Journal of Applied Physiology, Vol 67, Issue 6 2331-2334, Copyright © 1989 by American Physiological Society
Extracorporeal bicarbonate space after bicarbonate or a bicarbonate-carbonate mixture in acidotic dogs
N. B. Kindig, D. S. Sherrill, J. I. Shapiro and G. F. Filley
Department of Electrical Engineering, University of Colorado, Denver.
The effects of sodium bicarbonate and a bicarbonate-carbonate mixture on
expired CO2 and the volume of distribution of bicarbonate were studied in
eight anesthetized, paralyzed, and ventilated dogs made acidotic with HCl
(5 mmol/kg) infused over 90 min. Both sodium bicarbonate and Carbicarb
resulted in systemic alkalinization and comparable increases in the serum
bicarbonate at 50 min (7.07 +/- 0.91 vs. 7.99 +/- 0.77, respectively; P =
NS). Sodium bicarbonate infusion resulted in an increase in CO2 excretion
that accounted for a fractional CO2 excretion of 0.20 +/- 0.09, whereas
infusion of a bicarbonate-carbonate mixture resulted in a fractional CO2
excretion of -0.06 +/- 0.09 (P less than 0.01). The uncorrected volume of
distribution of bicarbonate after sodium bicarbonate infusion was higher
than that seen with the bicarbonate-carbonate mixture (0.60 +/- 0.07 vs.
0.34 +/- 0.03 l/kg; P less than 0.01). However, when the volume of
bicarbonate distribution was corrected for expired CO2, there was no
difference between treatment with sodium bicarbonate and the
bicarbonate-carbonate mixture (0.44 +/- 0.07 vs. 0.38 +/- 0.04 l/kg; P =
NS). These data demonstrate that, in this animal model of acidosis, sodium
bicarbonate treatment of systemic acidosis is accompanied by a generation
of a considerable amount of CO2, whereas treatment with a
bicarbonate-carbonate mixture is not. This suggests that in states of
impaired ventilation, a bicarbonate-carbonate mixture may offer more
efficient systemic alkalinization and may be associated with less CO2
generation than sodium bicarbonate.
