25-
degree head-up position compared to the supine position
in the same patients.Lee BJ, Kang JM, Kim DO. Laryngeal exposure during laryngoscopy is better in the 25
degrees back-up position than in the supine position. Br J Anaesth 2007;99:5816
In a study of 60 obese patients undergoing bariatric
surgery, the ramped position improved laryngeal viewwhen compared to a standard sniff position. Collins JS, Lemmens HJ, Brodsky JB, Brock-Utne JG, Levitan RM. Laryngoscopy and morbid
obesity: a comparison of the "sniff' and "ramped" positions. Obes Surg 2004;14:15
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Head up vs supine sniff position Optimal positioning during face-mask ventilation and intubation is
vital. A study conducted by Collins et al demonstrated that placingmorbidly obese patients (BMI of more than 40) in a ramped position
gives a better laryngeal view than the standard sniff position.
Collins JS, Lemmens HJ, Brodsky JB, Brock-Utne JG, Levitan RM. Laryngoscopy and
morbid obesity: a comparison of the sniff and ramped position. Obes Surg.
2004;14:11715.
The ramped position is achieved by elevating the upper body and
head with the sternum and ear aligned in a horizontal line.
Similarly, elevating the head to 25 was shown to improve
oxygenation by 25%, as compared with supine positioning, in obese
patients (BMI of more than 40).
Dixon BJ, Dixon JB, Carden JR, et al. Preoxygenation is more effective in the 25
degrees head-up position than in the supine position in severely obese patients.
Anesthesiology. 2005;102:1110-5.
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Head-Elevated
Laryngoscopy Position"
(HELP)
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Head up position in Obese pt
Due to the change in lung and chest wallcompliance, obese patients tend to desaturatequickly and may be better served if they are placedin the head-elevated position.
In obese patients, administration of oxygen in the25-degree head-up position allows a greater safetymargin for induction of anesthesia than the supine
position by achieving 23% higher ox
ygen tensions.Dixon BJ, Dixon JB, Carden JR, Burn AJ, Schachter LM, Playfair JM, Laurie
CP, O'Brien PE. Preoxygenation is more effective in the 25 degrees head-upposition than in the supine position in severely obese patients: a randomizedcontrolled study. Anesthesiology 2005;102:11105
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Head up position in Obese pt
the routine practice during patient positioning before inductionis to use folded blankets, stacked under the patient's upperbody, neck, and head to elevate the head.
However, the number of blankets used differs among patients,and obtaining the optimum position in each patient is tedious,as it requires adding or removing blankets while repositioningthe patient each time (trial and error method).
Use of other devices
including a commercially
available foam pillow(Troop Elevation Pillow,
Mercury Medical,
Clearwater, FL)
to achieve this position
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Blanket method
folded blankets arestacked under thepatient's upper body,neck, and head toelevate the head.
to achieve a head-elevated position, the
patient's externalauditory meatus and
sternal notch were inthe same horizontalplane.
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OR table-ramp method
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This head-up position also can be achieved by a simple
maneuver of configuring the operating room (OR) table,similar to a reclining chair with the back or trunk portion of
the table up. With the patient lying on the OR table, the
electronic table controls can be used to flex the table at the
trunk-thigh hinge and raise the "back" or "trunk" section of
the table up as necessary to achieve the optimum position.
This can be done with or without the head-piece at the head
end of the table.
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Whelen-Collicott position
in this modified position,a roll or pad can beplaced under the head to
achieve neck flexion, butthe head of the bed iselevated (reverseTrendelenburg position)to achieve optimal
positioning withouthaving to placeadditional pads underthe patient's shoulders.
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OBJECTIVE
This prospective, randomized study was
designed to determine if the table-ramp
method of patient positioning wasequivalent to the blanket method with
regard to the time required for tracheal
intubation.
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METHODS
conducted in the OR of a university teaching hospital with ananesthesia residency program.
Written informed consent was obtained from 85 patientsbetween March 2007 and August 2007.
