Capillary muscle blood flow in human sepsis.

Tissue perfusion was determined by cardiac index (Cl) and skeletal muscle capillary blood flow (MBF), and arteriovenous oxygen difference (AVD) and oxygen uptake were compared in seven patients with severe spesis and eight nonseptic patients. Skeletal capillary muscle blood flow also was measured before and after a 2 day fast in 14 normal volunteers. In both septic and nonseptic patients, MBF varied directly with Cl. The average muscle blood flow was greater in septic than in nonseptic patients and, in addition, was greater per unit Cl. AVD in septic patients was narrower than in nonseptic patients. Septic patients with an AVD of less than 4 ml. of O2 had markedly higher MBF and Cl than did septic patients with an AVD greater than 4 ml. of O2. Fasting normal volunteers who, like the septic patients, would be catabolic had a significant increase in MBF during the fast. Although peripheral shunts are not ruled out ans an explanation of the hyperdynamic circulation in sepsis, the evidence is against their existence, at least in skeletal muscle, since capillary flow increases in direct proportion to cardiac output. If capillary flow is increased in fact in sepsis, then flow like blood pressure becomes less of a critical factor in explaining the demise of the septic patient. It might be postulated that the increased capillary flow seen in sepsis is secondary to the mobilization of amino acids from the body cell mass for gluconeogenesis and energy.

Femoral arteriovenous amino acid differences in septic patients.

Femoral arteriovenous differences and flux of amino acids across the leg were measured in seven septic patients and compared with those of six nonseptic patients on days 1 and 3 following major surgery. The septic patients were seriously ill and judged clinically to be catabolic. The postoperative patients, although not septic, were expected to have a maximal catabolic response to operation during the first 3 days after operation. Both groups had increased release of phenylalanine from the leg, an index of muscle proteolysis. Septic patients had decreased femoral arteriovenous differences (--20 vs --74 and --60 mumoles/liter) and decreased flux (34 vs 169 and 128 nm/100 gm of calf muscle) of the branched-chain amino acids as compared with the nonseptic postoperative patients on days 1 and 3. The arterial plasmal levels of the branched-chain amino acids and alanine were not different, but phenylalanine was elevated in the septic patients (88 vs 49 and 55 mumoles/liter). The insulin:glucagon molar ratio was lower in the septic patients (2.4 vs 4.4 and 5.5). These findings suggest that in the catabolism of sepsis there is greater oxidation of branched-chain amino acids in muscle than in the catabolism associated with uncomplicated surgery.