Journal of Applied Physiology, Vol 66, Issue 3 1264-1267, Copyright © 1989 by American Physiological Society
Ethane production rates and minute ventilation
M. P. Habib and M. A. Katz
Benjamin W. Zweifach Microcirculation Laboratories, Tucson Veterans Administration Medical Center, Arizona.
Ethane quantitated in the expired alveolar gas is a noninvasive measure of
free radical activity. This method has been criticized for lack of control
of minute ventilation (VE) in spontaneously breathing animals, although
ethane, which is poorly soluble in tissues, should not be affected by
changes in VE. We measured ethane elimination rates in six strain 13 guinea
pigs (GP13) during spontaneous room air breathing and in six room air
breathing, pentobarbital-anesthetized, tracheostomized, externally warmed,
mechanically ventilated GP13s at various levels of VE. In the ventilated
animals, weight0.75/VE (metabolic activity corrected for VE) was a linear
function of arterial CO2 tension (PaCO2) drawn from arterial line (r =
0.72, P less than 0.005). However, weight0.75/VE did not correlate with
ethane elimination rates (r = 0.12, not significant). The mean (+/- SD)
ethane elimination rates in the spontaneously breathing animals was 3.15
+/- 0.96 pmol.min-1.100 g-1 and was not significantly different from the
mean rate in the mechanically ventilated animals (3.11 +/- 1.37) over a
range of VE's. These data demonstrate that ethane elimination rates are not
affected by changes in VE and are unaffected by pentobarbital anesthesia.
