Pulse volume changes recorded by air plethysmography during single hemodialysis sessions.

Aims: This study investigated whether fluid removal during a hemodialysis (HD) session affects the results of non-invasive pulse volume recording (PVR) on the lower extremities.

Methods: The results of PVR by air plethysmography (Portable Vascular Laboratory; BioMedix, USA) were compared with bioelectrical impedance analysis (Nutriguard-M device; Data Input, Germany) of the human body before and after a single HD in 28 anuric patients (10 women; 18 men) aged 33-76 years.

Results: Changes in the wave amplitude of the PVR correlated with the changes in the patient's weight during HD. Lower stroke volume at the end of HD due to blood volume withdrawal resulted in PVR reduction at the ankle level. Significant Spearman coefficients were found between extracellular water and PVR amplitude changes (r = 0.7, p < 0.01) as well as between intracellular water and PVR (r = 0.6, p < 0.04).

Conclusions: To avoid falsification connected with hypervolemia and stroke volume change, the most appropriate time for PVR in vascular diagnosing seems to be the period of a few hours after dialysis session.