American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Jan 1997
Comparative StudyBroxaterol increases force output of fatigued canine diaphragm more than salbutamol.
We previously demonstrated that broxaterol enhanced recovery of fatigued canine diaphragm. The aim of this study was to compare the inotropic effects of salbutamol and broxaterol on fatigued canine diaphragm. Low-frequency fatigue was induced in 14 mongrel dogs by electrophrenic stimulation, which was continued until transdiaphragmatic pressure (Pdi) at 20 Hz was reduced by 50% or for 1 h. ⋯ In contrast, salbutamol did not alter Pdi at 20 Hz. Neither drug affected Pdi at 100 Hz. We conclude that broxaterol promoted recovery of low-frequency fatigue of the canine diaphragm in vivo in a dose-dependent manner, whereas salbutamol only minimally improved force production by the fatigued diaphragm.
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Am. J. Respir. Crit. Care Med. · Jan 1997
Comparative StudyRacial differences in sleep-disordered breathing in African-Americans and Caucasians.
In this case-control family study of sleep-disordered breathing (SDB), we describe the distributions of SDB and SDB risk factors in African-Americans and Caucasians. A total of 225 African-Americans and 622 Caucasians, ages 2 to 86 yr, recruited as members of families with an individual with known sleep apnea (85 index families) or as members of neighborhood control families (63 families) were studied with an overnight home sleep-study, questionnaires, and physical measurements. A subsample underwent cephalometry. ⋯ In subjects < or = 25 yr, RDI level and IAA prevalence were higher in African-Americans (odds ratio, adjusted for obesity, sex, proband sampling, and familial clustering, 1.88, 1.03 to 3.52, 95% CI). In this age group, racial differences also were observed in the relationship between RDI and age (p < 0.001 for the RDI-age interaction). This suggests that young African-Americans may be at increased risk for sleep apnea.
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Am. J. Respir. Crit. Care Med. · Jan 1997
Chronic, episodic, reversible airway obstruction after viral bronchiolitis in rats.
Viral bronchiolitis in human infants has been associated with persistent airway abnormalities, but not proven as a cause. Previously we observed some adult rats had airway obstruction and hyperresponsiveness following bronchiolitis at an early age. The purpose of this study was to determine, via serial measurements of lung mechanics, whether the postbronchiolitis airway obstruction was episodic or continuous, and to determine the magnitude and duration of glucocorticoid effects. ⋯ The virus group had higher lung resistance (p = 0.03) and lower dynamic compliance (p = 0.005) than control rats, with airway obstruction occurring in an episodic pattern. Dexamethasone treatment had a transient effect in postbronchiolitis rats; lung resistance normalized in Week 15 (p = 0.006), then returned to pretreatment levels by Weeks 16-18. We conclude that viral bronchiolitis in rats can result in a chronic syndrome of intermittent, reversible airway obstruction which has multiple parallels with human asthma over a prolonged time period.
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Am. J. Respir. Crit. Care Med. · Dec 1996
Ventilatory function in British adults after asthma or wheezing illness at ages 0-35.
The impact of past and current asthma on ventilatory function was assessed among young adults born in Britain March 3-9, 1958 who had been followed from birth to ages 7, 11, 16, 23, and 33 yr. We compared 1,060 subjects with a history of asthma, wheezy bronchitis, or wheezing with 275 control subjects with no history of chest illness. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were measured at 34-35 yr of age before and 20 min after inhalation of 400 micrograms salbutamol, and adjusted for sex, height, and smoking by multiple regression. ⋯ Among 509 cases reporting wheeze in the past year, FEV1 and FEV1/FVC ratio were reduced to a greater extent in those with an earlier age of onset of wheeze (p < 0.001 for trend in each case). These relative reductions were greater if wheezing had persisted through childhood and adolescence, and were only partially reversed by inhalation of salbutamol. Progressive pulmonary changes related to chronic asthma may be an important mechanism underlying the association between childhood chest illnesses and chronic respiratory disease in adult life.