Abstract
Background: The novel influenza A (2009-H1N1) pandemic caused acute respiratory distress syndrome (ARDS) in some patients, who were treated with mechanical ventilation or extracorporeal membrane oxygenation (ECMO). Objective: To clarify the outcome of critical care for patients infected with 2009-H1N1 in Japanese ICU. Design, Setting, and Patients: An observational study using database information. Sixty-seven participating 67 ICUs in Japan were enrolled. The number of patients was 219 people. Results: Children (under 16 years of age) accounted for 162 patients (median age of 6 years; IQR (interquartile range): 5 to 9 years), adults (16 years of age or older) accounted for 57 patients (median age of 43 years; IQR: 31 to 56 years). Among the adults, the median Acute Physiology and Chronic Health Evaluation (APACHE) II score was 19 (IQR: 15 to 23). Among the adults, 35.7% (20/56) had a body mass index (BMI) of more than 25. Two patients were pregnant. The percentage of adults with underlying disease was 16.4% (9/55). The percentage of children with an underlying disease was 3.7% (6/162). The overall mortality rate among children was 2.5%, with 95% confidence interval (CI) of 0.7 to 6.2. The adult mortality rate was 28.1%, with a 95%CI of 16.9 to 41.5. Eighty percent of the pediatric patients (129/162) and 94.7% of the adult patients (54/57) were received mechanical ventilation. Of these patients, 6 had acute lung injury (ALI), 61 had ARDS. One patient with ALI was died. Among the patients with ARDS, 39 patients were adults and 22 were children, the mortality rates were 33.3% (13/39); 95%CI: 19.1 to 50.2 and 4.6% (1/22); 95%CI: 0.1 to 22.8, respectively. Among the 183 ventilated patients, 7.1% (13/183) were treated with percutaneous cardio-pulmonary support (PCPS) or ECMO. Of these patients, the mortality rate among adults was 20% (2/10); 95%CI: 2.5 to 55.6, and no deaths occurred among children. PCPS or ECMO for ARDS in adults tended to decrease the risk of death compared with mechanical ventilation (odds ratio, 0.364; 95%CI: 0.04 to 3.52; chi-square: 0.181; P = 0.671). Neither seasonal influenza vaccine and pandemic vaccine recipients died. The antiviral drugs, oseltamivir was prescribed for 96.8% (212/219) of the patients. Zanamivir was prescribed for 11.9% (26/219). Both drug were prescribed in 10.0% (22/219). Conclusions: The mortality rate was lower among children than among adults. The adult mortality rate was higher than among rates reported in other developed countries. PCPS or ECMO for the treatment of adult patients with 2009-H1N1-associated ARDS may be effective, but a statistically significant difference was not observed. Our database had selection bias (sampling bias); therefore, the results of this analysis are difficult to generalize.
