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Updated: May 5, 2026

Objective Nociceptive Assessment in Ventilated ICU Patients: A Feasibility Study Using Pupillometry and the Nociceptive Flexion Reflex
Published on: July 4, 2018
Responses to noxious stimuli in sedated mechanically ventilated adults
Mary Jo Grap1, Cindy L Munro2, Paul A Wetzel3
1Adult Health and Nursing Systems Department, School of Nursing, Virginia Commonwealth University, Box 980567, Richmond, VA 23298-0567, USA.
Objective:
To determine the effect of sedation on physiologic responses and comfort before, during and after a noxious stimulus (endotracheal tube suctioning).
Methods:
The sample was a subset of a larger, longitudinal descriptive study, blood for endorphins and saliva for alpha-amylase were obtained before and after suctioning. Heart rate (HR), respiration rate (RR), oxygen saturation (SPO2), and arm and leg actigraphy were continuously recorded.
Results:
67 subjects from medical and surgical ICUs were primarily deeply (37%) or mildly sedated (54%) prior to suctioning. Alpha-amylase increased post suctioning (p = 0.04); endorphins did not change (p = 0.58). Neither were modified by sedation. There were no changes in HR, RR or SPO2 post suctioning. Arm (p = 0.007) and leg actigraphy (p = 0.057) changed from baseline and depended on sedation level (p = 0.0005).
Conclusions:
While a stress marker did increase during suctioning, only the measure of patient arm movement was significantly affected by sedation level.
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