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* From the Departments of Anesthesia, Surgery, and Pharmacology, and the
Departments of Anesthesia and Surgery, Dalhousie University, Halifax, Nova Scotia, Canada.
Address correspondence to: Dr. Orlando Hung, Department of Anesthesia, Queen Elizabeth II Health Sciences Centre, Victoria General Hospital, 1278 Tower Rd., Halifax, Nova Scotia B3H 2Y9, Canada. Phone: 902-473-7767; Fax: 902-473-4493; E-mail: orlando.hung{at}dal.ca
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Airway module overview |
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Airway assessment
All airway management must begin with a proper airway assessment. In our recent editorials in this Journal, we stressed the importance of assessing a patient for ‘ventilatability’ and not just "intubatability".5,6 Thus, in addition to asking the question "Can I intubate this patient’s trachea using direct laryngoscopy or an alternative intubation technique, including surgical airway?" we should ask "Can I ventilate and oxygenate this patient using a bag-valve mask, or an extraglottic device?" Prediction of a difficult direct laryngoscopy using the Mallampati classification and a combination of other airway measurements7 has been well studied. For many anesthesiologists, predicting difficult laryngoscopy and intubation was the only aspect of the airway examination emphasized during residency training. Appropriately, more recent work has focused on the predictors of difficult bag-valve mask ventilation. Presence of a beard, obstructing airway pathology, a history of snoring, obesity, absent dentition, and advancing age have all been correlated with difficult bag-mask ventilation.5,8 Extraglottic devices such as the Laryngeal Mask Airway (LMA; LMA North America, San Diego, CA, USA), Esophageal-tracheal Combitube (Kendall Healthcare, Mansfield, MA, USA) and Laryngeal TubeTM (King Systems Corporation, Noblesville, IN, USA) are all effective rescue ventilation devices. While we await results from large-scale prospective trials examining predictors of difficulty with use of these devices, problems might be anticipated in several situations. These include:
Laryngeal mask airway
The LMA has emerged, during the past two decades, as one of the most important rescue ventilation and oxygenation devices in the management of a difficult and failed airway.2 However, it is not without limitations. Although exceedingly rare, serious and fatal aspiration of gastric contents during LMA use has been reported.9 The ProSeal LMA (PLMA; LMA North America, San Diego, CA, USA) was introduced in 2000, in part, to help address this issue. With the addition of a drainage tube running parallel to the airway tube and exiting at the mask tip, functional separation of the digestive and respiratory tracts is possible.10 The drainage tube also provides a mechanism to help confirm correct mask tip location, while additional design features enable an improved seal and ventilation at higher airway pressures. In a comprehensive review on the PLMA, Cook et al. examine the clinical utility and limitations of the PLMA,10 presenting the available evidence suggesting decreased (but not absent) risk of aspiration of gastric contents compared with the classic LMA. Aspiration risk increases with a malpositioned PLMA, which may in turn result from:
Use of the ‘gel’ or ‘soap’ test can help identify malposition of the PLMA. To facilitate proper placement, an Eschmann Introducer (gum elastic bougie) can be placed into the esophagus under direct laryngoscopic vision with subsequent advancement of the PLMA over the Eschmann Introducer through the drainage tube.
New extraglottic devices
New extraglottic devices have been introduced in recent years, many of which may also play an important role in rescuing a failed airway. Several recent reports have detailed successful use of the Laryngeal TubeTM,11 the CobraPLA12 (Engineered Medical System, Indianapolis, IN, USA) and the PAxpressTM13 (Vital Signs Inc., Totowa, NJ, USA) in providing effective ventilation and oxygenation in patients under a variety of difficult circumstances. Whether these devices will receive acceptance equal to that of the LMA and Combitube in the difficult airway is unknown.
While extraglottic devices have solidly established a role in ventilation and oxygenation, in many situations, they cannot replace a tracheal tube. Tracheal intubation through the classic LMA has been reported with some technical difficulties for many years. The intubating (Fastrach) LMA (ILMA; LMA North America, San Diego, CA, USA) was introduced to overcome the limitations of intubation through the classic LMA (e.g., small tube size). The effectiveness of blind tube passage through the ILMA has been studied by many investigators with somewhat contradictory results. Reported techniques to facilitate blind tracheal intubation through the ILMA include:
Successful use of adjunctive devices has also been described with the ILMA, including a lightwand,14 and a fibreoptic bronchoscope.15 Indeed, after reviewing the available evidence, the Difficult Airway Society in the United Kingdom recommends the use of the ILMA with a fibreoptic bronchoscope in their algorithm for managing the unanticipated difficult tracheal intubation in the non-obstetric adult patient with no upper airway obstruction.3
Rigid fibreoptic devices: video-laryngoscope and others
Specific anatomical characteristics make direct laryngoscopy impossible for some patients. The use of the new rigid fibreoptic or video-laryngoscopes may help to overcome this problem. Several studies have reported successful tracheal intubation using a new Canadian-developed video-laryngoscope (GlideScope®, Diagnostic Ultrasound Corporation, Bothell, WA, USA) in patients with a difficult or simulated difficult airway.16–18 Doyle et al. described successful tracheal intubation using this device in a small series of awake patients with an anticipated difficult airway under topical anesthesia.19 The technique was easy to use even in the presence of secretions or blood. Other rigid fibreoptic laryngoscopes, such as the Bullard laryngoscope20 (Circon Corporation, Santa Barbara, CA, USA), Shikani Seeing Optical Stylet21 (Clarus Medical LLC, Minneapolis, MN, USA), StyletScope22 (Nihon Kohden Corp., Tokyo, Japan), Angulated Video-Intubation Laryngoscope (AVIL; Acutronic Medical Systems AG, Baar, Switzerland),23 and the Video-Optical Intubation Stylet24 (Acutronic Medical Systems AG, Baar, Switzerland) have been used successfully for tracheal intubation in patients presenting with difficult airway anatomy. More studies with larger patient populations are needed to help define the role of these devices in airway management.
