Introduction: Liposomal bupivacaine has garnered significant interest in the peri-operative arena due to its predicted ability to provide analgesia for up to 60 hours. Multiple studies have now documented varying levels of success with intra-operative administration regarding pain score reporting and narcotic utilization. We aimed to evaluate liposomal bupivacaine (admixed with standard bupivacaine) against standard bupivacaine alone for the purposes of post-op analgesia following surgical sperm extraction.
Methods: Participants were randomized at the conclusion of their sperm extraction to either liposomal bupivacaine or standard bupivacaine. An unblinded surgeon scrubbed the conclusion of the case for purposes of block administration (spermatic cord, scrotal depot), allowing for blinding of the principle surgeon and the patient. Subjects used a numerical rating scale (NRS-11) for quantitating pain during the first 7 days after surgery. Narcotic utilization was also tracked during this time period. Data was collected through an online system that prompted subjects through cellular text messages. Unanswered prompts were followed-up with a phone call from study staff. Area under the curve (AUC) for NRS-11 scores were compared using Welch’s unpaired t-test for 48 hours, 60 hours, and 7 days post procedure. Poisson regression was used to analyze differences in pill counts for the 7 day period.
Results: 50 subjects were randomized 1:1, powered to detect a minimal clinically important difference of 2.4 on the NRS-11 scale. A total of 1750 survey prompts were administered, with a 92% overall response rate. NRS-11 AUC did not differ between arms for the 48 hr, 60 hr, and 7 day post-op intervals (p = 0.38, 0.53, and 0.84, respectively). A statistical difference for narcotic utilization (through post-operative day 7) was not detected. The percentage of patients who did not require any narcotics also did not reach statistical significance (control 56%, liposomal 69%, p=0.46). No significant adverse events were observed.
Conclusions: The addition of liposomal bupivacaine for post-operative pain control following surgical sperm extraction did not alter pain scores or narcotic utilization when powered for a minimal clinically important difference of 2.4 on the NRS-11. Source of