Background: Hypertension in dialysis patients is common. In daily practice, it is not always clear whether adjustment of dry weight or vasodilatory medication should be administered and treatment strategy is often based on clinical impression. We used a whole-body bio-impedance based, non-invasive, hemodynamics monitoring technology to acquire hemodynamic data in order to evaluate the incidence and causes of hypertension in dialysis patients.
Methods: Novel noninvasive impedance based technique was used to collect hemodynamic data from patients undergoing chronic hemodialysis in four different dialysis units. Patients were defined as having hypertension if their predialysis systolic or diastolic BP results were >140mmHg or >90 respectively and as hypervolemic if their total body water (TBW) was greater than normal according to the Kushner formula+1SD. Vasoconstriction was defined as total peripheral resistance index (TPRI) greater than 3000 dyn*sec/cm5*m2.
Results: Of 144 hemodialysis patients, 81 (56%) were male; mean age was 67.3±12.1 years and 67 (47%) had hypertension. Among the hypertensive patients, only 18(27%) met hypervolemia criteria and thirty (45%) met vasoconstriction criteria (mean TPRI of 4474±1592dyn*sec/cm5*m2). Patients with hypertension due to vasoconstriction had higher vintage (50±45 vs 20±8 months 0=0.018), lower heart rate (71±11 vs 79±11 BPM p=0.002), lower stroke index (28±7 vs 44±8ml/m2 p<0.001) and cardiac index (2.1±0.5 vs 3.5±0.6 p=0<0.001) compared to patients without vasoconstriction.
Conclusions: Vasoconstriction was the main etiology for pre-dialysis hypertension in chronic hemodialysis patients. This calls for individualized, hemodynamic-based therapeutic intervention.