Chest
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Comparative Study
Comparison of exercise cardiac output by the Fick principle using oxygen and carbon dioxide.
Theoretically, cardiac output (CO) calculated by the Fick principle should be the same using O(2) (CO[O2]) or CO2 (CO[CO2]) as the test gas. However, agreement depends on the accuracy of gas exchange and blood gas measurements and the validity of the equations to convert measured variables into blood gas contents. Considering the widespread use of indirect estimates of pulmonary artery blood PCO2 and CO2 content to measure Fick principle CO during exercise, we wished to determine whether CO[O2] and CO[CO2] were equal during exercise and whether CO[CO2] could be accurately and precisely determined using direct measures of pulmonary artery blood. PREPARATION AND METHODS: Five healthy young nonsmoking volunteer men performed incremental exercise from rest to peak exercise on two separate occasions with intervening rest. Catheters were placed in brachial and pulmonary arteries to allow repeated blood sampling every minute during concurrent breath-by-breath gas exchange measurements from rest to peak exercise. CO[O2] was compared with CO[CO2] at multiple levels of exercise. Using standard equations, arterial and mixed venous O2 contents were calculated from hemoglobin concentration (Hb), oxyhemoglobin saturation (SO2), and PO2, whereas CO2 contents were calculated from PCO2, pH, Hb, and SO2. Blood gas analyzers were used for measurement of pH, PCO2, and PO2, and a co-oximeter was used for measurement of Hb and SO2. Initial calculations suggested that exercise CO[CO2] was 14% higher than CO[O2] and helped disclose small systematic measurement errors in PCO(2) for values > 45 mm Hg detected by proficiency testing surveys and documented with blood tonometry in the blood gas analyzer. ⋯ The increased variability of Fick principle CO[CO2] compared with CO[O2] is attributable to the much lower extraction ratio for CO2 and the greater complexity in calculation of blood CO2 than O2 contents. These results raise concerns about the accuracy and precision of estimating CO and stroke volume using CO2 as a test gas, even with direct measurement of blood CO2 contents in normal subjects.
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Comparative Study
Correlation of changes in quality of life after lung volume reduction surgery with changes in lung function, exercise, and gas exchange.
To evaluate correlations between improvement in quality of life (QOL) in patients with severe COPD before and after they undergo lung volume reduction surgery (LVRS) with changes in pulmonary function tests, gas exchange, exercise performance, and alterations in medical management. ⋯ There is an association between an improvement in QOL and reduced hyperinflation after LVRS. Reduced hyperinflation may lead to more efficient work of breathing during exercise and, therefore, to an increased ability to perform daily activities. Changes in QOL scores correlate best with behaviorally based variables that directly affect the patient's well-being, such as systemic steroid administration.
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Randomized Controlled Trial Comparative Study Clinical Trial
Pulmonary function is a long-term predictor of mortality in the general population: 29-year follow-up of the Buffalo Health Study.
Results from several studies have described a relationship between pulmonary function and both all-cause and cause-specific mortality. The purpose of this study was to investigate the predictive value of pulmonary function by gender after 29 years of follow-up. ⋯ These results suggest that pulmonary function is a long-term predictor for overall survival rates in both genders and could be used as a tool in general health assessment.
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Multicenter Study Comparative Study
Management and outcome patterns for adult Pneumocystis carinii pneumonia, 1985 to 1995: comparison of HIV-associated cases to other immunocompromised states.
Encompassing periods preceding and following major advances in the diagnosis and management of HIV-related Pneumocystis carinii pneumonia (PCP), the purpose of this study was to determine whether management and outcome patterns of non-HIV PCP parallel the management and outcomes of AIDS-related PCP. ⋯ Despite major advances in diagnosis and management, PCP remains a significant problem in non-HIV-infected patients, and respiratory failure remains associated with a high mortality rate for patients with both HIV + PCP and non-HIV PCP.