Intravenous acetaminophen vs. ketorolac for postoperative analgesia after ambulatory parathyroidectomy

Background and methods Minimally invasive parathyroidectomy requires limited analgesia and short recovery times. The preferred post-operative analgesic regimen for this patient population has not been established but non-narcotic components would be quite appropriate. The aim of the study was to determine whether intravenous (IV) acetaminophen (1 g) or ketorolac (30 mg) provide better pain control after parathyroidectomy. A parallel, randomized, double blind, comparative study was completed on 180 patients scheduled for outpatient parathyroidectomy utilizing general anesthesia. Patients were randomized to a blinded administration of either intravenous acetaminophen 1 g or ketorolac 30 mg intra-operatively. Upon arrival but before premedication, baseline pain scores were assessed in all patients. A consecutive series of postoperative pain scores were collected every 15 min using a 10 cm visual analog pain scale (VAS) upon arrival to the post anesthesia care unit (PACU) until discharge by blinded study personnel. Other data collected included: anesthesia time, surgical time, time to discharge, supplemental morphine and postoperative side effects. Results Overall mean postoperative VAS scores were not significantly different between the two treatment groups (p = 0.07). However, ketorolac produced significantly lower pain scores compared with acetaminophen in the later postoperative periods (3.9 ± 1.9 vs. 4.8 ± 2.4 at 45 min, p = 0.009; 3.4 ± 1.7 vs. 4.5 ± 2.1 at 60min, p = 0.04; and 3.2 ± 2.1 vs. 4.4 ± 2.1 at 75 min, p = 0.03). Supplemental morphine was administered to 3 patients in the ketorolac group and 9 patients in the acetaminophen group but total consumption was not significantly different between groups (p = 0.13). The occurrence of nausea was significantly lower in the ketorolac group compared with the IV acetaminophen group (3.4% vs. 14.6%, respectively; p = 0.02). The overall incidence of morphine supplementation, vomiting, headache, muscular pain, dizziness, and drowsiness were not significantly different when compared between the treatment groups. Conclusions Both postoperative regimens provided adequate analgesia but patients receiving ketorolac intraoperatively had significantly lower pain scores at later recovery time points and significantly lower occurrences of nausea. Implications The large volume of patients undergoing parathyroidectomies at our facility warranted a study to develop a standardized postoperative analgesic regimen. We conclude both medications can be utilized safely in this patient population, but there is a slight advantage in pain control with the usage of ketorolac for minimally invasive parathyroidectomies.