硝普钠控制性降压对椎板减压术病人术中胃粘膜pH值的影响

Effect of SNP-induced hypotension on gastric intramucosal pH

目的观察硝普钠控制性降压对胃粘膜pH值(pHi)、胃粘膜内二氧化碳分压(PgCO2)、PgCO2-PaCO2和动脉血气的影响。方法 15例椎板减压术病人,手术中应用硝普钠控制性降压,观察降压前(T1)、降压后30min(T2)、60min(T3)和停降压后30min(T4)的pHi、PgC02、PgcO2-PaCO3和动脉血气的变化。结果 在T2和T3平均动脉压分别下降35％和33％,比T1显著降低(P<0.01)。T2与T1比较,pHi显著降低(P<0.01),PgCO2和PgCO2-PaCO2显著升高(P<0.01),T3这三项指标与T1比较差异无显著性(P>0.05);动脉血气变化:pH在T2、T3和T4、剩余碱(BE)在T3和T4低于降压前(P<0.01),PaCO2和呼气末二氧化碳(PETCO2)在T4高于T2(P<0.05)。结论 硝普钠控制性降压早期胃肠道微循环有一过性障碍。

Objective To assess the effect of sodium nitroprusside (SNP)-induced hypotension on gastric intramucosal pH (pHi), gastric intramucosal PCO2 ( PgCO2 ) and the difference between PgCO2 and PaCO2 (PgCO2-PaCO2) .Methods Fifteen ASA I patients (11 male, 4 female) aged 22-43 yr8, weighing 51-68 kg undergoing laminectomy for decompression of spinal cord in prone position were enrolled in this study. The patients were intubated and mechanically ventilated with 100% O2 after induction of general anesthesia. Anesthesia was maintained with isoflurane (1.2-1.4%) . Radial artery was cannulated for BP monitoring and boood sampling. TRIP tonometry catheter 14 F was inserted into stomach and connected to Tonocap ( Datex-Ohmeda, Finland) . Controlled hypotension was induced with SNP infusion at 1-5 μg kg-1 min-1 . MAP was reduced to (60 ±5) mm Hg in 5-7 min and maintained for 60 min. Blood samples were taken before induced hypotension (T, ) , at 30 min (T2 ) and 60 min of hypotension (T3) and 30 min after hypotension (T4) for blood gas analysis. pHi, PgCO2 -PaCO2 and PETCO2 were also determined.Results MAP decreased by 35% and 33% at T2 and T3 as compared with the baseline (T, ) . pHi decreased significantly and PgCO2, PgCO2-PaCO2 increased significantly at T, as compared with those at T( ( P < 0.01). There was no significant difference in pHi, PgCO2-PaCO2 between T3 and T, (P > 0.05). pH at T2 ,T3 and T4 and BE at T3 and T4 were significantly lower than the baseline value (T1). PaCO2 and PET CO2 were significantly higher at T4 than those at T, (P < 0.05) .Conclusion SNP-induced hypotension can produce early and transient disturbance of gastro-intestinal microcirculation.