Intraoperative management of renal function in the surgical patient at risk. Focus on aortic surgery

Although the search for effective methods of renal prophylaxis during aortic surgery spans many decades, definitive answers are scarce. The literature is voluminous, yet the amount of work clearly relevant to the specific clinical situation of perioperative prophylaxis is small. Given the significant morbidity and subsequent mortality involved with perioperative ARF, it is difficult to sit back and do nothing when pharmacologic agents empirically are believed to possibly benefit the patient. Care must be taken to apply data from different clinical scenarios in the literature to the situation at hand. Drugs felt to be innocuous, even in low doses, may be insidiously counterproductive or damaging if they are not managed properly. Maintaining an adequate preload and stable hemodynamics seems to be the most logical universal approach at this time. Furosemide treatment without maintaining an adequate volume status once diuresis commences may be detrimental, which is true with the diuretic effects induced by mannitol or dopamine. The tachycardia resulting from a relative hypovolemia and from the beta effects of dopamine can cause myocardial ischemia from increased oxygen demand. Low urine output does not portend a negative outcome in the face of an adequate intravascular volume any more than an induced diuresis prevents renal injury. Currently, minimization of renal ischemia and maintenance of an adequate intravascular volume and renal hemodynamics are the keys to optimizing renal outcome during aortic surgery. Other maneuvers are not definitive and should be cautiously undertaken.