Thorax
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Cyclical changes in systemic blood pressure occur during apnoeic episodes in patients with obstructive sleep apnoea (OSA). Although several factors including arterial hypoxaemia, intrathoracic pressure changes, and disruption of sleep architecture have been reported to be responsible for these changes in blood pressure, the relative importance of each factor remains unclear. This study assessed the role of hypoxaemia on the increase in blood pressure during apnoeic episodes. ⋯ The blood pressure response to desaturation whilst awake was about one third of that during apnoeic episodes. These results suggest that factors other than hypoxia may play an important part in raising the blood pressure during obstructive sleep apnoea.
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Comparative Study
Asthma, allergy, and atopy in three south-east Asian populations.
Whilst many recent reports have suggested a rise in the prevalence of asthma and allergic disease in Western countries, little is known about the epidemiology of these common conditions in south-east Asia. This study compared the prevalence of asthma and allergic disease amongst secondary school students in three south-east Asian populations--Hong Kong, Kota Kinabalu in Malaysia, and San Bu in China--and investigated the associations with atopy and family history. ⋯ Prevalence of asthma and allergic disease is low compared with Western countries, but considerable differences exist between the three south-east Asian populations despite similar rates of atopy. Asthma and allergic disease are more strongly associated with family history than atopy, which suggests that genetic and environmental factors common to the family, other than aeroallergen sensitisation, are important in the pathogenesis of asthma and allergy in the region.
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Prescribing rates for inhaled anti-asthmatic drugs in the UK vary considerably from area to area and between individual practices. The objectives of this study were to determine the prevalence of patients prescribed inhaled steroids and beta agonist bronchodilators, the indications for these prescriptions, and to relate prescribing to the recorded levels of morbidity for specific respiratory disease. ⋯ Inhaled steroid and bronchodilator prescribing have age-related and gender-related prevalences. Treatment for respiratory diagnoses varies with patient age and gender, and with the diagnosis. Prescribing differences between practices are attributable to variation in both diagnostic rates for respiratory disease and therapeutic intervention patterns. For asthma patients study practices show consensus in approach, perhaps illustrating the value of clear guidelines for asthma prescribing.
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Randomized Controlled Trial Comparative Study Clinical Trial
Measurement of transfer factor during constant exhalation.
Transfer factor of the lung for carbon monoxide (TLCO) was measured by a new method based on analysis of the ratio of the concentrations of carbon monoxide to an inert gas (methane) relative to lung volume during a constant exhalation. Since this new technique is based solely upon exhalation, anomalies associated with inspiration and breath holding do not affect results. Additionally, because prolonged breath holding is not required, measurements can readily be made in dyspnoeic patients. ⋯ Since the results were essentially identical between the techniques, it seems that comparable pathophysiological factors affect TLCO during breath holding and constant exhalation. Constant exhalation may therefore be a useful alternative to the breath holding technique for clinical measurement of TLCO.