Can J Anesth/J Can Anesth DOI 10.1007/s12630-013-0102-9
SPECIAL ARTICLE
From the Journal archives: Early clinical experience with a new video laryngoscope Edward T. Crosby, MD
Received: 5 October 2013 / Accepted: 18 December 2013 Canadian Anesthesiologists’ Society 2013
Editors’ Note: Classics Revisited Key Articles from the Canadian Journal of Anesthesia Archives: 1954-2013 As part of the Journal’s 60th anniversary Diamond Jubilee Celebration, a number of seminal articles from the Journal archives are highlighted in the Journal’s 61st printed volume and online at: www.springer.com/12630. The following article was selected on the basis of its novelty at the time of publication, its scientific merit, and its overall importance to clinical practice: 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. Dr. Edward T. Crosby provides expert commentary on the problems that the videolaryngoscope addressed and how this intubation tool changed the approach to the airway. Hilary P. Grocott MD, Editor-in-Chief Donald R. Miller MD, Former Editor-in-Chief Article summary Authors Cooper RM, Pacey JA, Bishop MJ, McCluskey SA. Citation Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients. Can J Anesth 2005; 52: 191-8.
E. T. Crosby, MD (&) Department of Anesthesia, The Ottawa Hospital – General Campus, University of Ottawa, Suite CCW1400, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada e-mail: [email protected]
Purpose This investigation was an observational study designed to evaluate the newly developed GlideScope video laryngoscope (GVL) and to assess its ability both to provide a laryngeal view and to facilitate intubation. Principal findings The study, which was conducted from November 2001 to March 2003, included 133 operators from five centres (Ontario and British Columbia, Canada and Washington State, USA) involving 728 patients. The resulting Cormack-Lehane (C/L) laryngeal exposure was excellent (1) in 92% of patients and good (2) in 7% of patients. The GVL provided a comparable or superior view in the 133 patients in whom both the GVL and the direct laryngoscope (DL) were used. Among the 35 patients with a C/L grade C 3 view with the DL, the view improved to a C/L grade 1 view in 24 patients and a C/L grade 2 view in three patients. Tracheal intubation with the GVL was successful in 96.3% of patients and failed in 3.7%. Fifty-four percent of the failed intubations occurred despite achieving a C/L grade 1 view and resulted from the inability to direct the endotracheal tube toward a clearly seen larynx. Conclusions The GVL consistently yielded a comparable or superior glottic view compared with the DL despite the operators’ limited or lack of prior experience with the device. Successful intubation was typically achieved even when direct laryngoscopy was predicted to be moderately or considerably difficult. Not only was the GVL a novice-friendly device, this novel study also suggested that a video laryngoscope might provide superior performance when compared with the DL, particularly in patients in whom the DL provided a poor laryngeal view.
Issues in airway management As part of efforts undertaken over the last several decades to improve the safety of anesthesia, airway management
123
E. T. Crosby
during anesthesia care has come under considerable scrutiny. At the outset of this process, esophageal intubations were acknowledged as being associated with severe patient morbidity and mortality. This complication was subsequently managed effectively using capnography, which became routine in the 1980s. Difficult intubation was another complication recognized as leading to occasional but also severe patient injury. At the time, the principal instrument available for airway management was the direct laryngoscope (DL) with either a curved Macintosh blade or a straight Miller-type blade. The DL was effective in facilitating tracheal intubation in the vast majority of patients, but it was difficult to use in a small population and impossible to use in an even smaller cohort. The common strategy to deal with difficult laryngoscopy was to make repetitive attempts, although perhaps with different and successive laryngoscopists. This strategy was eventually recognized as contributing to adverse patient outcomes rather than avoiding them, and as a result, different solutions were sought.1
Early innovations A large number of innovations were marketed to address the issue of difficult direct laryngoscopy. One of the more successful alternate technologies was the TrachlightTM lighted stylet. Introduced in the early 1990s, it became a popular device in Canada in the setting of anticipated difficult, difficult, and failed direct laryngoscopy before recently being removed from the active market.2 Thanks to technological improvements, fibreoptic laryngoscopes, including the WuScope, UpsherTM and BullardTM laryngoscopes, were introduced into the market at around the same time. Of the three, only the Bullard achieved some market penetration, although uptake was limited. The Bullard laryngoscope seemed to be of value in addressing some cases of difficult laryngoscopy; however, most reports were of individual cases or limited case series, and articles of large series or comparative studies were lacking. One article reported applying a surgical camera to the Bullard laryngoscope to create a video-enabled laryngoscope. The video component may have enhanced learning, but no evidence was advanced to support superior laryngoscope performance with video-enabling.3,4 In 2002, Kaplan et al. reported use of a video-integrated laryngoscope using a modified Macintosh blade with a camera and light bundle incorporated into the handle and the image displayed on a monitor.5 The Berci-Kaplan video laryngoscope (BKL) was used in 217 anticipated easy and 18 anticipated difficult intubations, and success was achieved in all but one of the easy intubations. The particular emphasis of this publication related to the value
