AJP - Heart and Circulatory Physiology, Vol 236, Issue 3 508-H512, Copyright © 1979 by American Physiological Society
Effect of implant duration on in vivo sensitivity of electromagnetic flow transducers
C. A. Astley, A. R. Hohimer, R. B. Stephenson, O. A. Smith and F. A. Spelman
Twenty-three electromagnetic flow transducers with lumen diameters of
3.5-6.0 mm were implanted in rhesus monkeys and baboonss for 12 h to 120
days. Each flow transducer was calibrated 1) in vitro on dialysis tubing
with saline before implantation, 2) in vivo the last day of the implant
period, and 3) again in vitro after the flow transducer was recovered.
Three other flow transducers were implanted on femoral arteries of baboon
just central to an arteriovenous Silastic shunt, and were calibrated in
vivo daily for 23-47 days. In vitro sensitivity was not affected by implant
durations of up to 120 days. In vivo sensitivity fluctuated unpredictably
for the first 3-4 wk of implant, after which it followed a systematic
course that depended on the lumen size. In vivo sensitivity at any time
during implant (after the initial period) could be accurately predicted by
knowing either the in vitro sensitivity or the terminal in vivo
sensitivity.
