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Lung computed tomography density distribution in a porcine model of one-lung ventilation
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology. (Hedenstierna)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
Department of Anaesthesiology and Intensive Care Medicine, Otto-von-Guericke-University Magdeburg, Germany.
Department of Anaesthesiology and Intensive Care Medicine, Otto-von-Guericke-University Magdeburg, Germany.
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2009 (English)In: British Journal of Anaesthesia, ISSN 0007-0912, E-ISSN 1471-6771, Vol. 102, no 4, 551-560 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: One-lung ventilation (OLV) exposes the dependent lung to increased mechanical stress which may affect the postoperative course. This study evaluates regional pulmonary gas/tissue distribution in a porcine model of OLV. METHODS: Nine anaesthetized and mechanically ventilated (V(T)=10 ml kg(-1), FI(O(2))=0.40, PEEP=5 cm H(2)O) pigs were studied. After lung separation by an endobronchial blocker, lateral thoracotomy and OLV were performed in six pigs. Three animals served as controls. Static end-expiratory and end-inspiratory spiral computed tomography (CT) scans were done before, during, and after OLV and at corresponding times in controls. CT images were analysed by defined regions of interest and summarized voxels were classified by defined lung X-ray density intervals (atelectasis, poorly aerated, normally aerated, and overaerated). RESULTS: Dependent lungs contained poorly aerated regions and atelectasis with a significant tidal recruitment during conventional two-lung ventilation (TLV) before OLV (expiration vs inspiration: atelectasis 29% vs 14%; poorly aerated 66% vs 44%; normally aerated 4% vs 41% of the dependent lung volume, P<0.05). During OLV (V(T)=10 ml kg(-1)), cyclic recruitment was increased. The density spectrum of the ventilated lung changed from consolidation to aeration (expiration vs inspiration: atelectasis 10% vs 2%; poorly aerated 71% vs 18%; normally aerated 19% vs 79%, P<0.05). After OLV, increased aeration remained with less atelectasis and poorly aerated regions. Lung density distribution in the non-dependent lung of OLV pigs was unaltered after the period of complete lung collapse. CONCLUSIONS: Cyclic tidal recruitment during OLV in pigs was associated with a persistent increase of aeration in the dependent lung.

Place, publisher, year, edition, pages
2009. Vol. 102, no 4, 551-560 p.
Keyword [en]
Animals Procedures Act, lung, tidel volume, measurement techniques, surgery, thoracic, ventilation, one-lung, ventilation volumes
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-108826DOI: 10.1093/bja/aep006ISI: 000264189700018PubMedID: 19224926OAI: oai:DiVA.org:uu-108826DiVA: diva2:241324
Available from: 2009-10-02 Created: 2009-09-30 Last updated: 2010-08-13Bibliographically approved
In thesis
1. Pathophysiological and Histomorphological Effects of One-Lung Ventilation in the Porcine Lung
Open this publication in new window or tab >>Pathophysiological and Histomorphological Effects of One-Lung Ventilation in the Porcine Lung
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Thoracic surgical procedures require partial or complete airway separation and the opportunity to exclude one lung from ventilation (one-lung ventilation, OLV). OLV is commonly associated with profound pathophysiological changes that may affect the postoperative outcome. It is injurious in terms of increased mechanical stress including alveolar cell stretch and overdistension, shear forces secondary to repeated tidal collapse and reopening of alveolar units and compression of alveolar vessels. Ventilation and perfusion distribution may thus be affected during and after OLV. The present studies investigated the influence of OLV on ventilation and perfusion distribution, on the gas/tissue distribution and on the lung histomorphology in a pig model of thoracic surgery.

Anaesthetised and mechanically ventilated piglets were examined. The ventilation and perfusion distribution within the lungs was assessed by single photon emission computed tomography. Computed tomography was used to establish the effects of OLV on dependent lung gas/tissue distribution. The pulmonary histopathology of pigs undergoing OLV and thoracic surgery was compared with that of two-lung ventilation (TLV) and spontaneous breathing.

OLV induced hyperperfusion and significant V/Q mismatch in the ventilated lung persistent in the postoperative course. It increased cyclic tidal recruitment that was associated with a persistent increase of gas content in the ventilated lung. OLV and thoracic surgery as well resulted in alveolar damage.  In the present model of OLV and thoracic surgery, alveolar recruitment manoeuvre (ARM) and protective ventilation approach using low tidal volume preserved the ventilated lung density distribution and did not aggravate cyclic recruitment of alveoli in the ventilated lung.

In conclusion, the present model established significant alveolar damage in response to OLV and thoracic surgery. Lung injury could be related to the profound pathophysiological consequences of OLV including hyperperfusion, ventilation/perfusion mismatch and increased tidal recruitment of lung tissue in the dependent, ventilated lung.  These mechanisms may contribute to the increased susceptibility for respiratory complications in patients undergoing thoracic surgery. A protective approach including sufficient ARM, application of PEEP, and the use of lower tidal volumes may prevent the ventilated lung from deleterious consequences of OLV.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 54 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 493
Alveolar Recruitment Manoeuvre, One-Lung Ventilation, Lung Protective Ventilation, Tidal Volume, Computed Tomography, Tidal Recruitment, Animal Model, Open Thoracic Surgery, Ventilation/ Perfusion Distribution, Single Photon Emission Computed Tomography, Diffuse Alveolar Damage
National Category
Biomedical Laboratory Science/Technology
Research subject
urn:nbn:se:uu:diva-108850 (URN)978-91-554-7647-2 (ISBN)
Public defence
2009-12-09, Enghoffsalen, Akademiska sjukhuset, 751 85 Uppsala, Ing. 50, 13:15 (English)
Available from: 2009-11-19 Created: 2009-09-30 Last updated: 2009-11-19Bibliographically approved

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