Effect of ultrasound-guided phrenic nerve block on shoulder pain after laparoscopic cholecystectomy—a prospective, randomized controlled trial

Background: Post-laparoscopic shoulder pain (PLSP) frequently follows a laparoscopic cholecystectomy. A proposed mechanism for PLSP is the irritation or injury of the phrenic nerve by the CO₂ pneumoperitoneum during laparoscopic surgery. Here, we investigated whether a phrenic nerve block (PNB), performed under ultrasound guidance, could reduce the incidence and severity of PLSP after laparoscopic cholecystectomy. Method: Sixty patients were randomized into two groups, with one group receiving PNB with 4 ml (30 mg) of 0.75% ropivacaine (group P, n = 28) and a control group (group C, n = 32). The existence and severity of PLSP were assessed for 2 days postoperatively. A pulmonary function test (PFT) and diaphragmatic excursion test were performed pre- and postoperatively. Results: With ultrasound guidance, all PNBs were performed successfully in group P. In group P, the overall incidence and severity of PLSP decreased significantly. There were no significant differences in incisional pain, visceral pain, and analgesic requirements between the groups. Right-side diaphragmatic excursion decreased significantly in group P at 1 h postoperatively. The PFT results and respiratory discomfort assessed by a modified Borg’s scale were not different significantly between the groups. Conclusion: Based on these findings, ultrasound-guided PNB can prevent or reduce the PLSP without clinically significant respiratory discomfort.