Cold as cardiovascular stabilizing factor in hemodialysis: hemodynamic evaluation

Vascular instability represents the most frequent intradialytic complication of uremic patients. Catecholamine impairment, changes in plasma sodium or osmolality and, more recently, temperature (T) of dialysate have been proposed to explain this phenomenon. In order to evaluate the role of T in hemodynamic stability, we studied the effect of cooling dialysate in 5 patients (3 m, 2 f), who often experienced hypotension during dialytic sessions. Dialysate T was lowered, leading to a body T decrease of 1.5 degrees C, measured by a thermistor in the pulmonary artery. Ultrafiltration was kept constant during both "warm" (W) and "cold" (C) hemodialysis (HD). Systemic and pulmonary hemodynamic parameters were studied by thermodilution technique. The evaluation was performed in the same patients during W-HD and C-HD with the same dialysate composition. MAP showed a significant reduction during the first hour under both dialysis conditions. Subsequently a further decrease of MAP was observed in W-HD, while it remained stable in C-HD. CI and SI demonstrated similar trends, whereas HR showed no major changes. TPRI appeared significantly higher during C-HD compared to W-HD, with no clinical symptoms of hypotension. Similarly pulmonary parameters resulted in a better cardiovascular stability during C-HD. Our hemodynamic study confirms the important role played by T on intradialytic vascular stability and may explain the better control observed during hemofiltration compared to standard W-HD.