American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Sep 1997
Chronic respiratory symptoms, skin test results, and lung function as predictors of peak flow variability.
We examined how chronic respiratory symptoms, reported in a questionnaire, and results of skin prick tests and spirometry predicted variability in peak expiratory flow (PEF) among 6-12-yr-old children (n = 1,854). After characterization with skin tests and spirometry, children were followed for 2-3 mo during the winter of 1993-1994. Peak expiratory flow was measured daily in the morning and evenings. ⋯ In conclusion, chronic respiratory symptoms reported in a questionnaire, spirometric lung function and skin prick test results among asthmatic children predicted variation in PEF measured during a 2-3 mo follow-up. The difference in morning PEF coefficient of variation (CV) between children with asthmatic symptoms and children with cough only was somewhat bigger in girls than in boys. The effect of atopy on morning PEF CV was somewhat bigger in young than in older children.
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This cost of illness analysis examines national cost and resource utilization by persons with asthma using a single, comprehensive data source, the 1987 National Medical Expenditure Survey. Direct medical expenditures included payments for ambulatory care visits, hospital outpatient services, hospital inpatient stays, emergency department visits, physician and facility payments, and prescribed medicines. Indirect medical costs included costs resulting from missed work or school and days with restricted activity at work. ⋯ More than 80% of resources were used by 20% of the population (defined as 'high-cost patients'). The estimated annual per patient cost for those high-cost patients was $2,584, in contrast with $140 for the rest of the sample. Findings from this study indicate that future asthma research and intervention efforts directed at hospitalizations and high-cost patients could help to decrease health care resource use and provide cost savings.
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Am. J. Respir. Crit. Care Med. · Sep 1997
Effect of volume recruitment on response to surfactant treatment in rabbits with lung injury.
We determined if surfactant treatment effect can be enhanced by mechanical volume recruitment during surfactant administration by measuring functional residual capacity, tidal volume, the alveolar portion of tidal volume, dynamic compliance of the respiratory system, a/A ratio, and PaCO2 by measuring before and after surfactant administration to rabbits with lung injury induced by airway lavage. There was improvement in all lung function indices when surfactant was given with volume recruitment, but when surfactant was given without volume recruitment, the only index to show significant improvement was a/A ratio of oxygenation. These results support the hypothesis that mechanical recruitment of terminal airspaces from a previously unventilated compartment will enhance the effectiveness of surfactant replacement by facilitating the distribution of instilled surfactant to this compartment.
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Am. J. Respir. Crit. Care Med. · Sep 1997
Ventilatory and arousal responses to hypoxia and hypercapnia in a canine model of obstructive sleep apnea.
We have previously described a canine model of obstructive sleep apnea (OSA) in which sleep-wake state is monitored continuously by a computer that produces tracheal occlusion when sleep occurs. Our aim was to assess the effects of long-term application of this model on resting ventilation and on the ventilatory and arousal responses to hypercapnia and hypoxia. Five dogs were maintained on the model for 15.5 +/- 1.7 (mean +/- SE) wk, with a mean apnea index of 57.5 +/- 4.5 occlusions/h of sleep. ⋯ During recovery, these responses reverted partly to baseline for W and reverted completely to baseline for SWS. There were no significant changes in arousal PCO2 during hypercapnic rebreathing in either SWS or REM across the pre-OSA baseline, OSA, and post-OSA recovery periods. We conclude that long-term application of the OSA model is associated with a selective, reversible decrease in ventilatory and arousal responses to hypoxia.