title: Tissue gas tensions and tissue metabolites for detection of organ hypoperfusion and ischemia.
abstract: BACKGROUND
  The aim of this study was to evaluate how tissue gas tensions and tissue metabolites measured in situ can detect hypoperfusion and differentiate between aerobic and anaerobic conditions during hemorrhagic shock. We hypothesized that tissue PCO(2) (PtCO(2)) would detect hypoperfusion also under aerobic conditions and detect anaerobic metabolism concomitantly with or earlier than other markers.
  
  
  METHODS
  Prospective experimental animal study with eight anesthetized pigs subjected to a continuous blood loss ∼8% of total blood volume per hour until death. We measured cardiac index, organ blood flows, and tissue levels of PO(2), PCO(2), glucose, pyruvate, lactate, and glycerol in intestine, liver, kidney, and skeletal muscle.
  
  
  RESULTS
  With reduction in blood flow to the organs under aerobic conditions, PtCO(2) increased ∼1-4 kPa from baseline. With the onset of tissue hypoxia there was a pronounced increase of PtCO(2), lactate, lactate-pyruvate (LP) ratio, and glycerol. Tissue pH and bicarbonate decreased significantly, indicating that metabolic acid was buffered by bicarbonate to generate CO(2).
  
  
  CONCLUSIONS
  Moderate tissue hypoperfusion under aerobic conditions is associated with increased PtCO(2), in contrast to metabolic parameters of ischemia (lactate, LP ratio, and glycerol) which remain low. From the onset of ischemia there is a much more rapid and pronounced increase in PtCO(2), lactate, and LP ratio. PtCO(2) can be used as a marker of hypoperfusion under both aerobic and anaerobic conditions; it gives an earlier warning of hypoperfusion than metabolic markers and increases concomitantly with or earlier than other markers at the onset of tissue anaerobiosis.
authors: The Acute Clinic, Department of Anesthesiology and Critical Care Medicine, Oslo University Hospital, Norway.
authors: L
authors: L
authors: Waelgaard
authors: B M
authors: BM
authors: Dahl
authors: G
authors: G
authors: Kvarstein
authors: T I
authors: TI
authors: Tønnessen
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D019540:Area Under Curve; D001639:Bicarbonates / Q000032:analysis; D001794:Blood Pressure / Q000502:physiology; D001831:Body Temperature; D002245:Carbon Dioxide / Q000032:analysis; D002302:Cardiac Output / Q000502:physiology; D005740:Gases / Q000032:analysis* / Q000378:metabolism; D006339:Heart Rate / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007511:Ischemia / Q000175:diagnosis*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D017551:Microdialysis; D010100:Oxygen / Q000032:analysis; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology*; D012771:Shock, Hemorrhagic / Q000175:diagnosis; D013552:Swine
chemical_list: D001639:Bicarbonates; D005740:Gases; D002245:Carbon Dioxide; D019344:Lactic Acid; D010100:Oxygen