Delirium incidence and risk factors in patients undergoing non-invasive ventilation for acute respiratory failure: a multicenter observational trial.

Background: Noninvasive ventilation (NIV) still has high failure rate when used for de novo acute respiratory failure (ARF). Delirium may impact the outcome, however data regarding its incidence, timing of occurrence and clinical predictors in this subset of patients are scarce.

Methods: Consecutive patients with de novo ARF subjected to NIV were recruited in 10 Italian Respiratory Intensive Care Units (RICUs) and Intensive Care Units (ICUs). Demographics and clinical features, including tolerance to interface and NIV setting were recorded on admission and during stay, whereas delirium onset and type was assessed by the Confusion Assessment Method for ICU (CAM-ICU)-7 scale and Richmond Agitation Sedation Scale (RASS) twice/per day up to a week. The association between clinical variables and the occurrence of delirium and its influence on NIV failure and other clinical outcomes were analyzed.

Results: Thirty-two out of 90 enrolled patients (36%) developed delirium over seven days upon admission; median time to onset was 48 hours (24-60). Older age (OR=2.7 [1.9-9], P=0.01), the presence of cancer OR=3.7 [2-5.4], P=0.002), sepsis (OR=1.7 [1.1-3.4], P=0.01), SOFA Score (OR=1.8 [1.1-3.1], P=0.01), low tolerance to interface (OR=3.2 [2.1-5], P=0.002), use of helmet (OR=1.9 [1.2-4.3] P=0.04), and higher PRE-DELIRIC (OR=3.5 [1.3-15], P=0.03) and BORG (OR=1.7 [1.1-4.6], P=0.02] scores were significantly associated with delirium. Delirium had high risk for NIV failure (HR=3.5 95% CI: [1.4-8.6], P=0.0002) and it significantly associated with longer RICU/ICU stay and higher mortality.

Conclusions: Delirium onset in acute hypoxic patients undergoing NIV is frequent and negatively affects the outcome. Multiple related clinical factors should be addressed early on admission to prevent the delirium-related risk of NIV failure in these patients.