The value of non-invasive measurement of cardiac output and total peripheral resistance to categorize significant changes of intradialytic blood pressure: a prospective study.

Background: Blood pressure (BP) is currently the main hemodynamic parameter used to assess the influence of fluid removal during hemodialysis session. Since BP is dependent on cardiac output (CO) and total peripheral resistance (TPRI), investigating these parameters may help to better understand the influence of fluid removal on patient's hemodynamics. We used a novel non-invasive whole-body bio-impedance cardiography device, recently validated in hemodialysis patients, to examine mechanisms of intradialytic hemodynamics in a Chinese dialysis population.

Methods: Chronic hemodialysis patients in Sichuan Provincial People's Hospital were enrolled. Demographic data and dialysis prescriptions were collected. Hemodynamic measurements were made pre-treatment, every 20 min during treatment and immediately after treatment in each random dialysis session. These included blood pressure, cardiac index (CI), total peripheral resistance (TPRI) and cardiac power index (CPI). Patients were divided into 5 hemodynamic groups as per their major hemodynamic response to fluid removal: low CPI, low TPRI, high TPRI, High CPI and those with normal hemodynamics.

Results: Twenty-seven patients were enrolled, with 12 (44.4%) males. The average age was 65 ± 12 y. The average body mass index (BMI) was 23.7 ± 3.9 kg/m2. 12 (44.4%) patients were diabetic. Three hundred twenty-four hemodynamic measurements were made. Weight, BMI, total fluid removal, pretreatment systolic BP, CI, TPRI and CI differed significantly among the 5 hemodynamic groups.11.1% of patients had low CPI, 25.9% had low TPRI, 18.5% had high CPI, 3.7% had high TPRI and 40.7% had normal hemodynamics. Hemodynamic differences among the 5 subgroups were significant.

Conclusion: This technology provides multi-dimensional insight into intradialytic hemodynamic parameters, which may be more informative than blood pressure only. Using hemodynamic parameters to describe patients' status is more specific and accurate, and could help to work out specific and effective therapeutic actions according to underlying abnormalities.