VENTILATORY CONTROL IN TWO ASTHMATICS RESUSCITATED FROM RESPIRATORY ARREST*

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Abstract
Two female patients revived from fulminant attacks of asthma are described. Ventilatory responses to asphyxia in these patients were 0.70 .+-. 0.10 l min-1% SaO2-1 and 0.64 .+-. 0.21 l min-1% SaO2-1 (mean .+-. standard error of the mean), respectively. These values were significantly less than the responses of 7 normal female subjects (1.54 .+-. 0.11 l min-1% SaO2-1 mean .+-. SEM; P < 0.01). Ventilatory responses to hypercapnia of the 2 patients were in the low normal range. Dopamine-receptor blockade with prochlorperazine significantly increased the ventilatory response to asphyxia in normal subjects (P < 0.05 or less for each subject) but did not alter the depressed responses in the asthmatic patients. In 1 patient, naloxone in a dose of 400 .mu.g reversed the decreased ventilatory responsiveness; the response to asphyxia was increased from 0.72 l min-1% SaO-1 to 1.80 l min-1% SaO2-1 (P < 0.01) and the response to hypercapnia was increased from 0.90 l min-1 mm Hg-1 to 4.80 l min-1 mm Hg-1 (P < 0.01). Naloxone had no effect in the 2nd asthmatic patient nor in 5 normal subjects. Defective chemoreceptor responses to chemical stimuli may play a role in sudden death from asthma; endogenous opioids may mediate this disorder of ventilatory control.