title: Inspired oxygen fraction achieved with a portable ventilator: determinant factors.
abstract: BACKGROUND
  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 (FiO2) delivered by a NIV portable ventilator is unknown. The main objectives of this study were to establish the maximal FiO2 that could be achieved by these devices and to analyse the FiO2 determinant factors.
  
  
  METHODS
  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 cmH2O [1.95 kPa]-expiratory pressure 8 cmH2O [0.78 kPa]) and a CPAP (10 cmH2O [0.981 kPa]) session. FiO2 was analysed by a probe located in the mask. Minute volume (MV) was measured using a pneumotachograph.
  
  
  RESULTS
  Maximal FiO2 was obtained with CPAP and distal oxygen connection point (67.39 +/- 15.39%). NIPPV achieved higher MV than CPAP. FiO2 was inversely correlated with MV.
  
  
  CONCLUSIONS
  FiO2 obtained while using a NIPPV portable ventilator depends on the ventilatory assistant mode, the oxygen connection point and the MV reached.
authors.affiliation: Respiratory Dept., Hospital de la Santa Creu i Sant Pau, Sant Antoni M(a) Claret 167, 08025 Barcelona, Spain. dsamolski@hsp.santpau.es
authors.forename: D
authors.initials: D
authors.lastname: Samolski
authors.forename: A
authors.initials: A
authors.lastname: Antón
authors.forename: R
authors.initials: R
authors.lastname: Güell
authors.forename: F
authors.initials: F
authors.lastname: Sanz
authors.forename: J
authors.initials: J
authors.lastname: Giner
authors.forename: P
authors.initials: P
authors.lastname: Casan
mesh_terms: D045422:Continuous Positive Airway Pressure / Q000295:instrumentation; D018592:Cross-Over Studies; D006801:Humans; D001239:Inhalation; D010100:Oxygen / Q000008:administration & dosage / Q000032:analysis*; D010102:Oxygen Inhalation Therapy / Q000295:instrumentation; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D012121:Respiration, Artificial / Q000295:instrumentation*; D012122:Ventilators, Mechanical
chemical_list: D010100:Oxygen