Measurement of AHR in children with A(H1N1)pdm09 infection
Studies on pediatric patients were carried out in accord with the Declaration of Helsinki. This study enrolled pediatric asthmatic patients with A(H1N1)pdm09 infection and hypoxia (SpO2≤90%) within the first day of fever admitted to Fukuokahigashi Medical Center between September 2009 and December 2010. Bronchial asthma was diagnosed according to the Japanese Pediatric Guidelines for the Treatment and Management of Bronchial Asthma 2008 (JPGL 2008)15. The participants were diagnosed with A(H1N1)pdm09 infection by polymerase chain reaction (PCR) at Fukuoka Institute of Health and Environmental Sciences. AHRs were measured at 1 and 3 months after discharge. Anti-inflammatory drugs and bronchodilators were prohibited 1 month after discharge. Increasing concentrations of acetylcholine (39, 78, 156, 312, 625, 1,250, 2,500, 5,000, 10,000, and 20,000 µg/mL) were inhaled by a nebulizer until the forced expiratory volume in 1 second (FEV1.0) was reduced by 20% from a post-nebulized saline value. FEV1.0 was measured using a spirometer (HI-801, CHEST M.I., Inc., Tokyo, Japan). AHR was defined as the provocative concentration causing a 20% fall in FEV1.0(PC20). This study was approved by the institutional review board of Fukuokahigashi Medical Center (2020-rin-8). Parents were explained this study and signed informed consent.