Effects of fluid and dobutamine treatment on renal function during partial superior mesenteric artery occlusion and reperfusion

Ringer's ethyl pyruvate solution attenuates hypoperfusion and renal injury after multivisceral ischemia-reperfusion in rabbits

Ringer's ethyl pyruvate solution (REPS) has been protective against experimental renal, intestinal, and spinal ischemia and may be useful for organ protection in major vascular surgery. The purpose of this study was to investigate whether REPS attenuates organ injury in a rabbit model of supraceliac aortic cross-clamp that simulates thoracoabdominal aortic surgery. Following the Institutional Animal Care and Use Committee's approval, 20 rabbits were undergone cross-clamping of the supraceliac thoracic aorta for 30 min, and observed for 180 min after reperfusion. Either REPS (33 mg/kg/h of ethyl pyruvate) or Ringer's lactate solution were infused throughout the study period. Arterial pressure and aortic blood flow were continuously monitored. Blood lactate concentration, serum transaminase levels, neutrophil activation, and urinary N-acetyl-beta-glucosaminidase (NAG) activity were evaluated. After reperfusion, supraceliac aortic blood flow was significantly higher, and urinary NAG was significantly lower in animals that received REPS, while the other parameters were not significantly different. In conclusion, REPS attenuated the reduction of aortic blood flow and urinary NAG elevation after the cross-clamp of supraceliac aorta.

Effects of meloxicam and phenylbutazone on renal responses to furosemide, dobutamine, and exercise in horses

OBJECTIVE

To compare the effects of 2 NSAIDs (phenylbutazone and meloxicam) on renal function in horses.

ANIMALS

9 Thoroughbred or Standardbred mares (mean ± SD age, 5.22 ± 1.09 years [range, 2 to 12 years]; mean body weight, 470 ± 25 kg [range, 442 to 510 kg]).

PROCEDURES

A randomized blinded placebo-controlled crossover study was conducted to examine the effects of treatment with phenylbutazone, meloxicam, or a placebo (control solution) on renal responses to the administration of furosemide, dobutamine, and exercise (15 minutes at 60% of maximum heart rate). Renal function was assessed by use of bilateral ureteral catheterization for simultaneous determination of creatinine clearance, sodium excretion, and urine flow rate.

RESULTS

Both phenylbutazone and meloxicam attenuated diuresis and natriuresis and reduced glomerular filtration rate, compared with results for the control solution, when horses were treated with furosemide. Mean arterial blood pressure, urine flow rate, and glomerular filtration rate were increased during or after (or both) dobutamine infusion. Both NSAIDs reduced urine flow rate and sodium excretion associated with dobutamine infusion and exercise but had no effect on glomerular filtration rate.

CONCLUSIONS AND CLINICAL RELEVANCE

Responses to meloxicam, a cyclooxygenase (COX)-2 preferential agent, appeared comparable to those detected after phenylbutazone treatment, which suggested that COX-2 was the mediator of prostanoid-induced changes to renal function in horses and indicated that COX-2-preferential agents would be likely to have adverse renal effects similar to those for nonselective COX inhibitors in volume-depleted horses.

The presence of oxidized low-density lipoprotein and inducible nitric oxide synthase expression in renal damage after intestinal ischemia reperfusion

Intestinal ischemia/reperfusion (I/R) is a complex phenomenon that causes destruction of both local and remote tissues. The objective of this study was to investigate the possible participation of oxidized low-density lipoproteins (oxLDLs) and inducible nitric oxide synthase (iNOS) expression in renal tissue damage after intestinal I/R. The superior mesenteric artery was blocked for 30 minutes, followed by 24 hours of reperfusion. At the end of the reperfusion period, renal tissues were removed; the presence of oxLDL, superoxide dismutase enzyme activity, malondialdehyde levels, and iNOS expression were evaluated. I/R resulted in positive oxLDL staining in renal tissue. Compared with control rats, tissue from the I/R group showed significantly higher malondialdehyde levels and lower superoxide dismutase enzyme activity. Strong and diffuse iNOS expression was present in the I/R group. Our findings support the hypothesis that I/R of intestinal tissue results in oxidative and nitrosative stress and enhances lipid peroxidation in the end organ. These data show that oxLDL accumulates in rat renal tissue after intestinal I/R. Antioxidant strategies may provide organ protection in patients with reperfusion injury, at least by affecting interactions with free radicals, nitric oxide, and oxLDL. This study demonstrates for the first time that oxLDL may play a role in renal tissue damage after intestinal I/R. Antioxidant strategies may be beneficial for protection from reperfusion injury.

Anesthetic management of acute mesenteric ischemia in elderly patients

Ischemic insult to the splanchnic vasculature can jeopardize bowel viability and lead to devastating consequences, including bowel necrosis and gangrene. Although acute mesenteric ischemia (AMI) may occur at any age, the elderly are most commonly affected due to their higher incidence of underlying systemic pathology, most notably atherosclerotic cardiovascular disease. Treatment options include pharmacology-based actions, endovascular, and surgical interventions. AMI remains a life-threatening condition with a mortality rate of 60% to 80%, especially if intestinal infarction has occurred and surgical intervention becomes emergent. Early recognition and an aggressive therapeutic approach are essential if the usually poor outcome is to be improved. Anesthetic management is complex and must account for comorbid disease as well as the patient's presumptive acute deterioration. Blood pressure support typically involves careful, but often massive, fluid resuscitation and may also additionally require pharmacologic support.