Advancing Airway Management: Video Laryngoscopes

In our last article we discussed the use of channeled optical and video laryngoscopes to obtain improved glottic views and increase intubation success rates. This month we are going to look at non-channeled video laryngoscopes and how they can improve intubation success rates, particularly in the predicted difficult airway patients. Our two representative, but non-exclusive, devices are the Verathon® GlideScope Ranger and the McGRATH® Series 5 video laryngoscopes.

The GlideScope GVL produced by Verathon Inc. was first described in the literature in early 2003 as an alternative indirect video laryngoscope for intubation of the predicted difficult airway patient by Agro, et el. Since that time the GlideScope line of indirect laryngoscopes has evolved and the GlideScope Ranger is their primary model marketed for EMS use. Each videoscope utilizes a rigid, disposable or non-disposable stat positioned around the base of the tongue with the tip placed at the vallecula. A video screen connected by a protected cable to the stat then displays a video image of the structures visualized within the patient’s posterior pharynx. Once visualization of the glottis is obtained, a styletted endotracheal tube—using either the proprietary GlideRite® stylet, or any other stylet that is shaped similarly—is placed into the corner of the patient’s mouth under direct visualization. The tube is advanced into the posterior pharynx and rotated so the tip of the tube just disappears behind the tongue. The clinician then returns their view to the video monitor, identifies the tip of the ETT with only minor manipulation of the stylet if necessary, and then advances the tube tip under video visualization to the entrance of the glottis. The ETT is then advanced carefully off from the stylet and gently into the glottis, and positioned at an appropriate depth for the patient. The stylet is removed, followed by the stat, and the ETT is secured and utilized per normal fashion. This approach is comparable to other similar video laryngoscopes such as the KARL STORZ® C-MAC.

Success using this the GlideScope has been demonstrated by a number of different studies and with a wide variance of clinical experience. In the Armstrong, et el study published in the June 2010 Anaesthesia, the success of visualization of the glottis was measured in pediatric patients with known difficult or failed airways prior. After generalized induction the experienced clinician performed direct laryngoscopy (DL) with a standard blade, recording the laryngoscopes’ view and the time to obtain this view. The clinician then switched to the GlideScope and performed indirect laryngoscopy recording the same parameters. The study found there was a significant improvement in the laryngoscope view with the GlideScope compared to DL. Time difference to obtain the view between the devices was not significant. This study showed a clear advantage of the video laryngoscope in comparison to DL for the experienced provider in laryngoscope view.

Since EMS involves patients who are not always in optimum positioning for airway management, a study completed by Nakstad & Sandberg in 2009 compared the GlideScope® Ranger versus the standard Macintosh blades in simulated patients positioned in two different positions. The first scenario provided the manikin in an unrestricted access position in an ambulance. All clinicians successfully intubated the manikin utilizing both the GlideScope Ranger and traditional DL. In the second scenario the manikin was positioned with no access from the head-end, as might occur with an entrapped patient. All clinicians attempted intubation of the manikin in this position. Surprisingly, only 50% succeeded in endotracheal intubation with standard DL, while 100% of the clinicians were successful with use of the GlideScope Ranger. This study clearly demonstrates the GlideScope Ranger is superior to DL in the access-limited patient.

The most recent study comparing video laryngoscopy to DL was Sakles, et el., December 2012 in Annals of Emergency Medicine. In this retrospective review of 750 intubations performed in an emergency department setting, 255 C-MAC intubations were compared to 495 Macintosh blade intubations. First pass success occurred in 79.2% of the patients with the C-MAC versus 73.1% with DL. Total airway success was 97.3% with the C-MAC versus 84.4% with DL. In addition the C-MAC was chosen more often for predicted difficult airway patients and trauma patients then DL. This study shows real world clinical evaluation of not only obtaining a view but also achieving endotracheal intubation.

The McGRATH Series 5 video laryngoscope is representative of another group of devices that place the video screen directly on top of the handle. This eliminates the cable running from the blade stat to the video monitor. Other devices in this category are the KARL STORZ C-MAC with the Pocket Monitor™, the McGRATH Mac™ and the KingVision™ with non-channeled blade, among others.

