Ischemic Organ Injury Research Articles

Central Hemodynamic and Regional Blood Flow Changes in the Newborn with Right Ventricular Hypertension

To evaluate the central hemodynamic and regional blood flow changes associated with right ventricular hypertension in the newborn, 13 anesthetized, mechanically ventilated piglets less than 3 d old were acutely instrumented to permit measurements of central vascular pressures, cardiac output, and regional blood flow (radio-labeled microsphere technique). After initial measurements, right ventricular afterload was progressively increased by means of a pulmonary arterial mechanical occluder until right-to-left foramen ovale shunt was observed. An increase in pulmonary arterial pressure from 32 +/- 2 to 55 +/- 3 mm Hg was associated with a decrease in PaO2 from 364 +/- 16 to 88 +/- 9 mm Hg and an increase in the shunt fraction from 13 +/- 1 to 28 +/- 1% (p less than 0.01) during ventilation with oxygen. Right ventricular hypertension induced a significant decrease in systemic arterial pressure from 79 +/- 3 to 63 +/- 4 mm Hg, and left ventricular cardiac output from 156 +/- 10 to 112 +/- 11 mL.min-1.kg-1 (p less than 0.01), likely secondary to a reduction in left ventricular compliance. Oxygen delivery to the brain and heart were unaffected, due to a substantial increase in regional blood flow, but a significant reduction in delivery to the bowel and kidneys were observed. Contrary to what has been reported in the adult, myocardial blood flow to the right ventricle increased during hypertension. Metabolic acidosis was seen in all animals and the changes in serum bicarbonate and whole body oxygen consumption were directly related to the magnitude of decline in systemic O2 delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of allopurinol on oxidant stress and hepatic function following ischemia and reperfusion in the rat.

Reactive oxygen species generated by xanthine oxidase during reperfusion of ischemic liver might in part be responsible for ischemic organ injury. Therefore, the effect of allopurinol, an inhibitor of xanthine oxidase, on the oxidant stress associated with reperfusion and on hepatic function 24 h after ischemia was assessed in a model of partial hepatic ischemia in rats. The increase in circulating glutathione disulfide (GSSG) was used as an index of oxidant stress. Hepatic function was assessed using a breath test to quantitative the demethylation of aminopyrine in vivo. In control animals the plasma concentration of GSSG 1 h after onset of reperfusion increased from 0.9 mumol/l in sham-operated controls to 4.2, 5.5, and 8.0 mumol/l following 45, 90 and 120 min of ischemia, respectively. The percent of the administered dose of (dimethylamine-14C)-aminopyrine appearing in breath as 14CO2 was not significantly different from sham-operated controls (40.2%) 24 h after 45 min of ischemia (34.1%), but decreased progressively to 26.0% (p less than 0.05) and 20.6% (p less than 0.05) after 90 and 120 min of ischemia, respectively. Allopurinol, administered at a dose of 50 mg/kg 18 h and 1 h prior to ischemia, did not prevent the rise in plasma GSSG, did not alleviate the release of transaminases, and did not improve the demethylation of aminopyrine 24 h after ischemia, suggesting that reactive oxygen species generated by xanthine oxidase during reperfusion of ischemic liver do not contribute significantly to ischemic injury.

Management of a complex, posttraumatic, pelvic arteriovenous fistula with the use of cardiopulmonary bypass: Case report and review of the literature

A 34-year-old man had a posttraumatic, pelvic arteriovenous fistula (AVF) and false aneurysm of 18 years' duration. He had undergone four previous unsuccessful attempts at operative repair, the last of which almost resulted in exsanguination. After the false aneurysm was exposed, the patient was placed on cardiopulmonary bypass. Core cooling (25° C) allowed the perfusion flow rates to be lowered (less than 0.5 L/min/m2) while the aneurysm was opened, thereby permitting visualization and ligation of the arteriovenous communications within the aneurysm. Total circulatory arrest was not required. There were no complications and the patient was discharged on the eleventh postoperative day. Arteriography 5 months later showed complete ablation of the AVF. We believe that cardiopulmonary bypass with hypothermia and reduced blood flow is a useful adjunct in the repair of complex AVFs and arteriovenous malformations. This technique avoids the use of total circulatory arrest, which increases the risks of air embolism and ischemic organ injury.