Journal of Applied Physiology, Vol 65, Issue 1 156-164, Copyright © 1988 by American Physiological Society
Effects of emboli, positive-pressure ventilation, and airway water on lung water measurements
W. H. Noble and J. C. Kay
Department of Anaesthesia, St. Michael's Hospital, Ontario, Canada.
We tested the effects of microemboli, continuous positive-pressure
ventilation (CPPV), and aspirated airway water on measurements of
extravascular lung water by use of the technique of thermal indicator
dilution (ETVL). A control group of dogs and a group of dogs in which
dextran was infused created all levels of pulmonary edema. In an emboli
group 0.125 g/kg of starch microemboli (63-74 micron diam) were infused. In
groups with emboli and CPPV, starch emboli were infused and CPPV was then
applied at 15 cmH2O. In an airway saline group measured amounts of saline
were poured into the airway. In all groups postmortem pulmonary
extravascular tissue weight (PETW) was determined and compared with the
last ETVL. Emboli created an increased scatter when the last ETVL is
compared with PETW because 1) blood trapped distal to emboli was included
in the ETVL measurement, and/or 2) diffusion limitations for the thermal
indicator were exceeded. Emboli and CPPV decreased ETVL/PETW. Airway saline
(80 +/- 5%) was measured by ETVL. In conclusion, the ETVL technique is
reliable in well-perfused lungs but loses accuracy in measuring lung water
after emboli of any size or with large amounts of airway fluid.
