Proteolysis associated with a deficit of peripheral energy fuel substrates in septic man.

Sixteen seriously septic patients were studied to determine whether proteolysis occurred to satisfy a deficit of peripheral fuel, as suggested by out previous experimental observations. Concentrations of glucose, lactate, free fatty acids,and alanine were measured in blood samples from the femoral artery and vein to determine extraction (+) and release (-) by the leg. Simultaneously, cardiac index (CI) was determined by thermal dilution, so that an estimate of uptake or production of fuel substrates could be made from the proportional relationship of cardiac index to peripheral blood flow. Due to the antilipolytic effect of elevated levels of insulin (42 +/- 4 muM per milliliter) in those patients with elevated cardiac indices (4.38 +/- 0.33 L. per square meter per minute), free fatty acid uptake (-0.59 +/- 0.021 mM.) was reduced. In low-flow septic shock (CI, 1.66 +/- .41 L. per square meter per minute), the majority of glucose taken up by the limb was converted to lactate (arterial lactate, 3.14 +/- 0.7 mM.; deltaA-V 0.68 +/- 0.17). Free fatty acid uptake also was impaired in low-flow sepsis. As opposed to fasting, arterial levels and uptake of ketone bodies were insignificant in sepsis. These findings suggest that there is a deficit of peripheral fuel with respect to glucose and fat. That protein is oxidized to fill this deficit is substantiated by the increased alanine release (-0.13 +/- 0.01, -0.33 +/- 0.12 mM.) in the high-flow and low-flow septic groups, respectively, whereas alanine production was three- and fourfold greater than that observed in fasting patients. Enhanced release of alanine reflects the magnitude of oxidation of branched-chain amino acids and accounts for the high rates of gluconeogenesis and proteolysis observed in sepsis.

A metabolic approach to the evaluation of peripheral vascular disease.

Thirty-five patients with occlusive disease of the arteries underwent metabolic studies. The arteriovenous differences of lactate, glucose and oxygen varied with the severity of the ischemic process, as assessed clinically. Lactate release and glucose extraction were significantly different from control values of patients with rest pain or with ischemic gangrene, while values in patients with claudication were comparable with those in the control group. Percutaneous muscle surface pH measurements, which reflect lactate release, decreased directly with diminished perfusion. Metabolic assessment of arterial occlusive disease may prove to be a useful clinical approach.

Ibuprofen pretreatment inhibits prostacyclin release during abdominal exploration in aortic surgery.

Mesenteric traction during aortic surgery produces facial flushing, reduced mean arterial pressure (MAP), and systemic vascular resistance (SVR) with increased heart rate (HR) and cardiac index (CI). Elevated 6-keto-prostaglandin-F1 alpha (6-keto-PGF1 alpha) suggests prostacyclin is the mediator. To test this hypothesis, the cyclooxygenase inhibitor, ibuprofen (n = 14), or placebo (n = 13) was administered to patients electively scheduled for aortic reconstruction. The hemodynamic measurements and plasma concentrations of prostanoids between groups were compared immediately before (0), and 5, 10, 15, 30, and 45 min following mesenteric traction. Following mesenteric traction significant differences (P less than 0.05) were observed between the ibuprofen pretreatment and placebo group over time in SVR, MAP, HR, CI, 6-keto-PGF1 alpha, and thromboxane B2 (TXB2). Significant differences between groups at individual times were found in SVR, HR, CI, 6-keto-PGF1 alpha, and TXB2. In the placebo group flushing was accompanied by reduced SVR and MAP and increased HR and CI. The greatest effect was seen at 10 min and resolved over 30 min. Plasma concentration of 6-keto-PGF1 alpha increased from 159 +/- 103 (mean +/- SEM) pg/ml to a peak value of 3,765 +/- 803 at 10 min. A late increase in TXB2 occurred with a peak value of 1,970 +/- 891 (mean +/- SEM) pg/ml at 30 min. In the ibuprofen pretreated group no significant changes occurred in hemodynamic measurements or concentrations of prostanoids. The inhibition of 6-keto-PGF1 alpha and its associated hemodynamic changes in the treatment group, but not in the placebo group, confirms the hypothesis that prostacyclin is the mediator of the mesenteric traction response in abdominal aortic surgery.