“…In surveying the existing literature, PMV has been variously defined as Ͼ 24 h, 1,2 Ͼ 2 days, 3 Ͼ 14 days, 4 or Ͼ 29 days 5 of mechanical ventilation or, alternatively, the need for post-ICUs mechanical ventilatory support. 6 The most widely applied definitions involve patients who fall under several of the Center for Medicare and Medicaid Services (CMS) Diagnosis Related Groups (DRGs) focused on mechanical ventilatory support (DRG 475, respiratory disease and mechanical ventilation Ͼ 96 h; DRG 483, tracheostomy with mechanical ventilation Ն 96 h with principal diagnosis except for face, head, and neck diagnoses; DRG 541, tracheostomy with mechanical ventilation Ն 96 h with principal diagnosis except face, mouth, and neck diagnosis with major operating room procedure; DRG 542, tracheostomy with mechanical ventilation Ն 96 h with principal diagnosis except face, mouth, and neck diagnosis without major operating room procedure. Generally, these patients who have required at least 6 h of mechanical ventilation for Ͼ 21 consecutive days.…”