急性等容血液稀释及联合降压对犬胃肠灌注的影响

Effects of acute normovolemic hemodilution combined with sodium nitroprusside-induced hypotension on gastrointestinal perfusion and oxygenation in anesthetized dogs

目的 观察急性等容血液稀释联合硝普钠控制性降压对犬胃肠灌注的影响。方法 健康杂种犬16只,随机分为血液稀释组和联合组。以6%羟乙基淀粉等量置换全血实施急性等容血 液稀释(ANH),分别使Hct降至20%～25%(HD1)、10%～15%(HD2);控制性降压期间,0.02%硝 普钠溶液泵入,使MAP降至50mmHg维持30min。监测各稀释水平以及稀释联合降压时的血液动 力学和胃粘膜二氧化碳分压(PgCO2)的变化。结果 (1)血液稀释组HD1及HD2时CO、SI显著增 高,SVRI、PVRI显著降低(P<0.01),MAP、HR、CVP、PAP、PCWP不变;(2)血液稀释组HD1及 HD2时Hb、CaO2、C VO2、DO2显著降低(P<0.01),而ERO2增高, VO2不变;(3)与基础值比,联合 组CO、SI、MAP、SVRI、PVRI显著降低(P<0.01);(4)血液稀释组PgCO2、胃粘膜与呼气末二氧化 碳分压差(Pg ETCO2)无显著变化;联合组PgCO2、Pg ETCO2分别由48.6mmHg、9.8mmHg增高至 70.7mmHg、29.3mmHg。结论 血液稀释联合硝普钠降压时,因静脉回心血量下降,心输出量因而 降低,内脏灌注受损。

Objective To investigate the effects of acute normovolemic hemodilution combined with sodium nitroprusside-induced hypotension on gastrointestinal perfusion in anesthetized dogs.Methods Sixteen mongrel dogs were randomly allocated to hemodilution group and combined hemodilution-hypotensive group.Hemodilution was achieved by drainage of artery blood and simultanelously i.v. infusion of equal volume of 6% hydroxyethl starch,during which target hematocrit was 20%-25% and 10%-15% respectively. Hypotension was induced with 0.02% sodium nitroprusside to lower MAP to 50mmHg. Blood gases and hemodynamic variables were measured 30 minutes after hemodilution and controlled hypotension.Results In hemodiluted dogs, the reduction in Hct was associated with significant decrease in CaO 2 and SVRI,PVRI,but CO,SI increased significantly(P<0.01),while MAP,HR,CVP,PAP,PCWP,O 2 remained unchanged. In combined group, CO,SI decreased significantly(P<0.01) , compared with hemodilution and baseline,but there was no further decrease in SVRI,PVRI,compared with hemodilution. In combined group, PgCO 2, P g-ETCO 2 significantly increased from 48.6mmHg ,9.8mmHg to 70.7mmHg, 29.3mmHg respectively. Conclusion ANH does not impair splanchnics perfusion,whereas controlled hypotension combined with hemodilution would impair splanchnic perfusion.