Relative risks of limb revascularization and amputation in the modern era.

A retrospective review of 266 patients undergoing infrainguinal revascularization for limb salvage and/or major amputation (transmetatarsal, below-knee or above-knee) from 1984 to 1990 was conducted to determine comprehensive procedure-specific 30-day operative morbidity and mortality rates. Some 211 patients underwent 295 infrainguinal vascular reconstructions (195 primary and 100 secondary reconstructions). There were 122 major amputations in 98 patients (29 above-knee, 70 below-knee and 23 transmetatarsal). Most amputations were performed in patients with unreconstructable vascular disease, including 39 patients (41 extremities) with failed infrainguinal reconstruction. Procedure-specific morbidity and mortality rates were 48 and 2% for primary revascularization, 35 and 2% for secondary revascularization and 37 and 4%, for amputation, respectively. The difference in mortality between revascularization and amputation approached but did not achieve statistical significance. Cardiac, graft and wound complications were the major causes of morbidity in all groups. Nine of the 12 deaths were of cardiac etiology. Revascularization can be performed in almost all patients with advanced limb ischemia, with a mortality rate equivalent to, or perhaps lower than, that of amputation. When limb amputation is required, it can be performed with a mortality rate remarkably lower than that described in the older literature.

Influence of age on venous physiologic parameters.

PURPOSE: The incidence of deep venous thrombosis increases significantly with age. Attempts to explain this association have failed to identify factors that could be contributory. We hypothesized that age-related changes in venous physiologic parameters might contribute to an increased risk of deep venous thrombosis. METHODS: Air plethysmography was used to measure a number of physiologic parameters in two sets of patients. Group A consisted of 17 subjects (33 limbs), age range 23 to 40 years. Group B consisted of 11 subjects (22 limbs), age range 60 to 83 years. No subject in either group had peripheral vascular disease or a history of deep venous thrombosis. Parameters measured were venous volume, venous filling index, ejection volume, ejection fraction, residual volume fraction, and outflow fraction. RESULTS: Venous volume and ejection fraction were significantly reduced in Group B compared with Group A. Residual volume fraction was significantly increased in Group B compared with Group A. There were no statistically significant differences in outflow fraction, venous filling index, or ejection fraction between the two groups. CONCLUSIONS: These results suggest that the efficiency of the calf muscle pump diminishes with increasing age, possibly contributing to the increased incidence of deep venous thrombosis in the elderly.

Inhibitory effect of high oxygen pressure on potassium- induced activation of pyruvate dehydrogenase and glucose metabolism in rat brain slices.

The effects of high oxygen pressure on pyruvate dehydrogenase (pyruvate: lipoate oxidoreductase (decarboxylating and acceptor-acylating), EC 1.2.4.1) activity, tissue concentration of ATP, and CO2 production from glucose were studied in rat brain cortical slices. The increase in pyruvate dehydrogenase activity and the lowering of cellular ATP, occurring during potassium-induced depolarization at 1 atm of oxygen, were reversed by increasing the oxygen pressure to 5 atm. When brain slices were incubated at 1 atm oxygen with [U-14C]glucose, a high potassium medium approximately doubled the production of 14CO2. Oxygen at 5 atm abolished this potassium-dependent increase in 14CO2 production with no significant effect on glucose oxidation in normal Krebs-Ringer phosphate medium. Adding 4 atm helium to 1 atm oxygen did not interfere with the ability of potassium ions to activate pyruvate dehydrogenase, lower ATP, or increase glucose oxidation. The results show that toxic effects of hyperbaric oxygen, not manifest in "resting" tissue, may be revealed during stress such as potassium depolarization. The site of the toxic effects of oxygen is probably the cell membrane where excess oxygen appears to interfere with the action of the sodium pump, calcium transport or other processes stimulated by increased concentrations of extracellular potassium.