Effect Of Sufentanil Administered Locally On Median Effective Concentration Of Ropivacaine For Thoracic Paravertebral Block

Objetive:To investigate effect of sufentanil administered locally on median effective concentration ropivacaine for thoracic paravertebral block.Methods:Sixty patients with lung disease,aged 30-65years,ASA I or III,no gender and BMI 18²8kg/m²,scheduled for lobectomy under video-assisted thoracoscopic surgery,requiring ultrasound-guided thoracic paravertebral block at the level of T_4-5andT_5-6.All the patients were randomly assigned into 2 groups:Control group（group C）and Test group（group T）.Paravenebral block was performed by using only ropivacaine in groupC.In groupT the mixture of ropivacaine and 0.6ug/ml sufentanil was injected for the block.The concentration of ropivacaine is determined by the up-and-down sequential method.The initial concentration of ropivacaine was0.5%and the ratio between the two successive concentrations was 1.2.If the block was effective.The next patient received a lower dose of ropivacaine,or if ineffective,a higher dose was given to the next patient.End point of study was 7 up-and-down cycles or ropivacaine concentration≤0.1%or≥1%,and continued for 7 cases.The EC₅₀0 and 95%confidence interval（CI）of ropivacaine were determined by using the formula of Dixion-Massey sequential method.The nerve block-related complications and VAS scores,HR,MAP at 4h（T1）,6h（T2）,8h（T3）,12h（T4）,24h（T5）after surgery in the two groups,the total amount of ropivacaine and opioids during the operation,the users of additional analgesic drugs were recorded.Results:The EC₅₀ of ropivacaine was 0.41%and 95%CI was 0.39%⁰.43%in group C,The EC₅₀ of ropivacaine was 0.33%and 95%CI was 0.31%⁰.35%in group T.Compared with group C,the VAS scores,HR and MAP of group T at 8h and 12h after surgery were significantly reduced（P<0.05）.The total amount of ropivacaine and were significantly reduced（P<0.05）;Nausea occurred in 2 patients（9.5%）and vomiting in 1 patient（4.8%）in group T;no adverse reactions related to nerve block occurred in patients in group C;There was no significant difference in the total amount of opioids during the two groups.Conclusions:The combined use of sufentanil can decrease the EC₅₀ of ropivacaine for ultrasound-guided thoracic paravertebral block.