Impedance cardiography: A potential monitor during hemodialysis

Abstract

Introductory Sentence: The hemodynamic data including thoracic fluid content (TFC) provided non-invasively by impedance cardiography (ICG) may provide information regarding patient fluid status during hemodialysis (HD). Methods: A convenience sample of patients with chronic renal failure undergoing HD was studied using ICG (BioZ®, CardioDynamics, Inc., San Diego, CA). Recordings were made prior to therapy and then at 15 minute intervals throughout the HD session. Parameters recorded included TFC, cardiac index (CI), blood pressures (BP)[systolic (SBP), diastolic (DBP) and mean arterial (MAP)], systemic vascular resistance index (SVRI) and heart rate (HR). Using the Pearson method, the percent change in each of the parameters during the HD session were correlated to the amount of fluid removed (FR), normalized to body weight. Results: Forty-one patients were enrolled, but six patients were excluded due to incomplete data and therefore 35 patients (13 men and 22 women) formed the basis of the analysis. The age range was 28 to 87 (mean 55.l ± 16.1) years. The amount of FR was 2.88 ±1.13 L (37.3 ± 14.6 ml/kg). TFC decreased in all patients during the HD session (average reduction 12.7 ± 8%), whereas all other hemodynamic parameters showed both increases and decreases. The correlation of TFC with FR was moderate (r = .58, p = 0.0003); other hemodynamic parameters showed poor correlation with FR. Conclusions: TFC as measured easily and noninvasively using ICG correlates with the amount of fluid removed during HD. In comparison to the other hemodynamic parameters measured, TFC changed most consistently with fluid removal and the magnitude of TFC changes correlated with amount of FR. Whether or not serial TFC measures in a given patient at different HD sessions can guide extent of FR will require additional study. Tabled 1 TFC DBP HR MAP SBP CI SVRI R 0.58 0.30 0.29 0.27 0.20 0.16 0.03 P 0.0003 0.08 0.09 0.11 0.24 0.36 0.86 # Decreased 35 14 11 17 17 20 12 # Increased 0 19 21 18 18 12 23 # No Δ 0 2 3 0 0 3 0 Open table in a new tab