(p. 613) Central venous pressure monitoring in the ICU 

Central venous pressure (CVP) is at the crucial intersection of the force returning blood to the heart and the force produced by cardiac function, which drives the blood back to the systemic circulation. The normal range of CVP is small so that before using it one must ensure proper measurement, specifically the reference level. A useful approach to hypotension is to first determine if arterial pressure is low because of a decrease in vascular resistance or a decrease in cardiac output. This is done by either measuring cardiac output or making a clinical assessment blood flow. If the cardiac output is decreased, next determine whether this is because of a cardiac pump problem or a return problem. It is at this stage that the CVP is most helpful for these options can be separated by considering the actual CVP or even better, how it changed with the change in cardiac output. A high CVP is indicative of a primary pump problem, and a low CVP and return problem. Understanding the factors that determine CVP magnitude, mechanisms that produce the components of the CVP wave form and changes in CVP with respiratory efforts can also provide useful clinical information. In many patients, CVP can be estimated on physical exam.