WITH THE increasing magnitude and complexity of surgical procedures and the everrising incidence of severe trauma, restoration and maintenance of adequate circulation assume an increasingly important role in the surgeon's work. Today, there are such excellent means of treating acute circulatory failure that relatively few patients will persist with refractory hypotension if the individual requirements of each patient are met with properly directed therapy. The chief problem in the management of shock is to identify accurately the circulatory defect present and thereby define the appropriate course of therapy. The greatest hazard to a patient's survival is not a lack of effective means of therapy but rather an inaccurate or uncertain diagnosis leading to inadequate treatment without benefit of available therapeutic resources. One reason for this paradox is the general tendency to think of shock in terms of etiology with the implication that such a diagnosis indicates a particular corresponding program