Rural Health at the University

1

The Difficult Airway What to do when _at_ hits
the fan!!
Adam Davidson Grand Rounds March 19th, 2009
2
The Reality

• 3-5 of academic ED intubations involve more than
  3 attempts and of those, 80 are intubated with
  standard laryngoscopy1
• Success rates approaching 99 with RSI and direct
  laryngoscopy1
• 7 out of 6000 cases were intubated with
  alternative methods to direct laryngoscopy in a
  20 center study2

1. Levitan R. Myths and Realities The Difficult
   Airway and Alternative Airways in the Emergency
   Setting. Acad EM, 2001 88, 829
2. Walls RM, et al. 6,294 emergency department
   intubations second report of the ongoing
   National Emergency Airway Registry (NEAR) II
   study. Ann Emerg Med. 2000 36(4, part 2)

3
EM physicians are airway experts and direct
laryngoscopy is very reliable
But what if things arent as straight forward??
4
Direct Laryngoscopy

• There are multiple variations and adjuncts to
  help with direct laryngoscopy
• These include the Macintosh blade, the Miller
  blade, the McCoy blade, and the bougie
• These have been around longer and most people are
  familiar with their use
• This talk will focus on alternatives to direct
  laryngoscopy further down the difficult airway
  algorithms

5
Objectives

• Review the anticipated and unanticipated
  difficult airway algorithms
• Present alternatives to direct laryngoscopy
• Review manual in-line stabilization
• Review case scenarios and present options for
  managing airway difficulties
• Glidescope Demo (Maybe)

6
July 1st 2008, Level 1 Trauma EMS unable to
intubate!
7
July 30th, 2008 - EMS Patch Cant intubate and
cant ventilate!
8
The Anticipated Difficult Airway
Difficult Bag-Mask (MOANS) Mask Seal (beard,
nose, etc) Obese/Obstruction Age gt55 No
teeth Stiff (asthma, COPD)
Difficult Intubation (LEMON) Look
externally-gestalt Evaluate 3-3-2 Mallampati Obstr
uction- stridor, drooling Neck Mobility
Walls, R. Manual of Emergency Airway Management.
2nd Ed, 2004
9
The Unanticipated or Failed Airway
Walls, R. Manual of Emergency Airway Management.
2nd Ed, 2004
10
Glidescope
11
Video Laryngoscopy (Glidescope)

• Similar shape to laryngoscope blade
• Exagerated curve designed to wrap around tongue,
  not displace into submental space
• Does not require anterior lift/pressure to bring
  glottis into view
• Accompanying rigid stylet increases ETT
  manouverability
• Camera protected in housing with anti-fog heating
• Overall glidescope success rates 99.963

• 3 Cooper RM, et al. Early clinical experience
  with a new videolaryngoscope in 728 patients. Can
  J Anesth. 2005 52 191-8.

12
Summarizing the Data
Can we recommend any of these devices? Most data
contains flaws, most data comes from normal
patients who are rarely difficult to intubate and
much of the data is heterogeneous. Accepting
these limitations, the devices with robust data
that performed best were the Bonfils and Ctrach
in normal patients, and the Bonfils, CTrach and
Glidescope in difficult patients. Before
drawing conclusions on device performance from
the difficult patient groups it is important to
note the small numbers of patients studied, for
each device. There is very limited and inadequate
comparative data between devices and compared to
the standard Macintosh laryngoscope.
13
Glidescope vs DL with neck imobility

• Ankylosing Spondylitis 60 had CL grade 3 or 4
  airways, improved to 1 or 2 in 854
• Another study of AS patients showed 93 of
  patients had CL grade improved by 1 or more5
• Manual In-Line Stabilization (MILS) Glidescope
  50 Grade 1, 50 grade 2
• DL 65 Grade 2, 35 Grade 3 (without BURP)6

