Airway management: Overview

Abstract
Introduction: Difficult or failed intubation significantly increases the risk of morbidity and mortality. Documentation of a prior difficult or failed tracheal intubation is a strong predictor of future difficult intubation.

Methods: We undertook a quality improvement project to create a redesigned difficult intubation alert with increased visibility in our electronic health record. We sought to determine whether this redesigned alert would be associated with a reduced incidence of difficult intubations. After reviewing many intubation procedure notes, we chose the following criteria to define a predicted future difficult intubation: requiring an awake technique, ease of intubation procedure charted as "difficult" or "unable", procedure requiring flexible bronchoscopy, a procedure requiring three or more attempts, and intubation with a grade three or four view during laryngoscopy. Patients meeting one or more of the above criteria were included in our study. An intervention was implemented which consisted of the introduction of a new difficult intubation alert that could easily be applied to a patient's chart by anyone on the anesthesia team. Further, if the anesthesia clinician filling out the intubation procedure note charted an intubation procedure as "difficult" or "unable", they were prompted by a pop-up asking if difficult intubation should be added to the patient's problem list. If yes was clicked, the electronic alert was activated, and a large red banner appeared. Outcomes included the number of patients who had the difficult intubation label in the pre-intervention period, the number of patients who had the new difficult intubation alert in the post-intervention period, the number of records with ease of intubation procedure charted as "difficult" or "unable", the number of records requiring three or more attempts at intubation, and the number of records with grade three or four view charted at intubation.

Results: There was an expected increase in the application of the difficult intubation alert from 9% of patients with a difficult intubation label in the pre-intervention period to 38% with the redesigned alert in the post-intervention period which was statistically significant (p<0.001). In the 21 months prior to the introduction of the alert, our screening process identified 988 records as predicted difficult intubations. Of these, 672 (68%) were charted by the intubating clinician as actual difficult intubations with 32% not being recorded as difficult. During the 20 months after the end of the interim period, the screening process identified 976 predicted difficult intubations with intubating anesthesia clinicians charting 416 (42%) of them as actual difficult intubations and 58% found not to be difficult. This reduction in monthly median percent of actual difficult intubations was statistically significant (p<0.001).

Conclusions: The introduction of a difficult intubation alert at our institution was associated with a reduced incidence of difficult intubation.

Abstract in English, French
Purpose: There is significant variability in the application of positive end-expiratory pressure (PEEP) in patients undergoing invasive mechanical ventilation. There are numerous studies assessing methods of determining optimal PEEP, but many methods, patient populations, and study settings lack high-quality evidence. Guidelines make no recommendations about the use of a specific method because of equipoise and lack of high-quality evidence. We conducted a scoping review to determine which methods of determining optimal PEEP have been studied and what gaps exist in the literature.

Source: We searched five databases for primary research reports studying methods of determining optimal PEEP among adults undergoing invasive mechanical ventilation. Data abstracted consisted of the titration method, setting, study design, population, and outcomes.

Principle findings: Two hundred and seventy-one studies with 17,205 patients met the inclusion criteria, including 73 randomized controlled trials (RCTs) with 10,733 patients. We identified 22 methods. Eleven were studied with an RCT. Studies enrolled participants within an intensive care unit (ICU) (216/271, 80%) or operating room (55/271, 20%). Most ICU studies enrolled patients with acute respiratory distress syndrome (162/216, 75%). The three most studied methods were compliance (73 studies, 29 RCTs), imaging-based methods (65 studies, 11 RCTs), and use of PEEP-FIO2 tables (52 studies, 20 RCTs). Among ICU RCTs, the most common primary outcomes were mortality or oxygenation. Few RCTs assessed feasibility of different methods (n = 3). The strengths and limitations of each method are discussed.

Conclusion: Numerous methods of determining optimal PEEP have been evaluated; however, notable gaps remain in the evidence supporting their use. These include specific populations (normal lungs, patients weaning from mechanical ventilation) and using alternate outcomes (ventilator-free days and feasibility) and they present significant opportunities for future study.

Study registration: Open Science Framework ( https://osf.io/atzqc ); first posted, 19 July 2022.

Abstract
Before completion of this study, there was insufficient evidence demonstrating the superiority of videolaryngoscopy compared with direct laryngoscopy for elective tracheal intubation. We hypothesised that using videolaryngoscopy for routine tracheal intubation would result in higher first-pass tracheal intubation success compared with direct laryngoscopy. In this multicentre randomised trial, 2092 adult patients without predicted difficult airway requiring tracheal intubation for elective surgery were allocated randomly to either videolaryngoscopy with a Macintosh blade (McGrath™) or direct laryngoscopy. First-pass tracheal intubation success was higher with the McGrath (987/1053, 94%), compared with direct laryngoscopy (848/1039, 82%); absolute risk reduction (95%CI) was 12.1% (10.9-13.6%). This resulted in a relative risk (95%CI) of unsuccessful tracheal intubation at first attempt of 0.34 (0.26-0.45; p < 0.001) for McGrath compared with direct laryngoscopy. Cormack and Lehane grade ≥ 3 was observed more frequently with direct laryngoscopy (84/1039, 8%) compared with McGrath (8/1053, 0.7%; p < 0.001) No significant difference in tracheal intubation-associated adverse events was observed between groups. This study demonstrates that using McGrath videolaryngoscopy compared with direct laryngoscopy improves first-pass tracheal intubation success in patients having elective surgery. Practitioners may consider using this device as first choice for tracheal intubation.