Comparison of arterial and venous blood gases analysis in patients with exacerbation of chronic obstructive pulmonary disease

Objective: To investigate whether venous blood gases (VBG) test can be replace by an arterial blood gases (ABG) in exacerbation of chronic obstructive pulmonary disease (COPD). Methods: From October 2005 to March 2006, at the Emergency Room of Kashan Beheshti Hospital, the data of 107 patients with exacerbation of COPD were assessed. Arterial blood gases and VBG samples were obtained simultaneously, and indexes of pH, carbon dioxide partial pressure (PCO2), bicarbonate (HCO3), oxygen partial pressure (PO2) and Oxygen (O-2) saturation level were analyzed. Results: The mean +/- SD of indexes in ABG and VBG samples were as follows: pH = 7.37 +/- 0.47 versus 7.34 +/- 0.047; PCO2 = 53.88 +/- 7.63 mm Hg versus 59.55 +/- 8.96 mm Hg, HCO3 = 30.66 +/- 4.49 mEq/L versus 31.94 +/- 4.39 mEq/L; PO2 = 55.37 +/- 11.19 mm Hg versus 43.08 +/- 10.54 mm Hg. The average difference between indexes in ABG and VBG samples were as follows: pH = 0.0241 +/- 0.004, p < 0.001, r = 0.864; PCO2 = 5.673 +/- 1.126 mm Hg, p < 0.001, r = 0.761; HCO3 = 1.279 +/- 0.604 mEq/L, p < 0.001, r = 0.749; and PO2 = 12.294 +/- 2.115 mm Hg, P < 0.001, r = 0.702. Conclusion: Venous blood gases, especially pH and PCO2 levels have relatively good correlation with ABG values. In view of the fact that, this correlation is not close, VBG cannot be substitute for ABG in exacerbation of COPD.