| Background: Due to the wide application of ultrasound in clinical practice and the guidance from Enhanced Recovery After Surgery(ERAS),peripheral nerve block(PNB)is widely used in patients' intraoperative anesthesia management and postoperative analgesia,and more and more related complications,especially local anesthetic systemic toxicity(LAST),are occurring at the same time.Anesthesiologists should be alert for LAST.The LAST clinical symptoms are positively correlated with the plasma local anesthetic concentration,and the prodromal symptoms,such as metallic taste in mouth,auditory disturbances and circumoral numbness,will appear as the blood drug concentration increases.Then central nervous excitation,seizures.Finally,cardiovascular depression,respiratory and cardiac arrest.Previous studies have reported that compared with peripheral nerve stimulators,ultrasound-guided PNB can reduce the incidence of LAST.The mechanism is related to the fact that ultrasound-guided PNB can avoid Local Anesthetics(LAs)intravascular injection,delay the absorption and reduce the amount of LAs.However,these studies mainly focus on superficial nerves,and it is still uncertain whether ultrasound-guided safety is superior to Peripheral nerve stimulator(PNS)for deep nerve block,such as lumbar plexus and sciatic nerve block.The purpose of this study was to investigate the effect of deep nerve block under ultrasound guidance on the incidence of LAST compared with PNS guidance,and to provide clinical basis for the selection of deep nerve block guidance mode in clinical anesthesia.Previous studies mainly included convulsion or cardiac arrest as the LAST inclusion criteria.In this study,the initial symptoms of LAST and mild toxic symptoms of the central nervous system were included in the control study.Although the incidence of LAST may be significantly increased,it has a high clinical significance from the perspective of prevention.Objective: This study aimed to investigate whether deep nerve block under ultrasound guidance could reduce the incidence of LAST compared with deep nerve block under PNS guidance,and to find out the risk factors related to LAST.Methods: This study had been approved by the ethics committee of our hospital and registered in the Chinese clinical trial registry.From June 2016 to June 2018,selected Joint surgery ward who were required to receive lumbar plexus-sciatic nerve block anesthesia for lower limb surgery in our hospital as research objects,and performed lumbar plexus-sciatic nerve block respectively under PNS localization(group N),ultrasound localization(group U)and ultrasound combined with PNS localization(group M).LAs was composed of a mixture of 0.4% ropivacaine and 0.4% lidocaine.The total amount of LAs was determined by the required dose of ropivacaine(3mg/kg),and half of the lumbar plexus nerve and the sciatic nerve were injected.When the total amount of ropivacaine was more than 200 mg,25ml was injected into the lumbar plexus nerve and the sciatic nerve respectively.The formula had been used for a long time in our hospital,Huaxi hospital and other hospitals.The main observation indicator was the occurrence of LAST.Secondary indicators include performance time,number of needle passes and puncture depth.Onset time of sensory and motor block and recovery time of sensory and motor block.Based on LAST's risk factors,preoperatively we addressed the patient's complications,including diabetes,kidney disease,liver disease,and whether infected with Hepatitis B Virus(HBV).Results: 300 patients were enrolled in this study.A total of 18 cases of LAST occurred,with an incidence of 6%.Most of the symptoms were initial symptoms and mild CNS symptoms,with one patient suffering from seizures(incidence: 3/1000)and no respiratory or cardiac arrest.There were 4 cases in N group,12 cases in U group and 2 cases in M group.Through multiple comparisons between groups,the LAST incidence in group U(12%)was significantly higher than that in group N(4%)(P=0.037)and group M(2%)(P=0.006).Of the 18 LAST patients,16 were women.Meanwhile,there were 52 patients with HBV infection and 7 cases of LAST.The Odds Ratio(OR)of HBV infection against women were 3.352(95%CI,1.233 ~ 9.108,P=0.013)and 9.488(95%CI,2.142 ~ 42.093,P=0.0004).The performance time of lumbar plexus block was(72±26.8)s in group U,(68±30.1)s in group N,and(91±42.9)s in group M.Compared with PNS alone or ultrasound localization,ultrasound combined with PNS extended the performance time(P < 0.05).The number of needle passes in the U group(2.4±0.85),N group(2.3±0.97)and M group(2.9±1.21)was higher than that in the PNS alone or in the ultrasound localization group.Sciatic Nerve Blocks(SNBs)performance time in group U(63±17.7)s,group N(63±27.2)s,and group M(81.9±39.1)s.Compared with PNS alone or ultrasound localization,ultrasound combined with PNS prolonged the performance time(P < 0.05).number of needle passes in the U group(2.2±0.63),N group(2.1±0.96)and M group(2.6±1.1)was higher than that in the PNS alone or in the ultrasound localization group.The onset time of LPBs motion block in group N(9.5±3.55)min was significantly shorter than that in group U(11.30±4.94)min and group M(11.10±4.38)min(P < 0.05).Compared with the U group and the M group in SNBs,the onset time of sensory block and motor block in the N group was significantly shortened.Meanwhile,the recovery time of sensory block and motor block in group N was significantly longer than that in group U and group M,and the difference was statistically significant(P < 0.05).Conclusion: Although ultrasound combined with PNS guided deep nerve block could not improve its blocking effect,instead,performance time was prolonged.However,in deep nerve block,the LAST incidence rate of ultrasonography alone was significantly higher than that of PNS localization alone or combined localization.It was suggested that ultrasonography combined with PNS guidance for such nerve block decreased the LAST incidence rate effectively. |
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