Predicting factors of intradialytic hypotension in the last half of hemodialysis therapy

Background Intradialytic hypotension (IDH) is one of the most frequent complications of hemodialysis. IDH alters a patient's quality of life and has a strong association with mortality. IDH mainly occurs when ultrafiltration during hemodialysis exceeds the pace of the plasma refill. Ultrasonography has been used to evaluate the intravascular volume status. We evaluated the association between IDH and baseline laboratory data or ultrasound findings during IDH during the latter half of a hemodialysis session. Methods Sixty-two patients who underwent hemodialysis were enrolled in this study. The peak early mitral inflow wave velocity (peak E-velocity), the inferior vena cava (IVC) dimensions, and number of B-lines were estimated at two time points (just after the start and at the midpoint of the hemodialysis session). We compared the parameters between the patients without IDH throughout the hemodialysis session (non-IDH group) and patients with IDH only during the latter half of the hemodialysis session (IDH in the latter half group). Results Of the 62 study participants, 28 patients were in non-IDH group, and 16 patients were in IDH in the latter half group. The serum sodium level was significantly lower in the IDH in the latter half group (135 +/- 4 mEq/L) than in the non-IDH group (138 +/- 4 mEq/L) (P = 0.015). The rate of decrease of the peak E-velocity was significantly higher in the IDH in the latter half group (0.33 +/- 0.13) than in the non-IDH group (0.24 +/- 0.14) (P = 0.037). The best cutoff point of the serum level of sodium was 137 mEq/L, with a sensitivity of 68.8% and specificity of 64.3%. The area under the receiver operating characteristic (ROC) curve was 0.71. The best cutoff point of the rate of decrease of the peak E-velocity was 0.295, with a sensitivity of 73.3% and a specificity of 71.4%. The area under the ROC curve was 0.71. Conclusions A low serum level of sodium at baseline and an early decrease in the peak E-velocity during hemodialysis may be related to intradialytic hypotension in the latter half of a hemodialysis session. Careful observation may be needed in the hemodialysis patients in whom the serum level of sodium is below 137 mEq/L or the rate of decrease of the peak E-velocity is over 0.295.