呼气末正压通气对低血容量患者静脉回流压力阶差的影响

目的 观察呼气末正压(PEEP)对低血容量并机械通气患者中心静脉压(CVP)、髂总静脉压(CIVP)及两者差值[D(c-i)VP]的影响.方法 将2007年5月-2009年5月本院重症监护病房(ICU)收治的30例低血容量并机械通气患者随机分3组,分别实施0、5及10 cm H2O(1 cm H2O=0.098 kPa)的PEEP通气(分别为PEEP0、PEEP5、PEEP10),选择同期10例基本条件相似但血容量正常的机械通气患者作为对照组.测定患者CVP、CIVP,并计算D(c-i)VP;同时记录心率、平均动脉压及呼吸力学数据;对静脉压力变化与呼吸压力各指标进行相关性分析.结果 ①试验组CVP随PEEP升高而明显增加,PEEP0、5、10时CVP分别为(1.3±0.9)、(3.1±1.3)、(4.5±1.3)mm Hg(1 mm Hg=0.133 kPa,P均<0.01);而对照组CVP变化小,分别为(6.9±1.3)、(7.2±1.2)、(8.0±1.5)mm Hg,PEEP10时CVP显著高于PEEP0和PEEP5时(P<0.01和P<0.05).两组CIVP均随PEEP升高而升高,但升高幅度小于CVP.试验组D(c-i)VP较对照组明显增加(P均<0.01),但随PEEP升高有降低趋势,从PEEP0时的(4.9±1.7)mm Hg降至PEEP10时的(2.8±1.4)mmHg,而对照组变化不明显;3个PEEP水平下,D(c-i)VP值差异≤1.5mmHg.②试验组在PEEP0、5、10时CVP与CIVP均无相关性(r1=0.236,r2=0.299,r3=0.262,P均>0.05),而对照组均有相关性(r1=0.485,r2=0.679,r3=0.748,P均<0.05).结论 低血容量并机械通气加用PEEP患者,在PEEP升高时CVP及CIVP值的升高较对照组明显,此对利用两值来评估血容量及指导容量复苏均会造成很大影响.

Effect of positive end-expiratory pressure on the pressure gradient of venous return in hypovolemic patients under mechanical ventilation

Objective To assess the effects of positive end-expiratory pressure(PEEP)on central venous pressure(CVP)and common iliac venous pressure(CIVP),and the difference between CVP and CIVP CD(c-i)VP]in hypovolemic patients under mechanical ventilation.Methods From May 2007 to May 2009,30 acute hypovolemic adult patients undergoing mechanical ventilation in intensive care unit(ICU)were enrolled.The patients were randomly divided into three groups,and PEEP with 0,5,10 cm H2O (1 cm H2O=0.098 kPa)levels were used respectively.Ten mechanically ventilated patients with similar basic clinical conditions but normal blood volume were selected randomly as the control group.CVP,CIVP and D(c-i)VP were measured and recorded at each PEEP level in both groups.The patients' heart rate,mean artery pressure and respiratory pressure data were also collected.The correlation analysis was used to analyze relationship between CVP and CIVP and between the changes in venous pressure and the changes in group.When PEEP was 0,5 and 10 cm H2O,the CVP was(1.3 ±0.9),(3.1 ±1.3)and(4.5±1.3)mm Hg,respectively(1 mm Hg=0.133 kPa,all P<0.01).Whereas,in the control group,the changes in CVP was small.At 0,5 and 10 cm H2O PEEP levels,CVP was(6.9±1.3),(7.2±1.2)and (8.0±l.5)mm Hg,respectively,but when CVP at PEEPO and PEEP5 was compared with that of PEEP10,the difference was significant(P<0.01 and P<0.05).There was slight increase of CIVP in both groups when PEEP was elevated.D(c-i)VP was increased significantly in the study group compared with control group(all P<0.01).But the value was gradually decreased when with elevation of PEEP.When PEEP level was elevated from 0 to 10 cm H2O,D(c-i)VP value was lowered from(4.9 ±1.7)mm Hg to(2.8±1.4)mm Hg.No significant difference in D(c-i)VP was found in the control group.The D(c-i)VP values in between CVP and CIVP at each PEEP level in the study group(r1=0.236,r2=0.299,r3=0.262,all P>0.05),but there was a statistically significant correlation between CVP and CIVP in the control group (r1=0.485,r2=0.679,r3=0.748,all P<0.05).Conclusion The findings suggest that it may not be appropriate to use CVP or CIVP to evaluate the patients' blood volume and effect of volume resuscitation in the hypovolemic patients undergoing mechanical ventilation in combination with PEEP.