Pain assessment in the postanaesthesia care unit using pupillometry

Abstract

Acute postoperative pain is not associated with pupillary diameter or PLRA. Further research is required to develop tools to assess pain in the PACU.

Infrared pupillometry helps to detect and predict delirium in the post-anesthesia care unit

“…When the patient was not able to cover the contralateral eye, the investigator closed it by applying gentle downward traction on the superior eyelid. This procedure was described by Kantor et al [31]. If the patient blinked during the critical measurement period, we stopped the scan and discarded the measurement.…”

“…Pupillary reactivity not only provides insight into the balance between the sympathetic and parasympathetic nervous systems, but also help to evaluate patients during acute neurologic disease [25], titration of anesthetic dose [26] and possibly postoperative recovery from anesthesia, the focus of this study. Previous studies using pupillary light reflex (PLR) in the perioperative environment have focused on intraoperative and postoperative pain [27][28][29], because of the inverse relationship of pupil diameter and administered opioid dose in perioperative patients [29][30][31][32]. One study highlights the potential of pupillometry to quantify subtle changes in neurocognitive states of arousal [25].…”

Pupil diameter during postanesthetic recovery is not influenced by postoperative pain, but by the intraoperative opioid treatment

“…Although neither spontaneous pain before morphine nor pain relief after morphine influenced the baseline PD before the additional noxious stimulation, both variables were well correlated to the intensity of PDR. Kantor et al [14] also measured PD 145 postoperative patients-of which 20% needed morphine for pain relief-without inducing any PDR. Description of the whole sample and the subgroups, as defined according to the need for analgesic intervention (see also Fig.…”

“…Feeling that such conditions were far from the clinical context, the immediate postoperative period was studied. Two similar observational studies failed to find a significant relation between early postoperative pain and PD [13,14].…”

Objective Assessment of Acute Pain

“…Both the pupil diameter response to the noxious stimulus itself and light induced dilatation are thought to reflect sympathetic responses to pain. However, there are inconsistent results regarding the correlation between pupillary responses and post-operative self-reported pain scores [33][34][35]. Responses can also be influenced by drugs including opioids and vasoactive agents, along with environmental luminance and genuine conditions of the eye [36].…”