Effect Of Different Doses Of Compound Sodium Chloride Injection Combined With Norepinephrine On Prevention Of Hypotension After Lumbar Anesthesia In Patients Undergoing Caesarean Section

Objective Hypotension after lumbar anesthesia is the most common anesthesia-related complication in cesarean section.To evaluate the effect of different doses of compound sodium chloride injection combined with norepinephrine on preventing hypotension after lumbar anesthesia in patients undergoing caesarean section by ultrasound evaluation of inferior vena cava.Methods 150 pregnant women aged 18-45 years old,single pregnancy,gestational weeks≥37 weeks,ASA grade II and planned to do elective cesarean section under lumbar anesthesia were included.The parturients were divided into three groups according to different doses of compound sodium chloride injection for maintenance by the random number table method:4ml/kg/h（group A,n=50）;8ml/kg/h（Group B,n=50）;12ml/kg/h（Group C,n=50）.All parturients received compound sodium chloride injection 4ml/kg preload before lumbar anesthesia（complete within 15min）,0.5%hyperbaric bupivacaine 12.5mg was injected to the subarachnoid space for lumbar anesthesia,and immediately given norepinephrine 6ug intravenous injection（BOLUS）+0.05ug/kg/min intravenous pumping when intrathecal administration（stop the drug 5 minutes after delivery）,and volume management was performed in groups.The maximum diameter of inferior vena cava（IVC-max）,minimum diameter of inferior vena cava（IVC-min）and the inferior vena cava collapse index（IVC-CI:[（IVC-max-IVC-min）/IVC-max*100%]）were recorded before fluid preload（T₁）,after fluid preload（T₂）,5min after anesthesia（T₃）,5min after fetal delivery（T₄）and before parturients exit（T₅）.General maternal data,surgical and anesthesia indicators（anesthesia sensory block plane,time of anesthesia administration to fetal delivery,time of surgical incision to fetal delivery,postoperative hospital stay）,incidence of adverse events（hypotension,bradycardia,nausea,vomiting,hypertension）,hemodynamic indicators（heart rate,blood pressure）,neonatal outcomes（umbilical artery blood gas indicators and Apgar score）were recorded.Results The data of 150 parturients were analyzed（50 in group A,50 in group B,and 50in group C）.There was no significant difference in baseline data and general data among the three groups.Compared with baseline（T₁）,IVC-max and IVC-min in all groups increased at T₂,T₃ and T₄.At the time of parturients exit（T₅）;IVC-max,IVC-min,and IVC-CI in group A had no significant changes compared with baseline,IVC-max,IVC-min increased while IVC-CI decreased significantly in group B and C compared with baseline.The interaction of IVC-max,IVC-min and IVC-CI group*time at different times in the three groups was statistically significant（repeated measures ANOVA,P<0.001）.IVC-min of group A（0.99±0.26cm）at T₅（before exit）was smaller than group B（1.17±0.24cm,P=0.003）and group C（1.25±0.29cm,P<0.001）;IVC-max of group A（1.43±0.27）was smaller than group C（1.61±0.32cm,P=0.012）.The IVC-CI of group A was significantly higher than that of group B and C[（31.38±7.69）%vs（24.33±5.13）%and（22.47±4.18）%,P<0.001for all].There was no significant statistical difference in the incidence of hypotension after lumbar anesthesia among the three groups（22.00%vs24.00 vs26.00%,P>0.05）,the incidence of maternal adverse events and neonatal outcomes were not statistically significant.There were no statistically significant differences among other observation indicators.Conclusion Compound sodium chloride injection at rate of 4,8,12 ml/kg/h/combined with norepinephrine contribute the same on preventing hypotension during caesarean section after lumbar anesthesia and does not increase maternal and infant adverse events.The effect of volume supplement of 8ml/kg/h and 12ml/kg/h are better than that of 4ml/kg/h.Maternal volume load was higher than non-pregnant population,8ml/kg/h group was the best choice.