"Renal dose" dopamine in surgical patients: dogma or science?

Renal-Dose Dopamine: From Hypothesis to Paradigm to Dogma to Myth and, Finally, Superstition?

Acute renal failure (ARF) is common in the critically ill and is associated with a high mortality rate. Its pathogenesis is not understood. Because animal models use ischemia to induce experimental ARF, there is the widespread belief that lack of blood flow is responsible for ARF. Low-dose dopamine (LDD) has been shown to increase renal blood flow in animal and in human volunteers. Thus, it has been administered to humans for almost 3 decades in the belief that it would lead to renal arterial vasodilation and increase renal blood flow (RBF). However, the etiology of ARF in critical illness is likely multifactorial, and the contribution of hypovolemia and reduced renal perfusion is unknown. Furthermore, interindividual variation in the pharmacokinetics of dopamine typically results in poor correlation between blood levels and administered dose, making accurate and reliable delivery of LDD difficult. Finally, dopamine is a proximal tubular diuretic that increases Na+ delivery to tubular cells, thus increasing their oxygen demands. Accordingly, even if LDD were able to preferentially increase RBF, there is no guarantee that it would restore renal parenchymal oxygen homeostasis. More important, 2 meta-analyses and a large double-blind, prospective, multiple-center, randomized controlled trial have failed to demonstrate that dopamine protects the kidney in critically ill patients with ARF. Currently, there is insufficient evidence to support the use of renal-dose dopamine in the intensive care unit.

The interface between monitoring and physiology at the bedside

Hemodynamic instability as a clinical state represents either a perfusion failure with clinical manifestations of circulatory shock or heart failure or 1 or more out-of-threshold hemodynamic monitoring values, which may not necessarily be pathologic. Different types of causes of circulatory shock require different types of treatment modalities, making these distinctions important. Diagnostic approaches or therapies based on data derived from hemodynamic monitoring assume that specific patterns of derangements reflect specific disease processes, which respond to appropriate interventions. Hemodynamic monitoring at the bedside improves patient outcomes when used to make treatment decisions at the right time for patients experiencing hemodynamic instability.

Renal endocrine manifestations during polytrauma: A cause of concern for the anesthesiologist

Nowadays, an increasing number of patients get admitted with polytrauma, mainly due to road traffic accidents. These polytrauma victims may exhibit associated renal injuries, in addition to bone injuries and injuries to other visceral organs. Nevertheless, even in cases of polytrauma, renal tissue is hyperfunctional as part of the normal protective responses of the body to external insults. Both polytrauma and renal injuries exhibit widespread renal, endocrine, and metabolic responses. The situation is very challenging for the attending anesthesiologist, as he is expected to contribute immensely, not only in the resuscitation of such patients, but if required, to allow the operative procedures in case of life-threatening injuries. During administration of anesthesia, care has to be taken, not only to maintain hemodynamic stability, but equal attention has to be paid to various renal protection strategies. At the same time, various renoendocrine manifestations have to be taken into account, so that a judicious use of anesthesia drugs can be made, to minimize the renal insults.

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.

Management of septic shock with a norepinephrine-based haemodynamic algorithm

Management of septic shock (SS) with a norepinephrine (noradrenaline)-based haemodynamic algorithm.

INTRODUCTION

The choice of the best vasopressor for haemodynamic management of septic shock is controversial. Nevertheless, very few studies have been focused on evaluating different management algorithms. The aim of this study was to evaluate the performance of a norepinephrine (NE)-based management protocol. Experience with NE as the initial vasopressor, even if not comparative, could bring relevant data for planning future trails. We also wanted to evaluate the compliance of critical care physicians and nurses with haemodynamic management protocol.

PATIENTS AND METHOD

A norepinephrine-based algorithm for the management of septic shock that commands different sequential interventions according to its requirements, was applied prospectively to 100 consecutive septic shock patients.

RESULTS

Norepinephrine was used as the first vasoactive drug in all patients with a maximum dose of 0.31+/-0.3 microg kg(-1)min(-1) and an ICU mortality of 33%. Physicians applied correctly all the steps of the algorithm in 92% of the patients. Applying the algorithm, avoided the use of pulmonary artery catheter in 31 patients and led to use of lower doses of vasoactive agents than in many other clinical experiences.

CONCLUSION

In conclusion, our data support extended use of an algorithm based on norepinephrine for treating septic shock patients. This is the first clinical study that uses NE as the initial vasopressor drug systematically, and although not comparative, the mortality rates adjusted to APACHE II, are comparable to other studies. It also gives support for future clinical trials comparing norepinephrine with dopamine in this setting.

