Tourniquet use during ankle surgery leads to increased postoperative opioid use

Study objective: Ankle surgery is often done using a tourniquet. Ischemia/reperfusion injury caused by the tourniquet may increase postoperative pain. The study objective was to investigate the amount of opioids given to patients after ankle surgery with and without tourniquet.

Design: We did a cohort study based on data from patient's records between January 2008 and December 2011.

Setting: Information is gathered from operating room, postanesthetic care unit, and surgical ward in a university hospital.

Patients: We identified patients undergoing reconstructive ankle fracture surgery from hospital records. We excluded multiple fractures of the same extremity, major trauma, reoperations, arthrodesis of the ankle joint, and missing data on tourniquet use. We included 603 patients.

Interventions: For each patient, we registered for how long (minutes) the tourniquet was inflated.

Measurements: Main outcome was opioid use during first 24 hours postoperatively (in equipotent intravenous morphine doses). Secondary outcomes were the peak pain on a verbal rating scale, time in postanesthetic care unit, and additional antiemetic medicine. We performed multiple regression to analyze the primary outcome.

Main results: Three hundred fifty-eight patients underwent surgery with tourniquet. There was a correlation between tourniquet time and postoperative opioid use (P value = .001) after controlling for confounders. The slope of the correlation was 0.04 mg/min (95% confidence interval, 0.02-0.07), which means there is an increase in postoperative opioid use by 0.43 mg for every 10 minutes of tourniquet time.

Conclusion: We found an increase in postoperative opioid consumption correlated to tourniquet use. Possible preventive measures with antioxidant treatment to prevent ischemia/reperfusion injury should be investigated.