Bioimpedance and Arterial Distension

Study Overview
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Brief Summary
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The overall objectives were to investigate if characteristic dimensions for tissue and vessels determined from measured bioimpedance spectra would provide the same values as dimensions determined from MR images of the upper arm and verify that temporal variations of impedances could be converted to blood pressure.

Detailed Description
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It is emphasized that measurements of pulse wave velocity was not a part of this trial, which implies that only uncalibrated blood pressures could be measured. The specific objectives were: To determine conductivities and permittivities in the spectral region from 1 KHz to 1 MHz for persons with: (a) a normal distribution of fat and muscles, (b) exceptionally thick layers of subcutaneous fat, and (c) exceptionally thin layers of subcutaneous fat. Both sexes should be represented. To verify that temporal variations synchronous with the heartbeat could be measured on all three groups. Hypotheses: A. That experimentally in vivo determined electrical parameters for tissues would differ considerably from theoretical values and from values measured in vitro experiments. B. That the variations of the electrical parameters would exhibit little variation from person to person. C. Those simple experimental relations can be established for the electrical parameters by including a simple vascularization model. D. That it is possible to measure temporal variation of the impedance, which are synchronous with the heartbeat. E. That the measured values would facilitate the calculation of the differential blood pressure with accuracies better than 10 mmHg.

Official Title
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Bioimpedance of Human Tissue of the Upper Arm and Arterial Distension

Conditions
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Hypertension

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18 - 80 years Mental ability to understand information to test subjects Exclusion Criteria: Serious illness Allergic reactions to ECG or EMG electrodes Mentally unstable or unable to perceive instructions Metal implants Claustrophobia Disqualified for MR scanning Pregnant

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Bioimpedance<br>8 females and 8 males BMI from 19 to 46 SBP from 119 to 182 | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Conductivities and permittivities in the spectral region from 1 KHz to 1 MHz. | Measured on persons with: (a) a normal distribution of fat and muscles, (b) exceptionally thick layers of subcutaneous fat, and (c) exceptionally thin layers of subcutaneous fat. Both sexes should be represented. Muscles and vessels followed expectations based on litterature values for electrical properties. Subcutaneous fat had a higher conductivity and permittivity than predicted from literature values in all cases. | 1 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Temporal variations synchronous with the heartbeat | The temporal variations of impedances measured on persons with: (a) a normal distribution of fat and muscles, (b) exceptionally thick layers of subcutaneous fat, and (c) exceptionally thin layers of subcutaneous fat. Both sexes should be represented. Temporal variations could be measured on all three groups. | 1 hour | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Impedance, Electrical, Tissue, Excitation frequency, arterial distension, distension wave form