123
of the video capability for teaching rather than for the management of difficult airways. It was only in 2009 that Jungbauer et al. reported that the BKL provided superior performance when compared with the DL in a population at risk for difficult laryngoscopy.6
Video laryngoscopy The GlideScope video laryngoscope (GVL) arrived on the scene at about the same time as the BKL. The GVL was invented by two Canadians, biomedical engineer Awni Ayoubi and vascular surgeon, Jack Pacey. The GVL initially comprised a black and white camera incorporated into a newly conceived curved blade attached to a dedicated monitor. The impetus for this innovation was to reduce the occurrence of failed intubation experienced with the DL.A The initial limited applications and small case series (including one by RM Cooper in the Journal in 2003) were encouraging7,8 and larger field trials were designed. Cooper et al. were first to publish a large series of patient applications, followed shortly thereafter by Sun et al.9,10 In Cooper et al.’s observational study, the authors analyzed GVL use by 133 operators in five centres involving 728 consecutive patients. Many of the operators had limited or no previous exposure to GVL use—experience ranged from that of students to senior anesthesiologists. Individually, they performed from one to 115 interventions each. Excellent or good laryngeal exposure was obtained in 92% and 7% of patients, respectively. The GVL provided a comparable or superior view to that obtained with the DL in the 133 patients in whom both the GVL and DL were used. Among the 35 patients with a Cormack-Lehane (C/L) grade C 3 view with the DL, the view improved to a C/L grade 1 view in 24 patients and a C/L grade 2 view in three patients with the GVL. Intubation with the GVL was successful in 96.3% of patients and failed in 3.7%. Fifty-four percent of the failed intubations occurred despite achieving a C/L grade 1 view and resulted from the inability to direct the endotracheal tube toward a clearly seen larynx.
Interpretation This report showed that the performance of the GVL was at least similar overall to that expected from the DL. This was an important finding because some alternatives previously introduced to the market were actually less effective when compared with the DL.11 Success with GVL use was also high despite the limited experience of many of the A
Jack Pacey, personal communication.
Key article from the journal archives
operators. This suggests that either the GVL was inherently easy to use or perhaps the video interface facilitated success by allowing supervisors to guide novice use of the device. Cooper et al. reported that the GVL was capable of providing an improved laryngeal view in some patients in whom DL could not. Sun et al. provided support for this opinion when they compared performance of the two devices in 200 patients. Using the GVL improved the C/L grade in the majority of patients who initially had a C/L view [ 1.10 All in all, this was pretty exciting stuff! Here was a device which, on first large-scale application, seemed easy to use, was very effective in achieving its purpose, and might actually perform better than the current technology, the old and reliable DL. Nevertheless, although unsuccessful intubation with GVL use was relatively uncommon, there was a concern that failure mostly occurred in the setting where a good to excellent laryngeal view could be obtained and yet the endotracheal tube could not be successfully directed into the larynx. Cooper et al. reported a number of findings requiring confirmation before larger-scale adoption of the GVL could be encouraged with confidence. First, would the GVL prove to be as consistently successful as the DL when applied to a general patient cohort by a larger variety of operators? Second, could the GVL be confirmed to provide superior laryngeal views when compared with the DL in settings of difficult laryngoscopy? Third, would novice users enjoy higher success rates with the GVL than with the DL, and could they achieve proficiency earlier in their experience? Finally, was there a solution for the cohort of patients in whom an excellent laryngeal view could be obtained and yet the endotracheal tube could not be successfully inserted? Specifically, was there a technical application for the GVL that would more likely result in a favourable outcome than the approach employed in the study, or would additional experience with the device enhance prospects for success?
