Dynamics of re-expansion of atelectasis during general anaesthesia.

Rothen, H. U.; Neumann, P.; Berglund, J. E.; Valtysson, J.; Magnusson, A.; Hedenstierna, G. (1999). Dynamics of re-expansion of atelectasis during general anaesthesia. British journal of anaesthesia, 82(4), pp. 551-556. Oxford University Press 10.1093/bja/82.4.551

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A major cause of impaired gas exchange during general anaesthesia is atelectasis, causing pulmonary shunt. A ‘vital capacity’ (VC) manoeuvre (i.e. inflation of the lungs up to 40 cm H2O, maintained for 15 s) may re-expand atelectasis and improve oxygenation. However, such a manoeuvre may cause adverse cardiovascular effects. Reducing the time of maximal inflation may improve the margin of safety. The aim of this study was to analyse the change over time in the amount of atelectasis during a VC manoeuvre in 12 anaesthetized adults with healthy lungs. I.v. anaesthesia with controlled mechanical ventilation (VT 9 (SD 1) ml kg-1) was used. For the VC manoeuvre, the lungs were inflated up to an airway pressure (Paw) of 40 cm H2O. This pressure was maintained for 26 s. Atelectasis was assessed by analysis of computed x-ray tomography. The amount of atelectasis, measured at the base of the lungs, was 4.0 (SD 2.7) cm2 after induction of anaesthesia. The decrease in the amount of atelectasis over time during the VC manoeuvre was described by a negative exponential function with a time constant of 2.6 s. At an inspired oxygen concentration of 40%, PaO2 increased from 17.2 (4.0) kPa before to 22.2 (6.0) kPa (P = 0.013) after the VC manoeuvre. Thus in anaesthetized adults undergoing mechanical ventilation with healthy lungs, inflation of the lungs to a Paw of 40 cm H2O, maintained for 7-8 s only, may re-expand all previously collapsed lung tissue, as detected by lung computed tomography, and improve oxygenation. We conclude that the previously proposed time for a VC manoeuvre may be halved in such subjects.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Intensive Care, Emergency Medicine and Anaesthesiology (DINA) > Clinic of Intensive Care

UniBE Contributor:

Rothen, Hans Ulrich

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0007-0912

Publisher:

Oxford University Press

Language:

English

Submitter:

Marceline Brodmann

Date Deposited:

30 Sep 2020 19:22

Last Modified:

30 Sep 2020 19:22

Publisher DOI:

10.1093/bja/82.4.551

BORIS DOI:

10.7892/boris.115141

URI:

https://boris.unibe.ch/id/eprint/115141

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