Objective: To evaluate the effects of positive end-expiratory pressure (PEEP) on central venous pressure (CVP) and common iliac venous pressure (CIVP), the relationship between CVP and CIVP, in order to analyze the correlation between CVP or CIVP and airway pressure in patients during mechanical ventilation.
Methods: Twenty mechanically ventilated adult patients with steady circulatory state and without cardiopulmonary ailment, abdominal distention or coagulopathy were enrolled for the study from February to August in 2007. 0, 5, 10 cm H(2)O (1 cm H(2)O=0.098 kPa) PEEP was used randomly in all cases during mechanical ventilation. CVP, CIVP, the gradient between CVP and CIVP at each PEEP level were measured. Linear correlation and linear regression analysis were used to analyze relative changes between CVP and CIVP. The data of airway pressure in the patients with mechanical ventilation were obtained for evaluating their correlation with CVP or CIVP.
Results: CVP and CIVP increased as PEEP was elevated (P<0.05 or P<0.01). There was a significant linear correlation between CVP and CIVP at 0, 5, 10 cm H(2)O PEEP level (r was 0.620, 0.658 and 0.777, respectively, P<0.01). The linear regression equation was Y (CVP)=0.402+0.732X (CIVP). The mean difference between CVP and CIVP at 0, 5, 10 cm H(2)O PEEP level was (1.9+/-1.7), (2.3+/-1.3), and (1.9+/-1.1) mm Hg (1 mm Hg=0.133 kPa, respectively P>0.05). There was a positive correlation between CVP or CIVP and the airway pressure, but only mean airway pressure and PEEP showed significant linear correlation with CVP (r was 0.634, 0.603, respectively, P<0.01) and CIVP (r was 0.751, 0.685, respectively, P<0.01). No obvious change was found in mean arterial pressure, heart rate, and expiratory tidal volume during the study.
Conclusion: CVP and CIVP increased when PEEP is set <or=10 cm H(2)O in mechanical ventilated patients, whose circulatory status is steady and who do not have cardiopulmonary ailment or abdominal distention. There is a significant positive linear correlation between CVP and CIVP. The difference between CVP and CIVP is constant, and no effect on hemodynamics of the patients is found. The changes in CVP and CIVP are primarily related to mean airway pressure and PEEP during mechanical ventilation.