The Effect of Arterial PaCO2 in COPD Exacerbations with and without Peripheral Edema

Introduction. Studies often suggest hypoxemia is an important factor for sodium retention in chronic obstructive pulmonary disease (COPD), although hypercapnia is also associated with sodium retention in these patients. Hence, we have presented the major role of PaCO² in edema due to COPD.

Method. COPD patients who were hospitalized due to exacerbation were enrolled in the study and divided into two groups: with and without edema. Exclusion criteria included primary hepatic diseases, nephrotic syndrome and other renal diseases, left heart failure, or using drugs that would interfere with these organs or endocrine function. Data were coded and analyzed by SPSS software. Arterial blood gas variables including bicarbonate, pH, and PaO₂, PaCO₂ and O₂ saturation, and FEV1, FVC, FEV1/FVC were measured and compared between the groups.

Results. No significant difference was found between the averages of bicarbonate, pH, PaO₂, O₂ saturation, FEV1, FVC and FEV1/FVC in COPD in the two groups. PaCO₂ levels were significantly higher in patients with edema, compared to those without edema (p = 0.05). A reverse and significant correlation between PaCo₂ and FEV1 levels (p = 0.03) (r = −0.501) was observed in patients with edema.

Conclusion. This study suggests that hypercapnia is a major factor in causing edema in COPD patients compared to hypoxemia.