Clinical impact of new airway technologies
With the development of these effective new intubation and ventilation devices, together with an improved understanding of the predictors of difficulty in all aspects (bag-mask, extraglottic device, intubation, and cricothyrotomy) of airway management, one would expect a change in the landscape of anesthesiology practice. However, in a 2002 survey of Canadian anesthesiologists, Jenkins et al. reported that direct laryngoscopy and fibreoptic bronchoscopy were still the preferred techniques for intubation when presented with a series of difficult airway patient scenarios, despite widespread availability of newer, and perhaps better airway equipment.25 In a more recent review of anesthesiology practice in a large American teaching centre, these findings were echoed: the most commonly used alternative airway device for a failed laryngoscopic intubation was the flexible fibreoptic bronchoscope.26 While fibreoptic intubation is an effective and safe technique of securing the airway, the presence of blood and secretions, together with significant set-up time may adversely limit its use in an emergency failed airway. Fortunately, signs are emerging that alternative airway techniques are being employed in different settings around the globe.27,28 In fact, in the 2005 study reported by Burkle et al., successful intubation was achieved using an Eschmann Introducer (Portex Limited, Hythe, UK) in 20.6% of patients and the ILMA in 11.6% of patients following a failed laryngoscopic intubation.26 These are encouraging signs and we must continue to foster the use of these adjuncts and alternative technologies through academic training and continuing medical education programs.
With the cumulative evidence of successful alternative airway techniques, it is time to change our way of thinking. Devices such as the TrachlightTM, the ILMA, flexible and rigid fibreoptic- and video-laryngoscopes, should no longer be looked upon as "rescue devices", but rather as effective primary techniques for use in difficult airway management. Many practitioners have effectively and safely mastered the use of the TrachlightTM 27,28 or other intubating devices29 to the extent that they use these instruments as a first choice in a difficult situation. Thus, when a patient is identified in whom a skilled clinician anticipates a high likelihood of a failed direct laryngoscopy, the clinician should choose appropriate alternative devices or techniques as Plans "A", "B", and "C" to maximize the probability of successful intubation in a minimum number of attempts.5,6
In summary, we must continue to learn and teach others about the importance of a careful airway assessment which includes a comprehensive evaluation of the predictors of difficult ventilation using a mask or an extraglottic device, difficult intubation using direct laryngoscopy or alternative intubating devices, as well as a difficult surgical airway. We should also strive to improve our strategies and techniques in managing the difficult airway using the best available clinical resources and evidence.
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Airway module objectives |
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Instructions for completing the continuing medical education module |
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This program is accredited for ten hours (20 credits) under category 3 of the Royal College of Physicians and Surgeons of Canada CME program.
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*2 American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98: 1269–77.[Medline]
*3 Henderson JJ, Popat MT, Latto IP, Pearce AC; Difficult Airway Society. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia 2004; 59: 675–94.[Medline]
4 Combes X, Le Roux B, Suen P, et al. Unanticipated difficult airway in anesthetized patients: prospective validation of a management algorithm. Anesthesiology 2004; 100: 1146–50.[Medline]
*5 Hung OR, Murphy M. Changing practice in airway management: are we there yet? Can J Anesth 2004; 51: 963–8.
*6 Murphy M, Hung O, Launcelott G, Law JA, Morris I. Predicting the difficult laryngoscopic intubation: are we on the right track? Can J Anesth 2005; 52: 231–5.
*7 Karkouti K, Rose DK, Wigglesworth D, Cohen MM. Predicting difficult intubation: a multivariable analysis. Can J Anesth 2000; 47: 730–9.
*8 Langeron O, Masso E, Huraux C, et al. Prediction of difficult mask ventilation. Anesthesiology 2000; 92: 1229–36.[Medline]
9 Keller C, Brimacombe J, Bittersohl J, Lirk P, von Goedecke A. Aspiration and the laryngeal mask airway: three cases and a review of the literature. Br J Anaesth 2004; 93: 579–82.
