Correlation Between FEV1 (Forced Expiratory Volume in First Second) and Pulmonary Arterial Pressure among Patients of Chronic Obstructive Pulmonary Disease
Background: To determine the relationship of Forced Expiratory Volume in first second (FEV1) with pulmonary arterial pressure among patients with chronic obstructive airway disease.
Methods: In this cross sectional study 276 patients, using -0.17 correlation between FEV1 and pulmonary artery pressure with 95% confidence level and 80% power of test, were enrolled . All patients 40 years or above, diagnosed with COPD of minimum duration 3 years were included. Doppler Echocardiography for the measurement of pulmonary arterial pressure was done. All the patients were also subjected to spirometery for the measurement of forced expiratory volume in one second. Spearman’s RANK correlation test was applied to see the relationship between FEV1 and pulmonary arterial pressure. P value of < 0.05 was considered significant.
Results: Mean age was 63.94+10.11 years. Mean duration of COPD was 13.19+5.15 years. The mean FEV1 (percent predicted) was 32.84+13.43. Among these 276 patients, 133 (48%) patients had Pulmonary Hypertension (PH). The mean PAP was 61.99 + 14.33. The correlation was calculated between FEV1 and PAP by using Pearson Correlation Coefficient and was found to be –0.406 (p=0.000).
Conclusion: Increase in severity of COPD (as measured by falling FEV1) is strongly correlated with increasing severity of pulmonary artery pressure and thus warrants echocardiographic screening of COPD cases with mild to very serious disease.