| Objective:Under the concept of Enhanced Recovery After Surgery(ERAS)and precision anaesthesia,the ideal goal of subarachnoid block is to adjust the dosing regimen according to individual patient differences,to meet the requirements of surgical analgesia while avoiding adverse effects after subarachnoid block,so that patients can pass through the perioperative period smoothly and safely and achieve rapid This allows the patient to pass through the perioperative period smoothly and safely and achieve a rapid recovery.There are various factors that influence the effectiveness of subarachnoid block,and spinal length is considered to be one of the most important factors in terms of individual patient characteristics.In this study,we investigated the effect of different spine lengths on the half effective dose(50%Effective Dose,ED50)of ropivacaine at the T10 block level in patients scheduled for lower limb surgery under subarachnoid block,in order to guide the precise and rational use of the drug according to individual patient differences.Methods:Fifty-six patients scheduled for lower limb surgery under subarachnoid block were divided into a short spine length group(group S,spine length<63 cm),a medium spine length group(group M,spine length 63 cm-67 cm)and a long spine length group(group H,spine length>67 cm)according to spine length.All patients were punctured at the L3-4 gap and an initial dose of isotonic ropivacaine was injected according to the principle of the sequential method,with the block level reaching at least the T10 level within 20 min and the maximum sensory block level being fixed for>90 min being considered as the effective criteria.When the effective standard is not met,the dose is increased by one level.The difference in dose between each level of isotonic ropivacaine was 0.5 mg,and the study was terminated after 7 inflection points had been obtained.The ED50 and 95%confidence interval(CI)for isotonic ropivacaine were calculated according to the Dixon-Massey formula,and the relationship between the ED50 of isotonic ropivacaine and the length of the patient’s spine was analysed to compare the effect of different doses of ropivacaine on sensory and motor nerve block.The effect of different doses of ropivacaine on the effect of sensory and motor blockade nerve block was compared.Results:Among patients with different spine lengths,the ED50 of isotonic ropivacaine at the T10 level and its 95%CI was 11.60mg(95%CI:11.37～11.84mg)for patients with spine lengths less than 63cm(group S)and 12.91mg(95%CI:12.75～13.08mg)for patients with spine lengths between 63 and 67cm(group M).12.75～13.08mg)and 13.52mg(95%CI:13.36～13.69mg)for patients with a spine length greater than 67cm(group H).The ED50 for subarachnoid block with medium gravity ropivacaine increased with increasing spinal length of the patients,and there were no significant differences in the recovery time of sensory block and the degree and recovery time of motor block between groups or between different ropivacaine doses.Conclusion:In subarachnoid blocks,the ED50 of isotonic ropivacaine at sensory block planes up to the T10 level increased with increasing patient spine length.In patients with different spine lengths,the ED50 of isotonic ropivacaine injected in subarachnoid block for sensory block plane up to T10 level and its 95%CI were Group S:11.60mg(95%CI:11.37～11.84mg);Group M:12.91mg(95%CI:12.75～13.08mg);Group H:13.52mg(95%CI:13.36～13.69mg).It was shown that the dose of medium gravity ropivacaine for subarachnoid block was related to the length of the patient’s spine. |
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