*10 Cook TM, Lee G, Nolan JP. The ProSealTM laryngeal mask airway: a review of the literature. Can J Anesth 2005; 52: 739–60.
11 Matioc AA, Olson J. Use of the Laryngeal TubeTM in two unexpected difficult airway situations: lingual tonsillar hyperplasia and morbid obesity. Can J Anesth 2004; 51: 1018–21.
12 Agro F, Carassiti M, Magnani C, Alfery D. Airway control via the CobraPLA during percutaneous dilatational tracheotomy in five patients. Can J Anesth 2005; 52: 418–20.
13 Dimitriou V, Voyagis GS, Iatrou C, Brimacombe J. The PAxpressTM is an effective ventilatory device but has an 18% failure rate for flexible lightwand-guided tracheal intubation in anesthetized paralyzed patients. Can J Anesth 2003; 50: 495–500.
14 Dimitriou V, Voyagis GS, Brimacombe JR. Flexible lightwand-guided tracheal intubation with the intubating laryngeal mask Fastrach in adults after unpredicted failed laryngoscope-guided tracheal intubation. Anesthesiology 2002; 96: 296–9.[Medline]
15 Kannan S, Chestnutt N, McBride G. Intubating LMA guided awake fibreoptic intubation in severe maxillo-facial injury. Can J Anesth 2000; 47: 989–91.
16 Cooper RM. Use of a new videolaryngoscope (GlideScope) in the management of a difficult airway. Can J Anesth 2003; 50: 611–3.
*17 Cooper RM, Pacey JA, Bishop MJ, McCluskey SA. Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients. Can J Anesth 2005; 52: 191–8.
18 Lim Y, Lim TJ, Liu EH. Ease of intubation with the GlideScope or Macintosh laryngoscope by inexperienced operators in simulated difficult airways (Letter). Can J Anesth 2004; 51: 641–2.
19 Doyle DJ. Awake intubation using the GlideScope video laryngoscope: initial experience in four cases (Letter). Can J Anesth 2004; 51: 520–1.
20 Dullenkopf A, Lamesic G, Gerber A, Weiss M. Video-enhanced visualization of the larynx and intubation with the Bullard laryngoscope--equipment report. Can J Anesth 2003; 50: 507–10.
21 Agro FE, Antonelli S, Cataldo R. Use of Shikani Flexible Seeing Stylet for intubation via the Intubating Laryngeal Mask Airway (Letter). Can J Anesth 2005; 52: 657–8.
22 Kihara S, Yaguchi Y, Taguchi N, Brimacombe JR, Watanabe S. The StyletScope is a better intubation tool than a conventional stylet during simulated cervical spine immobilization. Can J Anesth 2005; 52: 105–10.
23 Dullenkopf A, Holzmann D, Feurer R, Gerber A, Weiss M. Tracheal intubation in children with Morquio syndrome using the angulated video-intubation laryngoscope. Can J Anesth 2002; 49: 198–202.
24 Weiss M, Schwarz U, Gerber AC. Difficult airway management: comparison of the Bullard laryngoscope with the video-optical intubation stylet. Can J Anesth 2000; 47: 280–4.
*25 Jenkins K, Wong DT, Correa R. Management choices for the difficult airway by anesthesiologists in Canada. Can J Anesth 2002; 49: 850–6.
*26 Burkle CM, Walsh MT, Harrison BA, Curry TB, Rose SH. Airway management after failure to intubate by direct laryngoscopy: outcomes in a large teaching hospital. Can J Anesth 2005; 52: 634–40.
27 Agro F, Totonelli A, Gherardi S. Planned lightwand intubation in a patient with a known difficult airway (Letter). Can J Anesth 2004; 51: 1051–2.
28 Inoue Y. Lightwand intubation can improve airway management (Letter). Can J Anesth 2004; 51: 1052–3.
29 Sener EB, Sarihasan B, Ustun E, Kocamanoglu S, Kelsaka E, Tur A. Awake tracheal intubation through the intubating laryngeal mask airway in a patient with halo traction. Can J Anesth 2002; 49: 610–3.
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  H. Hooshangi and D. T. Wong Brief Review: The Cobra Perilaryngeal Airway (CobraPLA(R)) and the Streamlined Liner of Pharyngeal Airway (SLIPATM) supraglottic airways: [Article de synthese court : Les dispositifs supraglottiques Cobra Perilaryngeal Airway (CobraPLA(R)) et Streamlined Liner of Pharyngeal Airway (SLIPATM)] Can J Anesth, March 1, 2008; 55(3): 177 - 185. [Abstract] [Full Text] [PDF]
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F. Donati and D. R. Miller The role of scientific journals in continuing medical education/Le role des revues scientifiques en formation medicale continue Can J Anesth, December 1, 2006; 53(12): 1175 - 1179. [Full Text] [PDF]
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R. B.P. Stasiuk Styletted orotracheal intubation in difficult airway management. Can J Anesth, November 1, 2006; 53(11): 1162 - 1162. [Full Text] [PDF]
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