Kidney dysfunction in the postoperative period

The development of perioperative acute renal failure is associated with a high incidence of morbidity and mortality. Although this incidence varies with different surgical procedures and with the definition used for renal failure, we now understand better the aetiology of the underlying problem. However, successful strategies to provide renal protection or strategies for 'rescue therapy' are either lacking, unsubstantiated by randomized clinical trials, or show no significant efficacy. The present review considers the physiology and pharmacology of the kidney; the characterization of tests of renal function; the cause of postoperative renal dysfunction; what is presently available for its prevention and treatment; and the effect of postoperative renal impairment on patient outcome.

Should We Give Prophylactic “Renal‐Dose” Dopamine After Coronary Artery Bypass Surgery?

OBJECTIVE

A prospective double-blind randomized study undertaken to assess the effect of postoperative prophylactic "renal-dose" dopamine on post-coronary artery bypass grafting surgery's clinical outcome.

METHODS

Eighty-five consecutive patients undergoing CABG operation were randomized to receive either 3-5 microg/kg/min dopamine (group D, n = 41) or saline as placebo (group P, n = 45) for 48 postoperative hours. Clinical outcome parameters were collected for four postoperative days.

RESULTS

Preoperative and operative parameters were similar in both groups. Four patients from group P and none from group D reached an end-point of the study (oliguria, renal dysfunction) and received dopamine. Two patients from group P and none from group D needed an additional inotropic support. Mean arterial pressure values were similar during the first 24 hours after operation, but left atrial pressure values tended to be higher in group P (10 +/- 4 vs 7 +/- 3 mmH2O, p = 0.18). The mean pH was higher in group D at 8 hours after operation (7.38 +/- 0.2 vs 7.36 +/- 0.3, p = NS), due to higher bicarbonate levels (23 +/- 2 mmol/l vs 21 +/- 2, p = 0.49). The incidence of lung congestion in chest X-rays and CT scans was significantly higher in group P (50% vs 29%, p = 0.073 at 48 hours postoperatively). Room air blood O2 saturation and maximal expiratory volume tended to be higher in group D (at 72 hours after operation- 92 +/- 4 vs 90%+/- 5, p = 0.29 and 646 +/- 276 vs 485 ml +/- 206, p = 0.16, respectively). There was no statistical difference in urine output but the amount of furosemide given to patients in group P was significantly higher (during the first 8 hours 2.5 +/- 0.5 vs. 0.3 mg +/- 1.6, p = 0.07). Plasma creatinine levels were significantly lower in group D (at 24 hours 0.93 +/- 0.02 vs 1.05 mg/dL +/- 0.02, p = 0.02). Mobilization after surgery was faster in group D.

CONCLUSIONS

Prophylactic dopamine administration after coronary artery bypass grafting surgery improves patient hemodynamic and renal status, reduces the need for additional medical support (inotropes and furosemide) and thus, provides stable postoperative course.

Diltiazem may preserve renal tubular integrity after cardiac surgery

PURPOSE

To evaluate the influence of dopamine and diltiazem on renal function and markers for acute renal failure, including urinary alpha-glutathion s-transferase (alpha-GST), alpha-1-microglobulin (alpha(1)-MG) and N-acetyl-ss-glucosaminidase (ss-NAG) after extracorporeal circulation.

METHODS

In a randomized, placebo-controlled, double-blind trial we evaluated the efficacy of dopamine (2.5 micro g x kg(-1) x min(-1)), diltiazem (2 micro g x kg(-1) x min(-1)) or placebo administered over 48 hr postoperatively to maintain renal tubular integrity in 60 elective cardiac surgery patients. alpha-GST, alpha(1)-MG, ss-NAG, and creatinine clearance were measured from urine collected during surgery (T0), the first four hours (T1), 24 hr (T2) and 48 hr (T3) postoperatively.

RESULTS

Cumulative urine output in the diltiazem group (9.0 +/- 2.8 L) increased significantly compared with placebo (7.0 +/- 1.6 L), but not compared with dopamine (7.8 +/- 1.8 L). Creatinine clearance showed no significant intergroup differences. In all groups alpha(1)-MG increased from T0 to T3, but we found no significant intergroup differences. alpha-GST increased significantly from T0 to T3 in the placebo (2.1 +/- 1.8 to 11.4 +/- 8.6 micro g x L(-1)) and in the dopamine groups (2.7 +/- 1.8 to 13.6 +/- 14.9 micro g x L(-1)), but not in the diltiazem group (1.8 +/- 1.4 to 3.2 +/- 3.2 micro g x L(-1)). Forty-eight hours postoperatively alpha-GST was significantly lower in the diltiazem group than in both other groups.

