title: Transcutaneous oxygen tension monitoring in critically ill patients receiving packed red blood cells.
abstract: OBJECTIVE
  Whether transfusions of packed red blood cells (PRBCs) affect tissue oxygenation in stable critically ill patients is still matter of discussion. The microvascular capacity for tissue oxygenation can be determined noninvasively by measuring transcutaneous oxygen tension (tcpO2). The aim of this study was to assess tissue oxygenation by measuring tcpO2 in stable critically ill patients receiving PRBC transfusions.
  
  
  METHODS
  Nineteen stable critically ill patients, who received 2 units of PRBC, were prospectively included into this pilot study. Transcutaneous oxygen tension was measured continuously during PRBC transfusions using Clark's electrodes. In addition, whole blood viscosity and global hemodynamics were determined.
  
  
  RESULTS
  Reliable measurement signals during continuous tcpO2 monitoring were observed in 17 of 19 included patients. Transcutaneous oxygen tension was related to the global oxygen consumption (r=-0.78; P=.003), the arterio-venous oxygen content difference (r=-0.65; P=.005), and the extraction rate (r=-0.71; P=.02). The transfusion-induced increase of the hemoglobin concentration was paralleled by an increase of the whole blood viscosity (P<.001). Microvascular tissue oxygenation by means of tcpO2 was not affected by PRBC transfusions (P=.46). Packed red blood cell transfusions resulted in an increase of global oxygen delivery (P=.02) and central venous oxygen saturation (P=.01), whereas oxygen consumption remained unchanged (P=.72).
  
  
  CONCLUSIONS
  In stable critically ill patients, microvascular tissue oxygenation can be continuously monitored by Clark's tcpO2 electrodes. According to continuous tcpO2 measurements, the microvascular tissue oxygenation is not affected by PRBC transfusions.
authors.affiliation: Department of Medicine II, Division of Angiology, Medical University of Vienna, Vienna, Austria.
authors.forename: Oliver
authors.initials: O
authors.lastname: Schlager
authors.affiliation: Department of Medicine II, Division of Angiology, Medical University of Vienna, Vienna, Austria. Electronic address: michael.gschwandtner@meduniwien.ac.at.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Gschwandtner
authors.affiliation: Department of Medicine II, Division of Angiology, Medical University of Vienna, Vienna, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Willfort-Ehringer
authors.affiliation: Department for Blood Group Serology and Transfusion Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Kurz
authors.affiliation: Department of Medicine II, Division of Angiology, Medical University of Vienna, Vienna, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Mueller
authors.affiliation: Department of Medicine II, Division of Angiology, Medical University of Vienna, Vienna, Austria.
authors.forename: Renate
authors.initials: R
authors.lastname: Koppensteiner
authors.affiliation: Department of Medicine II, Division of Cardiology, Intensive Care Unit, Medical University of Vienna, Vienna, Austria.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Heinz
mesh_terms: D000368:Aged; D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation / Q000379:methods; D001809:Blood Viscosity / Q000502:physiology*; D016638:Critical Illness; D004566:Electrodes; D017707:Erythrocyte Transfusion; D005260:Female; D006400:Hematocrit; D006439:Hemodynamics / Q000502:physiology; D006441:Hemoglobin A / Q000378:metabolism*; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D019990:Perioperative Care; D010865:Pilot Projects; D011446:Prospective Studies
chemical_list: D006441:Hemoglobin A
keywords: Microcirculation; Tissue oxygenation; Transcutaneous oxygen tension; Transfusions