In this issue (see page 57) Cohn and his associates have described an interesting derangement in the plasma volume of patients with severe angina pectoris and normal left ventricular function. These patients have been shown by isotopic dilution techniques to have an abnormally low plasma volume. Red blood cell volume, although also low, was more nearly normal. Plasma volume deficits observed averaged 700 ml with deficits as large as 1,200 ml. Moreover, these authors show that this plasma volume deficit is present four to six months after adequate myocardial revascularization.
This study has important implications to the surgeon who operates on patients with angina pectoris. The data indicate that hypovolemia must be suspected in the angina patient with intraoperative hypotension. Indiscriminate vasopressor or inotropic therapy may further upset the critical balance between myocardial oxygen supply and demand in these precarious patients, resulting in intraoperative myocardial infarction. The work of Cohn