Abstract: Objective To analyze and summarize the epidemiological and clinical characteristics of severe pneumonia in children, and to improve the diagnosis and treatment of this disease. Method Retrospectively analyzed the clinical and radiology data of 148 children with severe pneumonia, which were hospitalized in the pediatric intensive care unit (PICU) at Shenzhen Children's Hospital from January 2020 to December 2021. The epidemiological information was collected, and the demographic characteristics, clinical symptoms, laboratory results, imaging features, complications, treatment, and prognosis data were analyzed. Result There were 148 children, 79 (53.4%) males and 69 (46.6%) females. The onset age ranged from 1 month to 17 years old (the median age was 12 months). Fifty-seven (38.5%) cases occurred in winter. One hundred and five cases (70.9%) were infected with a single pathogen, and 43 cases (29.1%) were infected with mixed pathogens. The top three pathogens were respiratory syncytial, rhinovirus, and pseudomonas aeruginosa. Respiratory syncytial virus and rhinovirus infections were mainly found in the infant group. Pseudomonas aeruginosa has the highest detection rate among school-age children. One hundred and eight cases (73.0%) had underlying diseases. The most common respiratory symptoms were cough (73.0%) and wheezing (65.5%). Hypotension was found in 133 cases (89.9%), and hypoxemia in 68 cases (45.9%). Hypersensitive C-reactive protein, procalcitonin, and lactate dehydrogenase increased. Variety extent segmental or lobular pneumonia were the common radiology findings, particularly in the lower lobe of the lungs. Atelectasis was found in eighty-eight cases (59.5%), pleural effusion was found in 30 cases (20.3%), empyema was found in 4 cases (2.7%), lung abscess was found in 2 cases (1.4%), and necrotizing pneumonia was found in 4 cases (2.7%). Severe complications included septic shock (11.5%), acute respiratory distress syndrome (7.4%), and multiple organ dysfunction syndrome (MODS) (6.1%). Seventy-eight cases (52.7%) required ventilator-assisted ventilation, 4 cases were treated with extracorporeal membrane oxygenation (ECMO), and 11 cases (7.4%) died eventually. The proportion of deaths with severe pneumonia combined with septic shock, acute respiratory distress syndrome, and MODS was significantly higher than those who survived (P<0.05). Conclusion Severe pneumonia in children is more common in infants, and the epidemiology of the infant group is "double peaks" in summer and winter; the pathogens are mainly respiratory syncytial virus, rhinovirus and Pseudomonas aeruginosa infection. Chest imaging showed multiple lobes/segment involvement, with the most common changes in the density of the lower lobe of the lungs. Combined underlying diseases and septic shock suggest a poor prognosis.

Key words: Children, Severe pneumonia, Epidemiology, Clinical characteristics, Pathogen