American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Jan 1997
Systemic, pulmonary and mesenteric perfusion and oxygenation effects of dopamine and epinephrine.
The response of the systemic, pulmonary, hepatic and portal circulations to infusion of dopamine and epinephrine was studied in newborn piglets 1 to 3 d of age. Anesthetized animals were instrumented to measure cardiac index (CI), hepatic arterial flow, and portal venous blood flow. Catheters were inserted for measurement of systemic arterial pressure (SAP), pulmonary arterial pressure (PAP), and for sampling of arterial, portal venous, and mixed venous oxygen saturations and plasma lactate levels. ⋯ Systemic and mesenteric oxygen extraction were not affected by dopamine or epinephrine infusions. Plasma lactate levels were significantly elevated with epinephrine infusion 3.2 microg/kg/min. The differential responses of dopamine and epinephrine on pulmonary and mesenteric circulations may be significant in the pathophysiology and management of persistent fetal circulation and necrotizing enterocolitis.
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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. · Jan 1997
Effects of menopause and nasal occlusion on breathing during sleep.
Prevalence of sleep-disordered breathing (SDB) is reported to increase in menopausal women. We examined response to a nocturnal respiratory challenge (nasal occlusion) during overnight polysomnography in 31 women (45 to 55 yr). Thirteen were premenopausal, four perimenopausal, and 14 postmenopausal by history and hormonal assay. ⋯ Responders and nonresponders were not distinguished by age, menopausal status, nor several cephalometric or anthropometric variables. Body mass index (31.1 +/- 8.5 versus 24.3 +/- 3.4, p < 0.003), neck circumference (34.0 +/- 2.5 versus 32.5 +/- 1.7 cm, p < 0.05), and mandibular-hyoid distance (18.5 +/- 3.8 versus 14.5 +/- 5.7 mm, p < 0.05) were greater in responders. These findings suggest hormonal factors may be less important than weight and facial morphology in midlife development of SDB in women.
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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.