A new reservoir-based CPAP with low oxygen consumption. The Bag-CPAP

Abstract

Background Several forms of noninvasive ventilatory supports have a high consumption of oxygen which may precipitate oxygen shortage, as experienced during the COVID-19 pandemic. In this bench-to-bedside study, we assessed the performances of a new continuous positive airway pressure (CPAP) device using a large a reservoir (the “Bag-CPAP”) designed to minimize oxygen consumption and compared it with other CPAP devices. Methods First, a bench study compared the performances of the Bag-CPAP and four CPAP devices to an intensive care unit ventilator. Two FiO2 targets (40-60% and 80-100%) at a predefined positive end expiratory pressure (PEEP) level between 5 and 10 cm H2O were tested and fraction of inspired oxygen (FiO2) and oxygen consumption were measured. Device-imposed work of breathing (WOB) was also evaluated. Second, an observational clinical study evaluated the new CPAP in 20 adult patients with acute respiratory failure in two hospitals in France. Actual FiO2, PEEP, peripheral oxygen saturation, respiratory rate and dyspnea score were assessed. Results All six systems tested in the bench study reached the minimal FiO2 target of 40% and four were able to reach at least 80% FiO2 while maintaining PEEP in the predefined range. The ratio of FiO2 delivered to the oxygen consumed was the highest with the new reservoir-based CPAP whatever the FiO2 target. The WOB induced by the device was slightly higher with the Bag-CPAP. In the clinical study, the Bag-CPAP was well tolerated and could reach high (>90%) and moderate (>50%) FiO2 with an oxygen flow rate of 15 [15-16] and 8 [7-9] L/min, respectively. Dyspnea score improved significantly after introduction of Bag-CPAP, and SpO2 increased. Conclusions In vitro, the Bag-CPAP exhibited the highest oxygen saving properties. It was well accepted clinically and reduces dyspnea. The Bag-CPAP may be useful to treat patients with acute respiratory failure in the field, especially when facing constraints in oxygen delivery.