Ambulatory impedance cardiography in hypertension: a validation study
Judith A McFetridge-Durdle1, Faye S Routledge, Monica J E Parry
1Dalhousie University, School of Nursing, Halifax, Nova Scotia, Canada. judith.mcfetridge@dal.ca
European Journal of Cardiovascular Nursing
|February 1, 2008
Summary
The Ambulatory Impedance Monitor (AIM) effectively detects hemodynamic changes during postural shifts in hypertensive patients. This technology offers valid and reliable cardiac function estimates for managing hypertension.
Area of Science:
- Cardiovascular physiology
- Biomedical engineering
- Hypertension management
Background:
- Knowledge of hemodynamics improves hypertension management.
- Impedance Cardiography (ICG) provides hemodynamic data but captures only fixed characteristics.
- Ambulatory technology advancements led to the Ambulatory Impedance Monitor (AIM) for continuous hemodynamic monitoring.
Purpose of the Study:
- To evaluate the sensitivity of the AIM in detecting hemodynamic changes associated with postural shifts in hypertensive individuals.
- To assess the validity and reliability of AIM-derived cardiac function estimates.
Main Methods:
- A repeated measures cross-over design was employed.
- Seventeen hypertensive participants underwent sitting and standing hemodynamic measurements.
- Measurements were taken using both the AIM-BpTRU (office use) and AIM-Spacelabs (ambulatory monitoring) systems.
Main Results:
- Both AIM systems detected significant postural changes in heart rate, stroke volume, left ventricular ejection time, systemic vascular resistance, and diastolic blood pressure.
- Cardiac function measures from both systems were highly correlated and not significantly different.
- p-values: HR (p=0.03), SV (p=0.002), LVET (p<0.001), SVR (p=0.03), DBP (p<0.001).
Conclusions:
- The AIM demonstrates sensitivity to hemodynamic alterations during postural changes in hypertension.
- AIM provides valid and reliable estimates of cardiac function in hypertensive patients.
- This supports the use of AIM for improved hypertension management through continuous hemodynamic monitoring.
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