blood gas determination, an analysis of the pH of the blood and the concentration and pressure of oxygen and carbon dioxide in the blood. It can be performed as an emergency procedure to assess acid-base balance and ventilatory status. Blood gas determination is often important in the evaluation of cardiac failure, hemorrhage, kidney failure, drug overdose, shock, uncontrolled diabetes mellitus, or any other condition of severe stress. The blood for examination is drawn from an artery, as ordered in a heparinized syringe, sealed from air, placed on ice, and immediately transported for analysis. Normal adult arterial blood gas values are pH 7.35 to 7.45; PCO2 35 to 45 mm Hg; HCO3− 21 to 28 mEq/L; PO2 80 to 100 mm Hg; O2 saturation 95% to 100%. See also acid-base balance, acidosis, alkalosis, oxygenation, PaCO2, pH, PO2.
