Use of nitroprusside during surgery for thoracoabdominal aortic aneurysm.

To assess the effects of sodium nitroprusside on the deleterious hemodynamic effects of clamping and unclamping of the aorta during resection of thoracoabdominal aortic aneurysm without the use of a shunt, 50 patients were studied. The risk factors included coronary artery disease (44%) associated with previous myocardial infarction (28%), hypertension (70%), congestive heart failure (6%), chronic obstructive pulmonary disease (34%), asthma (2%), and renal insufficiency (2%). Sodium nitroprusside infusion (3 micrograms/kg/min) was started before clamping and discontinued before unclamping of the aorta. The infusion rate was adjusted to maintain blood pressure and pulmonary capillary wedge pressure within the range of control. During cross-clamping cardiac index in the patients remained unchanged and even increased on unclamping, suggesting that left ventricular function was efficiently protected during these periods. All the patients survived the surgery, and the 30 day mortality was only 4%. Our data indicate that major aortic surgery can be carried out safely with the use of nitroprusside rather than of mechanical techniques to provide proximal decompression.