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

Prevention of Acute Renal Failure: Role of Vaso-Active Drugs, Mannitol and Diuretics

Evidence exists that acute renal failure (ARF) independently increases mortality risk in critically-ill patients. Therefore prevention of ARF seems of paramount importance. Preservation of renal blood flow and (sufficient) perfusion pressure favourably influences the prevention of renal function deterioration in the critically-ill septic patient. The first step to achieve this is infusion of fluids, either crystalloids or colloids, with the aim of optimal fluid resuscitation. Although “optimal fluid resuscitation” is poorly defined, in clinical practice it can be considered as the point where a certain preload is obtained, after which no further increase of cardiac output is observed with further fluid infusion. Vasoactive drugs can be added to this regimen in case of insufficient restoration of flow and especially perfusion pressure. The addition of norepinephrine can be of value if high doses of dopamine fail to restore perfusion pressure. No evidence exists that low-dose dopamine prevents renal failure and, therefore, dopamine should not be given for this indication. The use of diuretic agents can be harmful, as indicated by observational and cohort studies. Although mannitol flushes out intratubular casts and increases tubular flow, which is favorable in myoglobinuria or hemoglobinuria, so far no well designed clinical studies have demonstrated its efficacy in ARF. In conclusion, there is currently no convincing evidence for any benefit from diuretic agents and/or (low dose) dopamine in the prevention of ARF. High quality intenisve care and avoidance of harm is, therefore, the current standard of the prevention of ARF.

Treatment of Abdominal Aortic Pathology

Abdominal aortic pathology is a diverse topic, ranging through a broad span of possible pathologies. The treatment options are equally vast, particularly with the ever-expanding endovascular techniques. In this article, we discuss management strategies for abdominal aortic aneurysms and aortic occlusive disease, because they represent some of the most common pathologies encountered in clinical scenarios.

Renal function and dysfunction

Recent publications regarding perioperative renal dysfunction provide a 'potpourri' of topics worthy of discussion. The risk of perioperative renal dysfunction is higher in patients with heart failure, but other pre-existing conditions, such as genetic polymorphism, may have prognostic implications. Evaluation of renal risk and protective interventions are discussed for a number of specific operative entities, including cardiac surgery (with or without cardiopulmonary bypass), aortic surgery and renal revascularization. New publications on a wide variety of nephrotoxic insults are presented, including antifibrinolytic agents, obstructive jaundice, prostaglandin inhibitors, cyclosporine A, radiocontrast dyes and volatile anesthetic agents. Renal transplantation is discussed as a specific entity. Finally, we discuss recent papers describing outcome in patients in chronic renal failure undergoing cardiac surgery.

Effect of fenoldopam on renal function after nephrotomy in normal dogs

OBJECTIVE

To evaluate effects of fenoldopam on renal function in normal dogs subjected to bisection nephrotomy. In addition, effects of bisection nephrotomy on renal function in normal dogs were evaluated.

STUDY DESIGN

Controlled, randomized, blinded experiment.

SAMPLE POPULATION

Sixteen mixed-breed adult dogs.

METHODS

Dogs were paired for sex, body weight, and approximate age and assigned to 1 of 2 groups: fenoldopam (F) or placebo (P). Baseline glomerular filtration rate (GFR) based on quantitative renal scintigraphy using (99m)Tc-DTPA, blood urea nitrogen (BUN), serum creatinine (SCr), urinalysis, and urine culture were performed before surgery. Left nephrotomy was performed via median celiotomy. Group F dogs were administered intravenous (IV) fenoldopam (0.1 microg/kg/min) for 90 minutes, whereas group P dogs were administered an equivalent volume of saline (0.9 % NaCl) solution for 90 minutes. Temperature, heart rate, respiration, direct arterial blood pressure, and urine volume were recorded during anesthesia. Renal function was assessed by measuring SCr, BUN, and GFR at 1, 21, and 42 days after surgery.

RESULTS

There was no significant difference between groups in measured physiologic variables. No significant difference in GFR, BUN, or SCr between groups or between operated or control kidneys was detected.

CONCLUSIONS

Bisection nephrotomy in normal dogs with renal arterial occlusion of 15 minutes and using a simple continuous capsular closure does not adversely affect renal function.

CLINICAL RELEVANCE

Bisection nephrotomy, as described in this study, does not decrease renal function; perioperative administration of renoprotective agents is not necessary in normal dogs.