UCSF

Evaluations of Physiologic and Behavioral Responses to Noxious Procedures in Sedated, Ventilated Critically Ill Adult Patients

Denise Tsai-Yun Liu Li, RN, MS, PhD

Abstract

Acute pain is caused by strong noxious stimulation and is associated with unpleasant sensory and emotional signs and symptoms. The significance of acute pain in critically ill patients in the Intensive Care Unit (ICU) is well documented, yet a standardized objective measure of nociception for use in nonverbal ICU patients remains elusive. The purpose of this dissertation was to evaluate clinically useful physiologic and behavioral indicators of nociception for use in deeply sedated, nonverbal ICU patients.

The first study was a prospective description of mechanically ventilated ICU patients' perceptions of pain, dyspnea, thirst, nausea, hunger, tired/fatigue, anxiety, generalized discomfort, depressed feelings. Fifteen medical and surgical patients who were able to self-reported symptom intensity rated their symptoms by was assessed by using numeric rating scales (0=none, 10 worst possible intensity). The study found that over 33% of the patients experienced moderate to severe pain, thirst, tiredness, anxiety, hunger, and generalized discomfort. The study highlighted the need to develop an objective measure for pain and other symptoms since many ICU patients are not able to provide a self-report.

The second study addressed this problem by examining physiologic and behavioral indicators of pain as proxy measures in patients unable to provide a self-report. We compared changes in heart rate (HR), blood pressure (BP), pupil size, and cortical arousal per the Bispectral (BIS) Index, and behaviors between a noxious procedure [endotracheal suctioning (ETS) or turning] and a non-noxious procedure (gentle touch) in 48 sedated, ventilated ICU patients. Repeated measures of the outcome variables were taken at baseline, during the procedure, and after the procedure. The study found that HR, systolic BP, pupil size, and the BIS Index increased significantly during the noxious condition but not during the non-noxious condition (p<0.01). The effects of the significant changes in these physiologic responses during the noxious condition ranged from 4% (HR) to 16% (pupil size). There were little variations in sedated patients' behaviors during both conditions. The study suggested that certain physiological responses are potentially useful for the assessment of nonverbal patients' pain. Common pain behaviors do not sufficiently reflect sedated patients' response to noxious stimulation.