Summary

Background and objectives: To compare pain relief and motor impairment of 0.25% levobupivacaine with either an equivalent (0.25%) or equipotent (0.4%) concentration of ropivacaine for continuous interscalene block after open shoulder surgery. Methods: Seventy-two adult patients scheduled for elective major shoulder surgery received an interscalene injection of mepivacaine 1.5% 30 mL followed by 24 h patient-controlled interscalene analgesia (basal infusion rate: 5 mL h−1; incremental bolus: 2 mL; lockout period: 10 min; maximum boluses per hour: 4) with either 0.25% levobupivacaine (n = 24), 0.25% ropivacaine (n = 24) or 0.4% ropivacaine (n = 24). A blinded observer recorded the evolution of pain relief and recovery of motor block during the first 24 h. Motor function was assessed as the maximum pressure developed while squeezing a sphygmomanometer cuff with the blocked hand. The reduction from preoperative values was considered as an index of motor impairment. Results: No differences were reported among the three groups in the quality of postoperative analgesia. The number of incremental patient-controlled interscalene analgesia doses, total volume of local anaesthetic infused during the 24-h patient-controlled interscalene analgesia, and number of rescue ketoprofen analgesia were higher in the ropivacaine 0.25% group than in the other two groups ( P = 0.0005). The hand strength recovered to ≥90% of baseline values within the first 24 h of infusion in all groups, without differences among the three groups. Conclusion: When providing patient-controlled interscalene analgesia after open shoulder surgery 0.25% levobupivacaine and 0.4% ropivacaine performed equally in terms of pain relief, motor block and number of patient-controlled boluses required, while patients receiving 0.25% ropivacaine needed significantly more boluses and rescue analgesia to control their pain.

Summary

Background and objective: The timing of interscalene block in relation to general anaesthesia remains a controversial subject. We believe that the results of our study demonstrate that this block may be performed safely on anaesthetized patients, providing that certain conditions are met.

Methods: Five hundred and forty-eight cases of arthroscopic shoulder surgery were analysed retrospectively in order to identify the results of interscalene block performed after induction of general anaesthesia, but before the start of surgery. Patients were kept in hospital for 24 h and assessed before being discharged from the hospital and again in the period from 4 to 8 weeks after surgery. Duration of the block, quality of postoperative pain relief and neurological complications were recorded.

Results: Our study failed to reveal any permanent or long-term neurological complications attributable to interscalene block performed after induction of general anaesthesia.

Conclusion: It is our opinion that the primary factor for safe interscalene block is modification of the anaesthetic technique rather than the timing of regional block in relation to induction of general anaesthesia.