By Simmy Lahori, MD, and Alexander S. Niven, MD
Dr. Lahori is a Visiting Research Fellow in the Department of Radiology and Dr. Niven is Medical Co-Director, Pulmonary Function Laboratory, Education Chair, Division of Pulmonary and Critical Care Medicine, and the Critical Care Independent Multispecialty Practice, Mayo Clinic, Rochester, MN.
SYNOPSIS: In a large, prospective, multicenter, randomized, pragmatic trial, the use of a video laryngoscope resulted in a higher incidence of successful intubation on the first attempt on critically ill patients in the emergency department and intensive care unit compared to the use of the direct laryngoscope.
SOURCE: Prekker ME, Driver BE, Trent SA, et al; DEVICE Investigators and the Pragmatic Critical Care Research Group. Video versus direct laryngoscopy for tracheal intubation of critically ill adults. N Engl J Med 2023; Jun 16. doi: 10.1056/NEJMoa2301601. [Online ahead of print].
Critically ill adults undergo endotracheal intubation outside of the operating room more than 1.5 million times in the United States each year. Risks associated with these emergent procedures include hypoxemia, hemodynamic instability, cardiac arrest, and death, underlining the importance of a systematic approach to optimize physiologic conditions and maximize first-attempt success.1 Although a wide variety of advanced airway devices are available now to help overcome anatomic difficulties and deliver rescue oxygenation, the best evidence-based approach to use these tools in the emergency department (ED) and intensive care unit (ICU) remains poorly defined.2
A difficult airway, defined as either the inability to visualize glottic structures or to intubate the trachea, is encountered in approximately 10% of emergent intubations, and first-attempt failure rates have been reported to be as high as 20% to 30% in prior ED and ICU trials.3 Videolaryngoscopy (VL) was developed to provide better glottic visualization in difficult airway management, and its use has been increasing steadily over time. While it is an appealing alternative to direct laryngoscopy (DL) to improve first-attempt success rates in the acute care setting, prospective studies to date have been limited and have yielded mixed results regarding the benefits of VL in unselected critically ill patients.4
In this large, prospective, randomized, multicenter, pragmatic, clinical trial, Prekker et al compared the first-pass success rate and the frequency of severe complications using either VL or DL during the first intubation attempt in consecutive critically ill adult patients at seven EDs and 10 ICUs in 11 academic medical centers across the United States. Patients who were pregnant, were prisoners, required immediate tracheal intubation that precluded randomization, or situations where the clinician performing the procedure thought the use of VL or DL on the first attempt was either necessary or contraindicated were excluded. Severe complications were defined as severe hypoxemia (SpO2 < 80%), severe hypotension (systolic blood pressure < 65 mmHg), new or increased use of vasopressors, cardiac arrest, or death.
Of the 1,947 patients assessed for eligibility, 1,417 patients were included in the final analysis. The most common reasons for trial exclusion were urgent need for intubation that precluded randomization and clinician decision that VL was required. Approximately 70% of intubations in both arms were performed in the ED, with altered mental status and acute respiratory failure the most common indications for airway management. Patients were well-matched and majority male, with a median age of 55 years, body mass index of 26 kg/m2, Acute Physiology and Chronic Health Evaluation (APACHE) score of 16, and there was a similar distribution of difficult airway features in both groups. Of note, 91.5% of intubations were performed by an emergency medicine resident or critical care fellow, with a median experience of 50 prior procedures (interquartile range [IQR], 25-92). The vast majority of VL procedures were performed using the Storz C-MAC, McGrath MAC, or GlideScope MAC blades, with only 7% using a hyperangulated blade. In nearly all patients who underwent DL, a standard MAC blade was used. A bougie was used instead of a stylet in a little less than one-half of the patients in each group.
Successful intubation on the first attempt occurred in 85.1% of the VL group and 70.8% in the DL group (absolute risk difference, 14.3 percentage points; 95% confidence interval [CI], 9.9 to 18.7; P < 0.001). Glottic visualization was significantly better in the VL group, difficulty with tracheal intubation was similar, and median duration of intubation attempt was surprisingly longer in the DL group, in contrast to prior studies. Severe complications during intubation were similar, occurring in 151 patients (21.4%) in the VL group and 149 patients (20.9%) in the DL group (absolute risk difference, 0.5 percentage points; 95% CI, −3.9 to 4.9). The most common complications were new or increased vasopressor use (12.9% vs. 12.2%, respectively) and SpO2 < 80% (9.7% vs. 10.5%, respectively), with very low rates of hypotension and cardiac arrest compared to prior similar airway management trials in the critically ill.
COMMENTARY
The results of the DEVICE trial are compelling. This was a large, well-conducted, pragmatic, multicenter trial with comparable first-attempt DL intubation rates to prior studies and low overall complication rates, suggesting VL is a more effective and safe strategy to employ in the critically ill. However, there are several important issues to consider regarding the generalizability of these results and their implementation into clinical practice.
