The combination of 18 to 69 hours of complete diaphragmatic inactivity and mechanical ventilation results in marked atrophy of human diaphragm myofibers. These findings are consistent with increased diaphragmatic proteolysis during inactivity.

Background-Previous studies have shown that black race is an independent predictor of increased operative mortality after coronary artery bypass surgery. Given the higher incidence of hypertension and hypertension-associated left ventricular hypertrophy in blacks, we hypothesized that black race might be associated with increased risk of mortality and morbidity after aortic valve replacement (AVR) or mitral valve replacement (MVR). We could not identify a previous study that used a multivariable model to evaluate the association between race and operative mortality after AVR or MVR. Methods and Results-The Society of Thoracic Surgeons National Cardiac Database was used for a retrospective review of 3137 black and 46 249 white patients who underwent MVR alone or AVR alone from 1999 through 2002. Multivariate logistic regression was used to assess the association between race and mortality and 6 other adverse outcomes (stroke, renal failure, prolonged ventilation, prolonged postoperative stay, sternal infection, and bleeding) after adjustment for covariates. Unadjusted operative mortality for MVR only was 5.60% for blacks versus 6.18% for whites (OR 0.90 [95% CI 0.71 to 1.14]) and 4.60% for blacks versus 3.62% for whites for AVR only (OR 1.28 [95% CI 1.02 to 1.62]). After adjustment for other risk factors, black race was not a significant predictor of operative mortality after AVR or MVR; however, black race was associated with an increased risk of several complications: prolonged ventilation after AVR or MVR, postoperative stay Ͼ14 days after AVR or MVR, reoperation for bleeding after AVR, and postoperative renal failure after MVR. There was no significant association between race and the risk of stroke or deep sternal wound infection for either AVR or MVR. Conclusions-In contrast to previously published results that defined race as an independent risk factor for operative mortality after coronary artery bypass surgery, race does not appear to be a significant predictor of operative mortality after isolated AVR or MVR; however, there is evidence of an association between race and certain complications.

The overall profitability of a comprehensive vascular program is tremendously positive. This study verifies that new vascular-specific referrals are a significant catalyst for revenue.

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