Simultaneous peripheral and central venous pressure monitoring for evaluating cardiac preload in critically ill patients

Abstract

Purpose: Arterial waveform-derived dynamic variables, such as stroke volume variation (SVV), are useful for predicting fluid responsiveness in perioperative patients. Since specific catheters and machines must be used for measuring SVV, we tried to find a novel indicator that correlates with SVV values and can be calculated using usual monitoring equipment. Methods:A total of 50 patients admitted to the ICU, both intubated (n=25) and non-intubated (n=25), were enrolled in this prospective observational study. Intubated patients received mechanical ventilation under pressure controlled ventilation (PCV) or continuous positive airway pressure /pressure support ventilation (CPAP/PSV) modes. SVV values were used for assessment of cardiac preload. Besides SVV, central venous pressure (CVP) and peripheral venous pressure (PVP) were simultaneously recorded. In each patient, 10 data pairs were randomly acquired at 1 hour or longer intervals.Results: Regression analysis showed a slightly weaker but substantial association between PVP and CVP (Pearson's correlation coefficient r=0.91, p<0.0001). However, we found that PVP-CVP difference values correlated with SVV (r=0.64, p<0.0001). Moreover, we were able to predict whether SVV was normal (≤ 10%) or high (>10%) from PVP-CVP difference values with high accuracy. This prediction was not affected by the respiratory mode. Conclusion:The difference between PVP and CVP might serve as a novel indicator of the adequacy of cardiac preload that does not require specific equipment, such as the FloTrac/Vigileo Monitor®.