The Application And Significance Of Chest Bioelectrical Impedance Method In Monitoring Hemodynamic Parameters Of Hemodialysis Patients

Pulmonary congestion is prevalent and usually asymotomatic in patients with end-stage renal disease(ESRD).Thoracic fluid content(TFC)measured by thoracic electrical bioimpedance(TEB)is suggested to serve as a non-invasive measure of pulmonary congestion.We explored the clinical and echocadiographic correlates of thoracic fluid content as well as its prognostic value in hemodialysis patients.In this prospective observational study,we enrolled 114 patients from a single hemodialysis unit.We used different methods of evaluation: thoracic bioimopedance(pre-and post-dialysis)and echocardiography(pre-dialysis).Our aim was to test the prognostic value of TFC in this population.Mortality was analysed after a median of 560.5-day follow-up.The primary outcome was all-cause death.TFC was strongly associated with left atrial diameter(LAD)(r=0.454,P=0.001),left ventricular posterior wall thickness(LVPW)(r=0.473,P=0.001)and ejection fraction(EF)(r=-0.527,P=0.001).After a median follow-up of 520-day,compaired with those patients having lower TFC,patients with higher TFC had 4.95 –fold risk of death.TEB is a technique that could detect pulmonary congestion at a pre-clinical stage in hemodialysis patients and TFC emerged as a predictor for the mortality in this population.In hemodialysis,extracorporeal circulation is applied to remove accumulated uremic toxins,electrolyte and fluid in plasma into the dialysate through a membrane during a 4h HD session 3 times a week.The rate of exculsion in 4h is approximately 10 times faster than that of previous accumulation for 2 or 3 days.Hemodynamic stress during HD results in recurrent segmental ischemic injury that drives cumulative cardiac damage.We performed a observational study of the cardiovascular effect of dialysis sessions using intradialytic thoracic bioimopedance cardiography to examine the acute effects of standard HD in stable patients(n=114).Bioimpedance cardiography measurements included cardiac index,stroke volume index,systemic vascular resistance index,acceleration index and thoracic fluid content.Patients had mean ± SEM ultrafiltration rates of 3.8±2.9 ml/kg per hour during HD.All measures of stroke volume index fell during HD,with partial recovery after dialysis.After dialysis,cardiac index reduced obviously compared to the base lever before dialysis.All patients experienced some degree of segmental left ventricular dysfunction,with severity proportional to ultrafiltration rate and BP reduction.In conclusion,it suggested that TEB could assess the acute cardiac effects of dialysis during hemodialysis treatment.And fluid overload could in part explain the fell of cardiac index during dialysis.