Abstract: Severe pneumonia represents a common severe respiratory condition that poses a substantial threat to pediatric health. Its conceptual framework has been progressively refined with advancements in medical science. A clear understanding of its definition is essential to effective clinical diagnosis and treatment. The conceptual evolution of severe pneumonia has undergone three distinct phases. Currently，the definition of severe pneumonia encompasses both severe respiratory lesions and extrapulmonary organ involvement，but the integration of traditional system classification with modern objective indicators still deserves further exploration.

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摘要： 重症肺炎是危害儿童健康的常见呼吸系统重症疾病，其概念随医学发展不断更新，明确其内涵对临床诊疗至关重要。其概念发展历经3个阶段。目前重症肺炎内涵已涵盖呼吸系统严重病变与肺外系统受累，但传统器官分型与现代客观指标的融合仍值得进一步探索。

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