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.
