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Objective Nociceptive Assessment in Ventilated ICU Patients: A Feasibility Study Using Pupillometry and the Nociceptive Flexion Reflex
Published on: July 4, 2018
Pain assessment in the postanaesthesia care unit using pupillometry: A cross-sectional study after standard
Elie Kantor1, Philippe Montravers, Dan Longrois
1From the Département d'Anesthésie-Réanimation, Hôpital Bichat, AP-HP (EK, PM, DL, JG), Université Paris Diderot, Sorbonne Paris Cité (PM, DL, JG) and INSERM, UMR 738 (JG), Paris, France.
Background:
Patients assess their own pain with a numerical rating scale (NRS). In the postanaesthesia care unit (PACU), NRS helps to determine and monitor analgesic administration, but is useless in patients who are unable to communicate. In non-PACU patients, acute pain increases pupillary diameter and pupillary light reflex amplitude (PLRA), the difference between pupillary diameter before and after light stimulation.
Objectives:
To study the association between postoperative pain (NRS) and pupillary diameter or PLRA in PACU patients after routine anaesthetic care.
Design:
Cross-sectional cohort study.
Setting:
Bichat-Claude Bernard Hospital, Paris.
Patients:
One hundred and forty-five patients undergoing planned surgery under general anaesthesia.
Interventions:
NRS, pupillary diameter and PLRA were measured on arrival in the PACU. When NRS was more than 4, intravenous morphine titration was started and a second measurement performed.
Main Outcome Measures:
Association between NRS and pupillary diameter or PLRA was assessed with Pearson correlation coefficient (r) as was association between changes in these variables after morphine titration.
Results:
Mean NRS was 4.7, and was more than 4 in 79 patients (55%). No statistically significant association was observed between NRS and pupillary diameter (r = 0.10, P = 0.54) or PLRA (r = 0.03, P = 0.72). Twenty-seven patients (19%) received morphine titration with significant decreases in NRS, pupillary diameter and PLRA afterwards. No association was observed between NRS changes and pupillary diameter or PLRA changes.
Conclusion:
Acute postoperative pain is not associated with pupillary diameter or PLRA. Further research is required to develop tools to assess pain in the PACU.
