Protocol for a prospective, observational cohort study of awareness in mechanically ventilated patients admitted from the emergency department: the ED-AWARENESS study

Abstract

IntroductionAwareness with paralysis is a complication with potentially devastating psychological consequences for mechanically ventilated patients. While rigorous investigation into awareness has occurred for operating room patients, little attention has been paid outside of this domain. Mechanically ventilated patients in the emergency department (ED) have been historically managed in a way that predisposes them to awareness events: high incidence of neuromuscular blockade use, underdosing of analgesia and sedation, delayed administration of analgesia and sedation after intubation, and a lack of monitoring of sedation targets and depth. These practice patterns are discordant to recommendations for reducing the incidence of awareness, suggesting there is significant rationale to examine awareness in the ED population.Methods and analysisThis is a single centre, prospective cohort study examining the incidence of awareness in mechanically ventilated ED patients. A cohort of 383 mechanically ventilated ED patients will be included. The primary outcome is awareness with paralysis. Qualitative reports of all awareness events will be provided. Recognising the potential problem with conventional multivariable analysis arising from a small number of events (expected less than 10—phenomenon of separation), Firth penalised method, exact logistic regression model or penalised maximum likelihood estimation shrinkage (Ridge, LASSO) will be used to assess for predictors of awareness.Ethics and disseminationApproval of the study by the Human Research Protection Office has been obtained. This work will be disseminated by publication of peer-reviewed manuscripts, presentation in abstract form at scientific meetings and data sharing with other investigators through academically established means.

Awareness With Paralysis Among Critically Ill Emergency Department Patients: A Prospective Cohort Study*

“…Prior ED-based sedation research demonstrated clinical practice patterns placing patients at high risk for AWP (12,13,(15)(16)(17)(18)(19)(20)61). Given this, the severe psychologic trauma that can result from AWP, and the paucity of ED-based data, we previously conducted the ED-AWARENESS Study to rigorously assess this complication in mechanically ventilated ED patients (22,23). In that study, 2.9% of patients that were given neuromuscular blockers experienced AWP, with a higher proportion of AWP among patients exposed to rocuronium.…”

“…Sample size rationale was based off of the parent trial (26). Based on our prior work regarding AWP in mechanically ventilated ED patients, we were confident during the planning of the trial that enough AWP events would be detected in order to conduct analyses with sufficient precision (22, 23).…”

“…AWP was the primary outcome. The modified Brice questionnaire was used to evaluate for AWP, as done in multiple studies from the operating room and our prior ED-based work on AWP (3,(22)(23)(24)(25)37). To be considered for a possible AWP event, patients had to report a memory of wakeful paralysis, which could have occurred after losing consciousness (i.e., waking up while under paralysis) or before unconsciousness (i.e., memory of paralysis during intubation).…”

“…These include: 1) high frequency of neuromuscular blockade use in the ED, with an increase in use of longer acting agents (e.g., rocuronium) (11,12), 2) underdosing of IV analgesia and sedation (13)(14)(15), 3) high proportion of patients that receive no sedation after intubation (12,(15)(16)(17)(18)(19), 4) delays in provision of sedation after neuromuscular blockade (16,19,20), and 5) inconsistent monitoring and documentation of sedation depth (12,16,21). For these reasons, our research group conducted the ED-AWARENESS Study to estimate the frequency of AWP in mechanically ventilated ED patients and assess modifiable risk factors associated with its occurrence (22,23). AWP occurred in 2.9% of patients exposed to neuromuscular blockers (approximately 25 times higher than that in the operating room) and was more common in patients receiving rocuronium.…”

The Practice Change and Clinical Impact of Lung-Protective Ventilation Initiated in the Emergency Department: A Secondary Analysis of Individual Patient-Level Data From Prior Clinical Trials and Cohort Studies*

“…With respect to clinical outcomes, the analysis compared outcomes between patients in each intervention period. Data from the ED-AWARENESS Study were excluded from outcome analyses, as survival to extubation was a key inclusion criteria of that study (18, 25). This resulted in a comparatively less critically ill cohort, which would bias clinical outcome results in favor of the intervention period.…”