Abstract: Background　 Influenza is an acute respiratory infectious disease caused by influenza virus，which can cause outbreaks and epidemics in the world，and may result in serous outcomes in children。But the mechanism for critical-ill events occurring in children is still under exploration.Objective　To explore the clinical characteristics and risk factors of critical-ill events in children with severe influenza.Methods　We selected 76 children with severe influenza who were admitted to Hebei Children's Hospital from December 2018 to March 2019，and divided them into severe group（52 cases）and critically ill group（24 cases）according to disease severity.We collected their general clinical data（gender，months of age，influenza type，presence or absence of underlying diseases，complication involved system，white blood cell count，neutrophil count，hemoglobin，platelet count，C-reactive protein（CRP），calcitonin，lactate dehydrogenase（LDH），imaging findings，etiological results and other information，and compared the differences between severe and critically ill cases.Results　Nineteen of 76 cases（25.0%）had underlying diseases.The most common complication of severe influenza was respiratory system involvement（100.0%），followed by nervous system involvement（28.9%），and digestive system involvement（15.8%）.Critically ill cases had higher incidence of nervous system involvement and LDH level and lower hemoglobin level than severe cases（P<0.05）.Chest imaging found 56 cases of pulmonary light or patchy shadows，30 cases of lung consolidation，9 cases of pleural effusion，10 cases of uneven light transmittance in both lungs and 8 cases of air leak syndrome.All the decreased had lung consolidation，among whom 3 also had air leak syndrome，and 2 also had pleural effusion.The incidence of lung consolidation in critically ill group was higher than that in severe group（P<0.05）.Sixty-seven of the 76 cases（88.2%）were detected with other pathogenic microorganisms.A total of 67 cases（88.2%）were found with virus infection，among whom 59（77.6%）mainly with adenovirus.A total of 23 cases（30.3%）were found with bacteria infection，and 11（14.5%）of them mainly with Haemophilus influenzae.Ten cases（13.2%）were found with Mycoplasma pneumoniae infection.The detection rate of bacteria as the cause of influenza in critically ill group was higher than that of severe group（P<0.05）.Conclusion　Most children with severe influenza will suffer from respiratory system involvement.Lung consolidation，nervous system involvement，anemia，increased LDH，and bacterial infections may increase the risk of critical illness.

Key words: Influenza, human；Severe illness；Critical illness；Child；Risk factors；Root cause analysis

摘要： 背景　流行性感冒（简称“流感”）是由流感病毒引起的急性呼吸道传染病，可在世界范围内引起暴发和流行，可导致严重的不良后果，且目前儿童流感发生危重症的相关机制仍在探索中。目的　分析儿童重症流感的临床特点及发生危重症的危险因素。方法　选取2018年12月—2019年3月于河北省儿童医院收治确诊的重症流感患儿76例为研究对象，并按病情严重程度分为重症组（52例）与危重症组（24例），收集入组患儿的一般临床资料〔性别、发病月龄、流感分型、有无基础性疾病、并发症受累系统、白细胞计数、中性粒细胞计数、血红蛋白、血小板计数、C反应蛋白（CRP）、降钙素（PCT）、乳酸脱氢酶（LDH）〕、影像学表现、病原学结果等信息，并比较两组间的差异。结果　76例重症患儿中19例存在基础性疾病（25.0%）；重症流感最常见并发症为呼吸系统受累（100.0%），其次为神经系统受累（28.9%）、消化系统受累（15.8%）；危重症组神经系统受累比例、LDH水平高于重症组，血红蛋白水平低于重症组（P<0.05）。患儿胸部影像显示，肺部淡片或斑片影56例、肺实变30例、胸腔积液9例、双肺透光度不均10例、气漏综合征8例，死亡患儿均发生肺实变、3例并发气漏综合征、2例出现胸腔积液；危重症组肺实变发生率高于重症组（P<0.05）。76例重症患儿中88.2%（67/76）与其他病原微生物共检出；病毒共检出67例（88.2%），以腺病毒为主59例（77.6%）；细菌共检出23例（30.3%），以流感嗜血杆菌11例（14.5%）为主；肺炎支原体共检出10例（13.2%）；危重症组患儿细菌检出率高于重症组（P<0.05）。结论　儿童重症流感大多呼吸系统受累，当出现肺实变、神经系统受累、贫血、LDH增高、合并细菌感染时发生危重症的风险可能增加。

关键词: 流感, 人, 重症, 危重症, 儿童, 危险因素, 影响因素分析