Document Detail

Inhalation anesthesia increases V/Q regional heterogeneity during spontaneous breathing in healthy subjects.
MedLine Citation:
PMID:  21068662     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The underlying mechanism for the increased alveolar-arterial oxygen tension difference resulting from almost all forms of general anesthesia is unknown. We hypothesized that inhalation anesthesia influences the intrapulmonary distribution of ventilation (V) and perfusion (Q), leading to less advantageous V/Q matching.
METHODS: Ten healthy volunteers were studied in supine position on two separate occasions, once awake and once during mild anesthesia (sevoflurane inhalation) with maintained spontaneous breathing. On both occasions, the distribution of V and Q were simultaneously imaged using single photon emission computed tomography. V was tagged with [Tc]-labeled carbon particle aerosol and Q with [In]-labeled macroaggregates of human albumin. Atelectasis formation during anesthesia was prevented using low concentrations of oxygen in inhaled air.
RESULTS: Mean V and Q distributions in the ventral-to-dorsal direction, measured in 20 equally spaced volumes of interest and in three regions of interest of equal volume, did not differ between conditions. Anesthesia, when compared with the awake state, significantly decreased the total heterogeneity of the Q distribution (P = 0.002, effect size 1.16) but did not alter V (P = 0.37, effect size 0.41). The corresponding V/Q total heterogeneity was higher under anesthesia (P = 0.002, effect size 2.64). Compared to the awake state, the V/Q frequency distribution under anesthesia became wider (P = 0.009, 1.76 effect size) with a tendency toward low V/Q ratios.
CONCLUSION: Inhalation anesthesia alone affects Q but not V, suggesting that anesthesia has a direct effect on the active regulatory mechanism coordinating Q with V, leading to less favorable V/Q matching.
Sven Nyrén; Peter Radell; Margareta Mure; Johan Petersson; Hans Jacobsson; Sten G E Lindahl; Alejandro Sánchez-Crespo
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesiology     Volume:  113     ISSN:  1528-1175     ISO Abbreviation:  Anesthesiology     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-11-24     Completed Date:  2010-12-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1370-5     Citation Subset:  AIM; IM    
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
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MeSH Terms
Anesthesia, Inhalation*
Carbon Dioxide / blood
Data Interpretation, Statistical
Hemodynamics / physiology
Lung / physiology,  radionuclide imaging
Organometallic Compounds / diagnostic use
Oxygen / blood
Radiopharmaceuticals / diagnostic use
Respiration / drug effects*
Respiratory Mechanics / drug effects*
Serum Albumin / diagnostic use
Sodium Pertechnetate Tc 99m / diagnostic use
Tomography, Emission-Computed, Single-Photon
Ventilation-Perfusion Ratio / drug effects*
Young Adult
Reg. No./Substance:
0/Organometallic Compounds; 0/Radiopharmaceuticals; 0/Serum Albumin; 0/indium aggregated albumin; 112263-77-1/Technegas; 124-38-9/Carbon Dioxide; 23288-60-0/Sodium Pertechnetate Tc 99m; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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