Critical Care Nephrology

The practice of critical care has changed dramatically over the past three decades [1]. The costs associated with providing critical care services in the United States represent approximately 1% of the gross domestic product [2]. Over the past 30 years, advances in technology, therapeutics, and monitoring have improved the prognosis of critically ill patients and have also led to breakthroughs in other areas of medicine, such as transplantation, oncology, and traumatology [1]. An increasing number of critically ill patients are now being cared for by board-certified critical care physicians, and there is evidence that such care improves outcome [3].

As critical care has changed, so have patients with critical illness. Victims of critical illness are disproportionately elderly [2] and frequently have multiple organ dysfunction. As such, much of critical care is concerned with the interaction of various organs and disease states. Critical care practice is often defined by certain syndromes (eg, sepsis, acute renal failure) and pathophysiologic conditions (eg, shock, hypoxemia) that frequently cross the domains of more traditional subspecialties of medicine.

Critical care nephrology, as the name suggests, is an “overlap” field of medicine. Every intensivist must become experienced in the management of fluid, electrolyte, and acid-base disorders, and every intensivist will encounter patients with acute renal dysfunction. Management of these problems must be integrated into the care plan along with the management of other forms of organ dysfunction—it cannot be delegated to others. Similarly, the field of nephrology has amassed an enormous wealth of knowledge and experience in the evaluation and management of these problems. The talents and special knowledge of nephrologists should never be excluded from the intensive care unit. Cooperation and collaboration of intensive care specialists and nephrologists is most beneficial to patients with these conditions.

Critical care nephrology is coming of age. Significant advances in the understanding of epidemiology and pathophysology of disorders such as acute renal failure, fluid overload, and metabolic acidosis have occurred in the last decade alone. With these advances have come technologic advances in treatment and monitoring. Finally, clinical evidence to guide management is becoming ever more robust and widely applied.

Still, there remains enormous variation in treatment and outcome for patients with these “critical care nephrology syndromes.” Variation appears to exist among countries, institutions, and even individual practitioners within institutions. For example, some medical centers perform only continuous renal replacement therapy for patients in the intensive care unit who have acute renal failure, while other medical centers—similar with respect to size, demographics, and case mix—do not even offer the procedure [4], [5]. Some hospitals have embraced standing orders for so-called “renal protective drugs,” whereas others do not even have these agents on the formulary.

It is likely that some degree of variation in clinical practice will always be a part of medicine. However, variation tends to be greatest when pathogenesis is poorly understood and when treatments are largely empirical or ineffective. In this issue of the Critical Care Clinics, experts from nephrology and critical care medicine review both the latest advances and the “tried and true” for many of the most common critical care nephrology syndromes. From basic mechanisms of disease; to definitions, risk stratification, and epidemiology; to prevention and treatment; and even to the future of kidney support, these reviews provide powerful testimonies to how far this field has come. As the contributors to this issue clearly show, the age of empiricism in the management of disorders in the overlap between critical care and nephrology is coming to a close—and, for the sake of our patients, not a moment too soon.