Malnutrition and inflammation are associated with impaired pulmonary function in patients with chronic kidney disease.

Background: Inflammation and malnutrition are common findings in patients with chronic kidney disease (CKD). We hypothesized that in inflamed and malnourished patients, respiratory and peripheral muscle dysfunction may have significant consequences on pulmonary function. The aim of this study was to investigate possible associations between pulmonary function and inflammation and malnutrition in patients with CKD.
Methods: We studied 109 patients (63% males; 53+/-12 years) at the initiation of dialysis treatment (GFR 7.5+/-2.5 ml/min). Pulmonary function tests [forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and peak expiratory flow (PEF)] were performed and the percentages of predicted values were calculated (%FEV(1), %FVC and %PEF). Systemic inflammation, assessed by high-sensitivity C-reactive protein (hsCRP) and nutritional status assessed by subjective global assessment (SGA), lean body mass (LBM) (estimated with dual energy X-ray absorptiometry) and hand-grip strength (HGS), were evaluated at the same time.
Results: Significant negative correlations were found between hsCRP and the percent predicted values for all pulmonary function tests [%FEV(1) (Rho = -0.45), %FVC (Rho = -0.43) and %PEF (Rho = -0.38)], respectively. Malnourished patients defined as SGA >or=2 had lower %FEV(1) (64+/-19 vs 82+/-23%; P<0.001) and %FVC (67+/-18 vs 83+/-21%; P<0.001) than well nourished patients. Significant correlations were observed between HGS and %FVC (Rho = 0.38; P <0.001), %FEV(1) (Rho = 0.37; P<0.001) and %PEF (Rho = 0.22; P<0.05) and between LBM and %PEF (Rho = 0.20; P<0.05). Multivariate Cox analysis showed that cardiovascular disease and low %FVC were associated with poor survival.
Conclusions: Impaired pulmonary function is associated with malnutrition and inflammation, and predicts mortality in CKD patients. This may reflect an impact of malnutrition and inflammation on respiratory muscle performance, leading to pulmonary dysfunction, which could influence the clinical outcome.