Ketamine in status asthmaticus: A review

BACKGROUND AND AIMS: Status asthmaticus is a common cause of morbidity and mortality. The addition of ketamine to the standard treatment regimen of severe asthma has shown to improve outcome and alleviate the need for mechanical ventilation. The purpose of this review is to determine the pulmonary effects of ketamine and to determine whether sufficient evidence exists to support its use for refractory status asthmaticus. DATA SOURCE: MEDLINE, EMBASE, Google Scholar, and Cochrane data bases (from their inception to Jan 2012) using key words “ketamine”, “asthma”, “bronchospasm”, “bronchodilator”, and “mechanical ventilation” were searched to identify the reports on the use of ketamine as a bronchodilator in acute severe asthma or status asthmaticus, and manual review of article bibliographies was done. Relevant databases were searched for the ongoing trials on use of ketamine as a bronchodilator. Outcome measures were analyzed using following clinical questions: Indication, dose and duration of ketamine use, main effects on respiratory mechanics, adverse effects, and mortality. RESULTS: Twenty reports illustrating the use of ketamine as a bronchodilator were identified. In total, 244 patients aged 5 months to 70 years received ketamine for bronchospasm. Twelve case reports, 3 double-blind randomized placebo-controlled trials, 2 prospective observational studies, 2 clinical evaluation study, and 1 retrospective chart review were retrieved. Most of the studies showed improved outcome with use of ketamine in acute severe asthma unresponsive to conventional treatment. Patients who received ketamine improved clinically, had lower oxygen requirements, and obviated the need for invasive ventilation. Mechanically-ventilated patients for severe bronchospasm showed reduction in peak inspiratory pressures, improved gas exchange, dynamic compliance and minute ventilation, and could be weaned off successfully following introduction of ketamine. CONCLUSION: In various studies, ketamine has been found to be a potential bronchodilator in severe asthma. However, a large prospective clinical trial is warranted before laying down any definitive recommendations on its use in status asthmaticus.