Comparison of brachial venous and mixed blood gas tensions and pH values in the chicken.

Differences in blood gas tensions and pH between brachial venous blood (BVB) and mixed venous blood obtained from the pulmonary artery (PAB) were compared in anesthetized male White Leghorn chickens to determine if BVB as obtained in routine venipuncture cold be used to estimate mixed venous values of pO2, pCO2, and pH. When paired samples were compared over the range of 25 to 68 mm Hg, brachial pO2 was 5.7 mm Hg higher (P less than .001) than PAB pO2. Brachial pCO2 was 4.25 mm Hg higher (P less than .001) than PAB pCO2 over the range of 17 to 56 mm Hg. Brachial pH was .066 units lower (p less than .001) than comparable values for PAB over the range of 7.2-7.6 pH units. Regression equations are given for estimating mixed venous blood gas tensions and pH values from blood samples taken from the brachial vein.