Pupillary reflex measurement predicts insufficient analgesia before endotracheal suctioning in critically ill patients

Abstract

IntroductionThis study aimed to evaluate the pupillary dilatation reflex (PDR) during a tetanic stimulation to predict insufficient analgesia before nociceptive stimulation in the intensive care unit (ICU).MethodsIn this prospective non-interventional study in a surgical ICU of a university hospital, PDR was assessed during tetanic stimulation (of 10, 20 or 40 mA) immediately before 40 endotracheal suctionings in 34 deeply sedated patients. An insufficient analgesia during endotracheal suction was defined by an increase of ≥1 point on the Behavioral Pain Scale (BPS).ResultsA total of 27 (68%) patients had insufficient analgesia. PDR with 10 mA, 20 mA and 40 mA stimulation was higher in patients with insufficient analgesia (P <0.01). The threshold values of the pupil diameter variation during a 10, 20 and 40 mA tetanic stimulation to predict insufficient analgesia during an endotracheal suctioning were 1, 5 and 13% respectively. The areas (95% confidence interval) under the receiver operating curve were 0.70 (0.54 to 0.85), 0.78 (0.61 to 0.91) and 0.85 (0.721 to 0.954) with 10, 20 and 40 mA tetanic stimulations respectively. A sensitivity analysis using the Richmond Agitation Sedation Scale (RASS) confirmed the results. The 40 mA stimulation was poorly tolerated.ConclusionsIn deeply sedated mechanically ventilated patients, a pupil diameter variation ≥5% during a 20 mA tetanic stimulation was highly predictable of insufficient analgesia during endotracheal suction. A 40 mA tetanic stimulation is painful and should not be used.

Pain assessment by pupil dilation reflex in response to noxious stimulation in anaesthetized adults

“…It has been recently demonstrated that PDR can be elicited under general anaesthesia with an automated generated electrical stimulation protocol with increasing intensity 5, 6. These study results were consistent with findings from previous studies with a single (high) tetanic stimulation for PDR elicitation in non‐communicative patients 7, 8, 9…”

“…Although current research addressing this complex issue provides some promising innovative techniques, no standardized objective pain monitoring protocols exist 2. Furthermore, there is a need for consensus to use and interpret different pupil assessment features, such as light‐induced PDR,15, 26 nociceptive stimulation‐induced PDR,8, 27 pupillary unrest,28 constriction velocity and reaction latency29 or PPI score 5…”

Monitoring depth of anesthesia: from consciousness to nociception. A window on subcortical brain activity

“…The monitoring of pupillary diameter might also be relevant in intensive care unit. Indeed, in deeply sedated, mechanically ventilated patients, a pupil diameter variation ≥5% during a 20 mA tetanic stimulation was highly predictable of insufficient analgesia during endotracheal suction .…”

Higher doses of intraoperative analgesia are associated with lower levels of persistent pain and less analgesic consumption six months after total hip arthroplasty

“…Currently, a variety of different tools to measure intraoperative nociception and/or analgesia are under investigation in clinical studies. These are based on a wide range of physiological mechanisms including skin conductance (Storm, ), haemodynamics (Wennervirta et al., ; Rossi et al., ; Gruenewald et al., , ), electroencephalogram (Haenggi et al., ; Sahinovic et al., ) and a variety of nociceptive reflexes (von Dincklage et al., , , ; Paulus et al., ; Guglielminotti et al., ; Ly‐Liu and Reinoso‐Barbero, ; Jakuscheit et al., ). Currently, however, none of the tools have been shown to have enough specificity/sensitivity to outweigh the effort and cost of their routine clinical application (Gruenewald and Ilies, ; von Dincklage, ).…”