The role of venous return in critical illness and shock-part I: physiology.

OBJECTIVE: To provide a conceptual and clinical review of the physiology of the venous system as it is relates to cardiac function in health and disease.

DATA: An integration of venous and cardiac physiology under normal conditions, critical illness, and resuscitation.

SUMMARY: The usual teaching of cardiac physiology focuses on left ventricular function. As a result of the wide array of shock states with which intensivists contend, an approach that takes into account the function of the venous system and its interaction with the right and left heart may be more useful. This two-part review focuses on the function of the venous system and right heart under normal and stressed conditions. The first part describes the basic physiology of the venous system, and part two focuses on the role of the venous system in different pathophysiologic states, particularly shock.

CONCLUSION: An improved understanding of the role of the venous system in health and disease will allow intensivists to better appreciate the complex circulatory physiology of shock and may allow for better hemodynamic management of this disorder.