Arterial Blood Gas Tensions and Acid-Base Balance in Symptomatic and Asymptomatic Asthma in Childhood1, 2

Arterial blood gas tensions and pH were measured on 177 occasions in 139 asthmatic children 14 months to 14 years of age. Sixty-two patients were asymptomatic, and 115 were symptomatic. Fifty per cent of asymptomatic patients and all symptomatic patients were hypoxemic. The degree of hypoxemia correlated with the degree of airway obstruction. In some asymptomatic and mildly dyspneic patients, there was compensatory hyperventilation. In severely dyspneic patients, respiratory acidosis or combined respiratory and metabolic acidosis were present. The alveolar-arterial oxygen gradient was increased in both asymptomatic and symptomatic patients. The ratio of physiologic dead space to tidal volume was significantly increased in symptomatic patients. Arterial blood gas tensions are a useful guide for the treatment of acutely ill asthmatic children and for detecting sudden unexpected ventilatory failure.