No single aspect of patient care is more essential to survival than the maintenance of an optimal blood volume. Uncorrected hypovolemia may initiate a chain of events leading to severe shock and death, and even if hypovolemia is corrected before death ensues, a period of hypotension or poor tissue perfusion carries a significant risk of renal and myocardial complications, especially in the aged. On the other hand, inadvertent overloading of the heart by excessive fluid or blood volume replacement may precipitate heart failure and enhance the development of pulmonary edema.
Alterations of blood volume and cardiac action are so common that every clinician should be prepared to manage blood volume support in a seriously ill patient. Many of the critical and most perplexing problems in blood volume maintenance occur unexpectedly under commonplace and inconvenient circumstances. These problems must be solved urgently, where and when they arise, and with the equipment