The effects of intrathecal fentanyl on postoperative opioid utilization rates in elderly patients undergoing lower extremity orthopedic surgery: a randomized controlled trial.

Background: Various types of lower extremity orthopedic surgeries can cause severe postoperative pain in elderly patients. Achieving adequate pain control while minimizing the use of opioids is advantageous, as it helps reduce postoperative complications and facilitates recovery. In this randomized trial, we compared the opioid utilization rates of elderly patients who received or not receive intrathecal fentanyl as an anesthesia adjuvant.

Methods: A total of 180 elderly patients were enrolled in the study. They were randomly assigned to the BF1 group (bupivacaine plus 25 µg of fentanyl), the BF2 group (bupivacaine plus 50 µg of fentanyl), or the B group (bupivacaine), achieving a final between-group ratio of 2:2:1. Our primary outcome was the rate of opioid use, while secondary outcomes included the NRS score and the utilization rate of analgesic drugs on PODS1-3.

Results: The usage rate of opioid analgesics within the POD3 was higher in B group compared to BF1 and BF2 groups (100% vs. 79.2% and 80.3%, respectively; P < 0.05). However, there was no significant difference in the usage rate of opioid analgesics among the groups within the PODS1-2 (P > 0.05). The incidence of patients with NRS scores ≥ 4 was significantly lower in BF1 and BF2 groups compared to B group on PODS2-3 (POD2, 62.2% and 68.9% vs. 93.8%, respectively; P < 0.05; POD3, 16.2% and 17.6% vs. 40.6%, respectively; P < 0.05). Additionally, BF1 group had a lower incidence of NRS scores ≥ 4 compared to B group on POD1 (P < 0.05). The rate of analgesic drug use was similar among the three groups on POD1-3 (P > 0.05).

Conclusion: In elderly patients undergoing lower extremity surgery, intrathecal fentanyl as an anesthetic adjuvant may correlate with reduced pain scores on PODS1-3 and decreased opioid requirements on POD3.High-dose fentanyl does not provide significant therapeutic advantages.

Trial registration: The study registered on the Chinese Clinical Trial Registry ( www.chictr.org.cn ), Clinical Trials identifier ChiCTR2200058362 (2022/04/07).