| Objective To investigate the effects of phrenic nerve conduction(PNC) latency and compound muscle action potential(CMAP) amplitude of ultrasound-guided interscalene brachial plexus block(ISBPB).Methods 1、75 patients scheduled for ulnoradial fracture internal fixation removal were randomized into group A(0.375% ropivacaine), group B(0.5% ropivacaine) and group C(0.75% ropivacaine), three groups of local anesthetics capacity were 20 ml, There were 25 patients in each group. 2、All patients with routine fasting drink, enter the anesthesia to open the vein channel and routine monitor Electrocardiogram(ECG), noninvasive blood pressure(BP), pulse oxygen saturation(SPO2) without oxygen. 3、After ultrasound-guided ISBPB, PNC latency and CMAP amplitude were measured and recorded by intra-operative neurologic monitoring system before and 15 min, 30 min after drug injection, phrenic nerve conduction studies was over when PNC latency and CMAP amplitude was unavailable or 0, otherwise measurements went on until 30 min after drug injection. 4、All patients enter the anesthesia preparation room 30 min after drug injection, 2L/min oxygen were taken routinely, 0.5ug/kg dexmedetomidinewere given, 3ug/kg/h sustained 10 min by micro pump, fentanyl 0.05 mg was given if anesthesia effect was not perfect 30 min after drug injection, if anesthesia effect was still not satisfied, change the way of anesthesia and the patient was knocked out from experiment. 5、The degree and duration of sensory and motor block, the anesthetic effect and maintain time, the recovery time of motor block were evaluated and recorded 15, 30 min after block, at the same time complications were observed especially respiratory complications. 6、Statistical processing All data were analyzed using SPSS software version 12.0. patients’ general data, PNC latency and CMAP amplitude before drug injection were quantitative data, using single factor analysis of variance, compared the two of SNK-q test. Sensory blockade, motion blockade and PNC latency and CMAP amplitude after drug injection were count data, qualitative data were presented as numbers with percent, and were analyzed using row*column c2 test. P<0.05 was considered had statistical significance.Results 1、General data Comparison of gender, age, height and weight of three groups(P>0.05). 2、Cases of nerve root sensory blockade increased of three groups 15, 30 min after drug injection, compare group A with group B and C, the onset time of the sensory block of C8 and T1 anterior branch prolonged significantly 15 min after drug injection(P<0.05), there was no statistical significance between group B and group C(P>0.05).3、Cases of nerve root motion blockade increased 15, 30 min after drug injection, elbow and activity finger block 15 min after blockade showed group A was statistical difference than group C(P < 0.05), there were no other statistical difference in three groups(P>0.05). 4、There was a case who was too sensitive for current, CMAP amplitude was too high, so the PNC study was failed. The probability of PNC latency and CMAP amplitude unavailable or 0 of group A, B and C 15 min after drug injection were 52%, 88% and 92% respectively, they were 76%, 92% and 92% respectively 30 min after drug injection. 5、There was no case changed anesthetic way 6, 3, 1 of patients with 0.05 mg fentanyl in three groups respectively. There were no statistical difference in complications of three groups(P>0.05).Conclusion 0.375%, 0.5% and 0.75% ropivacaine 20 ml all can provided excellent blockade 30 min after ultrasound-guided interscalene brachial plexus block, while 0.5% and 0.75% ropivacaine provided more rapid onset than 0.375% ropivacaine. The probability of PNC latency and CMAP amplitude unavailable or 0 of group A, B and C 15 min after drug injection were 52%, 88% and 92% respectively, they were 76%, 92% and 92% respectively 30 min after drug injection. |
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