Nerve-stimulator Guided Thoracic Paravertebral Blockade For Thoracotomy

Objective:Nerve-stimulator guided thoracic paravertebral blockade is a new technique, which has been considered as the gold standard instead of thoracic epidural analgesia. There was rarely report about this technique in China. To observe the anaesthesia effect, postoperation pain relief, achievement rate and complications of nerve-stimulator guided thoracic paravertebral blockade for thoracotomy, as well as the impact on haemodynamics. In addition, the influence of the number of injections and different concentrations of local anesthetic solution on clinical efficacy will be assessed in this study.Methods:In the first part,40 patients undergoing thoracotomy were randomly divided into two groups:General Anesthesia group (GA,n=20) and Thoracic Paravertebral Nerve Block combined General Anesthesia (TPVB+GA,n=20).In group GA, patients received endotracheal intubation after intravenous anesthesia indution, In group TPVB+GA, patients received single-injection of thoracic paravertebral nerve block before anesthesia induction. And the injection point was identified due to the operative incision. The changes of arterial pressure and heart rate were observed and measured at the time points of 5,10,15,20, and 30min after the injection of ropivacaine. The dermatomes of intercostals nerver block, the depth from skin to paravertebral space, complications and the achievement rate were also recorded at the meantime. General anesthesia was induced 30 minutes later when the TPVB was completed. Sevoflurane combined anesthesia was given during the operation, and end-tidal concentration maintained 1.0 MAC. Heart rate (HR) and blood pressure(BP) were maintained±25% of base values. To compare the consumption of fentanyl and vasoconstrictor agents (ephedrine), pain grade evaluated visual analogue scale(VAS) of rest and movement at time points of 6,12,24,36,48h after operation, the consumption of supplemental opioid (morphine) administration during the periods of 0-6h (T0-6h),6-12h (T6-12h),12-24h (T12-24h),24-36h (T24-36h),36-48h (T36-48h) after the operation, and the rate of postoperative nausea and vomiting (PONV) was also compared between these two groups. In the second part,40 patients undergoing thoracotomy were randomly divided into two groups:Group 1 received 1 thoracic paravertebral injection(1 injection-TPVB, n=20), group 2 received 3 thoracic paravertebral injections(3 injection-TPVB, n=20). In 1 injection-TPVB group, patients were injected 0.5% ropivacaine (0.4ml/kg) into the thoracic paravertebral space of T4-5 by the nerve-stimulator guided TPVB before regular general anesthesia; while in 3 injection-TPVB group, patients were injected 0.5% ropivacaine into the consecutive dermatomal levels of T3-4, T4-5, T5-6, the total volume of local anesthetic solution was 0.4ml/kg. The dermatomes of intercostals nerver block, radiographic spreading pattern (Omnipaque300mg/ml 10ml), complications and the achievement rate were also recorded at the meantime. General anesthesia was induced 30 minutes later when the TPVB was completed. To compare the consumption of fentanyl and vasoconstrictor agents (ephedrine), pain grade evaluated visual analogue scale(VAS) of rest and movement at time points of Omin,30min, 1h,2h,6h,12h after operation, the consumption of supplemental morphine administration during the periods of 0-2h (To-2h),2-6h (T2-6h),6-12h (T6-12h) after the operation. In the third part,40 patients undergoing thoracotomy were randomly divided into two groups:high concentration group (0.5% ropivacaine, n=20) and low concentration group (0.375% ropivacaine, n=20). The total volume of local anesthetic solution of each group was 0.4ml/kg. The dermatomes of intercostals nerver block, onset time, complications and the achievement rate were also recorded at the meantime. General anesthesia was induced 30 minutes later when the TPVB was completed. To compare the consumption of fentanyl and vasoconstrictor agents (ephedrine), pain grade evaluated visual analogue scale(VAS) of rest and movement at time points of Omin,30min, 1h,2h,6h,12h after operation, the consumption of supplemental morphine administration during the periods of 0-2h (T0-2h),2-6h (T2-6h),6-12h (T6-12h) after the operation.Result:In the first part, five dermatomes of intercostal nerve block(from T4 to T8) were achieved by the nerve-stimulator guided TPVB. The achievement rate was 95%. Inadvertent vascular puncture was seen in 1 patients(5.1%), and there were no other complications. There were no significant changes in arterial pressure and heart rate after the injection of ropivacaine. The total dosage of fentanyl during the operation was more in group TPVB+GA(P<0.05), and the counts of patients who need ephedrine was less in group TPVB+GA(P<0.05). VAS of rest and movement at the time points of 6h,12h was lower in group TPVB+GA(P<0.05), however there was no difference at the time points of 24h,36h,48h between two groups. The consumption of morphine during To-6h, T6-12h was less in group TPVB+GA(P<0.05), however there was no difference during T12-24h, T24-36h, T36-48h between two groups. The rate of PONV was lower in group TPVB+GA(P<0.05). In the second part, the dermatomes of intercostal nerve block were more in 3 injection-TPVB group compare to 1 injection-TPVB(P<0.05), the rate of inadvertent vascular puncture was higher in 3 injection-TPVB group compare to 1 injection-TPVB(P<0.05). The total dosage of fentanyl during the operation was no difference between two groups (P>0.05), and the counts of patients who need ephedrine was was no difference between two groups (P>0.05). There was no difference about VAS of rest and movement at the time points of 0min,30min, 1h,2h,6h,12h after operation between two groups (P>0.05), and there was no difference about the consumption of supplemental morphine administration during the periods of 0-2h (T0-2h),2-6h (T2-6h),6-12h (T6-12h) after the operation(P> 0.05). In the third part, there was no difference about the dermatomes of intercostals nerver block, onset time, complications and the achievement rate between two groups (P>0.05). There was no difference about VAS of rest and movement at the time points of 0min,30min, 1h,2h,6h,12h after operation between two groups (P>0.05), and there was no difference about the consumption of supplemental morphine administration during the periods of 0-2h (T0-2h),2-6h (T2-6h),6-12h (T6-12h) after the operation(P>0.05).Conclusions:Nerve-stimulator guided TPVB is easy to perform and provides wide dermatomes of intercostal nerve block. It can promote relief effect on pain, reduce VAS in the early period after thoracotomy, and decrease the dosage of opioid and incidence of nausea and vomiting. It is especially applicable to thoracotomy because of its higher achievement rate and less complications. As a complement to general anesthesia,1 injection-TPVB can provides wide dermatomes of intercostal nerve block and relief effect on pain with less complications. TPVB can offer satisfied anaesthesia effect with low concentration of local anesthetic solution (0.375% ropivacaine).