CONCLUSIONS

Diltiazem stimulates urine output, reduces excretion of alpha-GST and ss-NAG and may be useful to maintain tubular integrity after cardiac surgery.

Understanding renal dose dopamine

Low-dose dopamine is a widely administered drug used often in critical care settings to prevent or treat patients with low urinary output. There are new data to support that low-dose dopamine may have side effects and not always increase renal perfusion to the kidneys. This article is a review of the current use of low-dose dopamine, the role of dopamine in the kidneys, and the potential risks of infusing this drug to patients.

Acute lung injury: pathophysiology, assessment and current therapy

Acute respiratory distress syndrome (ARDS) is a clinically defined entity describing the severity of diffuse alveolar injury caused by direct or indirect injury to the lung. Pathophysiology, clinical course and outcome of ARDS depend on the underlying cause, the severity of the disease and co-morbidities. Pulmonary function tests show restrictive lung disease, which is characterised by a reduction in lung compliance and functional residual capacity, resulting in marked ventilation-perfusion inequality. Current ventilator strategies aim to minimise ventilator-induced lung injury by targeting mechanical ventilation between the lower and upper inflection point of the pressure volume curve. This includes recruitment manoeuvres and the use of high PEEP to open the atelectatic lung and the use of permissive hypercapnia and the limitation of peak inspiratory pressure below 35 cm H2O to avoid overinflation. The clinical benefit of newer modes of ventilatory support such as inverse ratio ventilation, high frequency oscillatory ventilation, surfactant replacement, prone positioning and inhaled nitric oxide has yet to be determined in children.

The patient at risk for acute renal failure. Recognition, prevention, and preoperative optimization

Despite major advances in critical care medicine and extracorporeal renal support, the treatment of established postoperative ARF remains unsatisfactory and costly. The essential elements of perioperative renal preservation are early recognition of high-risk patients, preoperative optimization of fluid status and cardiovascular performance, intraoperative maintenance of renal perfusion, and avoidance of nephrotoxins. Pharmacologic interventions directed at preventing postoperative ARF are under intense investigation but presently are limited to renal transplant surgery.

New perspectives for prevention/treatment of acute renal failure

Acute renal failure continues to be a difficult clinical problem in critically ill patients, despite advances in critical care and dialysis. This review focuses on some of the current issues in the nondialytic and dialytic management of these patients. Critical analysis of some still frequently used drugs in these patients such as diuretics and dopamine in so-called 'renal doses' has revealed little beneficial effect. Recent data are in conflict with previous suggestions that biocompatible membranes have a positive effect on the recovery of renal function and on patient mortality. The choice between intermittent haemodialysis and continuous renal replacement therapy should be made on an individual basis and not on the basis of 'dogmatic' opinion.

Trauma intensive care

Management of the traumatically injured patient in the intensive care unit is a complex and challenging area of general surgery. The problems encountered in the intensive care unit are the source of exciting clinical and basic science research. The future of caring for the severely injured patient suffering from the complications of trauma will undoubtedly further bond the art of clinical medicine to the accomplishments of developing technology and molecular biology.

Perioperative renal protection

Acute renal failure continues to complicate the postoperative courses of our vascular and cardiac surgical patients, dramatically increasing mortality and decreasing quality of life when it occcurs. In spite of better understanding of the disease, few gains have been made in its prevention. We review its pathophysiology and discuss the most recent developments that may eventually lead to perioperative renal protection.

Preoperative cardiac preparation

Preoperative preparation of the cardiac patient is based on matching the cardiac reserve to the blood flow demands imposed by surgical stress and the underlying disease state. Evaluation must include functional assessment of any coronary artery disease or other organic cardiac disease that may place myocardial tissue at risk of ischemia as demand for cardiac output increases. Monitoring should be individualized based on anticipated problems and the risk assessment of the patient. Preoperative therapy should include maneuvers that reduce congestive heart failure, optimize volume status, and provide adequate cardiac output to deliver oxygen sufficient to meet or exceed demand. Underlying electrical and metabolic abnormalities should be corrected and controlled in the perioperative period. Long-term therapy should be evaluated and modified in the context of the anesthetic and surgical plan. Preventive interventions such as fluid loading and low-dose dopamine should be considered prior to surgery.