Arterial Blood Gas reveals information on:
    Oxygen and Carbon Dioxide Exchange
    Acid-base status

  A true arterial blood gas gives you three data points:
    PaO2- Partial pressure oxygen: 60-90 mm Hg
    PaCO2- Partial pressure carbon dioxide: 36-44 mmHg
    pH -normal 7.35-7.45

  These values are derived from the measured values above:
    HCO3- 22-26 meq/L: Calculated from the Henderson-Hasselbach equation.
    Base deficit

  How is a arterial blood gas obtained?

    Sample is obtained from an artery using a "blood gas" syringe coated with heparin.
    All air bubbles are removed and a cap placed on syringe.
    Best if run within 15 minutes.
    Place on ice if it will be longer than 15 minutes.

  Possible causes:
  1. Hypoventilation
  2. Pulmonary Disorder-Shunt.
  3. Do2/Vo2 imbalance: Oxygen delivered to the tissues is not
      being extracted.
  4. Alveolar-arterial oxygen gradient. (A-a gradient)

    A-a Gradient = PA02- Pa02
      PAO2 = 713 mm Hg x Fi02 - PaCO2/ 0.8
      Increased gradient: Shunt
      Normal gradient: Hypoventilation usually

   Hypercapnia:Elevated partial pressure of CO2 in blood.
           PaCo2>45mmHg.
   Possible causes:
   1. Hypoventilation
   2. Increased CO2 production
   3. Increased dead space ventilation.