By Lars P. Bjoernsen, MD, & M. Bruce Lindsay, MD
In the prehospital setting, emergency care providers must anticipate difficult airways. Air medical crews in particular are routinely tasked with managing the most difficult airways—those complicated by concomitant head injuries, multisystem trauma or presumed cervical spine injury.
Ideally, an airway should be efficiently secured with the method that offers the greatest safety and the least morbidity. The standard advanced prehospital method in trauma patients has been rapid sequence induction (RSI) oral intubation with direct laryngoscopy, which has been shown to be a safe air medical practice.1
In-flight airway management decision-making and practice are significantly influenced by practice setting and aircraft type, but the success rate of intubation in the air medical service is equal to the prehospital setting overall, with air medical personnel routinely contributing to the prehospital care of injured patients by establishing definitive airways.2 We believe innovative technologies, such as video laryngoscopy, will improve the success rates and decrease the morbidity of prehospital intubation, as it is in our aeromedical practice at the University of Wisconsin Hospitals and Clinics.
Difficult intubation is encountered in approximately 7–10% of patients requiring prehospital emergency endotracheal intubation.3 Stabilization of the cervical spine makes it more difficult to visualize the vocal cords using conventional direct laryngoscopy because optimal alignment of the airway axis requires neck extension.4 Further, cervical collars significantly reduce the ability to open a patient’s mouth, contributing to poor views on direct laryngoscopy.5 In addition, conventional laryngoscopy routinely causes movement of the unprotected cervical spine.6
The prehospital setting itself, particularly in limited workspaces (like that of a helicopter), further increases the difficulty of intubation. And yet, a 1998 study showed that air medical intubations, both pre-flight and en route, for scene calls and interhospital transports, are accomplished with a very high success rate.7
However, in-flight intubation takes approximately twice as long as intubation in a ground setting. This prolongation of intubation is primarily due to problems with positioning of the air medical crew and patient.8 Because a greater success rate is reported when intubation is performed before takeoff, there have been many documented cases in which the crew decided to perform an emergency landing and RSI rather than attempt in-flight intubation.9
Promising New Technology
Studies have proven the video laryngoscope as an effective device for tracheal intubation and shown it provides an improved view of the vocal cords compared with traditional laryngoscopy, even in difficult intubations.10 Although not yet extensively tested in the prehospital setting, case reports show that the video laryngoscope is a promising device for emergency intubation, leading experts to predict that video laryngoscopy will dominate the field of emergency airway management in the future.11
The goal of the video laryngoscope is to facilitate the visualization and recognition of anatomical structures and to facilitate manipulation of airway devices. With its low weight, high-resolution screen and compact size, the portable video laryngoscope has the potential to be a useful device for air medical crews.
Additionally, it provides significant benefit in situations where access to the patient’s head is limited, such as during automobile extrication or in air medical settings when the intubator may be placed adjacent to the patient instead of in line with the patient’s head. The intubator is not required to be “in line” with the patient and therefore can be easily applied in-flight and in other settings with limited space.12
No scientific studies have yet looked at intubation success rates in the air medical setting with video laryngoscopy or evaluated the benefit of intubation in-flight with video versus direct laryngoscopy on the ground. Until those studies have been conducted, we must look to case studies for anecdotal reports of this device’s impact on prehospital airway management, including a case report we have submitted to a peer-reviewed journal.13
Our air medical service was called to the scene of a high-speed motor vehicle crash, where the flight crew intubated a 26-year-old male driver pre-flight (in the ground ambulance). On first contact with the air medical crew, the immobilized patient had a Glasgow Coma Scale of three, with rapid, snoring respirations, a blood pressure of 106/60 and a heart rate of 118. Because of trauma to the head and possible cervical spine injuries, it was anticipated to be a difficult airway case.
While in the ambulance, the air medical crew secured the patient’s airway using RSI and oral-tracheal intubation with a GlideScope® Ranger video laryngoscope. In-line immobilization of the neck was provided by one of the paramedics and cricothyroid pressure held by the other. The GlideScope Ranger video laryngoscope provided an excellent, unobstructed view of the vocal cords and an endotracheal tube was easily passed. The patient was transported by helicopter to the regional Level 1 trauma center, where evaluation revealed extensive multisystem injuries.