This study was conducted at various academic medical centers, and the majority of procedures were performed by trainees. Prior studies have documented major changes in airway management training over the past decade, with a significant increase in VL training and use in emergency medicine and pulmonary and critical care fellowship programs.5-7 In this operator group, nearly 40% had used VL in more than 75% of their prior intubation attempts, and the shorter intubation time with VL compared to DL (in stark contrast to prior studies) suggests greater proficiency with the former technique. Early intubation performance has been shown in smaller studies to be accelerated by the use of VL, presumably because it allows individuals who still are learning upper airway anatomy a better opportunity to identify structures important to intubation success.8 This may explain why the greatest difference in first-pass intubation success using VL was seen in the operators with the least prior intubation experience, and no significant differences between the two techniques were seen in the hands of the most experienced operators. While reported drug utilization would suggest rapid sequence intubation was used in the majority of procedures, the DEVICE investigators do not report if a standard method of patient positioning was required. Poor patient positioning would disproportionately affect glottic visualization and first-attempt success using DL because of the greater importance of airway axis alignment using this technique. Most intubations were performed in the ED, and whether there were significant differences in the patient population or success rates compared to the ICU is unclear.
The majority of the VL intubations in the DEVICE trial were performed with blades of similar shape to a standard MAC DL blade. From a methodologic standpoint, this strengthens the comparison and reduces the risk of confounding from the wide variety of VL blades currently commercially available, but open questions remain as to when hyperangulated blades commonly used with many VL devices should be employed. These blades were designed to provide better glottic visualization in patients in whom airway axis alignment is difficult or impossible. However, the anterior position of the glottis in this setting often requires a similarly angulated, rigid stylet to deliver the endotracheal tube to the glottis, a different intubation technique that can be technically challenging and, in rare cases, result in mechanical injury.9 Retrospective data suggest that first-attempt success rates using VL with standard and hyperangulated blades in the ED are similar.10 However, the most commonly reported successful salvage strategy when VL fails is DL, and, therefore, the more conventional blade selection tested in the DEVICE trial may offer an advantage in these cases.11 Although routine use of a bougie has not been shown to improve first-attempt success in the critically ill, whether VL with a standard blade and bougie should be preferentially used for patients with difficult airway anatomy (a successful salvage strategy reported by other authors) given the low rate of complications in this trial also merits further investigation.12,13
The DEVICE investigators, in line with other investigations in this field, have chosen to include new or increased vasopressor use as a complication in this clinical trial. We would argue that vasopressor use was appropriate, and the subsequent low incidence of severe hypotension and cardiac arrest laudable. Hypovolemia and vasodilation are common at initial presentation in critical illness, which exaggerate the hypotension that occurs with many common induction agents used during intubation. Anticipating and preemptively addressing this expected and harmful physiologic response with early vasopressor use is not a complication, but, rather, good practice and reflective of thoughtful planning, preparation, and teamwork necessary to improve the safety of this common and still unacceptably high-risk procedure in our critically ill patients.14 Therefore, we urge this group and future airway investigators to stop reporting vasopressor use during intubation as a complication.
In experienced hands, the use of DL still appears to be safe and effective for emergent intubation in the critically ill when VL is not available. However, the shifting trends in training and experience, increasing availability of VL in many practice settings, and low complication rates seen in this study all strongly suggest that routine VL use is the future to maximize the safety and first-attempt success of endotracheal intubation in the ED and ICU.
REFERENCES
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- Apfelbaum JL, Hagberg CA, Connis RT, et al. 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology 2022;136:31-81.
- Niven AS, Doerschug KC. Techniques for the difficulty airway. Curr Opin Crit Care 2013;19:9-15.
- Higgs A, McGrath BA, Goddard C, et al. Guidelines for the management of tracheal intubation in critically ill adults. Br J Anaesth 2018;120:323-352.
- Joffe AM, Liew EC, Olivar H, et al. A national survey of airway management training in United States internal medicine-based critical care fellowship programs. Respir Care 2012;57:1084-1088.
- Silverberg MJ, Kory P. Survey of video laryngoscopy use by U.S. critical care fellowship training programs. Ann Am Thorac Soc 2014;11:1225-1229.
- Mosier JM, Malo J, Sakles JC, et al. The impact of a comprehensive airway management training program for pulmonary and critical care medicine fellows. A three-year experience. Ann Am Thorac Soc 2015;12:539-548.
- Howard-Quijano KJ, Huang YM, Matevosian R, et al. Video-assisted instruction improves the success rate for tracheal intubation by novices. Br J Anaesth 2008;101:568-572.
- Levitan RM, Heitz JM, Sweeny M, Cooper RM. The complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices. Ann Emerg Med 2011;57:240-247.
- Mosier J, Chiu S, Patanwala AE, Sakles JC. A comparison of the Glidescope video laryngoscopy to the C-MAC video laryngoscope for intubation in the emergency department. Ann Emerg Med 2013;61:414-420.
- Levitan RM. Video laryngoscopy, regardless of the blade shape, still requires a backup plan. Ann Emerg Med 2013;61:421-422.
- Driver BE, Semler MW, Self WH, et al. Effect of use of a bougie vs endotracheal tube with stylet on successful intubation on the first attempt among critically ill patients undergoing tracheal intubation. JAMA 2021;326:2488-2497.
- Martin LD, Mhyre JM, Shanks AM, et al. 3,423 emergency tracheal intubations at a university hospital: Airway outcomes and complications. Anesthesiology 2011;114:42-48.
- Mayo PH, Hegde A, Eisen LA, et al. A program to improve the quality of emergency endotracheal intubation. J Intensive Care Med 2011;26:50-56.
