Bioimpedance analysis and intradialytic hypotension in intermittent hemodialysis.
BACKGROUND: Intradialytic hypotension (IDH) is one of the most severe complications during hemodialysis. Its appearance is caused in part by rapid fluid removal with concomitant failure in blood pressure regulation but also by other dialytic-dependent and independent factors. PATIENTS AND METHODS: We investigated total (TBW), extracellular (ECW) and intracellular water (ICW) in chronic intermittent hemodialysis dialysis hypotension-prone (CRF-HP, n = 11) and nonhypotension-prone (CRF-NHP, n = 10) patients with end-stage renal disease before, every 30 minutes during, as well as after dialysis and within onset of intradialytic hypotension by multifrequent bioimpedance analysis (BIA). Additionally, intradialytic time course of BIA in patients with acute renal failure (ARF) and septic shock (n = 10) was observed. RESULTS: IDH occurred in 72.1% of CRF-HP and in 80% of ARF patients. In CRF-HP and CRF-NHP, ECW significantly decreased by -12.44 +/- 4.22% in CRF-HP and -9.0 +/- 6.2% in CRF-NHP comparing pre- and post-dialysis values (each p < 0.01). Conversely, ICW increased by +11.5 +/- 11.3% in CRF-HP and +18.4 +/- 25.2% in CRF-NHP (each p < 0.05). In patients with ARF no significant changes could be detected. Calculated ECW/ICW and ECW/TBW ratio significantly decreased in CRF patients with a higher rate in CRF-HP patients (p < 0.05). Neither ECW/ICW nor ECW/TBW ratio correlated with mean arterial pressure. The onset of intradialytic hypotension (n = 35) did not differ intraindividually compared to normotensive periods (n = 411). Fluid removal in CRF patients seems to be mainly from the extracellular space. The reduced decreases in ECW/ICW and ECW/TBW ratios in CRF-HP compared to CRF-NHP may indicate an insufficient refilling from intra- to extracellular compartment in CRF-HP. CONCLUSION: In conclusion, multifrequent BIA is not capable to predict hypotension in the individual patient during a particular dialysis session.