Subsequent studies Multiple studies were published addressing some of the questions raised, and eight years after Cooper et al.’s reported observations on the early experience with the GVL, Griesdale et al. summarized the results with a metaanalysis of 17 trials comparing the GVL with the DL in 1,998 patients.12 Use of the GVL was associated with an improved C/L view (particularly in patients with potential or simulated difficult airways), improved success at firstattempt intubation, and less time to intubation. After performing a systematic review of 77 articles from the literature assessing the efficacy of modern video
laryngoscopes, Healy et al. reported that the GVL provided better laryngeal views than the DL and a higher rate of successful intubation in patients assessed to be at increased risk of difficult direct laryngoscopy.13 In patients who had experienced previous difficult laryngoscopy (C/L view C 3), evidence showed improved views and a higher level of success. Finally, in patients with failed direct laryngoscopy, case series evidence showed improved views and a higher level of overall success when the GVL was compared with the DL. Overall, in response to the first two questions posed, recent evidence seems to confirm Cooper et al.’s conclusions: the GVL is probably at least as effective as the DL for routine laryngoscopy and intubation, and the GVL is likely more effective than the DL in patients for whom laryngoscopy is difficult.
A teaching aid The video capability of the GVL may enhance the rate of skills acquisition and steepen the slope of the learning curve in novices, thus enhancing the likelihood of initial success. Kory et al. assessed the GVL as the primary intubating device during urgent intubation in critically ill patients when performed by non-anesthesia critical care fellows, and they compared this experience to that of a historical cohort of fellows using the DL.14 The firstattempt success rate was 91% with the GVL compared with 68% with the DL. The incidence of intubations requiring C three attempts was 4% with the GVL vs 20% with the DL. Unintended esophageal intubations did not occur with the GVL but occurred in 14% of patients with the DL, and the average number of attempts required for success was less with the GVL. The optimal number of tries required to achieve proficiency or expert status with the GVL has not been determined, but Aziz et al. reported improved performance (higher rates of salvage of failed intubation) with increased use, even if the differences in experience were modest in the groups compared.15 The experience to date seems to confirm the view of Cooper et al., i.e., early success for novice users is more likely with the GVL than with the DL, and the number of procedures required to achieve proficiency may prove to be not more and possibly less than with many other airway devices.
Endotracheal tube insertion Cooper et al. commented that an excellent laryngeal view could be obtained in some patients, and yet, the endotracheal tube could not be inserted successfully. In fact, this complaint is still heard from both novice and infrequent users and has prompted the manufacturer of the
123
E. T. Crosby
GVL to release a dedicated stylet to help reduce the incidence of this event. It is the author’s view that this occurrence could be reduced to a relatively rare event with both increased experience with GVL use and deference paid to a number of considerations. First, in some patients, progression from a C/L grade 2 view to a C/L grade 1 view is achieved by rotating the blade closer to the glottis, an approach that improves the view but also displaces the glottis more anteriorly. This technique not only makes it more difficult to access the glottis inlet with the endotracheal tube but also increases the angle of the subsequent turn the tube must take to enter the trachea without abutting the anterior wall. Accepting a grade 2 view will often result in less anatomic distortion and easier access to the glottis inlet. Second, particularly in patients with low oropharyngeal volume and dimension, reduced compliance, or both, a stylet with a smaller blade and even with a swan-neck bend will often deal effectively with airway angles that prove to be irreducible and challenge even the dedicated stylet currently available.
Conclusion Skeptics might argue that there is insufficient evidence gathered to date to conclude that the GVL represents a new paradigm in airway management. They might be correct, but in this author’s opinion, if this conclusion is not accurate now, it is inevitable – it is only a matter of time. Like the laryngeal mask airway device beforehand, the GVL has made an important impact on airway management in anesthesia practice and has provided a means to deliver safer care. It is incumbent upon us to develop the skills necessary to leverage this gift optimally in order to ensure that our patients derive full benefit from this innovation.
