Timing of Intubation and Clinical Outcomes in Adults With Acute Respiratory Distress Syndrome

Abstract

Objective: The prevalence, clinical characteristics, and outcomes of critically ill, nonintubated patients with evidence of the acute respiratory distress syndrome remain inadequately characterized.

Design: Secondary analysis of a prospective observational cohort study.

Setting: Vanderbilt University Medical Center.

Patients: Among adult patients enrolled in a large, multi-ICU prospective cohort study between the years of 2006 and 2011, we studied intubated and nonintubated patients with acute respiratory distress syndrome as defined by acute hypoxemia (PaO2/FIO2 ≤ 300 or SpO2/FIO2 ≤ 315) and bilateral radiographic opacities not explained by cardiac failure. We excluded patients not committed to full respiratory support.

Interventions: None.

Measurements and main results: Of 457 patients with acute respiratory distress syndrome, 106 (23%) were not intubated at the time of meeting all other acute respiratory distress syndrome criteria. Nonintubated patients had lower morbidity and severity of illness than intubated patients; however, mortality at 60 days was the same (36%) in both groups (p = 0.91). Of the 106 nonintubated patients, 36 (34%) required intubation within the subsequent 3 days of follow-up; this late-intubation subgroup had significantly higher 60-day mortality (56%) when compared with the both early intubation group (36%, P<0.03) and patients never requiring intubation (26%; p = 0.002). Increased mortality in the late intubation group persisted at 2-year follow-up. Adjustment for baseline clinical and demographic differences did not change the results.

Conclusions: A substantial proportion of critically ill adults with acute respiratory distress syndrome were not intubated in their initial days of intensive care, and many were never intubated. Late intubation was associated with increased mortality. Criteria defining the acute respiratory distress syndrome prior to need for positive pressure ventilation are required so that these patients can be enrolled in clinical studies and to facilitate early recognition and treatment of acute respiratory distress syndrome.

Figure 1. Flow diagram of inclusion and exclusion criteria

This flow diagram illustrates the total number of patients enrolled in the VALID study and the number and reasons for excluding patients based on our pre-determined criteria. Following this process, 457 patients with ARDS were identified for our study. Abbreviations: VALID=Validation of biomarkers in Acute Lung Injury Diagnosis; ARDS=Acute Respiratory distress syndrome; DNI=Do Not Intubate

Figure 2

Intubation group (Early-intubation, never-intubated, late-intubation) among 457 patients with ARDS

Figure 3

Timing of intubation in 106 initially non-intubated patients with ARDS

Figure 4

Kaplan-Meier curve showing probability of survival at follow-up. a. At 60 days b. At two years follow-up

Figure 4

Kaplan-Meier curve showing probability of survival at follow-up. a. At 60 days b. At two years follow-up