Effects Of Different Prophylactic Infusion Rate Of Phenylephrine On Puerpera And Neonate Associated With Spinal Anesthesia For Elective Caesarean Section

Objective:To investigate the effects of different prophylactic infusion rate of phenylephrine on hemodynamics,incidence of nausea and vomiting of puerpera and conditions of neonate associated with spinal anesthesia for elective caesarean section.Methods:One hundred-fifty women having elective cesarean delivery under spinal anesthesia.ASA I or Ⅱ,aged21～38yr.weighing60-95kg,randomly were divided into six groups (n=25). P1～P4groups (phenylephrine groups) received infusion of phenylephrine respectively in rate of0.1.0.2.0.3and0.4μg/kgmin for ten minutes after spinal anesthesia. E group(ephedrine group) received prophylactic ephedrine10mg intravenous administration after spinal anesthesia. C group (control group) received ephedrine10mg intravenous administration in case of hypotension which was defined as systolic blood pressure of less than80%baseline(T1).It was ten minutes interval from end of intrathecal injection to start of operation.Heart rate(HR)、blood pressure(BP)、thoracic fluid content(TFC)、cardiac output (CO) and cardiac index (CI) were recorded by Noninvasive Heart Function Monitor(Solar8000M) at baseline(T1),before anesthesia(T2) and respective parameters of1min(T3),3min(T4),10min(T5) after anesthesia and delivery time (T6).Incidence of nausea and vomiting and Apgar score of newborns were recorded. Umbilical arterial blood samples were taken for measurment of blood gas analysis.Result:Compare with E group and C group,HR was decreased at T3,T4and T5in P1～P4groups(P<0.05),MAP was decreased at T6in P1,P2and P3group(P<0.05), frequency of additional vasopressors was lower in P3and P4groups(P<0.01).Compare with C group,MAP was higher at T4and T5in P4group(P<0.05).There was no significant difference in frequency of atropine in P1～P4groups(P>0.05).The average time of phenylephrine infusion time were10minutes,10minutes,10minutes,9.625minutes respectively in P1～P4.the infusion time of P4was significantly shorter than P1～P3(P<0.05). Compare with E group and C group,PH,BE and HCO3-of umbilical arterial blood were significantly higher in P1～P4groups(P<0.05), there was significant higher PO2in P1～P4and E groups compared with C group(P<0.01).There was no significant difference in1min and5min Apgar score of newborns in all groups(P>0.05). Compare with E group and C group, incidence of nausea and vomiting was significantly lower in P1～P4(P<0.05). There was no significant difference in incidence of nausea and vomiting within P1～P4(P>0.05).Conclusion:Prophylactic infusion of phenylephrine was recommendable in maintaining stable hemodynamics,decreasing incidence of nausea and vomiting,reducing risk of acidosis of neonates compared with ephdrine undergoing spinal anesthesia for elective caesarean section.0.3μg/kg·min was suitable rate of prophylactic phenylephrine infusion for elective caesarean section under spinal anesthesia.