Key points •
The GlideScope video laryngoscope (GVL) consistently improves the laryngeal view in patients with a Cormack-Lehane view C 2 with the direct laryngoscope (DL).
•
Use of the GVL in the setting of both difficult and failed laryngoscopy typically results in successful tracheal intubation. Novice users may experience higher levels of success earlier in their experience with the GVL when compared with the DL. Increased experience with the GVL is associated with an increased likelihood of successful rescue of failed intubation with the DL.
•
•
123
•
Complications with the GVL are uncommon but usually involve soft tissue injuries related to endotracheal tube passage after the GVL has been placed in the airway.
Conflicts of interest Funding sources
None declared.
None.
References 1. Mort TC. Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesth Analg 2004; 99: 607-13. 2. Hung OR, Pytka S, Morris I, Murphy M, Stewart RD. Lightwand intubation: II - Clinical trial of a new lightwand for tracheal intubation in patients with difficult airways. Can J Anaesth 1995; 42: 826-30. 3. Crosby ET. Techniques using the Bullard laryngoscope. Anesth Analg 1995; 81: 1314-5. 4. Shulman GB, Nordin NG, Connelly NR. Teaching with a video system improves the training period but not the subsequent success of tracheal intubation with the Bullard laryngoscope. Anesthesiology 2003; 98: 615-20. 5. Kaplan MB, Ward DS, Berci G. A new video laryngoscope – an aide to intubation and teaching. J Clin Anesth 2002; 14: 620-6. 6. Jungbauer A, Schumann M, Brunkhorst V, Borgers A, Groeben H. Expected difficult tracheal intubation: a prospective comparison of direct laryngoscopy and video laryngoscopy in 200 patients. Br J Anaesth 2009; 102: 546-50. 7. Cooper RM. Use of a new videolaryngoscope (GlideScope) in the management of a difficult airway. Can J Anesth 2003; 50: 611-3. 8. Agro F, Barzoi G, Montecchia F. Tracheal intubation using a Macintosh laryngoscope or GlideScope in 15 patients with cervical spine immobilization. Br J Anaesth 2003; 90: 705-6. 9. 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. 10. Sun DA, Warriner CB, Parsons DG, Klein R, Umedaly HS, Moult M. The GlideScope Video Laryngoscope: randomized clinical trial in 200 patients. Br J Anaesth 2005; 94: 381-4. 11. Fridrich P, Frass M, Krenn CG, Weinstabl C, Benumof JL, Krafft P. The UpsherScopeTM in routine and difficult airway management: a randomized, controlled clinical trial. Anesth Analg 1997; 85: 1377-81. 12. Griesdale DE, Liu D, McKinney J, Choi PT. Glidescope videolaryngoscopy versus direct laryngoscopy for endotracheal intubation: a systematic review and meta-analysis. Can J Anesth 2012; 59: 41-52. 13. Healy DW, Maties O, Hovord D, Kheterpal S. A systematic review of the role of videolaryngoscopy in successful orotracheal intubation. BMC Anesthesiol 2012; 12: 32. 14. Kory P, Guevarra K, Mathew JP, Hegde A, Mayo PH. The impact of video laryngoscopy use during urgent endotracheal intubation in the critically ill. Anesth Analg 2013; 117: 144-9. 15. Aziz MF, Healy D, Kheterpal S, Fu RF, Dillman D, Brambrink AM. Routine clinical practice effectiveness of the Glidescope in difficult airway management: an analysis of 2,004 Glidescope intubations, complications, and failures from two institutions. Anesthesiology 2011; 114: 34-41.
SPECIAL ARTICLE
From the Journal archives: Early clinical experience with a new video laryngoscope Edward T. Crosby, MD
Received: 5 October 2013 / Accepted: 18 December 2013 Canadian Anesthesiologists’ Society 2013
Editors’ Note: Classics Revisited Key Articles from the Canadian Journal of Anesthesia Archives: 1954-2013 As part of the Journal’s 60th anniversary Diamond Jubilee Celebration, a number of seminal articles from the Journal archives are highlighted in the Journal’s 61st printed volume and online at: www.springer.com/12630. The following article was selected on the basis of its novelty at the time of publication, its scientific merit, and its overall importance to clinical practice: 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. Dr. Edward T. Crosby provides expert commentary on the problems that the videolaryngoscope addressed and how this intubation tool changed the approach to the airway. Hilary P. Grocott MD, Editor-in-Chief Donald R. Miller MD, Former Editor-in-Chief Article summary Authors Cooper RM, Pacey JA, Bishop MJ, McCluskey SA. Citation Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients. Can J Anesth 2005; 52: 191-8.
