Analysis of eight fatal cases of severe influenza A (H1N1) in children

Objective To analyze the clinical characteristics of fatal cases with confirmed influenza A (H1N1) in children in order to improve the diagnosis and treatment. Methods The fatal cases of influenza A (H1N1) admitted to Pediatric Intensive Care Unit of Beijing Children′s Hospital from December 2017 to March 2018 were collected, whose clinical features, diagnosis, treatment, and the causes of death were analyzed retrospectively. Results A total of eight children were enrolled.The age ranged from 3 months to 9 years, and six cases were less than 5 years old.Four cases had underlying diseases.All patients had fever, cough, dyspnea, cyanosis, flaring nares and three depressions sign.Four cases had coma.On admission, the average score of pediatric index of mortality was 58.8%.Blood routine test showed that lymphocyte predominance in six cases, three cases had leukopenia.C-reactive protein elevated in five patients.Procalcitonin increased in all cases.P/F ratio (PaO2/FiO2) were less than 100 mmHg(1 mmHg=0.133 kPa) in four cases who were diagnosed as severe acute respiratory distress syndrome.The pulmonary imaging showed multiple parenchymal or mixed lesions.Three cases had air leakage syndrome, and one had pleural effusion.Bacterial culture was performed on the day of admission.Four cases were complicated with bacterial infection.Three cases had Gram-positive cocci infection, and multidrug-resistant bacteria were predominant.The average time from onset to definitive diagnosis was 8 days.Neuraminidase inhibitors were used in all patients, and the average time from onset to the first dose was 8 days.Mechanical ventilation were performed in all patients in this group.Extracorporeal membrane oxygenation was applied in one case.Four cases in this group died of severe acute respiratory distress syndrome.Three cases died of influenza associated encephalopathy, and one died of septic shock with multiple organ failure. Conclusion Fatal influenza A (H1N1) mostly appeares in children under 5 years old or with underlying diseases.Acute respiratory distress syndrome and influenza associated encephalopathy are the main causes of death.Delayed diagnosis and delayed use of anti-influenza drugs may be an important factors leading to death, and bacteria infection may be another important cause of death. Key words: Influenza A(H1Nl); Fatal case; Critical illness; Child