Hemodynamic monitoring is invaluable and should be initiated early in the course of the disease process in the appropriate intensive care unit setting. Patients with any evidence of ﬂuid overload should receive aggressive diuresis, whereas others may require ﬂuid resuscitation for maintenance of tissue perfusion while the pulmonary–capillary wedge pressure is maintained below 15 mm Hg. Pulmonary wedge pressure may be falsely elevated when PEEP is being applied. The goal of management is to maintain the lowest pulmonary–capillary wedge pressure, with acceptable cardiac output and blood pressure. In the setting of hypotension and oliguria, inotropic support with dopamine or dobutamine or both is helpful.
With aggressive management, particularly if the inciting cause is identified and treated, ARDS can be reversed during the first 48 hours with few sequelae. After the first 48 hours, progression of the ARDS will cause lung damage that may leave residual pulmonary fibrosis. The long-term outcome is usually apparent within the first 10 days, at which time approximately half of patients are weaned from ventilatory support or they die (244).
Renal Disease The need for surgical intervention in patients with renal impairment resulted in the development of a very specialized medical approach to their care. Precautions are necessary to compensate for the kidneys’ impaired ability to regulate ﬂuids and electrolytes and excrete metabolic waste products. Equally important are the unique problems that develop in patients with chronic renal impairment, including an increased risk of sepsis, coagulation defects, impaired immune function and wound healing, and a propensity to develop specific acid-base abnormalities. Special consideration must be given to a variety of different medications, anesthetic agents, and numerous hematologic and nutritional factors that are important in the successful surgical care of patients with renal insufficiency.
Management of ﬂuid levels and cardiovascular hemodynamics in patients with acute or chronic renal impairment is paramount. Intravascular ﬂuid volume changes that lead to hypertension or hypotension are very common in these patients and often are difficult to manage secondary to autonomic dysfunction, acidosis, and other problems that are inherent to the underlying kidney disease. Patients undergoing dialysis in whom major abdominal or pelvic surgery is contemplated should be treated using invasive monitoring, both intra-and postoperatively. The results of physical examination and CVP monitoring correlate poorly with left cardiac filling pressures. Swan-Ganz catheter measurements will help guide ﬂuid replacement and avoid volume overload. Invasive hemodynamic monitoring should be continued as needed throughout the first postoperative week because third spacing will occur during this period.
Postoperative dialysis usually is necessary to avoid problems associated with ﬂuid overload and hyperkalemia. Dialysis-dependent patients should undergo dialysis approximately 24 hours following surgery. A short-lived but rather significant fall in the number of platelets occurs during dialysis; in addition, heparin is used in hemodialysis equipment to prevent clotting. Because of these factors and concerns about postoperative bleeding, dialysis is usually avoided during the first 12 to 24 hours following surgery. Although ischemic heart disease is the most common cause of death in patients with renal insufficiency, it is not a major cause of perioperative mortality (247). A large percentage of perioperative deaths of patients with renal insufficiency are associated with hyperkalemia that is controlled most effectively by dialysis (248).
Patients with chronic renal failure are at an increased risk for postoperative infections resulting from abnormalities in neutrophil and monocyte function (249). Appropriate preoperative antibiotic prophylaxis and accurate assessment of nutritional status help lower the incidence of postoperative infectious complications.