• 4 Lai HY, et al. The use of the Glidescope for
  tracheal intubation in patients with ankylosing
  spondylitis. B J Anesth. 2006 973, 419.
• 5 Argo F, et al. Tracheal intubation using a
  Macintosh laryngoscope or a Glidescope in 15
  patients with cervical spine immobilization. B J
  Anesth. 2001 93 705.
• 6 Huang WT, et al. Clinical comparisons between
  GlideScope video laryngoscope and Trachlight in
  simulated cervical spine instability. J Clin
  Anesth. 2007 19(2)110-4

14
Cormack Lehane Grades
15
Other difficult airways

• Anesthesia staff/residents performing elective
  nasotracheal intubation CL G1- 94 vs 66, with
  time of 23.3sec vs 43 sec and less sore throat7
• 2 studies on obese patients w /BMIgt408,9
• Device used was Airtrach videolaryngoscope
• 318 pts Time 29s vs 109s, Grades 100/6/0/0 vs
  54/36/16/0. More desats blind attempts
• 108 pts Time 24 sec vs 56 sec, 1 vs 9 desats
  below 92

• 7 Jones PM, et al. A comparison of Glidescope
  videolaryngoscopy to direct laryngoscopy for
  nasotracheal intubation. Anesth and Analg. 2008
  1071, 144.
• 8 Dhonneur G, et al. Video-assisted versus
  conventional tracheal intubation in morbidly
  obese patients. Obes Surg. 2008 Sept.
• 9 Ndoko SK, et al. Tracheal intubation of
  morbidly obese patients a randomized trial
  comparing performance of Macintosh and Airtraq
  laryngoscopes. B J Anaes. 2008 1002, 263.

16
C-Spine Movement

• Healthy pts, C-spine motion from occiput to C5
  measured with fluoro during intubation
• No difference b/w GS and DL28
• Anther compared GS, Trachlight and DL10
• Movement measured with fluoro at 4
  sitesocciput/C1, C1/C2, C2-C5, C5-T1
• TL (decr) 49, 72, 64, 41 (Mean 57)
• GS (decr) 0, 0, 50, 0
• Possible benefit _at_ C2-C5??

28 Robitaille A, et al. Cervical spine motion
during tracheal intubation with manual in-line
stabilization direct laryngoscopy versus
Glidescope videolaryngoscopy. Anesth Analg. 2008
1063, 935 10 Turkstra TP, et al. Cervical
spine motion a fluoroscopic comparison during
tracheal intubation with lighted stylet,
Glidescope, and Macintosh laryngoscope. Anesth
Analg. 2005 101, 910-5..
17
Hemodynamics

• Glidescope shown to have no advantage or
  disadvantage hemodynamically compared to direct
  laryngoscopy
• No significant difference in MAP or HR6

• 6 Huang WT, et al. Clinical comparisons between
  GlideScope video laryngoscope and Trachlight in
  simulated cervical spine instability. J Clin
  Anesth. 2007 19(2)110-4

18
Glidescope Problems

• CJA study, 14 pts failed despite Gr1 view3
• Unable to maneuver ETT into glottis
• Thought to be overcome with 90 degree stylet
• Poor visualization with blood/secretions (better
  than flex scope)
• Needs to be sterilized b/w uses or require
  disposable handles ()
• Shown to take longer with increased apnea and no
  difference in success for easy airways12

• Cooper RM, et al. Early clinical experience with
  a new videolaryngoscope in 728 patients. Can J
  Anesth. 2005 52
• 12 Lim TJ, et al. Evaluation of ease of
  intubation with the Glidescope or Macintosh
  laryngoscope by anaesthetists in simulated easy
  and difficult laryngoscopy. Anaesth. 2005 60,
  180. 191-8.

