Isoflurane anesthesia for status asthmaticus: 10 years' experience

Mechanical ventilation (MV) for status asthmaticus (SA) is associated with high mortality [1]. Prolonged isoflurane (ISO) administration has been shown to be a safe and well-tolerated therapy in ICU patients and is a predictedable bronchodilator [2, 3]. We report our 10 years' experience with MV and use of isoflurance (ISO) as a therapy for refractory SA.

Results

Twenty-six of 47 patients (age 40 ± 20 years; 40 females) admitted to our ICU required MV. Cause for asthma exacerbation was infection in 57% of patients. Admission respiratory and heart rate, mean blood pressure, PO₂, PCO₂ and pH was 37 ± 14, 127 ± 22 bpm 100 ± 23 mmHg, 133 ± 101 torr, 48 ± 29 torr, and 7.30 ± 0.18, respectively. Six of 26 patients received ISO (dose, 84 ± 106 MAC hours) for 87 ± 109 hours (range 8–227 hours). Hypotension occurred in all ISO patients and in one non-ISO patient, who was adequately treated with fluid (100%), and one inotrope in 3/6 ISO patients. Continuous paralysis was required in five patients. Patients who received ISO required a longer duration of MV and ICU length of stay (LOS) (Table 1). There were no pneuomothoraces, air embolism or significant hypoxia in any patient. Five patients received sodium bicarbonate infusions for acidosis. Three patients in the ISO group died: one anoxic encephalopathy (VSA arrest prior to admission), one withdrawal of life support due to comorbid diseases, and one cardiac arrest (cause unknown). Two patients died in the non-ISO group; one anoxic encephalopathy (VSA arrest prior to admission) and one withdrawal of life support (comorbid diseases). None died due to failure to oxygenate/ventilate.

Table 1

Conclusions

Inhalational isoflurane anesthesia is a useful bronchodilator therapy in patients with severe exacerbations of asthma and should be considered in patients who do not respond adequately to conventional bronchodilator therapy.