Treatment of life-threatening hypercapnia with isoflurane in an infant with status asthmaticus

We encountered a 2-year-old child with life-threatening hypercapnia, with a PaCO₂ of 238 mm Hg and severe respiratory and metabolic acidosis, due to status asthmaticus that was refractory to steroid and bronchodilator therapy. Suspecting ventilatory failure and excessive ventilation-induced obstructive shock, we started respiratory physiotherapy in synchrony with her respiration, to facilitate exhalation from her over-inflated lungs. Isoflurane inhalation was commenced in preparation for extracorporeal circulation, to reduce the hypercapnia. The combination of respiratory physiotherapy and isoflurane inhalation resulted in a rapid decrease in ventilatory resistance and PaCO₂ levels within a few minutes, with recovery of consciousness within 60 min. Isoflurane inhalation was gradually discontinued and steroid and aminophylline therapy were commenced. The patient recovered completely without any recurrence of her bronchospasm and without any residual neurological deficits. In our patient with a severe asthmatic attack, decreased exhalation secondary to asthma and overventilation during artificial ventilation resulted in overinflation of the lungs, which in turn led to cerebral edema and obstructive cardiac failure. The favorable outcome in this case was due to the short duration of hypercapnia. Hence, we conclude that the duration of hypercapnia is an important determinant of the morbidity and mortality of status asthmaticus-induced severe hypercapnia.