The McGRATH Series 5 video laryngoscope was evaluated for glottic view and intubation success in a well-designed prospective study completed by Noppens, et el and published in Anaesthesia, 2010. In this study of 61 patients, who had poor glottic visualization by a standard Macintosh blade, significant improvements in visualization of the glottis were obtained with the McGRATH. Specifically, 10% of the patients had a single grade view improvement, 80% by two grades and an additional 10% by three grades. This is a significant finding since it is well documented that patients with a grade III or grade IV view during DL have a decreased success with endotracheal intubation and increased complications.

Increasing intubation successes through use of non-channeled video laryngoscopes represent another viable option when moving from traditional DL to video laryngoscopy. The choice of device depends on many factors, including but not limited to: proven success; familiarity; ease of use and training; initial cost of procurement; on-going costs; and the specific operating environment. In an upcoming article we will break these factors down and compare DL to both channeled and non-channeled video devices to help identify what will be the best tool for a particular operation. Until then, happy intubations.

References

1. Wetsch WA, Carlitscheck M, Spelten O, Teschendorf P, Hellmich M, Genzwürker HV, Hinkelbein J. Success rates and endotracheal tube insertion times of experienced emergency physicians using five video laryngoscopes: a randomised trial in a simulated trapped car accident victim. Eur J Anaesthesiol. 2011 Dec; 28(12):849–58.

2. Noppens RR, Möbus S, Heid F, Schmidtmann I, Werner C, Piepho T. Evaluation of the McGrath Series 5 videolaryngoscope after failed direct laryngoscopy. Anaesthesia. 2010 Jul; 65(7):716–20

3. Ayoub CM, Kanazi GE, Al Alami A, Rameh C, El-Khatib MF. Tracheal intubation following training with the GlideScope compared to direct laryngoscopy. Anaesthesia. 2010 Jul; 65(7):674–8.

4. Armstrong J, John J, Karsli C. A comparison between the GlideScope Video Laryngoscope and direct laryngoscope in paediatric patients with difficult airways - a pilot study. Anaesthesia. 2010 Apr; 65(4):353–7.

5. Serocki G, Bein B, Scholz J, Dörges V. Management of the predicted difficult airway: a comparison of conventional blade laryngoscopy with video-assisted blade laryngoscopy and the GlideScope. Eur J Anaesthesiol. 2010 Jan; 27(1):24–30.

6. Nakstad AR, Sandberg M. The GlideScope Ranger video laryngoscope can be useful in airway management of entrapped patients. Acta Anaesthesiol Scand. 2009 Nov; 53(10):1257–61.

7. van Zundert A, Maassen R, Lee R, Willems R, Timmerman M, Siemonsma M, Buise M, Wiepking M. A Macintosh laryngoscope blade for videolaryngoscopy reduces stylet use in patients with normal airways. Anesth Analg. 2009 Sep; 109(3):825–31.

8. Walker L, Brampton W, Halai M, Hoy C, Lee E, Scott I, McLernon DJ. Randomized controlled trial of intubation with the McGrath Series 5 videolaryngoscope by inexperienced anaesthetists. Br J Anaesth. 2009 Sep; 103(3):440–5.

9. Sakles, J, Mosler J, Chiu S, Cosentino M, Kalin L. A Comparison of the C-MAC Video Laryngoscope to the Macintosh Direct Laryngoscope for Intubation in the Emergency Department. Annals of Emerg Med. 2012 Dec; 60(6):739–48

Kevin Franklin, CFRN/EMT-P, is currently a flight nurse with West Michigan Air Care in Kalamazoo, Michigan. He is the Utilization Review Coordinator and Credentialing Coordinator for Air Care in addition to his clinical flight nurse responsibilities. Kevin is also involved in inter-facility and scene transport research and is currently the principle investigator for the SAME ETI study in progress at Air Care. In addition, he works with the Western Michigan University School of Medicine, Department of Emergency Medicine as a research coordinator for an active Phase I clinical trial. Kevin is an active lecturer in EMS locally and regionally through Airway Authority Education LLC, a company he co-founded and developed for initial and continuing education of EMS and other professional emergency providers. Kevin is the Midwest Regional Course Director for The Difficult Airway Course: EMS and Fundamentals of Airway Management.

Kevin is board certified in flight nursing by the Board Certification of Emergency Nurses and maintains certification in ACLS, PALS, and NRP as well as instructor certifications in BLS, ACLS and PALS. He has an extensive educational and research background beyond the Paramedic and Registered Nurse degrees that includes an A.D. in Molecular biology, a dual major B.S. in Microbiology and Physiology and attendance of graduate school at Michigan State University in the Department of Microbiology and Molecular Genetics.

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