Inspired oxygen fraction achieved with a portable ventilator: Determinant factors

Non-invasive positive pressure ventilation (NIPPV) is an effective treatment in respiratory failure. Continuous positive pressure (CPAP) may also be useful in acute hypoxaemic patients. Supplementary oxygen is usually necessary in both systems. However, the inspired oxygen fraction (FiO 2) delivered by a NIV portable ventilator is unknown. The main objectives of this study were to establish the maximal FiO 2 that could be achieved by these devices and to analyse the FiO 2 determinant factors. Ten healthy volunteers were evaluated using a BiPAP ST30 ventilator (Respironics, USA) with a single-limb circuit, expiratory port and nasal mask (Respironics, USA). Oxygen (15 L/min) was administered at two connection points (proximal and distal). Each volunteer carried out a NIPPV (inspiratory pressure 20 cmH 2O [1.95 kPa]—expiratory pressure 8 cmH 2O [0.78 kPa]) and a CPAP (10 cmH 2O [0.981 kPa]) session. FiO 2 was analysed by a probe located in the mask. Minute volume (MV) was measured using a pneumotachograph. Maximal FiO 2 was obtained with CPAP and distal oxygen connection point (67.39+/−15.39%). NIPPV achieved higher MV than CPAP. FiO 2 was inversely correlated with MV. FiO 2 obtained while using a NIPPV portable ventilator depends on the ventilatory assistant mode, the oxygen connection point and the MV reached.