All 85 patients were
- ASA class I or II,
- age 2165 yr,
- undergoing elective surgeryunder general anesthesia.
- 64 underwent bariatric surgery (openor
laparoscopic gastric bypass, or gastric banding),
the remainder 21 underwent orthopedic, urologic,
or gynecologic surgery.
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PILOT STUDY
pilot study of 11 subjects undergoing
bariatric surgery using the current method
of patient positioning using blankets.
Pilot study were used to obtain an
estimate of the variability in the time
required to secure the airway for use in
power and sample size estimation for this
study.
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METHODS
only patients with a BMI >30 kg/m2 were approached tobe enrolled in the study
Patients with a history of difficult intubation were notenrolled.
Data collections:
obstructive sleep apnea
Age and gender
visibility of oropharyngeal structures was assessedusing the Mallampati Classification Method
Neck circumference (cm) at the level of the thyroidcartilage,
width of mouth opening (inter-incisor distance) (cm),
thyromental distance (cm)
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METHODS
2 mg of midazolam was administered IV to all
patients before transport to the OR.
Patients were then randomized using permuted
blocks randomization scheme of size 6 (known only
to the biostatistician during the study)
with subjects equally allocated to be positioned using
either the
1) blanket method or
2) OR table-ramp method.
The trial was designed to be stopped if there were
more than eight intubation failures (defined as more
than three attempts at laryngoscopy and intubation)
in the 85 study patients
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Blanket method
In the OR, patients in the blanket group lay on aramp made by layering multiple folded blankets on a
flat OR table.
Blankets were then added or removed to ensure that
the patient's head was above the shoulders and the
external auditory meatus and sternal notch were in
the same horizontal plane
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OR table-ramp method
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OR table-ramp method
Patients in the table-ramp group were placed on the flatOR table with a hospital pillow under their heads toelevate their occiput, and the OR table was thenreconfigured to the position of a reclining chair.
With the patient lying on the OR table, the electronic
table controls were used to flex the table at the trunk-thigh hinge and raise the "back" or "trunk" section of thetable up as necessary to achieve the optimum positionofaligning the external auditory meatus to the sternalnotch.
This was done with the head-piece at the head end ofthe table in tall patients and without the head-piece inother patients.
The foot portion of the table was lowered by flexing theleg-thigh hinge so that the knees were slightly flexed to
avoid stretching the sciatic nerve
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OR table-ramp method the head piece of the table can be
moved independently to elevate thepatient's head if necessary to improve
glottic visualization
During bariatricsurgery, the patients
were positioned on the OR table atinduction in such a manner that they
could be placed in low lithotomy
position during surgery without moving
them.
if further flexion was required, one would have had to actively elevate the
patient's head manually.
This maneuver was not required in any of the study patients.
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METHODS
All pts were positioned by the same anesthesiologist. Using routine monitoring, anesthesia was induced using
100 g of fentanyl IV and
22.5 mg/kg (ideal body weight) propofol IV to achievehypnosis (loss of eyelash reflex).
Muscle relaxation was achieved with
1.01.5 mg/kg of succinylcholine or
0.61.0 mg/kg of rocuronium (lean body mass). Thechoice of muscle relaxant was at the discretion of theattending anesthesiologist in the room.
Manual bag-mask ventilation was attempted beforelaryngoscopy. An oral airway was inserted if the airwaywas obstructed.
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METHODS After loss of visible twitches using the single1 Hz stimulation at
the ulnar nerve, laryngoscopy was performed using a Macintosh
blade size 3.
The first laryngoscopy and attempt at tracheal intubation were
performed by the anesthesia resident or certified registerednurse anesthetist (CRNA) caring for the patient that day.
Second and subsequent laryngoscopies using a Macintosh 4 or
Miller 2 blade were performed by the attending anesthesiologist
taking care of the patient.
Each patient's trachea was intubated under direct vision using
an endotracheal tube (8.0 mm ID for men; 7.5 mm ID for
women).
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METHODS
The best view obtained during laryngoscopy was graded by the
Lehane-Cormack classification
The number of attempts at laryngoscopyand tracheal intubation were
noted separately.
