Document Detail

Lung ventilation and perfusion in prone and supine postures with reference to anesthetized and mechanically ventilated healthy volunteers.
MedLine Citation:
PMID:  20179506     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The literature on ventilation (V) and lung perfusion (Q) distributions during general anesthesia and controlled mechanical ventilation in supine and prone position is contradictory. The authors aimed to investigate whether V, Q, and ventilation to perfusion ratio (V/Q ratio) matching in anesthetized and mechanically ventilated volunteers are gravity dependent irrespective of posture. METHODS: Seven healthy volunteers were studied at two different occasions during general anesthesia and controlled mechanical ventilation. One occasion studied ventral to dorsal V and Q distributions in the supine posture and the other in the prone posture. Imaging was performed in supine posture at both occasions. A dual radiotracer technique and single photon emission computed tomography were used. V and Q were simultaneously tagged with Tc-Technegas (Tetley Manufacturing Ltd., Sydney, Australia) and In-labeled macroaggregates of human albumin (TechneScan LyoMAA, Mallinckrodt Medica, Petten, The Netherlands), respectively. RESULTS: No differences in V between postures were observed. Q differed between postures, being more uniform over different lung regions in prone posture and dependent in supine posture. The contribution of the vertical direction to the total V/Q ratio heterogeneity was larger in supine (31.4%) than in prone (16.4%) (P = 0.0639, two-tailed, paired t test) posture. CONCLUSIONS: During mechanical ventilation, prone posture favors a more evenly distributed Q between lung regions. V distribution is independent of posture. This results in a tendency toward lower V/Q gradients in the ventral to dorsal direction in prone compared with supine posture.
Sven Nyr?n; Peter Radell; Sten G E Lindahl; Margareta Mure; Johan Petersson; Stig A Larsson; Hans Jacobsson; Alejandro S?nchez-Crespo
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Anesthesiology     Volume:  112     ISSN:  1528-1175     ISO Abbreviation:  Anesthesiology     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-02-24     Completed Date:  2010-03-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  682-7     Citation Subset:  AIM; IM    
Department of Molecular Medicine and Surgery, Karolinska Institute, Solna, SE 171 76 Stockholm, Sweden.
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MeSH Terms
Anesthesia, General*
Indium Radioisotopes / diagnostic use
Lung / physiology*,  radionuclide imaging
Oxygen / blood
Prone Position / physiology*
Pulmonary Circulation / physiology*
Radiopharmaceuticals / diagnostic use
Respiration, Artificial*
Respiratory Mechanics / physiology*
Sodium Pertechnetate Tc 99m / diagnostic use
Supine Position / physiology*
Tomography, Emission-Computed, Single-Photon
Reg. No./Substance:
0/Indium Radioisotopes; 0/Radiopharmaceuticals; 112263-77-1/Technegas; 23288-60-0/Sodium Pertechnetate Tc 99m; 7782-44-7/Oxygen

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