E. T. Crosby, MD (&) Department of Anesthesia, The Ottawa Hospital – General Campus, University of Ottawa, Suite CCW1400, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada e-mail: [email protected]
Purpose This investigation was an observational study designed to evaluate the newly developed GlideScope video laryngoscope (GVL) and to assess its ability both to provide a laryngeal view and to facilitate intubation. Principal findings The study, which was conducted from November 2001 to March 2003, included 133 operators from five centres (Ontario and British Columbia, Canada and Washington State, USA) involving 728 patients. The resulting Cormack-Lehane (C/L) laryngeal exposure was excellent (1) in 92% of patients and good (2) in 7% of patients. The GVL provided a comparable or superior view in the 133 patients in whom both the GVL and the direct laryngoscope (DL) were used. Among the 35 patients with a C/L grade C 3 view with the DL, the view improved to a C/L grade 1 view in 24 patients and a C/L grade 2 view in three patients. Tracheal intubation with the GVL was successful in 96.3% of patients and failed in 3.7%. Fifty-four percent of the failed intubations occurred despite achieving a C/L grade 1 view and resulted from the inability to direct the endotracheal tube toward a clearly seen larynx. Conclusions The GVL consistently yielded a comparable or superior glottic view compared with the DL despite the operators’ limited or lack of prior experience with the device. Successful intubation was typically achieved even when direct laryngoscopy was predicted to be moderately or considerably difficult. Not only was the GVL a novice-friendly device, this novel study also suggested that a video laryngoscope might provide superior performance when compared with the DL, particularly in patients in whom the DL provided a poor laryngeal view.
Issues in airway management As part of efforts undertaken over the last several decades to improve the safety of anesthesia, airway management
123
E. T. Crosby
during anesthesia care has come under considerable scrutiny. At the outset of this process, esophageal intubations were acknowledged as being associated with severe patient morbidity and mortality. This complication was subsequently managed effectively using capnography, which became routine in the 1980s. Difficult intubation was another complication recognized as leading to occasional but also severe patient injury. At the time, the principal instrument available for airway management was the direct laryngoscope (DL) with either a curved Macintosh blade or a straight Miller-type blade. The DL was effective in facilitating tracheal intubation in the vast majority of patients, but it was difficult to use in a small population and impossible to use in an even smaller cohort. The common strategy to deal with difficult laryngoscopy was to make repetitive attempts, although perhaps with different and successive laryngoscopists. This strategy was eventually recognized as contributing to adverse patient outcomes rather than avoiding them, and as a result, different solutions were sought.1
Early innovations A large number of innovations were marketed to address the issue of difficult direct laryngoscopy. One of the more successful alternate technologies was the TrachlightTM lighted stylet. Introduced in the early 1990s, it became a popular device in Canada in the setting of anticipated difficult, difficult, and failed direct laryngoscopy before recently being removed from the active market.2 Thanks to technological improvements, fibreoptic laryngoscopes, including the WuScope, UpsherTM and BullardTM laryngoscopes, were introduced into the market at around the same time. Of the three, only the Bullard achieved some market penetration, although uptake was limited. The Bullard laryngoscope seemed to be of value in addressing some cases of difficult laryngoscopy; however, most reports were of individual cases or limited case series, and articles of large series or comparative studies were lacking. One article reported applying a surgical camera to the Bullard laryngoscope to create a video-enabled laryngoscope. The video component may have enhanced learning, but no evidence was advanced to support superior laryngoscope performance with video-enabling.3,4 In 2002, Kaplan et al. reported use of a video-integrated laryngoscope using a modified Macintosh blade with a camera and light bundle incorporated into the handle and the image displayed on a monitor.5 The Berci-Kaplan video laryngoscope (BKL) was used in 217 anticipated easy and 18 anticipated difficult intubations, and success was achieved in all but one of the easy intubations. The particular emphasis of this publication related to the value