The time intervalbetween the loss of consciousness (loss of eyelash
reflex) anddetection of CO2 on the end-tidal CO2 monitor after the
successful placement of the tracheal tube was noted as the time to
secure the airway.
Although the anesthesia resident or CRNA and the attending
anesthesiologist administering the anesthetic could not be blinded to
the method used to position the patient, theywere not aware of the
data points with regard to the outcome variables.
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after three failed attempts at laryngoscopy and
intubation, the patient would be managed at the
discretion of the attending anesthesiologist using the
anesthesia department's difficult airway practice
guidelines.
A "call for help" would be generated and the
attending anesthesiologist would be free to choose
the next modality or airway device at their discretion.
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Statistical Analysis
Equivalence trial: the time to tracheal intubation in obesepatients would be equivalent between the blanket and table-ramp groups
Pilot study: mean time and estimate of variability in the time tosecure the airway was obtained (mean time = 160 s, sd = 81 s)for use in power and sample size estimation for this study.
Equivalence bounds for time to intubation was defined as
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RESULTS
No difference in demographics between the groups.
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RESULTS
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RESULTS
The mean intubation time was175 (66) s in the blanket groupand
163 (71) s in the table-ramp group.
40 of 43 in the blanket group(93.0%)and
39 of 42 (92.8%) patients in thetable-ramp group underwentsuccessful tracheal intubation on thefirst attempt.
the 95% confidence interval forobserved difference in this studyfalls within the range of equivalence,therefore, the two methods areequivalent.
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RESULTS
There was no difference in the number of
attempts at laryngoscopy (P= 0.21) and
tracheal intubation (P
= 0.76) required tosecure the airway between the two
groups.
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DISCUSSIONS
the optimal position should be achieved beforeintubation, regardless of the means to achieve this
position.
It may indeed be easier, for both the patient and theanesthesiologist, to achieve the ideal position by
maneuvering the OR table, rather than inserting
wedges and blankets under the patient's torso.
The head-elevated laryngoscopic position could be
useful in delaying arterial desaturation as it would
allow better conditions for both spontaneous and
mask ventilation in an obese patient.
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DISCUSSIONS
The same head-elevated position can be used aftersurgery while weaning the patient off the ventilatorduring the extubation process. This is done moreeasily using the electronic controls of the OR table torecreate a table ramp during emergence instead of
reinserting blankets under the patient.
injury to OR personnel may occur when an attempt ismade to lift or move patients so that the blankets canbe removed from under the patients after tracheal
intubation.
Use of the electronic controls of the OR table toposition patients avoids these problems.
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DISCUSSIONS
As the proportion of obese patients has been
steadily increasing, the method of positioning
such patients becomes increasingly
important.
in obese patients, the head-elevated position
achieved by the simple maneuver of
elevating the back section of the OR tableshould be used, providing a greater margin
for safety, especially with trainees.
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DISCUSSIONS
Methods to secure airway in Obese patients:
Awake fibreoptic intubation
Various Laryngeal mask airways (LMAs)
LMA-fastrach LMA Ctrach
Glidescope
AirtraqTM laryngoscope etc
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DISCUSSIONS
The elevation pillow
used to achieve Head-Elevated LaryngoscopyPosition (HELP)
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HELP - Elevation pillow
Morbidly obese patient inrecumbent position withstandard intubation pillow only.This position creates
misalignment of the laryngeal,pharyngeal, and oral axis of theairway in the morbidly obese andlarge framed patients.
Morbidly obese patient properlypositioned for laryngoscopy usingstandard intubation pillow inconjunction with elevation pillow.Elevation of the shoulders and
upper back facilitates alignment ofthe laryngeal, pharyngeal and oralaxis of the airway in morbidlyobese and large framed patients.
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LMA-FASTRACH/ WHISTLE TECHNIQUE
The intubating laryngeal
mask airway (ILMA) is alsoknown as the LMA-Fastrach
The ILMA is inserted orally
to a depth where it restsupon the supraglotticlaryngeal structures of theupper airway.
