Cardiac and peripheral failure in hemorrhagic shock in the dog

Cardiac output by the indocyanine-green-dilution technique, systemic arterial, right atrial, pulmonary arterial, and ventricular end-diastolic pressures were measured without thoracotomy to evaluate cardiac function in seven dogs. In other series of seven, mercury-in-rubber displacement transducers were placed around the left ventricles about 5 days before the experiments. In a third group of five, hemorrhagic hypotension was continued until 40% uptake of the maximum shed volume. Transfusions of blood, plasma, and dextran were given, as needed, to maintain arterial blood pressure above 100 mm Hg. Such therapy prolonged life. In a fourth group of 33, increases in hematocrit and plasma protein concentration, and decreases in central venous pressure suggested a progressive loss of intravascular fluid late in the hypotensive period and following transfusion. It appears that only with extreme degrees of oligemic hypotension, or with moderate hypotension plus prior cardiac damage does the cardiac weakness engendered by the prolonged hypotension become the most significant factor leading to death.