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Two methods of evaluating children with acute asthma are compared: determination of peak expiratory flow (PEF, the maximal rate at which air can be forced out of the lungs) versus the extent to which blood hemoglobin (to which oxygen is bound) is saturated with oxygen (SaO2, measured by a small, noninvasive finger probe). One hundred ten children (average age, nine) served as subjects; all were under regular or episodic treatment for asthma. Their PEF and SaO2 were determined in the emergency department, and then the patients underwent clinical examination. Follow-up telephone calls were placed to the children's parents 10 days later to learn more concerning the course of the acute episode. Seventy-nine children were released from the emergency ward, while 31 remained as inpatients. Children who were admitted had lower PEF and SaO2 values (less peak flow and oxygen saturation, respectively) than those who went home, and children who went home with additional asthma medication had lower values than those who went home without a new prescription. However, PEF did not differ between children who went home and stayed there, and children who had to return to the hospital, while SaO2 values did discriminate between these two groups. A low SaO2 level was a better predictor of outcome than a low PEF. The SaO2 test is easy to perform on young patients who may be uncooperative or too ill to participate in determining PEF. It may also reflect the pathological changes that occur in asthma, which are briefly discussed. (Consumer Summary produced by Reliance Medical Information, Inc.)

The effect of inhaled bronchodilators in bronchiolitis has been difficult to evaluate due to problems with techniques for assessing respiratory function in infants. Two new techniques were used to assess the response to inhaled salbutamol in 17 infants with bronchiolitis. With one technique, expiratory flow, volume, and airway occlusion pressure were measured and used to derive compliance (Crs) and conductance (Grs) of the respiratory system from a passive expiration induced by a brief end-inspiratory airway occlusion. With the other technique, the maximum flow at functional residual capacity (VmaxFRC) was measured from a partial maximum expiratory flow-volume curve generated by external chest compression. For the group, there was no change in compliance or conductance after salbutamol, but salbutamol caused a fall in maximum flow at functional residual capacity (p< 0.01) and in the time constant of tidal expiration (p< 0.01). The decrease in maximum flow at functional residual capacity with salbutamol is consistent with increased airway collapse on forced expiration. The decrease in tidal time constant suggests that the drug decreases expiratory braking. Presence of such braking activity may be an important strategy for maintaining lung volume. In summary, salbutamol failed to produce a beneficial effect on airways in bronchiolitis, but did produce changes in expiration which may be harmful in some infants.