American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Feb 1996
The determinants of pulmonary diffusing capacity in a national sample of U.S. adults.
Racial and gender differences in single-breath pulmonary diffusing capacity for carbon monoxide (DLCO) have previously received little attention. Between 1971 and 1975, the first National Health and Nutrition Examination Survey determined DLCO for 4,439 adults ages 25 to 74 residing in the United States, including 2,345 women and 438 blacks. The large sample permitted an evaluation of interactions and nonlinear relationships with DLCO, and its association with biomarkers of inflammation. ⋯ In current smokers, cigarettes per day and pack-years were predictive of DLCO even after control for FVC and controlling for these variables fully explained the difference in DLCO between never and current smokers. Peripheral neutrophil count, a biomarker of inflammation, was associated with reduced DLCO. Thus, substantial sex and race differences exist for DLCO within the general United States population.
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Am. J. Respir. Crit. Care Med. · Feb 1996
Comparative StudyDifferences in interleukin-8 and tumor necrosis factor-alpha in induced sputum from patients with chronic obstructive pulmonary disease or asthma.
Asthma and chronic obstructive pulmonary disease are characterized by chronic airway inflammation. Studies using bronchoalveolar lavage (BAL) have shown an increased proportion of eosinophils in the BAL fluid from asthmatics compared with that from normal subjects, whereas studies of chronic obstructive pulmonary disease (COPD) have shown increased numbers of neutrophils. Induced sputum allows sampling of respiratory tract secretions from patients and control subjects, providing a noninvasive method of studying airway secretions and allowing characterization of cells and measurement of soluble markers. ⋯ We found a significant increase in neutrophils and increased concentrations of tumor necrosis factor-alpha (TNF alpha) and interleukin-8 (IL-8) in the patients with COPD compared with the smoking and nonsmoking control subjects. Interleukin-8, but not TNF alpha, was significantly higher in the COPD group than in the asthmatic group. We conclude that the cytokines TNF alpha and IL-8 may be involved in the inflammation in COPD.
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Am. J. Respir. Crit. Care Med. · Feb 1996
Randomized Controlled Trial Clinical TrialEfficacy of auto-CPAP in the treatment of obstructive sleep apnea/hypopnea syndrome.
The auto-CPAP (Morphée Plus) is characterized by its ability to modify the positive-pressure level applied during the night for the presence or absence of sleep-induced respiratory disorders. The aim of the study was to compare the efficacy of this new mode of CPAP therapy with that of conventional constant-CPAP in the treatment of sleep apnea/hypopnea syndrome (SAHS). Sixteen patients with SAHS were randomly allocated to two groups that were paired for age, apnea/hypopnea index, and mean sleep latency. ⋯ During the control CPAP sleep study, the positive pressure level was significantly lower during Stage III-IV than during the other sleep stages (p = 0.004). The improvement in the MWT and the TMT observed with CPAP therapy was identical in both groups. We conclude that (1) the amount of use during CPAP treatment is higher with auto-CPAP than with constant-CPAP, and (2) Morphée+auto-CPAP is an efficient as conventional CPAP in correcting nocturnal breathing disorders, daytime sleepiness, and cognitive impairment in SAHS.
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Am. J. Respir. Crit. Care Med. · Feb 1996
Hypothalamic-pituitary-adrenal axis in corticosteroid-resistant bronchial asthma.
We have examined whether the lack of clinical response to corticosteroids seen in corticosteroid resistant (CR) bronchial asthma is reflected in abnormalities of endogenous cortisol secretion and in the sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis in CR subjects by using a modification of the standard dexamethasone suppression test (DST) in response to 0.25 and 1 mg oral dexamethasone. Five corticosteroid-sensitive (CS) and five CR asthmatic subjects were studied on two occasions 1 mo apart. In the first limb of the study subjects received 0.25 mg of oral dexamethasone, and in the second limb they received 1 mg. ⋯ The levels of urinary free cortisol (nmol/24 h) and predose plasma ACTH (ng/L) and cortisol (nmol/L) were 199 +/- 42, 27.4 +/- 5.7, and 300 +/- 48 (mean +/- SEM), respectively, in the CS group, and 210 +/- 74, 23.4 +/- 6.7, and 263 +/- 32 (mean +/- SEM), respectively, in the CR group (p > 0.05 for all comparisons). Plasma ACTH and cortisol concentrations were not significantly suppressed in either group after 0.25 mg dexamethasone, but were equally suppressed in both groups to undetectable levels by 1 mg dexamethasone. We conclude that CR asthma is not reflected in an altered secretory rate of endogenous cortisol or in an altered sensitivity of the HPA axis to dexamethasone suppression.
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Am. J. Respir. Crit. Care Med. · Feb 1996
Comparative StudyExogenous surfactants in a piglet model of acute respiratory distress syndrome.
Evidence for surfactant dysfunction in acute respiratory distress syndrome (ARDS) suggests a role for exogenous surfactant which contains apoprotein for resistance to protein inhibition. We compared the effects of KL-4-Surfactant, an artificial preparation containing a synthetic 21 amino acid peptide with SP-B-like activity, with Exosurf, an artificial protein-free surfactant, and Survanta, a bovine protein-containing surfactant, in a saline lung lavage model of ARDS in neonatal piglets. Two sequential series of lung lavages were performed to lower PaO2 < 100 mm Hg, each followed by administration of surfactant or air and a 90-min observation period. ⋯ Only KL-4-Surfactant demonstrated greater pressure-volume characteristics and lower bronchoalveolar protein than those of Controls. We conclude that the physiologic effects of KL-4-Surfactant are more like Survanta in this model. We speculate that KL-4-Surfactant may improve pulmonary function, reduce alveolar protein leak, and thus be efficacious in the treatment of ARDS.