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Published on: March 21, 2013
Blood volume measurement as a tool in diagnosing syncope
Fetnat Fouad-Tarazi1, J Calcatti, R Christian
1Department of Cardiovascular Medicine, Hemodynamic and Neuroregulation Laboratory, Syncope Clinic, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
The American Journal of the Medical Sciences
|July 17, 2007
Summary
Blood volume abnormalities are common in syncope patients and often missed by standard tests. Measuring blood volume is crucial for accurate syncope diagnosis and appropriate treatment selection.
Area of Science:
- Cardiology
- Nephrology
- Internal Medicine
Background:
- Syncope etiology remains unknown in a significant percentage of cases (24-37%) despite standard diagnostic evaluations.
- Blood volume assessment may clarify syncope mechanisms and guide personalized therapy.
- This study presents the largest dataset of blood volume measurements in syncope patients.
Purpose of the Study:
- To investigate the role of blood volume measurement in diagnosing syncope of unclear origin.
- To determine the prevalence of blood volume derangements in syncope patients.
- To assess the utility of standard hemodynamic measurements and tilt table testing in predicting blood volume status.
Main Methods:
- Radioisotopic blood volume measurement (Daxor BVA-100) was performed on 539 syncope patients.
- Demographic and clinical data, including blood pressure, heart rate, and cardiac index, were collected before and during tilt testing for 411 patients.
- Blood volume status was analyzed in relation to patient characteristics and tilt test results.
Main Results:
- Blood volume abnormalities were prevalent, with 44.7% of patients showing volume depletion and 11.7% showing volume expansion.
- Hematocrit levels did not reliably predict volume status.
- Hemodynamic parameters (blood pressure, heart rate, cardiac index) before and during tilt testing did not correlate with blood volume and could not predict volume status.
Conclusions:
- Syncope patients exhibit significant heterogeneity in blood volume, with common derangements often undetected by tilt table testing.
- Empirical pharmacological treatments for syncope are frequently misaligned with the patient's actual volume status.
- Incorporating blood volume measurement into the diagnostic workup for syncope is recommended for improved diagnostic accuracy and therapeutic guidance.
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