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End‐expiratory lung volume and ventilation distribution with different continuous positive airway pressure systems in volunteers
Author(s) -
ANDERSSON B.,
LUNDIN S.,
LINDGREN S.,
STENQVIST O.,
ODENSTEDT HERGÈS H.
Publication year - 2011
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2010.02337.x
Subject(s) - medicine , continuous positive airway pressure , tidal volume , positive end expiratory pressure , anesthesia , lung volumes , ventilation (architecture) , respiratory system , lung , mechanical ventilation , obstructive sleep apnea , mechanical engineering , engineering
Background: Continuous positive airway pressure (CPAP) has been shown to improve oxygenation and a number of different CPAP systems are available. The aim of this study was to assess lung volume and ventilation distribution using three different CPAP techniques. Methods: A high‐flow CPAP system (HF‐CPAP), an ejector‐driven system (E‐CPAP) and CPAP using a Servo 300 ventilator (V‐CPAP) were randomly applied at 0, 5 and 10 cmH 2 O in 14 volunteers. End‐expiratory lung volume (EELV) was measured by N 2 dilution at baseline; changes in EELV and tidal volume distribution were assessed by electric impedance tomography. Results: Higher end‐expiratory and mean airway pressures were found using the E‐CPAP vs. the HF‐CPAP and the V‐CPAP system ( P <0.01). EELV increased markedly from baseline, 0 cmH 2 O, with increased CPAP levels: 1110±380, 1620±520 and 1130±350 ml for HF‐, E‐ and V‐CPAP, respectively, at 10 cmH 2 O. A larger fraction of the increase in EELV occurred for all systems in ventral compared with dorsal regions ( P <0.01). In contrast, tidal ventilation was increasingly directed toward dorsal regions with increasing CPAP levels ( P <0.01). The increase in EELV as well as the tidal volume redistribution were more pronounced with the E‐CPAP system as compared with both the HF‐CPAP and the V‐CPAP systems ( P <0.05) at 10 cmH 2 O. Conclusion: EELV increased more in ventral regions with increasing CPAP levels, independent of systems, leading to a redistribution of tidal ventilation toward dorsal regions. Different CPAP systems resulted in different airway pressure profiles, which may result in different lung volume expansion and tidal volume distribution.