Background: This study aims to preliminarily explore the impact of delayed influenza virus nucleic acid conversion (more than five days) to negative on treatment and length of hospital stay in children with severe influenza. Methods: This was a single-center retrospective study. General information, influenza virus nucleic acid test (per 3-5 days) results after receiving antiviral medication, antiviral drug usage, comorbid infections, invasive mechanical ventilation, and discharge prognosis of children with severe influenza were collected. Results: A total of 39 patients were included in the study. The patients were divided into four groups based on the time when the patient’s viral nucleic acid turned to negative after receiving antiviral medication: 3-5 days (35.8%, 14/39), 6-10 days (38.4%, 15/39), >10 days (12.8%, 5/39), and maintaining as positive when discharge (12.8%, 5/39). More than half of pediatric patients with severe influenza exhibited delayed nucleic acid conversion (more than 5 days) after antiviral medication. The >10 days group had a longer time from onset to PICU admission, PICU stay, and antiviral drug use duration, as well as a higher proportion of CBP use (P < 0.05, respectively). Within the first 3 days of PICU admission, the proportion of patients with persistently reduced lymphocytes was lower in the 3-5 days group (28.6% (4/14)) than other two groups (P > 0.05). Conclusions: Delayed nucleic acid conversion was associated with longer PICU length of stay. Persistent fever, co-infections, and impaired cellular immune function may contribute to the delay.

Objectives: To report a severe case of severe chlorine poisoning inducing acute respiratory distress syndrome (ARDS) and shock required venous-arterial extracorporeal membrane oxygenation (V-A ECMO). Design: Case report. Setting: Pediatric intensive care unit (PICU). Patients: A 11-year-old boy who admitted to our PICU after inhaled chlorine poisoning. Interventions: V-A ECMO. Measurements and Main Results: After inhaling chlorine, the children quickly developed hypoxia, cyanosis and unconsciousness. After high-condition mechanical ventilation, hypoxia was only slightly improved for a short time, and then deteriorated rapidly and shock occurred. The highest oxygen saturation index was 27.3, and the chest X-ray showed extensive diffuse interstitial parenchyma changes. The oxygenation and circulation was recovered quickly under ECMO. The children received methylprednisolone intravenous injection for 3 days, the pulmonary lesions basically recovered 5 days after onset. He was successfully removed from the ventilator 1 day after the successful removal of ECMO. Follow-up 3 months after discharge showed the pulmonary lesions were completely absorbed and there were no other sequelae. Conclusion: Chemical pneumonia caused by chlorine inhalation can lead to severe ARDS or even shock, but the prognosis is often good. ECMO support should be considered when conventional treatment is ineffective.