Low-dose "renal" dopamine

From Pre-Existing Renal Failure to Perioperative Renal Protection: The Anesthesiologist's Dilemmas

CONTEXT

Pre-existing renal dysfunction presents specific features that anesthesiologists must deal with. Anesthesia and renal function are connected and can interfere with each other. Induced hypotension anesthesia and the toxic effects of anesthetic drugs can further deteriorate renal function.

EVIDENCE ACQUISITION

Decreased renal function can prolong anesthetic drug effects by decreased elimination of these drugs. Anesthesia can deteriorate renal function and decreased renal function can interfere with drug elimination leading to their prolonged effect. The anesthesiologist must understand all the physiological aspects of the patient, renal protection, and the relationships between anesthetic drugs and renal function. This review article aims to summarize these aspects.

RESULTS

Perioperative renal failure and renal protection is a crucial moment in clinical practice of every anesthesiologist.

CONCLUSIONS

Good knowledges for renal function remain a hallmark of daily practice of the anesthesiologist, considering renal function as an important determinant factor in anesthesia practice.

Current treatment in acute and chronic cardio-renal syndrome

Cardio-renal syndrome (CRS) is a renal dysfunction occurring in a large percentage of patients hospitalized with congestive heart failure (HF). Cardiac and renal dysfunctions often occur simultaneously because they share causes and pathogenetic mechanisms. Current therapies for HF are focused on improving myocardial function and hemodynamic balance, but may have potential consequences for worsening renal function. The lack of specific trials in this field highlights the need for further studies aimed to assess efficacy and safety, titration and appropriate dosages of drugs, according to the etiology and severity of both myocardial and renal dysfunction. Moreover, the most recent clinical trials evaluating new drugs on clinical and renal outcome in acute heart failure syndromes (AHFS) failed to demonstrate an improvement in renal function and perfusion. In this context, several questions regarding the priority of drugs, their recommended dosage and potential adverse effects on cardiac and renal outcome need to be addressed. Although clinical guidelines for managing both HF and chronic kidney disease (CKD) have been drawn, until now agreed guidelines about patients with cardio-renal and reno-cardiac syndromes are lacking. Future treatment directions should take into consideration both kidney and heart function. Only this comprehensive approach might lead to an improvement in the management and outcomes of patients affected by CRS.

Low-dose dopamine: a physiologically based review

BACKGROUND

In an attempt to prevent or alter the course of acute renal failure, many surgeons continue to use low-dose dopamine. This article critically reviews the physiologic reasons why low-dose dopamine is not clinically efficacious.

METHODS

A critical review of English language literature.

RESULTS

The effect of dopamine on renal blood flow remains controversial. If dopamine does increase renal blood flow, the vascular anatomy of the kidney would limit its effectiveness. Rather than improving renal function, dopamine has been shown to impair renal oxygen kinetics, inhibit feedback systems that protect the kidney from ischemia, and may worsen tubular injury. Dopamine has not been proven useful in the prevention or alteration of the course of acute renal failure as a result of heart failure, cardiac surgery, abdominal aortic surgery, sepsis, and transplantation. Dopamine has been associated with multiple complications involving the cardiovascular, pulmonary, gastrointestinal, endocrine, and immune systems.

CONCLUSIONS

Based on the anatomy and physiology of the kidney, low-dose dopamine would not be expected to improve renal failure and this has been demonstrated by the lack of efficacy in clinical trials.

Acute renal failure in the surgical setting

Acute renal failure (ARF) is an unwelcome complication of major surgical procedures that contributes to surgical morbidity and mortality. Acute renal failure associated with surgery may account for 18-47% of all cases of hospital-acquired ARF. The overall incidence of ARF in surgical patients has been estimated at 1.2%, although is higher in at-risk groups. Mortality of patients with ARF remains disturbingly high, ranging from 25% to 90%, despite advances in dialysis and intensive care support. Appreciation of at-risk surgical populations coupled with intensive perioperative care has the capacity to reduce the incidence of ARF and by implication mortality. Developments in understanding the pathophysiology of ARF may eventually result in newer therapeutic strategies to either prevent or accelerate recovery from ARF. At present the best form of treatment is prevention. In this review the epidemiology, pathophysiology, diagnosis, treatment and possible prevention of ARF will be discussed.

Acute renal failure in hospitalized patients: part II

BACKGROUND

Acute renal failure (ARF) is a common condition in hospitalized patients. Research has been unable to identify the optimal target for therapeutic intervention; hence, effective prevention of and/or treatment for ARF remain elusive.

OBJECTIVE

To examine the usefulness of current and potential pharmacologic treatments in seriously ill, hospitalized patients.

DATA SOURCES

A MEDLINE search (1996-June 2002) was conducted using the search terms kidney (drug effects) and acute kidney failure (drug therapy). Bibliographies of selected articles were also examined to include all relevant investigations.

STUDY SELECTION AND DATA EXTRACTION

Review articles, meta-analyses, and clinical trials describing prevention of and treatment for hospital-acquired ARF were identified. Results from prospective, controlled trials were given priority when available.

CONCLUSIONS

Appropriate management of ARF includes prospective identification of at-risk patients, fluid administration, and optimal hemodynamic support. Drug treatments, including low-dose dopamine and diuretics, have demonstrated extremely limited benefits and have not been shown to improve patient outcome. Experimental agents influence cellular processes of renal dysfunction and recovery; unfortunately, relatively few drugs show promise for the future.