Optimal Infusion Rate Of Remifentanil For Maintaining Great Pulmonary Compliance In Anesthesia Without Neuromuscular Blocking Agents

ObjectiveTo explore the correlation between the different infusion rates of remifentanil and the changes of pulmonary compliance and respiratory mechanics in patients without neuromuscular blocking agents anesthesia,and to provide a reasonable and valuable reference value for perioperative lung protection during non muscle relaxant anesthesia.MethodsForty five patients（ASAⅠ～Ⅱ,16-50 years old,BMI 18.5-28）who underwent thyroidectomy and intraoperative nerve monitoring in our hospital were selected.The patients were randomly divided into group A and group B,22 patients in group A and23 patients in group B.Breathe oxygen for 3 minutes behind the hood.Both groups of patients were anesthetized with remifentanil,propofol,sufentanil and lidocaine,and then intubated.In group A,remifentanil was first used for continuous infusion of0.1μg·kg^-1·min^-1for 20 minutes;After that,the infusion speed was changed to0.2μg·kg^-1·min^-1for 20min;The infusion speed was changed to 0.4μg·kg^-1·min^-1again for 20min;After that,the infusion speed was changed to 0.2μg·kg^-1·min^-1for 20min;Then the infusion speed was changed to 0.1μg·kg^-1·min^-1for 20min.In group B,remifentanil was first used for continuous infusion of 0.4μg·kg^-1·min^-1for 20 minutes;After that,the infusion speed was changed to 0.2μg·kg^-1·min^-1for 20min;The infusion speed was changed to 0.1μg·kg^-1·min^-1again for 20min;After that,the infusion speed was changed to 0.2μg·kg^-1·min^-1for 20min;Then the infusion speed was changed to 0.4μg·kg^-1·min^-1for 20min.The BIS is maintained at 40-60 by adjusting propofol.Observe and record the airway platform pressure,airway peak pressure,tidal volume,positive end expiratory pressure,end-expiratory carbon dioxide partial pressure,blood oxygen saturation,heart rate and blood pressure of patients in the two groups when the blood concentration of remifentanil at different infusion rates is stable（20 min after infusion）during anesthesia.Results1.During the maintenance of anesthesia without neuromuscular blocking agents,remifentanil was infused at different rates in the two groups,and pulmonary static compliance was recorded and calculated while the blood concentration was stable,when the remifentanil infusion rate was 0.1μg·kg^-1·min^-1and 0.2μg·kg^-1·min^-1,there was no significant difference in static lung compliance between them.Remifentanil infusion rate 0.1μg·kg^-1·min^-1,0.2μg·kg^-1·min^-1,respectively,versus 0.4μg·kg^-1·min^-1,the difference in pulmonary static compliance was statistically significant（P<0.05）,The results of this study show that when the infusion rate of remifentanil is.4μg·kg^-1·min^-1,compared to 0.1μg·kg^-1·min^-1,0.2μg·kg^-1·min^-1,the patient’s pulmonary static compliance is optimal.2.During the maintenance of anesthesia without muscle relaxation,remifentanil was infused at different rates among patients in each group,and when the remifentanil infusion rate was 0.1μg·kg^-1·min^-1.The incidence of choking was significantly elevated at 0.1μg·kg^-1·min^-1.Remifentanil infusion rate was 0.2μg·kg^-1·min^-1versus0.4μg·kg^-1·min^-1,and the incidence of choking on both was not significantly different（P>0.05）.3.Patients were given an infusion of remifentanil at different speeds,and correlation analysis showed that their infusion rate of remifentanil was negatively correlated with the changes in blood pressure and heart rate（P<0.05）.When the remifentanil infusion rate was 0.4μg·kg^-1·min^-1,the incidence of hypotension was significantly higher.4.There was no significant difference in the peak airway pressure,partial pressure of end respiratory carbon dioxide and oxygen saturation between the groups of patients infused with remifentanil at different speeds（P>0.05）.Conclusion2.During the maintenance without neuromuscular blocking agents anesthesia,when the infusion rate of remifentanil is 4μg·kg^-1·min^-1,compared to 0.1μg·kg^-1·min^-1,0.2μg·kg^-1·min^-1,the patient’s pulmonary static compliance is optimal.but it has a large effect on the patient’s mean arterial pressure and heart rate.When the continuous infusion rate of remifentanil was 0.1μg·kg^-1·min^-1,the incidence of cough was significantly increased.