19
Glidescope Conclusions

• Will improve glottic view and success with most
  difficult airways
• Useful teaching tool and easier for novices
• Can be used as an adjunct with other devices
  Trachlight, Bronchoscope
• Doesnt appear to convey any C-spine or
  hemodynamic advantages
• Still not first-line for anticipated easy airways

20
Other Fiberoptic Laryngoscopes
C-Trach
Airtrach
McGrath
Bonfils
21
Trachlight

• Flexible stylet with bright LED _at_ end
• Blind intubation technique
• Re-usable

22
Trachlight vs DL

• Similar success rates with CL Grades 1213
• Improved success, faster and decreased trauma
  with Grades 3413
• Decreased C-Spine motion compared to DL and
  Glidescope10
• One study has shown smaller rise in HR and MAP
  compared to DL6
• 4 other studies show no difference in
  hemodynamics13-16

13 Davis L, et al. Lighted stylet tracheal
intubation A review. Anesth Analg. 2000 90,
745. 14 Knight RG, et al. Arterial blood pressure
and heart rate response to lighted stylet or
direct laryngoscopy for endotracheal intubation.
Anesthesiology. 1988 69 269. 15 Friedman PG, et
al. A comparison of light wand and suspension
laryngoscopic intubation techniques in
outpatients. Anesth Analg. 1997 85
578. 16 Hirabayashi Y, et al. Effects of
lightwand (Trachlight) compared with direct
laryngoscopy on circulatory responses to tracheal
intubation. B J Anaes. 1998 81 253.
23
Potential Advantages

• Micro/retrognathia Treacher-Collins, Pierre
  Robin, etc
• Neck immobility C-spine
• Blood/Secretions (alone/with DL/Glidescope)
• Traditional markers of difficult intubation dont
  appear to affect success with Trachlight
• Lack of mandibular protrusion, Mallampati, CL
  grade, short hyomental distance 13,17

13 Davis L, et al. Lighted stylet tracheal
intubation A review. Anesth Analg. 2000 90,
745. 17 Agro F, et al. Lightwand intubation
using the Trachlight a brief review of current
knowledge. Can J Anesth. 2001 February 592.
24
Disadvantages

• Those with lt6 attempts with both Trachlight and
  DL showed 67 success rate and averaged 22 sec
  longer with Trachlight compared with DL (94
  success)18
• Suggest benefits only to those with practice and
  regular use
• Limited with grossly obese habitus and brightly
  lit rooms
• Contraindicated with oropharyngeal tumours,
  infections, trauma, or presence of FB17

17 Agro F, et al. Lightwand intubation using
the Trachlight a brief review of current
knowledge. Can J Anesth. 2001 February 592. 18
Soh CR, et al. Tracheal intubation by novice
staff the direct vision laryngoscope or the
lighted stylet (Trachlight)? Emerg Med J. 2002
19 292.
25
Intubating LMAs
26
Pro-Seal LMA

• Shown to have better seal than classic LMA11
• Allows passage of OG tube to allow stomach
  decompression
• Larger size makes it more difficult to place than
  classic LMA11
• 99 success with 2114 pts when a bougie is
  placed through OG opening and into esophagus to
  guide proper placement20
• Excellent when all else fails

20 Goldmann K, et al. Use of Proseal laryngeal
mask airway in 2114 adult patients a prospective
study. Amb Anesthesiology. 2008 1076, 1856.
11 Brimacombe J, et al. A multicenter study
comparing the Proseal and Classic laryngeal mask
airway in anesthetized, non-paralyzed patients.
Anesthesiology. 200296 289.
27
Intubating LMAs (Classic Fasttrach)

• Rescue device for failed airway
• Useful adjunct for fiberoptic intubation
• Definitive airway can be placed blind or with
  fiberoptic guidance
• Multiple options to place ETT blind, fiberoptic
  assist, fiberoptic placement of bougie or tube
  exchanger, Trachlight assist26
• Can be done with patient awake21,22

21 Muraika L, et al. Fiberoptic tracheal
intubatin through a laryngeal mask airway in a
child with Treacher-Collins syndrome. Anesth
Analg. 200397 1298. 22 Asai T, et al. Awake
tracheal intubation through the laryngeal mask in
neonates with upper airway obstruction. Ped
Anesth. 2008 18 77.
26 Barnett R, et al. Augmented fiberoptic
intubation. Crit Care Clinics. 2000 163, 453.
28
Classic LMA

