Chronic Critical Illness: Definition, Epidemiology, Pathogenesis, and Clinical Manifestations (Brief Review)

The combination of syndromes and organ failure manifestations that develop after an acute critical illness (ACI) and demand the continuation of intensive care does not currently have a single definition. Meanwhile, the steadily increasing number of patients with such manifestations poses a challenge to the entire healthcare system. The complex pathogenesis and the differences in subtypes of chronic critical illness (CCI) necessitate a personalized approach to management of these patients.

Objective. To clarify the available data on the terminology of CCI, its prevalence, development timelines, clinical manifestations, pathogenesis, subtypes, and outcomes.

Materials and Methods. A literature review wasconducted using the PubMed, Google Scholar, and eLibrary databases. The review included 60 papers covering approaches to CCI definition, associated terminology, the investigation on of pathogenesis, clinical aspects, and CCI subtypes.

Results. Several case definitions were identified for CCI, reflecting the attitude toward this condition — either as one of the phases of acute critical illness or as a new disease. Additionally, two main approaches to diagnosing CCI were established: the first based on the duration of patient's stay in post-anesthesia care and intensive therapy (PACU/ICU) due to the need for intensive care, and the second based on the emergence of newly identified specific clinical and laboratory manifestations. The development of CCI is an unfavorable outcome of acute critical illness, leading to increased patient disability and a rise in mortality.

Conclusion. Further research is needed for deeper insights into development of CCI, establishing unified approaches to its definition, assessing risk factors, identifying its subtypes and associated organ dysfunctions.

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