Efficacy of femoral periarterial block in preventing thigh tourniquet pain: a randomized controlled trial

BACKGROUND: Tourniquet pain, described as a dull, tight, poorly localized aching sensation, is common in conscious patients. Although various pain-reduction methods have been implemented, none are completely effective. Femoral periarterial block (FAB) has been shown to attenuate tourniquet-induced hypertension in patients undergoing general anesthesia. We aimed to test the feasibility of FAB in inhibiting thigh tourniquet pain in orthopedic patients under conscious sedation.METHODS: Forty-two patients (aged 18-64 years and ASA I-II) scheduled for below-knee orthopedic surgeries with an anticipated tourniquet duration of more than 40 min were recruited and received FAB (Group 1) or not (Group 2). The primary outcome was the occurrence of tourniquet pain. The onset time and severity of the tourniquet pain were recorded. Total doses of sedatives and analgesics administered intraoperatively and hemodynamic changes were documented. The occurrence of local anesthetic systemic toxicity was recorded.RESULTS: Kaplan-Meier time-to-event curves indicated an improved tourniquet tolerance and delayed pain onset. Tourniquet pain occurrence was lower in Group 1 than in Group 2 (30% vs. 95.5%, P=0.02). Tourniquet pain onset was delayed in Group 1 (80[67,84] min vs. 58[51.5,60] min, P<0.01). Fewer patients in Group 1 experienced severe pain (3(15%) vs. 18(81.8%), P<0.01), and less hemodynamic changes (2(10%) vs. 12(54.5%), P<0.01). Local anesthetic systemic toxicity was absent.CONCLUSIONS: FAB, applied with regional anesthesia in patients undergoing below-knee orthopedic surgeries, could reduce thigh tourniquet pain, stabilize blood pressure and heart rate, and prolong tourniquet duration.