• Common adult sizes 3, 4, 5
• Need to have bars removed in order to pass ETT
  (newer versions)
• 3 6-0 tube, 4 6.5 tube, 5 7-0 tube19

19 http//www.geocities.com/HotSprings/Villa/2613
/textpicjip.html (Aids to fiberoptic intubation)
Dr. Srinivasan, Kuwait.
29
I-LMA (Fastrach)

• Accomodates up to size 8-0 ETT19
• Metal handle for maneuverability
• Comes with flexible, cuffed ETT and stabilizing
  rod

19 http//www.geocities.com/HotSprings/Villa/26
13/textpicjip.html (Aids to fiberoptic
intubation) Dr. Srinivasan, Kuwait.
30
Youtube Video Awake I-LMA
http//www.youtube.com/watch?vKAskavry0jw
31
Intubating LMAs

• Success rates of 100 for fiberoptic and
  lightwand assisted intubations19,23
• 2 small studies showed blind ETT passage with
  I-LMA 9524,25
• For those with predicted short course of
  intubation LMA can be left in place
• Prolonged LMA placement can lead to tissue
  ischemia, prevent NG/OG placement as well as
  access to possible bleeding tissue etc26
• LMA will eventually need to be removed for most
  ER patients

24 Combes X, et al. Intubating laryngeal mask
airway in morbidly obese and lean patients.
Anesthesiology. 2005 102 1106. 25 Frappier J,
et al. Airway management using the intubating
laryngeal mask airway for the morbidly obese
patient. Anesth Analg. 2003 96 1510.
32
Intubating LMAs and Bronchoscope

• Fiberoptic ETT placement can be difficult or
  impossible in certain situations
• Retro/micrognathia posterior tongue and anterior
  larynx can create angles too steep to maneuver
  scope26
• Blood/secretions unable to visualize larynx
• Fiberoptic takes time to set up. LMA allows
  ventilation while preparing ETT placement

26 Barnett R, et al. Augmented fiberoptic
intubation. Crit Care Clinics. 2000 163, 453.
33
Retro/micrognathia
Pierre Robin
Treacher Collins
34
Intubating LMAs and Difficult Airways

• Case reports 4 patients with Treacher-Collins
  and 2 with Pierre Robin
• Failed awake fiberoptic intubation
• 100 successful with first attempt at ETT
  placement through I-LMA21,22
• Obese pts (avg BMI 42 vs 23 control)
• Blind passage of ETT 96 obese vs 9424
• Another study of pts with average BMI 45
• 96.3 success rate at blind ETT passage25

• 21 Muraika L, et al. Fiberoptic tracheal
  intubatin through a laryngeal mask airway in a
  child with Treacher-Collins syndrome. Anesth
  Analg. 200397 1298.
• Asai T, et al. Awake tracheal intubation through
  the laryngeal mask in neonates with upper airway
  obstruction. Ped Anesth. 2008 18 77.
• 24 Combes X, et al. Intubating laryngeal mask
  airway in morbidly obese and lean patients.
  Anesthesiology. 2005 102 1106.
• 25 Frappier J, et al. Airway management using the
  intubating laryngeal mask airway for the morbidly
  obese patient. Anesth Analg. 2003 96 1510.

35
Issues/Problems w/ ILMAs

• Sellicks increases difficulty of passing ETT23
• Only small ETTs able to pass through classic
  LMAs (not ideal for long intubations)
• Removing the LMA once ETT placed!!
• This is not a simple procedure and there is a
  high risk of accidental extubation

23 Reardon R, et al. The intubating laryngeal
mask airway suggestions for use in the emergency
department. Acad Emerg Med. 2001 88, 833.
36
Removing the LMA

• Needs to be planned-out and should be done with
  help of an assistant
• Several options for LMA removal
• Fasttrach comes with stabilizing rod that is
  designed to hold ETT in place while LMA is
  withdrawn (not ventilating during procedure)
• Other reports of coupling 2 ETTs together to
  continue ventilation while ETT is withdrawn 21,27
• Once distal part of ETT visible, have assistant
  hold with McGill forceps

• Muraika L, et al. Fiberoptic tracheal intubatin
  through a laryngeal mask airway in a child with
  Treacher-Collins syndrome. Anesth Analg. 200397
  1298.
• 27 Weiss M, et al. Continuous ventilation
  technique for laryngeal mask airway removal after
  fiberoptic intubation in children. Ped Anesth.
  200414 936.

