RT Journal Article
SR Electronic
T1 Impact of exhalation system and additional leak on oxygenation during noninvasive ventilation
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 1434
VO 38
IS Suppl 55
A1 Jan Storre
A1 Sophie Huttmann
A1 Emelie Ekkernkamp
A1 Stephan Walterspacher
A1 Michael Dreher
A1 Claudia Schmoor
A1 Wolfram Windisch
YR 2011
UL http://erj.ersjournals.com/content/38/Suppl_55/1434.abstract
AB Objective: Supplemental oxygen (O2) when added to longterm noninvasive ventilation (NIV) is usually inserted into the ventilatory circuit next to the ventilator, but the impact of different exhalation systems and leaks on actual FiO2 needs to be elucidated.Methods: Four daytime measurements (each 60 minutes, randomized) were performed in 20 patients receiving NIV and ≥2L O2/min: active valve circuit (AVC) or leak circuit (LC) with and without additional artificial leak (4mm I.D.) next to the fullface mask. FiO2 was measured at the site of oxygen (FiO2-ventilator) as well as mask (FiO2-mask) following exhalation system (AVC or LC) and opened or closed artificial leak. Capillary blood gas analyses were performed at start and end of each measurement.Results: Overall, FiO2-mask (29±5%) was lower compared to FiO2-ventilator (34±4%) with a mean (95%CI) difference of 5.1 (4.2 to 5.9, p<0.0001)%. With LC FiO2-mask decreased by 3.2 (2.6 to 3.9, p<0.0001)% compared to AVC (Figure). PaO2 tended to be 6.3 (-1.0 to 13.7)mmHg lower after 60 minutes of NIV comparing LC and ACV, p=0.08. Implementing an artificial leak FiO2-mask decreased by 5.7 (5.1 to 6.4, p<0.0001)% (Figure) with lowered PaO2 of 10.4 (3.1 to 17.7, p<0.0001)mmHg.Conclusion: Leak circuits regularly used for exhalation during NIV and unintended air leak significantly reduce FiO2 in patients receiving NIV and O2, which substantially deteriorates patients' oxygenation.