Journal of Applied Physiology, Vol 51, Issue 2 524-528, Copyright © 1981 by American Physiological Society
A method of producing calibrated microtubules for air embolism studies
B. A. Hills and B. D. Butler
Utilizing the differential absorption techniques in conjunction with gas
injection methods has enabled the production of calibrated microtubules
with diameters ranging from 14 to 300 micron. Nitrogen was blended with
CO2, the "diluent" gas, to produce the initial bubbles, while
tris(hydroxymethyl)-aminomethane hydrochloride (THAM) was used as an
absorbent to remove the diluent gas from the bubbles. Hence, the diameters
of the initial bubbles were significantly reduced with only the inert gas
remaining. The Coulter counter was used for immediate size monitoring of
the microtubules. To verify the inertness of the absorbent medium, nine
anesthetized dogs were infused with increasing amounts of the solution. In
five of the animals plasma surface tension and pH (arterial) were measured,
while in the remaining four arterial blood pressure, heart rate, breathing
frequency, and pulmonary artery pressure was measured before, during, and
after the injections. Changes in plasma surface tension and pH were minimal
while acceptable physiological values were recorded, all of which were in
agreement with previous investigations. Differential absorption techniques
provided a reliable means for producing calibrated micro-bubbles for air
embolism studies.
