Pulmonary Functions and Factors Affecting Them in Patients with Chronic Kidney Disease.

Objective: To determine the pulmonary functions in patients with chronic kidney diseases (CKD) and factors affecting them.

Study Design:  Observational study.

Place And Duration Of Study: Nephrology Department, Mayo Hospital, Lahore, from October 2018 to April 2019.

Methodology: All patients of CKD, coming in Nephrology OPD, were included. Patients on maintenance hemodialysis (HD), chronic obstructive pulmonary disease (COPD), smokers, chronic heart disease, and neuromuscular diseases were excluded from the study. Demographic data, physical examination findings and laboratory parameters were taken. Patients underwent spirometry at Pulmonology Department for measurement of forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) and FEV1/FVC.

Results: One hundred and forty patients were included in the study. Mean GFR was 27.75 ± 17.49 ml/min/1.73m2 and 7(5%) patients belonged to stage 2 CKD, 48 (34.3%) belonged to stage 3 CKD, 45 (32.1%) belonged to stage 4 CKD and rest 40 (28.6%) were from stage 5 CKD. Pulmonary functions were FEV1 (90.81±25.84), FVC (88.91±28.54), and FEV1/FVC (108.57±13.0). According to laid down criteria, 62 (44.3%) cases had restrictive lung disease (RLD), 5 (3.6%) cases had mixed and 78 (55.7%) cases normal lung function status. Important factors affecting pulmonary functions were GFR (p=0.038), monthly income (p=0.017) and education (p=0.041). Drop in GFR and anemia have negative correlation and age has positive correlation with pulmonary dysfunctions.

Conclusion: Pulmonary functions were abnormal in almost half of the patients and restrictive lung disease was the most common pattern in these patients. Factors affecting the pulmonary functions were progression of CKD, falling hemoglobin level, monthly income and education. Drop in GFR and anemia had negative correlation and age had positive correlation with pulmonary functions. Key Words: CKD, Pulmonary functions, Restrictive lung disease, GFR, Anemia.