We have utilized the video laryngoscope for simulated patients (manikins) in the patient care compartment of both an EC-135 and Agusta 109 Power aircraft. Intubation position varied, both from the head of the patient and next to the patient, during daylight and limited light settings. We found the device easy to use when standard direct laryngoscopy would have been difficult or impossible.
No single airway device offers a solution to all scenarios, but we consider the video laryngoscope a useful addition to the range of devices available to the air medical crew. The use of these devices has been suggested in recent guidelines as an alternative technique in difficult intubations, and case reports have suggested that it can be beneficial when managing a patient with cervical immobilization.13-14
However, no studies yet compare prehospital use of video laryngoscopy and direct laryngoscopy by ground EMS or air medical crews. One randomized, single-blinded study that compares different types of video laryngoscopes and traditional direct laryngoscopy with Macintosh laryngoscope was recently started.15 This study will hopefully provide guidance toward implementation of a video laryngoscope for prehospital difficult airway management.
1. Vilke GM, Hoyt DB, Epperson M: “Intubation techniques in the helicopter.” Journal of Emergency Medicine. 12(2):217–224, 1994.
2. Thomas SH, Harrison T, Wedel SK: “Flight crew airway management in four settings: a six-year review.” Prehospital Emergency Care. 3(4):310–315, 1999.
3. Adnet F, Jouriles NJ, Le Toumelin P, et al: “Survey of out-of-hospital emergency intubations in the French prehospital medical system: A multicenter study.” Annals of Emergency Medicine. 32(4):454–460, 1998.
4. Hastings RH, Wood PR: “Head extension and laryngeal view during laryngoscopy with cervical spine stabilization maneuvers.” Anesthesiology. 80(4):825–831, 1994.
5. Heath KJ: “The effect of laryngoscopy of different cervical spine immobilisation techniques.” Anaesthesia. 49(10):843–845, 1994.
6. Hastings RH, Marks JD: “Airway management for trauma patients with potential cervical spine injuries.” Anesthesia & Analgesia. 73(4):471–482, 1991.
7. Slater EA, Weiss SJ, Ernst AA, et al: “Preflight versus en route success and complications of rapid sequence intubation in an air medical service.” Journal of Trauma. 45(3):588–592, 1998.
8. Stone CK, Thomas SH: “Is oral endotracheal intubation efficacy impaired in the helicopter environment?” Air Medical Journal. 13(8):319–321, 1994.
9. Braude D, Boling S: “Case report of unrecognized akathisia resulting in an emergency landing 10. Rai MR, Dering A, Verghese C: “The GlideScope system: a clinical assessment of performance.” Anaesthesia. 60(1):60–64, 2005.
11. Sakles JC, Rodgers R, Keim SM: “Optical and video laryngoscopes for emergency airway management.” Internal and Emergency Medicine. 3(2):139–143, 2008.
12. Braude D, Richards M: “Rapid Sequence Airway (RSA): A novel approach to prehospital airway management.” Prehospital Emergency Care. 11(2):250–252, 2007.
13. Bjoernsen LP, Parquett B, Lindsay B: “Prehospital use of video laryngoscope by an air medical crew.” Air Medical Journal. In Press (scheduled September/October 2008).
14. Henderson J, Popat M, Latto P, et al: “Difficult Airway Society guidelines.” Anaesthesia. 59(12): 242–1243; author reply 1247, 2004.
15. Samuels J, Brody R: “Comparison study in adult surgical patients of five airway devices.” (Prospective, randomized comparison of intubating conditions with Airtraq Optical, Storz DCI Video, McGRATH Video, GlideScope Video, and Macintosh Laryngoscope in randomly selected elective adult surgical patients.) Weill Medical College of Cornell University: ClinicalTrials.gov identifier: NCT00602979. (Planned start April 2008.)