Pulmonary dysfunctions in end stage chronic renal failure children on regular hemodialysis; possible risk factors

ABSTRACT

Lung and kidney functions are intimately related in both health and disease. In renal failure respiratory changes help to mitigate the systemic effects of renal acid-base disturbances. Changes in the function of the respiratory system are among the frequent complications of renal impairment. Alteration in the respiratory drive, mechanics, muscle function, lung volumes, gas exchange and hemodynamics are frequent and could occur in the lungs without obvious pulmonary symptoms. Their effects could be the way to pulmonary functional disorders. Patients with chronic renal failure treated with hemodialysis may exhibit various changes in ventilation and gas exchange. Moreover, hemodialysis and peritoneal dialysis may have their own impact on the respiratory functions. The main objectives of this work were to assess the pulmonary functions and arterial blood gases as well as assessment of echocardiographic changes in a group of children with chronic renal failure undergoing regular hemodialysis. We also aimed to explore possible risk factors that make these children more liable to disturbed pulmonary function. The study included 19 patients with CRF on regular hemodialysis during the period from January to March 2005. Their ages ranged from 8-17 years [mean 13.63 +/- 2.65]. They were 12 males and 7 females. These patients were attending the pediatric nephrology unit in Assiut University Hospital. The duration of dialysis varied from 1-5 years. Patients with known or recent cardiac, infectious, inflammatory or pulmonary diseases were excluded from the study, They were classified according to the duration of dialysis into two groups. Group [1] 8 CRF children with duration of dialysis<3 years and Group [2] 11 CRF children with duration of dialysis >/= 3 years, Fifteen apparently healthy children of matchable age, and sex were included as control group. All subjects had full clinical assessment including body weight, height, wt/ht ratio and full examination including pulse, blood pressure measurement, chest and cardiac examination. The following investigations were also done complete blood picture, total serum protein, albumin, urea, creatinine, calcium, phosphorus, and arterial blood gases [before and after a hemodialysis session]. Posteroanterior and lateral chest X-ray and echocardiographic examination. Spirometry was performed at the chest department of Assiut University hospital using sensor Medics [IBM] apparatus. The following parameters were obtained Forced vital capacity [FVC]; Forced expiratory volume in one second [FEV1]; FEVI/FVC ratio; and Peak expiratory flow rate [PEFR]. Out of the studied patients, 15.79%had pulmonary venous congestion while 10.52%had pleural effusions. On the other hand 15.79%had pericardial effusion and a similar percent had cardiomegaly. Cases as a whole and also both subgroups [A and B] showed significantly lower mean levels of wt/ht ratio, Hb, albumin, Ca, and FS but significantly higher mean levels of systolic blood pressure, blood urea, creatinine, P, LVESD, LVEDD, and indexed LVM than controls. Cases as a whole showed significantly lower mean levels of FVC, FEV1 and PEFR than controls. Cases in group B showed significantly lower mean level of FVC and FEVI and PEFR than controls. Analysis of blood gases showed that cases as a whole and also both groups [A and B] had significantly lower mean levels of pH and HCO3 and base excess than controls. Furthermore both groups showed significantly lower PCO2 before and after a HD session. FVC, FEV1 and PEFR correlated positively with each of wt/ratio ratio, Hb, albumin, Ca and FS and negatively with the duration of the dialysis, creatinine, P, and indexed LVM. Restrictive pattern of pulmonary dysfunctions is frequent in ESCRF patients. Structural and functional cardiac abnormalities are very important among the many predisposing factors for pulmonary function disturbances. Other factors such as malnutrition, hypocalcemia, hyperphosphatemia and anemia may also affect the pulmonary functions indirectly through cardiac affection. Uremic toxins are important factors for both system dysfunctions and the longer the duration of the disease, the more are the disturbances of the pulmonary functions. Low PCO[2] in uremic patients may be a trial by the respiratory system to compensate for acidosis by CO[2] wash in order to elevate the pH to near normal. This is very important since the possible noxious effect of overcorrection of acidosis may lead to alkalosis in such patients who are liable to be alkalosis after dialysis. Although standard treatment of malnutrition in CRF, include measures such as early and adequate dialysis, nutritional counseling, oral protein and amino acid supplements, these interventions cannot restore the nutritional status in all malnourished uremic patients. Adequate management of anemia is critically needed for breaking the cycle connecting renal failure, anemia and cardiac disease [all are predisposing factors for pulmonary dysfunctions]. Adequate management of the cardiac problems as well as appropriate monitoring and follow up is necessary to ameliorate the effects on the lungs and may prevent or delay the occurrence of pulmonary dysfunctions. Hemodialysis itself has its own impact on various organs. This points to the importance of renal transplantation as a better therapeutic alternative particularly in children