Evaluations of physiologic reactivity and reflexive behaviors during noxious procedures in sedated critically ill...

Sedated patients' responses to noxious stimulation are not well characterized. A standardized measure of nociception for use in the intensive care unit (ICU) is elusive. The study aimed to describe cardiovascular and pupil reactivity and behavioral responses between noxious and nonnoxious procedures in sedated ICU patients.

This prospective, descriptive study performed repeated measures using within-subject and crossover techniques. Forty-eight sedated, ventilated cardiac surgery patients from 2 institutions were included. Pupil sizes, heart rate, blood pressure, cortical arousal changes per the bispectral index, and behaviors were recorded at baseline, during, and after a noxious procedure (endotracheal suctioning or turning), and gentle touch.

The majority of patients was deeply sedated with propofol infusion and were unresponsive or responsive only to physical stimulation. Significant changes in heart rate, pupil size, and bispectral index occurred with the noxious procedure but not with the nonnoxious procedure (P < .01). Reflexive behaviors were not evident during both procedures.

Certain physiologic reactions and pupil size changes may be potentially useful nociceptive indicators in ICU settings. Further research is needed to determine the clinical parameters of physiologic response change and to evaluate the effects of opioids and sedatives on these physiologic responses.