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Reexpansion of atelectasis during general anaesthesia may have a prolonged effect
Author(s) -
Rothen H. U.,
Sporre B.,
Engberg G.,
Wegenius G.,
Hedenstierna G.
Publication year - 1995
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.1399-6576.1995.tb05602.x
Subject(s) - medicine , atelectasis , general anaesthesia , anesthesia , oxygen tension , lung , oxygen , chemistry , organic chemistry
Pulmonary atelectasis, as found during general anaesthesia, may be reexpanded by hyper‐inflation of the lungs. The purpose of this study was to determine whether such a recruitment is maintained and whether this is accompanied by an improved gas exchange. We studied a consecutive sample of twelve lung healthy adults, scheduled for elective surgery. After induction of intravenous anaesthesia, the lungs were hyperinflated manually. The ventilationperfusion relationship (Va/Q) was estimated with the multiple inert gas method, and in six patients atelectasis was assessed by computed x‐ray tomography. The mean pulmonary shunt was 7.5% of cardiac output after induction of anaesthesia and this decreased to 1.0% and 2.8% at 20 and 40 min after the recruitment manoeuvre. Perfusion of poorly ventilated lung regions (low Va/Q), however, increased from 3.7% to 10.6% and 7.8% at 20 and 40 min after the recruitment, respectively. The mean alveolar‐arterial oxygen tension difference (P A‐a o 2 ) was 14.3 kPa after induction of anaesthesia and 11.1 kPa immediately after recruitment. Forty minutes later P A‐a o 2 was still 2.0 kPa lower than after induction of anaesthesia (95% conficence interval [CI] 0.3 to 3.8 kPa). P A‐a o 2 decreased more in obese patients. The mean area of atelectasis decreased from 9.0 cm 2 after induction of anaesthesia to 0.1 cm 2 immediately after recruitment, and there was a slow increase to 1.9 cm 2 (95% CI 0.0 to 3.9 cm 2 ) 40 min later. During general anaesthesia in lung healthy patients, most of the reexpanded atelectatic lung tissue remains inflated for at least 40 min. The recruitment manoeuvre decreases pulmonary shunt, but increases low Va/Q. The net effect on gas exchange is a small reduction of P A‐a o 2 .