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

Abstract

We encountered a 2-year-old child with life-threatening hypercapnia, with a PaCO(2) 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 PaCO(2) 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.

Hypercapnia: An Aggravating Factor in Asthma

“…The medical literature reports cases of severe hypercapnia in asthmatic patients with values of PaCO 2 reaching 202 and 218 mmHg (pH value, 6.68 and 6.90, respectively) in two 24 and 28 year-old women during severe status asthmaticus [ 12 ], 208 mmHg (pH = 6.73) in a 35 year-old woman during an episode of near fatal asthma [ 13 ] and 175 mmHg (pH = 6.99) in a 33 year-old woman during severe status asthma [ 17 ]. Pediatric reports are scarce, but an eight year-old boy during an episode of near fatal asthma had PaCO 2 values of 293 mmHg (pH = 6.77) [ 14 ], a two year-old girl with status asthmaticus had the values of 238 mmHg (pH = 6.71) [ 16 ] and an eleven year-old boy with status asthmaticus with 187 mmHg and pH of 6.84 [ 15 ].…”

“…Hypercapnia, an elevation in the arterial carbon dioxide (CO 2 ) tension, is a complication of inadequate alveolar gas exchange in patients with severe acute and chronic lung diseases [ 7 ] including asthma [ 5 , 6 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. It has been initially reported that hypercapnia was innocuous or even protective in mechanically ventilated patients with severe asthma [ 9 , 10 ], acute lung injury and acute respiratory distress syndrome (ARDS) [ 18 , 19 , 20 , 21 ], where the concepts of “permissive” and even “therapeutic” hypercapnia have been proposed for the mechanically ventilated patients.…”

Adjunct Therapies for Refractory Status Asthmaticus in Children

“…Multiple case reports present successful application of inhaled anesthetics to children and young adults with refractory status asthmaticus, [105][106][107][108][109][110][111][112] but no clinical trials exist comparing this therapy with other adjunct therapies. Retrospective reviews demonstrate that the initiation of these gases is consistently associated with a decrease in P aCO 2 around 20 mm Hg and concomitant rise in pH of about 0.1 within a few hours of administration.…”

“…Retrospective reviews demonstrate that the initiation of these gases is consistently associated with a decrease in P aCO 2 around 20 mm Hg and concomitant rise in pH of about 0.1 within a few hours of administration. 105,108,111,[113][114][115] The largest case series to date includes 31 children over a 15-y period, in which children received isoflurane for a mean duration of 55 h (range 1-181 h) and were invasively ventilated for a mean of 252 h (range 16 -1,444 h). The majority (77%) of these children developed hypotension requiring vasopressor support, but all survived without long-term sequelae.…”