Long-term Survival in Patients with Severe Acute Respiratory Distress Syndrome and Rescue Therapies for Refractory Hypoxemia

Abstract

<italic>Objective</italic>: To assess survival up to 5 years in patients who develop severe acute respiratory distress syndrome (ARDS) and evaluate differences in characteristics and outcomes for patients selected for treatment with a rescue therapy (inhaled nitric oxide, inhaled epoprostenol or prone position ventilation) versus conventional treatment. <italic>Design and Setting</italic>: Retrospective cohort study of patients admitted to the intensive care unit (ICU) at a 413-bed Level 1 trauma university hospital. <italic>Patients</italic>: Patients diagnosed with severe ARDS, according to the Berlin definition, within 72 hours of ICU admission between 1/1/2008 and 12/31/2011. <italic>Methods</italic>: Data were abstracted from the electronic medical record and included demographic and clinical variables, hospital and ICU length of stay, discharge disposition, and hospital costs. We compared patients placed on inhaled nitric oxide, inhaled epoprostenol or ventilated in the prone position with patients treated conventionally. To determine survival beyond hospital discharge, patient-level data were linked to the Washington State Death Registry. Kaplan-Meir survival analysis methods were used to assess survival. Cox's proportional hazards models were used to compare differences in outcomes between patients treated with a rescue therapy and those treated conventionally. Costs were analyzed using the Lin method to estimate mean total costs in the presence of censoring. <italic>Main Results</italic>: 428 patients meeting the inclusion criteria were identified, of whom 62 (14%) were placed on a rescue therapy. Five-year survival for all patients was 54.9% (95% CI: 50.2%, 60.1%). For patients who were discharged from the hospital alive, 5-year survival was 84.5% (95% CI: 79.8%, 89.4%). Mean hospital cost was $701 K (95% CI: $97K, $846 K). Admission PaO2/FIO2 ratios were similar between patients treated with a rescue therapy and those treated conventionally. However, prior to initiation of rescue therapy, patients treated with a rescue therapy had substantially lower PaO2/FIO2 ratios by 72 hours (54 mm Hg ± 17 versus 69 mm Hg ± 17; p=<.01). The hazard ratio of death up to 5 years following their ICU admission was not different between patients with and without rescue therapy (HR: 1.31, 95% CI: 0.89, 1.94; p = 0.17). <italic>Conclusions</italic>: Severe ARDS patients surviving to hospital discharge have relatively good long-term survival. Patients with worsening hypoxemia are selected to receive a rescue therapy. Future prospective studies should investigate the impact of the timing of initiation of a rescue therapy prior to the development of life-threatening critical hypoxemia on long-term outcomes.