37
Intubating LMAs-Conclusions

• Rescue device for failed airways while retaining
  the option for definitive airway placement
• Facilitating fiberoptic intubation in difficult
  patients
• LMA should be removed for most ER cases and this
  is a technical and risky process
• ET tubes that fit with the Pro-Seal and Classic
  LMAs are too small for prolonged intubations

38
Manual In-Line Stabilization (MILS)
39
(No Transcript)
40
MILS

• Adopted in 1980s after stabilization during
  transport improved spinal outcomes29
• Since its advent there have been 10 cases of 2o
  injury associated with airway management29
• These cases reviewed in Br J Anesthesiology in
  2000 and found 1 possibly due to DL and
  intubation
• This case had a neck hematoma, prolonged hypoxia
  and required an emergent cric.

29 Manoach S, et al. Manual in-line
stabilization for acute airway management of
suspected cervical spine injury historical
review and current questions. Annals Emerg Med.
2007503, 236.
41
Does MILS work?

• 2 cadaveric studies of C-spine motion with total
  of 9 patients29
• Data using MILS in live patients comes from 5
  case series of 275 injured patients.
• In this series, 120 patients had unstable but
  salvageable injuries. No secondary injury
  observed.
• Were these results because of MILS or in spite
  of??

42
Is MILS a bad thing?

• MILS worsens CL view, increases chance of failed
  intubation29,30
• Jaw thrust has shown to cause more segmental
  motion than DL29
• Jaw thrust is ubiquitous in suspected C-spine
  injuries and no reports of 2o injury exist29
• 4 cadaveric studies and 1 on healthy volunteers
  found no difference or worsening of cervical
  motion with MILS.29 Why??

30 Santoni BG, et al. Manual in-line
stabilization increases pressures applied by the
laryngoscope blade during direct laryngoscopy and
endotracheal intubation. Anesthesiology. 2009
110 24.
43

• Each patient underwent standard DL and then
  laryngoscopy with MILS
• Pressure averaged 2x greater with MILS
• Previous study done by same group showed pressure
  transmitted to cranio-cervical motion
• 66 of patients with MILS had worse CL views

44
MILS Conclusions

• Annals review states more research needed to come
  to a firm conclusion
• Anesthesiology 2009 editorial by Annals authors,
  states lack of 2o injury in-spite, not because of
  MILS31
• Stabilization in transport and caution during
  intubation likely all thats required to prevent
  2o injury
• Is MILS worth a potential failed intubation??

31 Manoach S, et al. Laryngoscopy force,
visualization, and intubation failure in acute
trauma. Anesthesiology. 2009 110 6-7.
45
Case 1
46
Awake Intubation

• OK if you have time
• OK if no C-spine concerns
• Obese pts can desat even with sedation for awake
  intubation

Glidescope can be used to help position
bronchoscope tip32
Glidescope can be used to move tongue and
visualize landmarks for patients with large
tongue, retrognathia33
Glidescope shown to be tolerated and successful
for awake intubations34
32 Xue FS, et al. Glidescope-assisted awake
fiberoptic intubation initial experience with 13
patients. Anesthesiology. 200661 1007 33 Vitin
AA, et al. A difficult case with
Glidescope-assisted fiberoptic intubation. J Clin
Anesth. 2007 564. 34 Doyle DJ. Awake intubation
using the Glidescope videolaryngoscope initial
experience in 4 cases. Can J Anesthesia. 2004
555, 520.
47
Case 1 RSI

• Easiest and most important maneuver to maximize
  success????

