What is the preferred central venous pressure zero reference for hepatic resection?

Abstract

The common practice of maintaining central venous pressure (CVP) below 5 mm Hg to reduce blood loss during hepatic resection increases the risk of venous air embolism (VAE). We initiated this study after observing that the anteroposterior (AP) diameter of the liver can be much larger than 7 cm, which is the approximate hydrostatic pressure corresponding to a CVP of 5 mm Hg (1 mm Hg = 1.36 cm H(2)O). The purpose of this study was to characterize the liver AP diameter and thereby describe how this might affect the placement of the CVP transducer to balance the risks of bleeding and VAE. We measured the AP liver diameter and its distance from other anatomic sites using consecutive archived chest tomograms with IV contrast from 100 adults. The results of our study demonstrate a large interindividual range in AP liver dimensions (17.9 + or - 2.8 cm, range = 12.0-28.5 cm) and standardized anatomic landmarks relative to the portal triad. The significant variability in AP liver diameter, along with the variability in the liver surgical site, suggests that we rethink the zero reference point for the CVP transducer during hepatic surgeries. By considering the actual hepatic venous pressure itself, rather than the CVP, we can minimize the risks of VAE and hemorrhage. Two methods for zeroing the reference transducer are suggested.