Comparison of ultrasound-guided brachial plexus blocks in different interscalene levels

Abstract

Objective To compare the safety and effectiveness of two different interscalene brachial plexus blocks. Methods Sixty patients scheduled for shoulder surgery (American Society of Anesthesiologists grading I-II) were randomly divided into two groups: those who received ultrasound-guided interscalene brachial plexus block in the sixth cervical vertebra level were chosen as control group (n=30) and those who received in the seventh cervical vertebra level were as experimental group (n=30). They were all injected with 0.5% ropivacaine 10 mL. The incidence of phrenic nerve palsy, results of blood gas before and 30 min after brachial plexus block, brachial plexus block range, motor block of shoulder and duration of analgesia were recorded and evaluated. Results Phrenic nerve block rate of the fourth cervical vertebra in the experimental group was significantly lower than that in the control group (93.3% vs. 33.3%, P 0.05). No statistical difference was found between the two groups in the blood gas before brachial plexus block (P>0.05); 30 min after brachial plexus block, the oxgen partial pressure of the experimental group was significantly higher than that of control group ([78.1±6.3] mmHg vs. [70.2±6.4] mmHg, P 0.05). The motor block of shoulder showed no significant difference between the two groups (P>0.05). There was no significant difference in the duration of analgesia between the two groups ([16.3±4.3] h vs. [15.8±4.1] h, P>0.05). No other complications were noted besides phrenic nerve block in the two groups. Conclusion As compared with the control group, the experimental group has lower phrenic nerve block rate and downward of anesthesia level, and similar analgesic effect. Key words: Ropivacaine; Ultrasound guidance; Interscalene; brachial plexus; Nerve block