Biomedical subjects
G P Naylor
Publications and source records attributed to G P Naylor.
The hydraulic impedance of the lower limb: its relevance to the success of bypass operations for occlusion of the superficial femoral artery.
Simultaneous measurements of pressure and flow waves were made in the course of 25 femoropopliteal bypass operations. From these measurements the the hydraulic impedance of the arterial system in the lower limb was calculated. The values obtained were correlated with the results of the operations. Although reconstruction reduced the impedance we were unable to predict accurately the probable result of the operation on the basis of these measurements. The results suggest that success is more closely related to a good collateral circulation than to "run off".
Impedance plethysmography: evaluation of a simplified system of electrodes for the measurement of blood flow in the lower limb.
Venous occlusion plethysmography was used to measure the flow of blood into the lower limbs of 30 normal volunteers. An impedance plethysmograph, using disposable point electrodes, was compared with a mercury in Silastic strain gauge plethysmograph in 20 subjects. The effect of changes in the configuration of the point electrodes was studied in 10 subjects. Impedance plethysmography was shown to be reproducible, and one particular configuration of point electrodes was shown to be superior to the others.
Pulsatile changes of electrical impedance in the lower limb.
The ratio of the pulsatile and the mean value of the volume of blood flowing through the calves of normal subjects with each heart beat was calculated from electrical impedance changes during venous occlusion plethysmography. Measurements made concurrently by proven Doppler ultrasound techniques did not correlate with ratios derived from the impedance measurements. The pulsatile change in electrical impedance in the limbs appears to be due more to changes of resistance in the blood than to pulsatile changes in the volume of the limb.
Measurement of blood viscosity using a conicylindrical viscometer.
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Comparison of impedance and strain gauge plethysmography in the measurement of blood flow in the lower limb.
Simultaneous measurement of the flow of blood in the calf in 24 normal volunteers by impedance and mercury strain gauge plethysmography has revealed a systematic difference in the results from the two methods. Possible reasons for this discrepancy are discussed.
Digital measurement system for radiation dose distribution.
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Proceedings: Femoropopliteal vein bypass: a new approach to assessing "run-off".
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