123
of the video capability for teaching rather than for the management of difficult airways. It was only in 2009 that Jungbauer et al. reported that the BKL provided superior performance when compared with the DL in a population at risk for difficult laryngoscopy.6
Video laryngoscopy The GlideScope video laryngoscope (GVL) arrived on the scene at about the same time as the BKL. The GVL was invented by two Canadians, biomedical engineer Awni Ayoubi and vascular surgeon, Jack Pacey. The GVL initially comprised a black and white camera incorporated into a newly conceived curved blade attached to a dedicated monitor. The impetus for this innovation was to reduce the occurrence of failed intubation experienced with the DL.A The initial limited applications and small case series (including one by RM Cooper in the Journal in 2003) were encouraging7,8 and larger field trials were designed. Cooper et al. were first to publish a large series of patient applications, followed shortly thereafter by Sun et al.9,10 In Cooper et al.’s observational study, the authors analyzed GVL use by 133 operators in five centres involving 728 consecutive patients. Many of the operators had limited or no previous exposure to GVL use—experience ranged from that of students to senior anesthesiologists. Individually, they performed from one to 115 interventions each. Excellent or good laryngeal exposure was obtained in 92% and 7% of patients, respectively. The GVL provided a comparable or superior view to that obtained with the DL in the 133 patients in whom both the GVL and DL were used. Among the 35 patients with a Cormack-Lehane (C/L) grade C 3 view with the DL, the view improved to a C/L grade 1 view in 24 patients and a C/L grade 2 view in three patients with the GVL. Intubation with the GVL was successful in 96.3% of patients and failed in 3.7%. Fifty-four percent of the failed intubations occurred despite achieving a C/L grade 1 view and resulted from the inability to direct the endotracheal tube toward a clearly seen larynx.
Interpretation This report showed that the performance of the GVL was at least similar overall to that expected from the DL. This was an important finding because some alternatives previously introduced to the market were actually less effective when compared with the DL.11 Success with GVL use was also high despite the limited experience of many of the A
Jack Pacey, personal communication.
Key article from the journal archives
operators. This suggests that either the GVL was inherently easy to use or perhaps the video interface facilitated success by allowing supervisors to guide novice use of the device. Cooper et al. reported that the GVL was capable of providing an improved laryngeal view in some patients in whom DL could not. Sun et al. provided support for this opinion when they compared performance of the two devices in 200 patients. Using the GVL improved the C/L grade in the majority of patients who initially had a C/L view [ 1.10 All in all, this was pretty exciting stuff! Here was a device which, on first large-scale application, seemed easy to use, was very effective in achieving its purpose, and might actually perform better than the current technology, the old and reliable DL. Nevertheless, although unsuccessful intubation with GVL use was relatively uncommon, there was a concern that failure mostly occurred in the setting where a good to excellent laryngeal view could be obtained and yet the endotracheal tube could not be successfully directed into the larynx. Cooper et al. reported a number of findings requiring confirmation before larger-scale adoption of the GVL could be encouraged with confidence. First, would the GVL prove to be as consistently successful as the DL when applied to a general patient cohort by a larger variety of operators? Second, could the GVL be confirmed to provide superior laryngeal views when compared with the DL in settings of difficult laryngoscopy? Third, would novice users enjoy higher success rates with the GVL than with the DL, and could they achieve proficiency earlier in their experience? Finally, was there a solution for the cohort of patients in whom an excellent laryngeal view could be obtained and yet the endotracheal tube could not be successfully inserted? Specifically, was there a technical application for the GVL that would more likely result in a favourable outcome than the approach employed in the study, or would additional experience with the device enhance prospects for success?
