Based on initial success using the medical antishock trouser (MAST) suit in treating 150 patients in traumatic, hypovolemic shock in the city of Bellingham and Whatcom County, Washington, at St. Luke's Hospital, the indications for its use have been expanded to include certain types of cardiogenic shock. The rationale was based on the frequent inability to differentiate hypo-, hyper-, and normovolemia in patients in cardiogenic shock and the need for a safe, reversible fluid challenge to differentiate these conditions. Changes in the condition of 14 patients in cardiogenic shock after application of the MAST suit were evaluated. Six patients responded with improved cardiac output and blood pressure. Four had no significant change in their condition and four became worse. In all patients whose condition was unchanged or worsened, the fluid challenge was reversed by deflating the suit. Based on these preliminary findings, it would seem that extended indications exist for using the MAST suit.