Characteristics of patients with hypoxemic respiratory failure due to pneumonia that respond to the application of a positive end expiratory pressure

The use of non invasive ventilation in patients with pneumonia is controversial. Our aim is to assess the prevalence, clinical characteristics and outcomes of patients with severe hypoxemic ARF due to pneumonia that benefit from PEEP application (PEEP-responders) in comparison to PEEP-non responders evaluated through a continuous positive airway pressure (CPAP) trial. We performed a prospective, single-center study of patients with hypoxemic ARF due to pneumonia (PaO 2 /FiO 2 ≤ 200) admitted to the respiratory high-dependency unit, San Gerardo Hospital, Monza, Italy, between 2011 and 2015. All patients underwent a CPAP trial using helmet-CPAP. To test PEEP-responsiveness we evaluated vital signs, respiratory distress and hemogasanalysis 1) with oxygen supplementation only and 2) with helmet-CPAP. PEEP-responders were defined as: patients hemodynamically stable with PaCO2 20% and/or respiratory distress improvement compared to oxygen supplementation only. A total of 33 patients (median age 68 years; 67% males) were enrolled: 23 PEEP-responders (70%) and 10 PEEP-non responders (30%). PEEP-non responders were significantly older and more likely to have COPD compared to PEEP-responders. In-hospital mortality was 6% (1 PEEP-responder and 1 PEEP-non responder, p=0.52), endotracheal intubation criteria were fullfilled by 1 PEEP-responder patient (3%), p=1. In conclusion, in our population 30% of patients with hypoxemic ARF due to pneumonia do not respond to PEEP application and PEEP-non responsiveness might not be associated with worse outcomes. Further studies are needed to evaluate predictors of CPAP failure.