Sedative use in patients receiving neuromuscular blocking agents from a helicopter flight team

Cognitive awareness under general anesthetic may occur in up to 0.2% of patients, with approximately twice the risk in chemically paralyzed patients. Patients in emergency and critical care areas frequently receive neuromuscular blocking agents (NMBA), but a recent survey indicated that only 90% to 96% of critical care nurses routinely provide concurrent sedative medications to those patients. We sought to determine the potential for awake paralysis in patients transported by helicopter critical care transport teams and to evaluate for associations with clinical factors.

A retrospective review was performed of the rotor-wing transport records of 103 consecutive patients receiving NMBAs and without cardiac arrest during their care. Using hospital-approved pharmacological references, independent reviewers determined whether individual patients were likely to be under the effects of sedative medications during their period of neuromuscular blockade. Descriptive statistics are reported, and the chi-square test was used to evaluate relationships.

The sample population was 70.9% male, 89.3% adult, 53.4% trauma/surgical, 66% interhospital, and 88.3% normotensive (SBP>90 mm Hg). Clinically, 91.3% of patients were judged as probably to have been under the effects of some sedative during their period of paralysis. There was not a significant association between the use of sedatives and any of the factors studied: sex, age, diagnosis, site of origin, flight nurse experience, or systolic blood pressure. Patients most commonly received benzodiazepine alone (70.2%), followed by benzodiazepine+opioid (23.4%), opioid alone (5.3%), and propofol (1.1%). Medication choice was also unrelated to any of the clinical factors studied.

Awake paralysis is difficult to detect but is a serious practice complication. In anesthesia practice, 96% of such cases were considered substandard care, even with prompt recognition and management. Flight nurses administer sedatives at rates similar to other critical care nurses but not to all chemically paralyzed patients. We were unable to identify clinical correlations with medication use or omission. Additional phenomenological and quantifiable evaluations of consciousness during the transport of chemically paralyzed patients would be valuable studies.

Patients receiving NMBAs during transport by helicopter flight teams are at risk for awareness during paralysis. Both practice development and research efforts in this area would be useful.