By John Allen Pacey, MD, FRCSc
In 1829, the first known device for direct laryngoscopy was invented by British physician Benjamin Guy Babington. Later, the work of the widely recognized father of laryngology, Manuel Garcia, led to the first mirror laryngoscope prior to 1849, with a light source later introduced by Alfred Kirstein in 1895.(1)
In the century since then, the devices available to view the larynx have gone through many evolutions. Most devices have been difficult to use, and injuries related to failed or delayed tracheal intubation have resulted. Recognizing that optimal airway management involves the direct visualization of the airway during intubation, modern direct laryngoscopy has produced different blade lengths, prisms and fiber-optic light channels. However, the emergence of video capabilities in the surgical suite was perhaps the most significant step in laryngoscopy development.
Video laryngoscopy systems provide a clear picture of the larynx and vocal cords on a display monitor, enabling control of the endotracheal tube (ETT) in its trajectory toward the airway. This type of clearly displayed view facilitates fast, accurate ETT placement in difficult airways, preventing complications resulting from improper tube placement.
Other advantages of video laryngoscopy compared with older, fiber-optic systems are substantial. Video images are easily stored on servers and low-cost SD cards, and can be transmitted to other users, allowing for remote recording of activity, skills coaching and quality assurance reviews. The use of Internet display is easy either with real-time transmission or by display of the captured images, so that the captured sequences can be used for teaching purposes to improve the skills of many. As HDTV technology improves, so will the image quality of video laryngoscopy. Last, video laryngoscopic techniques are easier to master than those necessary for direct laryngoscopy, an important factor in its successful use by personnel working in less-than-optimal circumstances.
Initial advocates of video laryngoscopy were anesthesiologists in Vancouver, Canada, who performed intubations daily. Such luminaries as Richard Cooper, BSc, MSc, MD, FRCPC; John Doyle, MD, PhD; and Ron Walls, MD, raised questions about the viability of direct laryngoscopy compared with video laryngoscopy and sponsored the adoption of the technology in other areas of the hospital, such as the emergency department (ED) and the ICU. While recognizing the expense of adding the video component, Cooper in particular has commented that video laryngoscopes are “more robust and resistant to damage.”(2) Adoption in EDs and ICUs has been rapid, and it seemed only a matter of time until video laryngoscopy was introduced into prehospital medicine.
The Need in the Field
The literature shows that intubation performed in an out-of-hospital emergency environment carries with it a higher rate of complications and death.(3) Rapid sequence intubation (RSI), called for by Rosen and others, initially appeared to be effective when coupled with direct laryngoscopy (97% in some reports).(4) But optimism dissipated when a 2003 San Diego study reported that 45% of “easy” or successful intubations carried out on head-injured patients were associated with hypoxemia or bradycardia.(5)
In pediatric patients, the literature shows a need for improved methods. A 2000 San Diego study of 305 pediatric patients showed a success rate of 57%, esophageal intubation of 2% and displaced ETT of 15%.6 An older study, from 1989, reported a 50% success rate in children one year in age or younger.(7)
The reasons for these failure rates are obvious to anyone who has worked in the field: the variable intubation skill levels among EMS personnel and adverse conditions, such as weather, limited lighting, foreign bodies in the airway and trauma (leading to hemorrhage and distorted anatomy). Because direct laryngoscopy in these conditions continues to be fraught with difficulty, EMS medical directors are reconsidering their airway management protocols. Although it’s clear some EMS personnel are able to overcome the deficiencies of direct laryngoscopy and produce acceptable results, the failure rates have provoked questions of whether direct laryngoscopy has become a “legacy technique,” introduced when there were no alternatives.(8)
GlideScope in Use
In 2001, the GlideScope® was introduced as the first commercially available video laryngoscope. The device was designed with the recognition that a camera positioned away from the tip of the device would provide the best perspective and enhance visualization. The 60º angle allows for 99% Grade 1 and 2 views.2 Another significant design feature is the device’s unique anti-fog component, which reduces lens contamination.
