title: Measurement of systemic oxygen consumption in patients during extracorporeal membrane oxygenation--description of a new method and the first clinical observations.
abstract: BACKGROUND
  Extracorporeal membrane oxygenation (ECMO) provides temporary life-saving support for patients with severe cardiac failure, but is associated with significant morbidity and mortality. While ECMO enables oxygen delivery (DO2), little is known about oxygen consumption (VO2), largely due to technical difficulties. We aimed to introduce the adaptation of respiratory mass spectrometry to measure VO2 in patients during ECMO and to use this unique model to determine the pathological dependency of VO2 on DO2 in humans.
  
  
  METHODS
  Respiratory mass spectrometry remains the 'state-of-the-art' method, allowing the highly sensitive and rapid measurement of VO2 in critically ill patients. The principle and design of the respiratory mass spectrometer are described, together with the setting up of this machine with the ECMO oxygenator and the native lungs of the patients. In two patients with severe dilated cardiomyopathy and little cardiac contraction, the decrease in pump flow and, hence, DO2 by 20% was associated with a decrease in VO2 by 5% and 8%, respectively, whereas the increase in pump flow was not associated with any significant change in VO2.
  
  
  CONCLUSIONS
  The direct measurement of VO2 by respiratory mass spectrometry in ECMO patients provides a unique technique for clinical research on the metabolism and VO2-DO2 relationship in this special group of critically ill patients. Our pilot study is the first to demonstrate a pathological dependency of VO2 on DO2 in humans. Further studies are warranted with this technique to examine the changes and the factors affecting systemic oxygen transport in patients during ECMO.
authors.affiliation: 1Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Cheypesh
authors.forename: X
authors.initials: X
authors.lastname: Yu
authors.forename: J
authors.initials: J
authors.lastname: Li
mesh_terms: D002675:Child, Preschool; D015199:Extracorporeal Membrane Oxygenation / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010865:Pilot Projects
chemical_list: D010100:Oxygen
keywords: extracorporeal membrane oxygenation; intensive care; oxygen consumption; oxygen delivery; respiratory mass spectrometry