Variables associated with successful intubation attempts using video laryngoscopy: a preliminary report in a helicopter emergency medical service

Abstract

Background: Multiple studies have demonstrated varying rates of successful endotracheal intubation (ETI). Until the application of video laryngoscopy, little information regarding prehospital intubation could be analyzed objectively by individuals other than the provider performing the ETI.

Objective: To evaluate the association of variables recorded during video laryngoscopy and successful ETI attempts, defined as placing the endotracheal tube in the trachea.

Methods: We retrospectively reviewed intubations performed by a single helicopter emergency medical service (HEMS) using a video larygoscope from March 1, 2010, to October 1, 2010. All videos were de-identified and analyzed by a single researcher. Time intervals (e.g., attempt time) and intubation process variables (e.g., Cormack-Lehane [C-L] view) were abstracted from all videos. Time intervals were begun when the laryngoscope blade passed the lips and entered the oral cavity (entry). We describe variables using means and standard deviations (continuous), medians with interquartile ranges (ordinal), and percentages with 95% confidence intervals (categorical). We then looked at univariate associations between these variables and ETI success using logistic regression.

Results: We recorded 116 intubations during the study period. Twenty-nine recordings were either incomplete (n = 26) or of insufficient quality for analysis (n = 3). The remaining 87 videos represented 87 different patients with a total of 102 attempts at laryngoscopy. Thirty-six providers performed 64 cases, with the majority of providers (n = 21) performing only one intubation. The first-pass success rate in this series was 76% (n = 66), with 98% success within three attempts. Successful ETI attempts had lower entry-to-percentage of glottic opening (POGO) times (16.6 sec vs. 32.1 sec, p = 0.013), entry-to-first view of the endotracheal tube or entry-to-tube times (17.6 sec vs. 27.4 sec, p = 0.04), higher POGO scores (76 vs. 39, p < 0.001), and a lower C-L view (one vs. three, p < 0.001). Recognized esophageal intubation was more likely to occur during unsuccessful ETI attempts (43% vs. 8%, p < 0.001).

Conclusion: Video laryngoscopy can measure multiple components of ETI performance. Successful ETI attempts have significantly shorter entry-to-POGO times and entry-to-tube times, obtain better views of the glottic opening (POGO and C-L view), and have a lower incidence of recognized esophageal intubation.

Figures

Figure 1

Time interval variables. POGO = percentage of glottic opening.

Figure 2

Consolidated Standards of Reporting Trials (CONSORT) diagram of airway cases.

Figure 3

Attempt time for those with first-pass success (top); any successful attempts, including both first and second attempts (middle); and all unsuccessful attempts whether first or second overall attempt (bottom).