Dacheng Xiong,1,2 Huixian Geng,1,2 Xuechun Lv,1,2 Shuqi Wang,1,2 Lijing Jia1,2 

1Department of Intensive Care Medicine, Hebei Medical University, Shijiazhuang, People’s Republic of China; 2Department of Intensive Care Medicine, Hebei General Hospital, Shijiazhuang, People’s Republic of China

Correspondence: Lijing Jia, Department of Intensive Care Medicine, Hebei General Hospital, Shijiazhuang, Hebei Province, People’s Republic of China, Tel +86 31185989925, Fax +86 31185989925, Email 90030200@hebmu.edu.cn

Abstract: Many patients now survive their initial critical events but subsequently develop chronic critical illness (CCI). CCI is characterized by prolonged hospital stays, poor outcomes, and significant long-term mortality. The incidence of chronic critical illness (CCI) is estimated to be 34.4 cases per 100,000 population. The incidence varies significantly with age, peaking at 82.1 cases per 100,000 in individuals aged 75– 79. The one-year mortality rate among CCI patients approaches 50%. A subset of these patients enters a state of persistent inflammation, immune suppression, and ongoing catabolism, a condition termed persistent inflammation, immunosuppression, and catabolism syndrome (PICS) in 2012. In recent years, some progress has been made in treating PICS. For instance, recent advancements such as the persistent expansion of MDSCs (myeloid-derived suppressor cells) and the mechanisms underlying intestinal barrier dysfunction have provided new directions for therapeutic strategies, as discussed below. Persistent inflammation, a key feature of PICS, has received comparatively little research attention. In this review, we examine the potential pathophysiological changes and molecular mechanisms underlying persistent inflammation and its role in PICS. We also discuss current therapies about inflammation and offer recommendations for managing patients with PICS.

Keywords: persistent inflammatory-immunosuppressive-catabolic syndrome, chronic critical illness, inflammation, immunosuppression, anti-inflammatory therapy