Clinical assessment after a life-threatening attack of asthma; the role of bronchial hyperreactivity.

Between 1973 and 1986, 19 patients were treated on 21 occasions for life-threatening attacks of asthma. Twelve times mechanical ventilation was needed. None of the patients died. Most of the patients had been recognized as severely asthmatic before the life-threatening attack. Thirteen out of the 19 patients had previously been admitted with a severe asthmatic attack. All patients, except one, were already using maintenance treatment, and 17 had previously been referred to a pulmonologist. During follow-up the bronchial obstruction was, in most cases, fully reversible while using a rather extensive maintenance treatment (maximum forced expiratory volume in one second (FEV1), 69-138% of predicted). Recently, 17 of the 19 patients were reinvestigated, while in stable phase. The patients who had been mechanically ventilated were significantly more sensitive to inhaled histamine than the patients who had not been mechanically ventilated. This was not explained by any difference in basal FEV1 % pred or dosage of corticosteroids. A very low provocation concentration of histamine producing a 20% fall in FEV1 (PC20) may indicate the risk of a severe, life-threatening attack of asthma.