Independent risk factors for postoperative pain in need of intervention early after awakening from general anaesthesia

Despite advances in postoperative pain management, the proportion of patients with moderate to severe postoperative pain is still ranging 20-80%. In this retrospective study, we investigated 1736 patients to determine the incidence of postoperative pain in need of intervention (PPINI)defined as numeric rating scale >4 at rest in the post anaesthesia care unit early after awakening from general anaesthesia, and to identify possible risk factors. The proportion of patients with PPINI was 28.5%. On multivariate analysis, younger age (OR=1.300 [1.007-1.678], p=0.044), female gender (OR=1.494 [1.138-1.962], p=0.004), obesity (OR=1.683 [1.226-2.310], p=0.001), use of nitrous oxide (OR=1.621 [1.110-2.366], p=0.012), longer duration of surgery (OR=1.165 [1.050-1.292], p=0.004), location of surgery (musculoskeletal OR=2.026 [1.326-3.095], p=0.001; intraabdominal OR=1.869 [1.148-3.043], p=0.012), and ASA-PS I-II (OR=1.519 [1.131-2.039], P=0.005) were identified as independent risk factors for PPINI. Patients with PPINI experienced significantly more PONV (10.3% vs. 6.2%, p=0.003), more psychomotor agitation (5.5% vs. 2.7%, p=0.004), needed more application of opioid in PACU (62.8% vs. 24.2%, p<0.001), stayed significantly longer in PACU (89.6min [70-120] vs. 80min [60-100], p<0.001), had a longer median length of hospital stay (6.6 days [4.0-8.8] vs. 6.0 days [3.2-7.8]], p<0.001), and longer postoperative stay (5.0 days [3.0-6.5] vs. 4.1 days [2.5-5.8], p<0.001]). Patients with PPINI required more piritramid (8.0mg [5.0-12.0] vs. 5.0mg [3.0-7.8], p<0.001) in PACU than patients without. The identification of patients at high risk for immediate postoperative pain in need of intervention would enable the formation of effective postoperative pain management programs.