American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Feb 2000
Effects of decreased respiratory frequency on ventilator-induced lung injury.
To determine if decreased respiratory frequency (ventilatory rate) improves indices of lung damage, 17 sets of isolated, perfused rabbit lungs were ventilated with a peak static airway pressure of 30 cm H(2)O. All lungs were randomized to one of three frequency/peak pulmonary artery pressure combinations: F20P35 (n = 6): ventilatory frequency, 20 breaths/min, and peak pulmonary artery pressure, 35 mm Hg; F3P35 (n = 6), ventilatory frequency, 3 breaths/min, and peak pulmonary artery pressure of 35 mm Hg; or F20P20 (n = 5), ventilatory frequency, 20 breaths/min, and peak pulmonary artery pressure, 20 mm Hg. Mean airway pressure and tidal volume were matched between groups. ⋯ The F20P35 group showed at least a 4.5-fold greater mean weight gain and a 3-fold greater mean incidence of perivascular hemorrhage than did the comparison groups, all p
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Am. J. Respir. Crit. Care Med. · Feb 2000
Comparative StudyClinical correlates and prognostic significance of six-minute walk test in patients with primary pulmonary hypertension. Comparison with cardiopulmonary exercise testing.
The six-minute walk test is a submaximal exercise test that can be performed even by a patient with heart failure not tolerating maximal exercise testing. To elucidate the clinical significance and prognostic value of the six-minute walk test in patients with primary pulmonary hypertension (PPH), we sought (1) to assess the relation between distance walked during the six-minute walk test and exercise capacity determined by maximal cardiopulmonary exercise testing, and (2) to investigate the prognostic value of the six-minute walk test in comparison with other noninvasive parameters. The six-minute walk test was performed in 43 patients with PPH, together with echocardiography, right heart catheterization, and measurement of plasma epinephrine and norepinephrine. ⋯ Among noninvasive parameters including clinical, echocardiographic, and neurohumoral parameters, only the distance walked in 6 min was independently related to mortality in PPH by multivariate analysis. Patients walking < 332 m had a significantly lower survival rate than those walking farther, assessed by Kaplan-Meier survival curves (log-rank test, p < 0.01). These results suggest that the six-minute walk test, a submaximal exercise test, reflects exercise capacity determined by maximal cardiopulmonary exercise testing in patients with PPH, and it is the distance walked in 6 min that has a strong, independent association with mortality.
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Am. J. Respir. Crit. Care Med. · Feb 2000
Comparative StudyAsthma mortality in U.S. Hispanics of Mexican, Puerto Rican, and Cuban heritage, 1990-1995.
We used national vital statistics data for 1990 through 1995 to examine both national and regional age-adjusted asthma mortality rates for U. S. Hispanics of Mexican, Cuban, and Puerto Rican heritage, as well as for non-Hispanic whites and non-Hispanic blacks. ⋯ S., Puerto Ricans had the highest asthma mortality rates among Hispanics, followed by Cuban-Americans and Mexican-Americans. In addition, among Hispanic national groups, mortality rates were consistently higher in the Northeast than the Midwest, South, or West regions. These results further support that Hispanics do not represent a uniform, discrete group in terms of health outcomes, and that further public health research and interventions should take Hispanic national origin into account.
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Am. J. Respir. Crit. Care Med. · Feb 2000
Effect of the prone position on patients with hydrostatic pulmonary edema compared with patients with acute respiratory distress syndrome and pulmonary fibrosis.
This study examined the effect of the prone position on mechanically ventilated patients with hydrostatic pulmonary edema (HPE). Eight patients with acute HPE and mechanically ventilated in the prone position (Group 1) were studied. Six patients with acute HPE and mechanically ventilated in the supine position (Group 2), 20 patients with ARDS (Group 3), and 5 patients with pulmonary fibrosis (PF) (Group 4) served as control patients. ⋯ Our results show that the prone position may be a useful maneuver in treating patients with severe hypoxemia due to pulmonary edema. The presence of pulmonary edema, as in early ARDS and HPE predicts a beneficial effect of the prone position on gas exchange. In contrast, the presence of fibrosis, as in late ARDS and pulmonary fibrosis, predisposes to nonresponsiveness to prone positioning.