ABSTRACT
The use of invasive hemodynamic monitoring in the SICU remains controversial. Singer,
in an insightful review of cardiac output determination and significance, recalls the state-
ment of Karl Ludwig: “The fundamental problems in the circulation derive from the fact
that the supply of adequate amounts of blood to the organs of the body is the main purpose
of the circulation while the pressures that are necessary to achieve it are of secondary
importance; but the measurement of flow is difficult while that of pressure is easy so
that our knowledge of flow is usually derivatory (1).” Although the technology for measur-
ing flow exists, the value of measuring flow in improving outcomes continues to be con-
tentious. In several studies of high-risk surgery patients, increasing oxygen transport
preoperatively by manipulating cardiac output resulted in significantly better outcomes
(2-4). In the critically ill patient, data are contradictory. Chapter 63 provides a review
and analysis of flow manipulation in the critically ill patient.
