Efficacy of nerve stimulator-guided thoracic paravertebral block in patients undergoing segmental mastectomy

Abstract

Objective To evaluate the efficacy of nerve stimulator-guided thoracic paravertebral block in patients undergoing segmental mastectomy.Methods Fifty ASA Ⅰ or Ⅱ female patients,aged 18-64 yr,with body mass index ＜ 24 kg/m2,undergoing segmental mastectomy,were randomly divided into 2 groups ( n =25 each):thoracic epidural block group (group A) and nerve stimulator-guided thoracic paravertebral block group (group B).In group A,an epidural catheter was placed at T3,4 interspace and 0.5％ ropivacaine 7-10 ml was administrated via the epidural catheter.In group B,thoracic paravertebral block was performed at T4 under the guide of the nerve stimulator and 0.5％ ropivacaine 25 ml was administrated.The perioperative adverse cardiovascular events (hypotension and bradycardia) were recorded.Shivering,chest distress,and dyspnea during operation and nausea and vomiting after operation were also recorded.The range of block on the operated side was determined by pinprick test.The efficacy of anesthesia was evaluated.Results The incidence of shivering,chest distress,and dyspnea during operation and nausea and vomiting after operation was significantly lower in group B than in group A (P ＜ 0.05).Adverse cardiovascular events and respiratory depression were not found in the two groups.There was no significant difference in the range of block on the operated side in the two groups ( P ＞ 0.05).The satisfactory anesthesia was found in 100％ of cases.Conclusion Nerve stimulator-guided thoracic paravertebral block can be safely and effectively used in patients undergoing segmental mastectomy and the efficacy is better than that of thoracic epidural block. Key words: Nerve block; Thoracic vertebrae; Transcutaneous electric nerve stimulation; Mastectomy,segmental