Subsequent studies Multiple studies were published addressing some of the questions raised, and eight years after Cooper et al.’s reported observations on the early experience with the GVL, Griesdale et al. summarized the results with a metaanalysis of 17 trials comparing the GVL with the DL in 1,998 patients.12 Use of the GVL was associated with an improved C/L view (particularly in patients with potential or simulated difficult airways), improved success at firstattempt intubation, and less time to intubation. After performing a systematic review of 77 articles from the literature assessing the efficacy of modern video
laryngoscopes, Healy et al. reported that the GVL provided better laryngeal views than the DL and a higher rate of successful intubation in patients assessed to be at increased risk of difficult direct laryngoscopy.13 In patients who had experienced previous difficult laryngoscopy (C/L view C 3), evidence showed improved views and a higher level of success. Finally, in patients with failed direct laryngoscopy, case series evidence showed improved views and a higher level of overall success when the GVL was compared with the DL. Overall, in response to the first two questions posed, recent evidence seems to confirm Cooper et al.’s conclusions: the GVL is probably at least as effective as the DL for routine laryngoscopy and intubation, and the GVL is likely more effective than the DL in patients for whom laryngoscopy is difficult.
A teaching aid The video capability of the GVL may enhance the rate of skills acquisition and steepen the slope of the learning curve in novices, thus enhancing the likelihood of initial success. Kory et al. assessed the GVL as the primary intubating device during urgent intubation in critically ill patients when performed by non-anesthesia critical care fellows, and they compared this experience to that of a historical cohort of fellows using the DL.14 The firstattempt success rate was 91% with the GVL compared with 68% with the DL. The incidence of intubations requiring C three attempts was 4% with the GVL vs 20% with the DL. Unintended esophageal intubations did not occur with the GVL but occurred in 14% of patients with the DL, and the average number of attempts required for success was less with the GVL. The optimal number of tries required to achieve proficiency or expert status with the GVL has not been determined, but Aziz et al. reported improved performance (higher rates of salvage of failed intubation) with increased use, even if the differences in experience were modest in the groups compared.15 The experience to date seems to confirm the view of Cooper et al., i.e., early success for novice users is more likely with the GVL than with the DL, and the number of procedures required to achieve proficiency may prove to be not more and possibly less than with many other airway devices.
Endotracheal tube insertion Cooper et al. commented that an excellent laryngeal view could be obtained in some patients, and yet, the endotracheal tube could not be inserted successfully. In fact, this complaint is still heard from both novice and infrequent users and has prompted the manufacturer of the
123
E. T. Crosby
GVL to release a dedicated stylet to help reduce the incidence of this event. It is the author’s view that this occurrence could be reduced to a relatively rare event with both increased experience with GVL use and deference paid to a number of considerations. First, in some patients, progression from a C/L grade 2 view to a C/L grade 1 view is achieved by rotating the blade closer to the glottis, an approach that improves the view but also displaces the glottis more anteriorly. This technique not only makes it more difficult to access the glottis inlet with the endotracheal tube but also increases the angle of the subsequent turn the tube must take to enter the trachea without abutting the anterior wall. Accepting a grade 2 view will often result in less anatomic distortion and easier access to the glottis inlet. Second, particularly in patients with low oropharyngeal volume and dimension, reduced compliance, or both, a stylet with a smaller blade and even with a swan-neck bend will often deal effectively with airway angles that prove to be irreducible and challenge even the dedicated stylet currently available.
Conclusion Skeptics might argue that there is insufficient evidence gathered to date to conclude that the GVL represents a new paradigm in airway management. They might be correct, but in this author’s opinion, if this conclusion is not accurate now, it is inevitable – it is only a matter of time. Like the laryngeal mask airway device beforehand, the GVL has made an important impact on airway management in anesthesia practice and has provided a means to deliver safer care. It is incumbent upon us to develop the skills necessary to leverage this gift optimally in order to ensure that our patients derive full benefit from this innovation.
Key points •
The GlideScope video laryngoscope (GVL) consistently improves the laryngeal view in patients with a Cormack-Lehane view C 2 with the direct laryngoscope (DL).
•
Use of the GVL in the setting of both difficult and failed laryngoscopy typically results in successful tracheal intubation. Novice users may experience higher levels of success earlier in their experience with the GVL when compared with the DL. Increased experience with the GVL is associated with an increased likelihood of successful rescue of failed intubation with the DL.
•
•
123
•
Complications with the GVL are uncommon but usually involve soft tissue injuries related to endotracheal tube passage after the GVL has been placed in the airway.
Conflicts of interest Funding sources
None declared.
None.
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