Emergency department length of stay for patients requiring mechanical ventilation: a prospective observational study

Background: Recommendations for acceptable emergency department (ED) length of stay (LOS) vary internationally with <= 8 h generally considered acceptable. Protracted ED LOS may place critically ill patients requiring mechanical ventilation at increased risk of adverse events as most EDs are not resourced for longitudinal delivery of critical care. Our objective was to quantify the ED LOS for mechanically ventilated patients (invasive and/or non-invasive ventilation [NIV]) and to explore patient and system level predictors of prolonged ED LOS. Additionally, we aimed to describe delivery and monitoring of ventilation in the ED. Methods: Prospective observational study of ED LOS for all patients receiving mechanical ventilation at four metropolitan EDs in Toronto, Canada over two six-month periods in 2009 and 2010. Results: We identified 618 mechanically ventilated patients which represented 0.5% (95% CI 0.4%-0.5%) of all ED visits. Of these, 484 (78.3%) received invasive ventilation, 118 (19.1%) received NIV; 16 received both during the ED stay. Median Kaplan-Meier estimated duration of ED stay for all patients was 6.4 h (IQR 2.8-14.6). Patients with trauma diagnoses had a shorter median (IQR) LOS, 2.5 h (1.3-5.1), compared to ventilated patients with non-trauma diagnoses, 8.5 h (3.3-14.0) (p < 0.001). Patients requiring NIV had a longer ED stay (16.6 h, 8.2-27.9) compared to those receiving invasive ventilation exclusively (4.6 h, 2.2-11.1) and patients receiving both (15.4 h, 6.4-32.6) (p < 0.001). Longer ED LOS was associated with ED site and lower priority triage scores. Shorter ED LOS was associated with intubation at another ED prior to transfer. Conclusions: While patients requiring mechanical ventilation represent a small proportion of overall ED visits these critically ill patients frequently experienced prolonged ED stay especially those treated with NIV, assigned lower priority triage scores at ED presentation, and non-trauma patients.