A seal is produced whenthe mask is inflated,allowing the patient toeither breathespontaneously or beventilated manually via the
ILMA tube.
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LMA-FASTRACH TECHNIQUE
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LMA CTrach
LMA CTrachTM (CT), a modified version ofthe intubating LMA FastrachTM, allowscontinuous video-endoscopy of thetracheal intubation procedure.
British Journal of Anaesthesia 200697(5):742-745
Tracheal intubation of morbidlyobese patients: LMA CTrachTM vsdirect laryngoscopy
This study demonstrated that CT wasan efficient airway device for ventilationand tracheal intubation in case of adifficult airway in morbidly obesepatients.
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AirtraqTM laryngoscopes
British Journal of Anaesthesia 2008 100(2):263-268
Tracheal intubation of morbidly obese patients: a randomizedtrial comparing performance of Macintosh and AirtraqTM
laryngoscopes S. K. Ndoko*, R. Amathieu, L. Tual, C. Polliand, W. Kamoun, L. El Housseini, G. Champault and G. Dhonneur
Anaesthesia and Intensive Care Department and Visceral and Obesity Surgery Department,
Jean Verdier Public University Hospital of Paris (APHP), 93143 Bondy, France.
Paris 13 School of Medicine, 93000 Bobigny, France
the AirtraqTM laryngoscope shortened the duration oftracheal intubation and prevented reductions in arterialoxygen saturation in morbidly obese patients.
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AirtraqTM laryngoscopes
In this study, the AirtraqTM laryngoscope shortened the durationof tracheal
intubationand prevented reductions in arterialoxygen saturation in morbidly
obesepatients.
An operator intubating a manikinwith the AirtraqTM.
The operator slides the
endotracheal tube along the
channel along the AirtraqTM.
The tube is then removed fromthe Airtraq from the side
opening channel.
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Videolaryngoscope
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DISCUSSIONS
Equivalence Trials
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DISCUSSIONS
Equivalence Trials: Introduction The aim of an equivalence trial is to show the therapeutic
equivalence of two treatments
Problems:
Often include too few patients
Have intrinsic design biases which tend towards theconclusion of no difference
The application of hypothesis testing in analysing andinterpreting data from such trials sometimes lead toinappropiate conclusions
Inclusion and exclusion of patients from analysis may be
poorly managed
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DISCUSSIONS
Equivalence Trials:
failure to detect a difference does not imply equivalence.
A confidence interval defines a range for the possible truedifference between treatments, any point of which is compatible
with the observed data.
If every point within this range corresponds to a difference of no
clinical importance then the treatments may be considered tobe equivalent.
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DISCUSSIONS
Equivalence Trials:
a range of equivalence is predefined as the interval from -to +.
If the confidence interval centered on the observed difference lies entirely
between and +, equivalence is demonstrated.
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CONCLUSIONS
proper positioning before laryngoscopy and tracheal intubation
is important.
head-elevated laryngoscopic position(HELP) achieved by using
blankets under a patient's head and shoulders or by configuringthe OR table into a back-up position are equivalent with regard
to the quality of laryngeal exposure and time required to
achieve tracheal intubation.
This study propose that positioning patients in the head-elevated position by elevating the back or trunk section of the
OR table can be considered by clinicians as part of their
preformulated strategy in their daily clinical practice in
managing the airways of obese patients.
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THANK YOU
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1. Start with the patient on the back, in the middle of the bed and in goodalignment. The patient's hips should be at the place where the bend bends whenthe bed head is rolled up. Place the head of the bed at 30 for semi-Fowler's, 45to 60 for Fowler's, and 90 for high Fowler's.
2. Place one or two pillows behind the patient's head to extend four to fiveinches below the patient's shoulders.
3. Flex elbows and place a pillow under each arm to prevent pull on theshoulders.
4. Place a pillow under each leg to extend from above the knee and to the ankle,to prevent pressure on heels.
5 Place footboard or folded pillow to keep feet in position if necessary