POSITION!!!
48
Troop Pillow
Available in the ORs of all 3 hospitals. Or
could just use lots of blankets!!
49
Case 1 Rescue or Adjunct

• Glidescope works well
• Intubating LMA shown to be highly successful with
  obese patients
• Allows ventilation while definitive airway placed
• Trachlight not a good option in obese patients

50
Case 2
51
Retro/Micrognathia

• Direct laryngoscopy difficult because no place to
  displace tongue
• Fiberoptic intubation difficult because of
  posterior tongue and anterior larynx33
• Glidescope doesnt require displacement of tongue
• Options Glidescope, Glidescope combination with
  bronchoscope or lighted stylet35
• Intubating LMA as a rescue device or to
  facilitate fiberoptic intubation

33 Vitin AA, et al. A difficult case with
Glidescope-assisted fiberoptic intubation. J Clin
Anesth. 2007 564. 35 Leissner KB, et al.
Intubation with simultaneous use of the
Glidescope and the Trachlight. J Anesth. 2008
22 328.
52
Case 3 Bleeding
53
Case 3

• Suction, suction, suction
• Yonkers are your friend
• Direct Laryngoscopy push on chest and aim for
  bubble
• Trachlight excellent light transmission through
  blood/secretions17,35
• Can use in combo with DL, Glidescope35
• Intubating LMA with trachlight for rescue

17 Agro F, et al. Lightwand intubation using
the Trachlight a brief review of current
knowledge. Can J Anesth. 2001 February 592. 35
Leissner KB, et al. Intubation with
simultaneous use of the Glidescope and the
Trachlight. J Anesth. 2008 22 328.
54
Thank You!!
55
References

• Levitan R. Myths and Realities The Difficult
  Airway and Alternative Airways in the Emergency
  Setting. Acad EM, 2001 88, 829
• Walls RM, et al. 6,294 emergency department
  intubations second report of the ongoing
  National Emergency Airway Registry (NEAR) II
  study. Ann Emerg Med. 2000 36(4, part 2)
• Cooper RM, et al. Early clinical experience with
  a new videolaryngoscope in 728 patients. Can J
  Anesth. 2005 52 191-8.
• Lai HY, et al. The use of the Glidescope for
  tracheal intubation in patients with ankylosing
  spondylitis. B J Anesth. 2006 973, 419.
• Argo F, et al. Tracheal intubation using a
  Macintosh laryngoscope or a Glidescope in 15
  patients with cervical spine immobilization. B J
  Anesth. 2001 93 705.
• Huang WT, et al. Clinical comparisons between
  GlideScope video laryngoscope and Trachlight in
  simulated cervical spine instability. J Clin
  Anesth. 2007 19(2)110-4
• Jones PM, et al. A comparison of Glidescope
  videolaryngoscopy to direct laryngoscopy for
  nasotracheal intubation. Anesth and Analg. 2008
  1071, 144.
• Dhonneur G, et al. Video-assisted versus
  conventional tracheal intubation in morbidly
  obese patients. Obes Surg. 2008 Sept.
• Ndoko SK, et al. Tracheal intubation of morbidly
  obese patients a randomized trial comparing
  performance of Macintosh and Airtraq
  laryngoscopes. B J Anaes. 2008 1002, 263.
• Turkstra TP, et al. Cervical spine motion a
  fluoroscopic comparison during tracheal
  intubation with lighted stylet, Glidescope, and
  Macintosh laryngoscope. Anesth Analg. 2005 101,
  910-5.

