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Positive end‐expiratory pressure prevents atelectasisduring general anaesthesia even in the presence of a high inspired oxygen concentration
Author(s) -
Neumann P.,
Rothen H. U.,
Berglund J. E.,
Valtysson J.,
Magnusson A.,
Hedenstierna G.
Publication year - 1999
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 - 10.1034/j.1399-6576.1999.430309.x
Subject(s) - atelectasis , medicine , anesthesia , oxygenation , positive end expiratory pressure , general anaesthesia , mechanical ventilation , ventilation (architecture) , peak inspiratory pressure , lung , respiratory system , tidal volume , mechanical engineering , engineering
Background: General anaesthesia impairs the gas exchange in the lungs, and moderate desaturation (SaO 2 86–90%) occurred in 50% of anaesthetised patients in a blinded pulse oximetry study. A high FiO 2 might reduce the risk of hypoxaemia, but can also promote atelectasis. We hypothesised that a moderate positive end‐expiratory pressure (PEEP) level of 10 cmH 2 O can prevent atelectasis during ventilation with an FiO 2 =1.0. Methods: Atelectasis was evaluated by computed tomography (CT) in 13 ASA I–II patients undergoing elective surgery. CT scans were obtained before and 15 min after induction of anaesthesia. Then, recruitment of collapsed lung tissue was performed as a “vital capacity manoeuvre” (VCM, inspiration with Paw=40 cmH 2 O for 15 s), and a CT scan was obtained at the end of the VCM. Thereafter, PEEP=0 cmH 2 O was applied in group 1, and PEEP=10 cmH 2 O in group 2. Additional CT scans were obtained after the VCM. Oxygenation was measured before and after the VCM. Results: Atelectasis (>1 cm 2 ) was present in 12 of the 13 patients after induction of anaesthesia. At 5 and 10 min after the VCM, atelectasis was significantly smaller in group 2 than group 1 ( P <0.005). A significant inverse correlation was found between Pa O 2 and atelectasis. Conclusions: PEEP=10 cmH 2 O reduced atelectasis formation after a VCM, when FiO2=1.0 was used. Thus, a VCM followed by PEEP=10 cmH2O should be considered when patients are ventilated with a high FiO 2 and gas exchange is impaired.