Temporal stability of twenty-four-hour ambulatory hemodynamic bioimpedance measures in African American adolescents.
BACKGROUND
The reliability of ambulatory impedance cardiography has not been evaluated.


OBJECTIVE
The purpose of this study was to determine the reproducibility of daytime and night-time ambulatory bioimpedance-derived measures of hemodynamic function in youth.


METHODS
Thirty-five African American adolescents (ages 16.2+/-1.4 years, 14 girls, 21 boys) with high normal systolic resting blood pressure (BP) were evaluated twice, separated by a 2-month interval. Measures were collected using the AIM-8-V3 Wearable Cardiac Performance Monitor (Bio-impedance Technology, Inc., Chapel Hill, North Carolina, USA) and the Spacelabs ambulatory BP monitor 90207 (Spacelabs Inc., Redmond, Washington, USA) from 0600 h to midnight every 20 min and from midnight to 0600 h every 30 min in the natural environment.


RESULTS
There were no significantly different means (P>0.15) between the two visits for daytime ambulatory heart rate (HR, r = 0.81), stroke volume (SV, r = 0.54), cardiac output (CO, r = 0.56), pre-ejection period (PEP, r = 0.59), left ventricular ejection time (LVET, r = 0.74), Heather Index (HI, r = 0.79), systolic BP (SBP, r = 0.79), diastolic BP (DBP, r = 0.66), mean arterial pressure (MAP, r = 0.65) and total peripheral resistance (TPR, r = 0.47). Overall means for night-time ambulatory HR (r = 0.76), SV (r = 0.49), CO (r = 0.45), LVET (r = 0.43), HI (r = 0.82), SBP (r = 0.65), DBP (r = 0.62), MAP (r = 0.63) and TPR (r = 0.20) were not significantly different between visits (P > 0.06). Mean differences (P < 0.01) were observed for PEP (r = 0.57).


CONCLUSIONS
The findings demonstrate that across 2 months in youth daytime and night-time ambulatory bioimpedance-derived measures of HR, HI, SBP, DBP and MAP are highly repeatable and SV, CO, PEP and LVET are moderately repeatable. This methodology should prove useful in cardiovascular research and clinical care.
Department of Pediatrics, Medical College of Georgia, Augusta, Georgia 30912, USA. vbarnes@mail.mcg.edu
Vernon A
VA
Barnes
Maribeth H
MH
Johnson
Frank A
FA
Treiber
D000293:Adolescent; D001741:Black or African American; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods*; D002302:Cardiac Output / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005845:Georgia; D006321:Heart / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D013318:Stroke Volume / Q000502:physiology