A Clinical Study On The Relationship Between Length,Abdominal Circumference And The Dosage Of Isobaric Bupivacaine For Subarachnoid Block In Pregnant Women

Objective:In isobaric bupivacaine subarachnoid block,the relationship between spinal length,abdominal circumference and block level was studied to investigate the correlation between spinal length and abdominal circumference and the dose of bupivacaine required for block level,and a regression equation was established.Methods:Term pregnant singleton parturients,aged 20 to 40 years,ASAⅠ～Ⅱ,and BMI<40 kg/m2,who underwent elective cesarean section were selected.All pregnant women:Fasted for 8～10 hours before surgery,intravenous access was routinely established after admission,and 7 mL/kg Ringer’s lactate was given for volume expansion 30 minutes before anesthesia.Routine monitoring,blood pressure,heart rate,respiration,SpO2,measurement of maternal spine length X1(C7～coccyx)and abdominal circumference X2(end-expiratory at the navel level).The needle was inserted through the midline approach at the L2/3 intervertebral space in the left lateral decubitus position,and combined spinal-epidural anesthesia was performed.After successful puncture,1.2～3 ml of 0.5%isobaric(relative cerebrospinal fluid)bupivacaine was injected at a constant rate of 15s,and a 3 cm epidural catheter was catheterized cephalad for future use.The level of arachnoid block was assessed in the midclavicular line every 2 min after intrathecal injection,and the block level(disappearance of needling pain)reached and fixed the T6 level at 15 minwas the selected study subjects.Results:1.when the block level reached T6,there was a correlation between 0.5%isobaric bupivacaine dose and the patient’s spinal length,abdominal circumference,andheight,(P<0.05).the difference was statistically significant.2.The results of multiple regression analysis showed that maternal spinal length and abdominal circumference were determinants of local anesthetic spread(P<0.001),the difference was statistically significant.3.The regression equation was YT6=-0.684+0.282X1-0.083X2;[Y,0.5%isobaric bupivacaine dose;X1,spine length(C7～coccyx);X2,abdominal circumference.]Degree of fit of equation R2=0.775.Conclusions:1.Spinal length and abdominal circumference were significantly correlated with intrathecal 0.5%isobaric bupivacaine diffusion in cesarean section.2.The regression equation between the dose of 0.5%isobaric bupivacaine at the level of pain disappearance in spinal block of T6 andmaternal spinal length and abdominal circumference is:Y16=-0.684+0.282X1-0.083X2;[Y,0.5%isobaric bupivacaine dose;X1,spinal length(C7～coccyx);X2,abdominal circumference].