Document Detail

A noninvasive method for evaluating the effect of thoracotomy on shunt and ventilation perfusion inequality.
MedLine Citation:
PMID:  9244019     Owner:  NLM     Status:  MEDLINE    
A new noninvasive method was used to evaluate gas exchange in 12 patients undergoing thoracotomy for a variety of surgical procedures. A plot of inspired oxygen partial pressure versus oxygen saturation was analysed to calculate the independent contribution of shunt and intermediate ventilation/perfusion ratio which occurs during general anaesthesia for thoracotomy. A model based on the inspired to arterial oxygen difference involving the shunt equation was used to show how the relationship between inspired oxygen partial pressure and oxygen saturation could be used to derive two parameters of oxygen exchange, the virtual shunt and an index of low ventilation/perfusion ratio. In all cases, there was a very good fit of the data to the model. Thoracotomy caused a mean increase in shunt from 13.8% to 20.8% and a worsening ventilation/perfusion ratio from 0.5 to 0.2, the magnitude of which depended on the underlying pathology. In two patients, the ventilation/perfusion ratio decreased to less than 0.1. The method enables the prediction of oxygen saturation at different inspired oxygen partial pressures and allows the two components of gas exchange to be isolated using simple routine measurements of inspired oxygen and pulse oximetry.
L de Gray; E M Rush; J G Jones
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Publication Detail:
Type:  Clinical Trial; Journal Article    
Journal Detail:
Title:  Anaesthesia     Volume:  52     ISSN:  0003-2409     ISO Abbreviation:  Anaesthesia     Publication Date:  1997 Jul 
Date Detail:
Created Date:  1997-08-14     Completed Date:  1997-08-14     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0370524     Medline TA:  Anaesthesia     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  630-5     Citation Subset:  AIM; IM    
Department of Anaesthesia, Ipswich Hospital NHS Trust, UK.
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MeSH Terms
Anesthesia, General
Computer Simulation
Models, Biological
Monitoring, Intraoperative / methods*
Oxygen / blood
Partial Pressure
Pulmonary Gas Exchange*
Reg. No./Substance:

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