Central Venous Pressure as a Guide to Volume Expansion

RECENT HEMODYNAMIC STUDIES i n a n u m- „ ber of centers have prompted revision of the older concept that blood volume should be expanded only to replace obvious losses. It has now been clearly established that the vast majority of patients with shock, oliguria, or peripheral circulatory failure responds well to aggressive volume expansion, even when there is no demon-strable site for blood or plasma loss (1-3). Such functional deficits in blood volume are presumably related to intravascular or extravascular sequestration that may ac-company fever, septicemia, myocardial in-farction, infusion of sympathomimetic drugs (4), or any illness associated with intense reflex sympathoadrenal discharge (5). The diversity of clinical situations that may precipitate functional hypovolemia has confronted the clinician with the problem of deciding when to give additional volume and how much to give. Central venous pressure (CVP) monitoring has gained wide popularity in recent years (6), but consid-erable confusion still exists as to how the CVP can be used most effectively as a guide to volume expansion. Furthermore, advo-cates of repeated measurements of blood volume in the management of the critically ill patient continue to plead their case in the literature (7). An understanding of the interrelationships of blood volume, venous pressure, and cardiac function is necessary for a physiological approach to the patient with suspected volume depletion