Observer Scales of Facial Pain Expression Can Significantly Predict Acute Postoperative Pain in the Recovery Room.

Objectives: Immediately after surgery and general anesthesia patients may experience periods of dizziness, disorientation and sedation, which can hinder valid pain reports. Observational pain assessment, especially focusing on the face, may add to the subjective pain report in the recovery room. With the present study we wanted to put this assumption to test.

Methods: 63 patients wo had undergone a wide range of surgical procedures under general anesthesia were observed twice: 10 and 40 minutes after arrival in the recovery room. At these two time points, a trained examiner observed the patients' facial expression and filled out the face items of the Brief Pain Scale non intubated (BPS-NI) and of the Pain and Impaired Cognition15 (PAIC-15) scale. After that, a nurse asked the patients to rate their pain on a Numerical Rating Scale (NRS).

Results: For both time points, the observer scales significantly predicted NRS ratings, with the BPS-NI being slightly superior (moderate/strong effect sizes) compared to the PAIC-15 (small/moderate effect sizes). On a group level, observational pain assessment showed a decrease in pain across the two time points, whereas NRS ratings remained stable. Despite this disparity, individual changes in pain ratings between the two time points were also significantly predicted by changes in both observer scales (moderate effect sizes).

Discussion: In the recovery room, observational pain assessment can serve as a valid predictor of subjective pain. Thus, in cases where the validity of the pain report may be hampered, especially the face item of the BPI-NI may give substituting information about acute post-operative pain.