Effects of Different 0.2% Ropivacaine Infusion Regimens for Continuous Interscalene Brachial Plexus Block on Postoperative Analgesia and Respiratory Function After Shoulder Arthroscopic Surgery: A Randomized Clinical Trial

OBJECTIVE: Continuous interscalene brachial plexus block (cIBPB) is an effective perioperative analgesic therapy for shoulder arthroscopic surgery (SAS) patients. This trial aimed to compare the effect of different cIBPB infusion methods on postoperative analgesia and respiratory function in patients undergoing SAS. METHODS: After SAS, 88 patients were randomly assigned to four groups. Through interscalene catheter, all the patients received an initial dose of 10 mL 0.2% ropivacaine. The CI group received 0.2% ropivacaine 4 mL/h, and the PIBI1, PIBI2, and PIBI3 groups received intermittent 0.2% ropivacaine boluses at 4 mL/h, 8 mL/2 h, and 12 mL/3 h, respectively. The patients could also use a patient-controlled analgesia (PCA) pump to self-inject a tramadol bolus each time he/she felt pain. The primary outcome was the cumulative tramadol consumption over the 48 h after surgery. Secondary outcome measures included PCA frequency, pain (visual analogue scale, VAS) score, patient satisfaction, diaphragmatic excursion, pulmonary function, and adverse events. RESULTS: The cumulative tramadol consumption and PCA frequency over the 48 h after surgery in groups PIBI2 and PIBI3 were lower than in both the CI and PIBI1 groups (p<0.001). The VAS scores (at rest and on movement) in groups PIBI2 and PIBI3 were lower than those in the CI and PIBI1 groups at 8 and 12 h after surgery (all p<0.001). Patient satisfaction scores were significantly higher in the PIBI2 group than in the other three groups (all p<0.001). Diaphragmatic excursion was significantly decreased in the PIBI3 group compared to the other three groups (p<0.05). The incidence of adverse events over the 48 h after surgery was significantly higher in the PIBI3 group compared to the other three groups (p<0.001). CONCLUSION: Programmed intermittent bolus infusion with 0.2% ropivacaine 8 mL/2 h for cIBPB can achieve lower tramadol consumption, along with better analgesia after surgery, lower reduction in diaphragmatic excursion, lower incidence of adverse events, and higher patient satisfaction.