We evaluated the effect of elevated airway pressure on the validity of intravascular pressure obtained in the distal inferior vena cava (IVC) as a measure of central venous pressure (CVP) in a group of children receiving mechanical ventilation. The IVC pressure correlated well with CVP in the patients without abdominal distention, but the disparity was wider in those with abdominal distention. Elevated mean airway pressure or positive end-expiratory pressure had no effect on the relationship of IVC to CVP.