The GlideScope Ranger single-use laryngoscope—designed to eliminate the need for disinfecting the blade for fast-paced intubation settings—is being used in Iraq and Afghanistan. The backpack-sized, rugged and shockproof version of the original device with an antiglare screen was trialed at the R. Adams Cowley Shock Trauma Center, Fort Sam Houston and Andrews Air Force Base. Following successful trials of the device at these world-renowned medical facilities, the Ranger was deployed in hospitals and combat settings.
In particular, a number of reports from the Canadian Expeditionary Hospital in Kandahar, Afghanistan, involve the management of bloody airways, intubation around expanding hematomas and other challenging ETT exchanges. The Ranger is also in trials with Whatcom County (Wash.) EMS, where the early results are encouraging, according to Medical Director Marvin Wayne, MD.
Aeromedical applications, notably in helicopter environments, are also under study with the GlideScope Ranger. It’s notable that first-time aeromedical users had a high success rate even in the most adverse conditions. Reports of Ranger intubation under unusual conditions include two intubations prior to extrication from crushed vehicles, in flight re-intubation, and in-flight primary intubation (where direct laryngoscope use is limited).
A Look Forward
There’s considerable pressure on EMS to improve successful intubation rates, and the advent of video laryngoscopy designed for the field is poised to produce findings that support its use in this demanding context. How extensive a role this technology will play is complicated by the debate over whether intubation—considered the gold standard in anesthesia practice—is necessary for all compromised airways. EMS personnel work with patients who are often treated under adverse conditions, and there will always be a need for difficult airway management in the trauma setting. A growing amount of evidence supports the view that video laryngoscopy will be a standard in that setting, but more studies are needed before it’s an established reality.
As for speculation about the future of video laryngoscopy in the prehospital setting, aeromedical studies will likely continue to demonstrate the efficacy of RSI using video laryngoscopy. It’s felt that “time on the ground” can be significantly reduced by the use of video laryngoscopy-assisted RSI, either pre-flight or in-flight. Also, many feel RSI coupled with video laryngoscopy will be shown as the most effective strategy for prehospital intubation management, which will likely involve development of supraglottic airway technology.
The cost of failed or difficult intubation can be very high as reflected in a private settlement in excess of $15 million in 2002.(9) There’s also the cost associated with emotional burden to the providers involved, who may face insurmountable obstacles to care.
The added value of video recording will allow medical directors to more accurately measure personnel competency and skill success rates, document the depth of ETT insertion and enhance education. Overall, these devices can aid emergency airway management and likely lead to better patient care—a universal goal of all EMS providers.
1. Proceedings of the Royal Society of London. vii:399–410, 1856.
2. Cooper RM, Pacey JA, Bishop MJ, et al: “Early clinical experience with a new video laryngoscope (GlideScope) in 728 patients.” Canadian Journal of Anaesthesia. 52(2):191–198, 2005.
3. Murray JA, Demetriades D, Berne TV, et al: “Prehospital intubation in patients with severe head injury.” Journal of Trauma. 49(6):1065–1070.
4. Bulger EM, Copass MK, Maier RV, et al: “An analysis of advanced prehospital airway management.” Journal of Emergency Medicine. 23(2):183–189, 2002.
5. Dunford JV, Davis DP, Ochs M, et al: “Incidence of transient hypoxia and pulse rate reactivity during paramedic rapid sequence intubation.” Annals of Emergency Medicine. 42(6):721–728, 2003.
6. Gausche M, Lewis RJ, Stratton SJ, et al: “Effect of out-of-hospital pediatric endotracheal intubation on survival and neurological outcome: A controlled clinical trial.” JAMA. 283(6):783–790, 2000.
7. Aijian P, Tsai A, Knopp R, et al: “Endotracheal intubation of pediatric patients by paramedics.” Annals of Emergency Medicine. 18(5):489–494, 1989.
8. Cooper RM: “Is direct laryngoscopy obsolete?” Internet Journal of Airway Management. Vol. 4, 2006–2007. www.adair.at/ijam/volume04/specialcomment01/default.htm
9. Law Offices of Wade E. Byrd, P.A. 232 Person St. Fayetteville, NC 28301.
Disclosure: The author is the inventor of the GlideScope, and president and research director for Verathon Medical Canada, the makers of GlideScope systems.
This article originally appeared in The Perfect View.