The incidence, clinical characteristics and outcomes of critically-ill, non-intubated patients with evidence of the acute respiratory distress syndrome (ARDS) remain inadequately characterized.
Among adult patients enrolled in a large, multi-intensive care unit prospective cohort study between the years of 2006 and 2011, we studied intubated and non-intubated patients with ARDS as defined by acute hypoxemia (PaO 2/FiO 2 ≤ 300 or SpO 2/FiO 2 ≤ 315) and bilateral radiographic opacities not explained by cardiac failure. We excluded patients not committed to full respiratory support.
Of 457 patients with ARDS, 106 (23%) were not intubated at the time of meeting all other ARDS criteria. Non-intubated patients had lower morbidity and severity of illness compared to intubated patients; however, mortality at 60 days was the same (36%) in both groups (P=0.91). Of the 106 non-intubated patients, 36 (34%) required intubation within the subsequent 3 days of follow-up; this “late” intubation subgroup had significantly higher 60-day mortality (56%) compared to both the “early” intubation group (36%, P<0.03) and to patients never requiring intubation (26%, P=0.002). Increased mortality in the “late” intubation group persisted at 2 years follow-up. Adjustment for baseline clinical and demographic differences did not change the results.
A substantial proportion of critically ill adults with ARDS were not intubated in their initial days of intensive care, and many were never intubated. Late intubation was associated with increased mortality. Criteria defining ARDS prior to need for positive pressure ventilation are needed so that these patients can be enrolled in clinical trials and to facilitate early recognition and treatment of ARDS.