Obstructive Sleep Apnea and Postoperative Hyperalgesia in Bariatric Surgery: A Prospective Observational Cohort Study

Postoperative hyperalgesia (POH) is a common clinical phenomenon that will increase the experience of patients' pain. Previous studies have confirmed that surgical site, opioid analgesics, gender, and age were risk factors of POH. Limited research has been investigated to prove the association between obstructive sleep apnea (OSA) and POH. This study investigated the relationship between severity of OSA and POH in patients undergoing bariatric surgery.

We conducted a single-center prospective observational study in the Affiliated Hospital of Xuzhou Medical University from April 2022 to September 2022. Patients were stratified for OSA risk according to their scores of STOP-Bang questionnaire. Postoperative pain was assessed using a 100 mm Visual Analogue Scale (VAS). Mechanical pain threshold was measured with Von Frey filaments in order to determine whether patients developed POH. Characteristic variables were selected by means of least absolute shrinkage and selection operator (LASSO) regression. Multivariate logistic regression was used to identify the independent risk factors associated with POH.

Postoperative hyperalgesia was diagnosed in 69.1% of all patients, and the risk factors for POH were: male(OR, 2.43; 95% CI, 1.04-6.10), age(OR, 2.03;95% CI, 1.28-3.31), BMI≥35 kg·m^-2(OR, 3.13;95% CI, 1.46-6.83), high risk of moderate to severe OSA (OR, 6.43;95% CI, 2.71-15.52), preoperative mechanical pain thresholds(OR, 4.05;95% CI, 2.35-9.14).

Our study found that patients with high risk of moderate to severe OSA were more likely to have postoperative hyperalgesia than those in the low-risk group, and the hyperalgesia was more severe in patients with high risk of moderate to severe OSA within 24 hours after surgery. These results highlight the need for OSA screening in preoperative assessments to mitigate postoperative hyperalgesia.