Variation in definition of prolonged mechanical ventilation

Consistency of definitional criteria for terminology applied to describe patient cohorts receiving mechanical ventilation within intensive care unit and post-acute care settings is important for understanding prevalence, risk stratification, effectiveness of interventions, and projections for resource allocation. Our objective was to quantify application and definition of terms for prolonged mechanical ventilation.We conducted a scoping review of studies (all designs except single case study) reporting a study population (adult and paediatric) using the term prolonged mechanical ventilation or synonym. We screened 5331 references, reviewed 539 full text references and excluded 120. Of the 419 studies (representing 38 countries) meeting inclusion criteria, 297 (71%) reported data on a heterogeneous patient cohort, 66 (16%) studies included surgical patients only (46/66, 70% cardiac surgery). Other studies described chronic obstructive pulmonary disease (16, 4%), trauma (22, 5%), neuromuscular (17, 4%), and sepsis (1, 0.2%) cohorts. A total of 741 terms were used to refer to the 419 study cohorts. Most common terms were: prolonged mechanical ventilation (253, 60%), admission to specialized unit (107, 26%), and long-term mechanical ventilation (79, 19%). Some authors (282, 67%) defined their cohorts based on duration of mechanical ventilation with 154 (55%) using this as the sole criterion. We identified 37 different durations of ventilation ranging from 5 hours to 1 year with more than 21 days being the most common (28/282, 7%). For studies describing a surgical cohort, minimum ventilation duration required for inclusion was greater ≥24 hours for 20/66 (30%) studies. More than half (237, 57%) did not provide a reason/rationale for definitional criteria used, with only 28 (7%) studies referring to a consensus definition.We conclude that substantial variation exists in the terminology and definitional criteria for cohorts of patients receiving prolonged mechanical ventilation. Standardization of terminology and definitional criteria is required for study data to be maximally informative.