Surgical intensive care unit (ICU) stay of longer than 10 days is often described by the experienced intensivist as a "complicated
clinical course" and is frequently attributed to persistent immune dysfunction. "
Systemic inflammatory response syndrome" (SIRS) followed by "compensatory anti-inflammatory response syndrome" (CARS) is a conceptual framework to explain the immunologic trajectory that ICU patients with
severe sepsis,
trauma, or emergency surgery for abdominal
infection often traverse, but the causes, mechanisms, and reasons for persistent immune dysfunction remain unexplained. Often involving
multiple-organ failure (MOF) and death, improvements in
surgical intensive care have altered its incidence, phenotype, and frequency and have increased the number of patients who survive initial
sepsis or surgical events and progress to a persistent
inflammation, immunosuppression, and catabolism syndrome (PICS). Often observed, but rarely reversible, these patients may survive to transfer to a
long-term care facility only to return to the ICU, but rarely to self-sufficiency. We propose that PICS is the dominant pathophysiology and phenotype that has replaced late MOF and prolongs surgical ICU stay, usually with poor outcome. This review details the evolving epidemiology of MOF, the clinical presentation of PICS, and our understanding of how persistent
inflammation and immunosuppression define the pathobiology of prolonged
intensive care.
Therapy for PICS will involve innovative interventions for immune system rebalance and
nutritional support to regain physical function and well-being.