• 11 Brimacombe J, et al. A multicenter study
  comparing the Proseal and Classic laryngeal mask
  airway in anesthetized, non-paralyzed patients.
  Anesthesiology. 200296 289.
• 12 Lim TJ, et al. Evaluation of ease of
  intubation with the Glidescope or Macintosh
  laryngoscope by anaesthetists in simulated easy
  and difficult laryngoscopy. Anaesth. 2005 60,
  180.
• 13 Davis L, et al. Lighted stylet tracheal
  intubation A review. Anesth Analg. 2000 90,
  745.
• 14 Knight RG, et al. Arterial blood pressure and
  heart rate response to lighted stylet or direct
  laryngoscopy for endotracheal intubation.
  Anesthesiology. 1988 69 269.
• 15 Friedman PG, et al. A comparison of light wand
  and suspension laryngoscopic intubation
  techniques in outpatients. Anesth Analg. 1997
  85 578.
• 16 Hirabayashi Y, et al. Effects of lightwand
  (Trachlight) compared with direct laryngoscopy on
  circulatory responses to tracheal intubation. B
  J Anaes. 1998 81 253.
• 17 Agro F, et al. Lightwand intubation using the
  Trachlight a brief review of current knowledge.
  Can J Anesth. 2001 February 592.
• 18 Soh CR, et al. Tracheal intubation by novice
  staff the direct vision laryngoscope or the
  lighted stylet (Trachlight)? Emerg Med J. 2002
  19 292.
• 19 http//www.geocities.com/HotSprings/Villa/2613/
  textpicjip.html (Aids to fiberoptic intubation)
  Dr. Srinivasan, Kuwait.
• 20 Goldmann K, et al. Use of Proseal laryngeal
  mask airway in 2114 adult patients a prospective
  study. Amb Anesthesiology. 2008 1076, 1856.

56
References

• 21 Muraika L, et al. Fiberoptic tracheal
  intubatin through a laryngeal mask airway in a
  child with Treacher-Collins syndrome. Anesth
  Analg. 200397 1298.
• 22 Asai T, et al. Awake tracheal intubation
  through the laryngeal mask in neonates with upper
  airway obstruction. Ped Anesth. 2008 18 77.
• 23 Reardon R, et al. The intubating laryngeal
  mask airway suggestions for use in the emergency
  department. Acad Emerg Med. 2001 88, 833.
• 24 Combes X, et al. Intubating laryngeal mask
  airway in morbidly obese and lean patients.
  Anesthesiology. 2005 102 1106.
• 25 Frappier J, et al. Airway management using the
  intubating laryngeal mask airway for the morbidly
  obese patient. Anesth Analg. 2003 96 1510.
• 26 Barnett R, et al. Augmented fiberoptic
  intubation. Crit Care Clinics. 2000 163, 453.
• 27 Weiss M, et al. Continuous ventilation
  technique for laryngeal mask airway removal after
  fiberoptic intubation in children. Ped Anesth.
  200414 936.
• 28 Robitaille A, et al. Cervical spine motion
  during tracheal intubation with manual in-line
  stabilization direct laryngoscopy versus
  Glidescope videolaryngoscopy. Anesth Analg. 2008
  1063, 935.
• 29 Manoach S, et al. Manual in-line stabilization
  for acute airway management of suspected cervical
  spine injury historical review and current
  questions. Annals Emerg Med. 2007503, 236.
• 30 Santoni BG, et al. Manual in-line
  stabilization increases pressures applied by the
  laryngoscope blade during direct laryngoscopy and
  endotracheal intubation. Anesthesiology. 2009
  110 24.

• 31 Manoach S, et al. Laryngoscopy force,
  visualization, and intubation failure in acute
  trauma. Anesthesiology. 2009 110 6-7.
• 32 Xue FS, et al. Glidescope-assisted awake
  fiberoptic intubation initial experience with 13
  patients. Anesthesiology. 200661 1007
• 33 Vitin AA, et al. A difficult case with
  Glidescope-assisted fiberoptic intubation. J Clin
  Anesth. 2007 564.
• 34 Doyle DJ. Awake intubation using the
  Glidescope videolaryngoscope initial experience
  in 4 cases. Can J Anesthesia. 2004 555, 520.
• 35 Leissner KB, et al. Intubation with
  simultaneous use of the Glidescope and the
  Trachlight. J Anesth. 2008 22 328.