Recall of Awareness During Paralysis Among ED Patients Undergoing Tracheal Intubation

Abstract

Background: Critically ill patients sometimes remember periods of neuromuscular blockade.

Research question: What is the prevalence of recalled awareness during paralysis in patients who underwent emergency tracheal intubation and mechanical ventilation, and what clinical variables are associated with this outcome?

Study design and methods: This study analyzed data from a prospectively collected continuous quality improvement database of emergency tracheal intubation in an urban, county hospital. Patients who received a neuromuscular blocking agent to facilitate emergency tracheal intubation in the ED were included. The database contained details of intubation management, including medications received and patient mental status prior to intubation. Patient recall of awareness of paralysis was assessed by trained staff during an in-person interview following extubation using a modified Brice questionnaire. For this analysis, three expert reviewers used these data to adjudicate whether patients may have had awareness of paralysis, the primary outcome. A logistic regression model was constructed to determine whether clinical variables were associated with the primary outcome.

Results: A total of 886 patients were analyzed. There were 66 patients (7.4%; 95% CI, 5.8-9.4) determined to possibly (61 patients) or definitely (5 patients) have experienced and recalled awareness of paralysis. A logistic regression model revealed that a decreased level of consciousness prior to intubation was associated with lower odds of awareness (adjusted OR, 0.39; 95% CI, 0.22-0.69), whereas the class of neuromuscular blocking agent used, sedative used, preintubation shock index, and postintubation sedation were not significantly associated with recall of this outcome.

Interpretation: Among patients intubated emergently using a neuromuscular blocking agent, 7.4% of patients recalled awareness without being able to move, which was more likely when patients had a normal level of consciousness prior to intubation.

Keywords: awareness of paralysis; critical illness; mechanical ventilation; neuromuscular blocking agents; sedation.