Characteristics of chronically critically ill patients: comparing two definitions

Approximately 80% of the patients admitted into intensive care units survive the acute event, and most remain in this unit briefly.1 However, a subgroup does not recover sufficiently quickly to become independent and from then they recover slowly.2 These patients are called chronically critically ill (CCI) patients, and, depending on the definition criteria, comprise 5 to 10% of the patients admitted into intensive care units.3-5 There is a great deal of controversy regarding the definition of a CCI patient. The two most commonly used definitions are the duration of mechanical ventilation (MV) and tracheostomy.2 The advantage of the latter is that the patients are identified by a code, simplifying the extraction of information from a secondary database.2 However, the great variability in the indication of tracheostomy and its tendency to be performed increasingly early may contribute to the selection of patients with different evolutions than those of chronic patients.6,7 MV varies from 4 to 29 days across different studies.2 A recent consensus conference defined patients with cases of prolonged MV as those who need invasive MV for at least 21 days.8 Regardless of the definition, the main characteristics of this population are repeated episodes of shock and infection during their stays in the Intensive Care Unit (ICU).9 It is clear that a chronic critical illness is not simply an extension of an acute critical illness but, rather, is a complex syndrome characterized by metabolic, neuroendocrine, neuropsychiatric and immunological changes.10 This study aims to compare the two definitions of CCI patients: tracheostomy (Tracheo group) and MV ≥ 21 days (MV group). In addition, we described the clinical, epidemiological and outcome characteristics of the CCI patients and tried to identify the factors that predispose patients to the evolution to chronic critical illness.