title: Using blood gases for the v.i.p..
abstract: We have tried to expand the routine analysis of blood gases to include some fine-tuning aspects of critical care. Test your understanding by answering the following question: A 70-year-old smoker falls into Lake Dillon (outside Denver) suffering a near-drowning episode. The pulse oximeter shows 93% on 6L nasal oxygen. His pulse and blood pressure are normal. Because you've read this article, you know that the patient's smoking habit and the city's elevation can affect the pulse oximeter's accuracy, leading one to underestimate the severity of the problem. So, you draw labs and note that his hemoglobin is 12, with blood gases showing PaO2 of 90, PaCO2 of 30 and a pH of 7.36. The lab forgot to calculate the base excess for you and his temperature is 89 degrees F rectally. A diagnosis of life-threatening inadequate oxygenation is supported by which of the following astute observations: a) An abnormal base deficit is proven by the borderline acidic pH and the low PaCO2. b) His anemia reduces both his buffer base and his oxygen carrying capacity. c) His hypothermia overstates his PO2 because the blood was heated up before measurement. d) His smoking makes a CO level likely, worsening his anemia and ignored by the pulse oximeter. e) The high level of supplemental oxygen has minimal effect on his arterial oxygen tension, showing severe pulmonary gas transfer problems (shunting). f) The measurement of his PaO2 is artificially high because he is at altitude.
  
  
  CONCLUSIONS
  All of the following except (f). Measuring his oxygen tension at altitude actually works in his favor, since the barometric effect will be to reduce the PaO2 at a given level of sea level pathology. Now you are ready to give your patients the V.I.P. treatment!
authors.forename: C G
authors.initials: CG
authors.lastname: Bayne
mesh_terms: D000136:Acid-Base Equilibrium; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D006801:Humans; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D014692:Ventilation-Perfusion Ratio
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen