Management of Acute Respiratory Distress Syndrome and Refractory Hypoxemia. A Multicenter Observational Study.

RATIONALE

Clinicians' current practice patterns in the management of acute respiratory distress syndrome (ARDS) and refractory hypoxemia are not well described.

OBJECTIVES

To describe mechanical ventilation strategies and treatment adjuncts for adults with ARDS, including refractory hypoxemia.

METHODS

This was a prospective cohort study (March 2014-February 2015) of mechanically ventilated adults with moderate-to-severe ARDS requiring an Fi of 0.50 or greater in 24 intensive care units.

RESULTS

We enrolled 664 patients: 222 (33%) with moderate and 442 (67%) with severe ARDS. On Study Day 1, mean Vt was 7.5 (SD = 2.1) ml/kg predicted body weight (n = 625); 80% (n = 501) received Vt greater than 6 ml/kg. Mean positive end-expiratory pressure (PEEP) was 10.5 (3.7) cm HO (n = 653); 568 patients (87%) received PEEP less than 15 cm HO. Treatment adjuncts were common (n = 440, 66%): neuromuscular blockers (n = 276, 42%), pulmonary vasodilators (n = 118, 18%), prone positioning (n = 67, 10%), extracorporeal life support (n = 29, 4%), and high-frequency oscillatory ventilation (n = 29, 4%). Refractory hypoxemia, defined as Pa less than 60 mm Hg on Fi of 1.0, occurred in 138 (21%) patients. At onset of refractory hypoxemia, mean Vt was 7.1 (SD = 2.0) ml/kg (n = 124); 95 patients (77%) received Vt greater than 6 ml/kg. Mean PEEP was 12.1 (SD = 4.4) cm HO (n = 133); 99 patients (74%) received PEEP less than 15 cm HO. Among patients with refractory hypoxemia, 91% received treatment adjuncts (126/138), with increased use of neuromuscular blockers (n = 87, 63%), pulmonary vasodilators (n = 57, 41%), and prone positioning (n = 32, 23%).

CONCLUSIONS

Patients with moderate-to-severe ARDS receive treatment adjuncts frequently, especially with refractory hypoxemia. Paradoxically, therapies with less evidence supporting their use (e.g., pulmonary vasodilators) were over-used, whereas those with more evidence (e.g., prone positioning, neuromuscular blockade) were under-used. Patients received higher Vts and lower PEEP than would be suggested by the evidence.