Pulmonary Function During Clinical Remission of Asthma How Reversible is Asthma?*

Abstract

Summary: The frequency, range and severity of functional abnormalities during complete clinical remission of asthma were studied in 57 patients. Ninety per cent had abnormal tests, the usual pattern being impaired ventilatory capacity, hyperinflation, maldistribution of ventilation, ventilation/blood‐flow inequality and hyperventilation with norm‐al arterial oxygen tension and gas transfer. If spirometry had been used as the sole screening procedure, nearly one third of patients with abnormal function would have been missed. The measurement of lung volumes appeared to be the most practical way to detect these latter patients. Since there is a poor relation between symptoms and functional abnormalities in asthma, laboratory measurements are an important adjunct to clinical assessment. Although asthma is generally regarded as reversible airways obstruction, the extent of reversibility appears to be frequently incomplete.