PICS can be represented as a recurring, vicious cycle. First, the inciting inflammatory event stimulates an emergency myelopoietic response. While the ensuing expansion of MDSC can be protective, prolonged expansion promotes suppression of adaptive immunity and chronic inflammation. Following this initial response, the patient may convalesce or progress to CCI. In a subset of CCI patients PICS develops and is characterized by manageable organ dysfunction, ongoing inflammation and immune suppression, protein catabolism, muscle wasting, and unmet nutritional needs. This predisposes the patient for recurrent infections and recidivism of this cycle.
Modified from Mira et al (in press).