Mechanically ventilated children with 2009 pandemic influenza A/H1N1: results from the National Pediatric Intensive Care Registry in Japan.

OBJECTIVE: To outline the characteristics, clinical course, and outcome of pediatric patients requiring mechanical ventilation with influenza A/H1N1 infection in Japan.

DESIGN: Prospective case registry analysis.

SETTING: Eleven pediatric or general intensive care units in Japan.

PATIENTS: Consecutive patients infected with A/H1N1, aged from 1 month to 16 yrs old admitted to the intensive care unit for mechanical ventilation between July 2009 and March 2010.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Eighty-one children, aged 6.3 [0.8-13.6] (median [interquartile range]) years, were enrolled. Seventy-four (91%) had mechanical ventilation with tracheal intubation. Median duration of mechanical ventilation was 4 days (range 0.04-87) and 18 patients (23%) required mechanical ventilation >7 days. Two patients (2%) required extracorporeal membrane oxygenation. The in-hospital mortality was 1%. Forty-one patients (50%) had at least one underlying chronic condition, including 31 with asthma. Associated clinical symptoms and diagnosis were as follows: acute respiratory distress syndrome (9%), asthma or bronchitis (37%), pneumonia (68%) with 8 (14%) having bacterial pneumonia, neurological symptoms (32%), myocarditis (2%), and rhabdomyolysis (1%). Therapeutic interventions include inotropic support (21%), methylprednisolone therapy (33%), and antimicrobial therapy (88%). Multivariate analysis revealed that inotropic support was the only statistically significant factor associated with mechanical ventilation for more than a week (odds ratio 5.5, 95% confidence interval 1.5-20.5, p = .005).

CONCLUSIONS: The clinical presentations of pediatric patients requiring mechanical ventilation for A/H1N1 in Japan were diverse. In-hospital mortality of this population was remarkably low. Rapid access to medical facilities in combination with early administration of antiviral agents may have contributed to the low mortality in this population.