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Biomedical subjects

K Barbey

Publications and source records attributed to K Barbey.

At least 19 recordsLinked to original sources
PubMed1984

[Error magnitude of measurement sensors in air segment plethysmography].

Besides examining the properties of the material involved, this investigation assesses the so-called static and dynamic measurement errors of sensors used for air segment plethysmography. The static error which has been found with the new BN sensors amounts to 8% (old models: 31%-44%). The folding of the interior membrane of the sensor resting upon the skin, which increases proportionately to the stiffness of the material, is discussed as a source of error. If a lockable steel wrapping is employed as an exterior cover for the sensors, the static measurement error decreases by 30%-50%. These results suggest a recommendation to use a metal wrapping for the sensors as described above even with routine air segment plethysmographic examinations, and additionally to correct by mathematical means the static measurement error (which has to be determined for each sensor individually). The measurement error of the sensors of the new BN series amounts to less than 5% for a frequency of not more than 0.5 Hz; this means that blood flow values amounting to more than 50 ml/(min X 100 ml) are indicated correctly with respect to the actual frequency. If the usual linen covering is used instead of the steel cover, the linearity of the frequency is only valid up to 0.1 Hz--the corresponding blood flow value being 15 ml/(min X 100 ml).

Diagnosis, Differential↗
PubMed1984

[Evaluation of air segment plethysmography using computer tomography].

The measurement of tissue volume in the calf area carried out by computer-tomography and planimetry showed a nearly elliptic form, an average bony part of 9.9 ml (9.3%), and an average tissue volume of 97.7 ml (90.7%). When compared with the tissue volume approximation (cylinder formula) the tissue volumes thus specified were too large. The error, depending on the circumference of the calf, was about 5 to 15%. There was a difference of 5% between the venous capacity measured by computer-tomography on the one hand and air segment plethysmography on the other. The reason for this is found in the varying density of veins in the examined area. The application of the sensor on the skin caused an average reduction of 5.4% in total volume and thus in the blood volume of about 59% in the examined area. The pressure-dependent venous capacity was measured with and without application of the sensors on the skin and controlled by computer-tomography. The results showed an average difference of only 2.1%. Thus it is obviously unimportant for the results of the investigation presented, if the venous capacity is measured on the basis of the reduced total volume caused by the application of the sensors on the skin. With regard to the computer-tomographical and planimetrical control and the error of measurement discussed, the results suggest a sufficient precision of the venoextensiometry measuring the pressure-dependent venous capacity.

Blood Volume↗
PubMed1976

[Pressure-depending venous capacity in relation to age and sex in an average population group].

Pneumatic segment-plethysmography (Barbey et al.) was used to investigate the pressure-dependent venous capacity of the lower extremities on 443 test persons (a cross-section taken from the population aged between 15 and 64 years). The middle pressure-volume diagrams of men and women with no apparent blood-vessel disorders, of men and women with varicous-veins disorders and of men and women with obvious postural circulatory instability were compared. From 308 men with no blood-vessel disorders normal values were established for men in five age groups. There is a significant correlation between pressure-dependent venous capacity and age, applying to both men and women. In relation to healthy men healthy women have a significantly lower pressure-dependent venous capacity.

Adolescent↗
PubMed1975

[Methodical aspects of pneumatic segment plethysmography. I. The problem of posture and distal venous occlusion].

Pneumatic segment-plethysmography was used to investigate the influence of the position and of distal venous occlusion on the arterial inflow to the calf and on the pressure-dependent venous capacity. It was demonstrated that (1) two of three investiaged positions have no significant influence on the arterial inflow to the calf; (2) the pressure-dependent venous capacities, however, show statistically significant differences related to position of the leg. The following reasons for these results were discussed: the varying tension of the surrounding tissue of the vessels, the basic volumes and the relation of intravenous pressure and the flexibility of the vessels. (3) It could be shown that the arterial inflow at rest measured without distal venous occlusion is significantly higher than the flow measured with distal venous occlusion. (4) On the contrary distal venous occlusion is of no importance in reactive hyperemia after 3 minutes of arterial obstruction. The arterial inflow to the following distal tissue was assumed to be the reason of these findings.

Blood Pressure↗
PubMed1975

[Methodical aspects of pneumatic segment plethysmography. II. The problem of cuff width and cuff-pressure].

Pneumatic segment-plethysmography was used to investiage the influence of different cuff-widths and cuff-pressures on arterial inflow to the calf. It was demonstrated that 1. using consistently 80 Torr for the small respectively 50 Torr for the wide cuff no significant difference for small suprapatellar thigh-circumferences was found. On the contrary for large suprapatellar thigh-circumferences there was a statistically significant difference of the arterial inflow; 2. using both cuffs for all thigh-circumferences, a confirmity of arterial inflow was found if a coupling-factor was individually calculated in each case from upper arm- and thigh-pressure; 3. the arterial inflow to the calf did not differ at pressures of 42 Torr and 50 Torr, whereas at 70 Torr arterial inflow was significantly diminished.

Adolescent↗