Respiration
Physiology
(1975) 23, 4147;
North-Holland Publishing Company, Amsterdam
CARBON MONOXIDE ELIMINATION’
JEAMES A. WAGNER,
STEVEN M. HORVATH
and THOMAS
E. DAHMS
Institute of Environmental Stress, University of California, Santa Barbara, Santa Barbara, California 93106, U.S.A.
Abstract.
The elimination
were determined hemoglobin
(COHb)
monoxide,
the decline
level could blood
of carbon
acute
induced
according
which
and high (2@43°/0) COHb
5 and
%COHb distribution
was linear
to the initial
in anesthetized,
of varying
between
blood
as an initial
curve
monoxide
inhalation
ranged
in arterial
be described
by an elimination from
rates
following
amounts
43%. Following
was biphasic. curve
which
levels eliminated
are
50% of their
equations
total
load
dogs2
of carbon
in the blood
was exponential
presented.
breathing
levels of carboxy-
the administration
The decline
for 90 min. Prediction
levels of COHb
spontaneously
of this gas. Blood
in nature,
“/;COHb followed
for elimination
Animals in 19Ok6.4
having and
of CO
low (5-167,) 134k 5.3 min,
respectively. Arterial
blood
Blood gas
Carboxyhemoglobin Dog
Description and documentation of the rates of uptake, degradation and elimination of air pollutants by living organisms are basic both to the treatment or prevention of their pathological effects and to the development of health and safety tolerance limits of exposure to air pollutants. Since much of the research on carbon monoxide intoxication has been done using experimental animals, the following report describes the elimination of carbon monoxide from anesthetized, spontaneously breathing dogs which were being used to study the effects of carbon monoxide on the cardiovascular system. Accepted for publication I7 September 1974.
’ This research # SA Chpt
was supported
1599/1970
2 In conducting
in part
by the California
State
Air Resources
Board
under
Grant
ARB-2096.
this
research,
Facilities and Care” as promulgated of the Institute of Animal Laboratory
the investigators
adhered to the “Guide for Laboratory Animal by the Committee for Laboratory Animal Facilities and Care, Resources, National Academy of Sciences - National Research
Council.
c411
42
J. A. WAGNER,
S. M. HORVATH
AND T. E. DAHMS
Methods Nineteen male mongrel dogs, weighing between ,20 and 38 kg, were anesthetized by intravenous administration of pentobarbital sodium (25 mg/kg). Studies were made on two occasions separated by 334 weeks. In some instances these were duplicate studies and in others different COHb levels were produced. A cuffed endotracheal tube was inserted to ensure a patent airway and to enable the measurement of minute ventilation. Catheters were positioned by fluoroscopic guidance into the right and left ventricles. Cardiac output was determined by the dye dilution method using indocyanin green’. Throughout each experiment minute ventilation was’measured using a Parkinson-Cowen dry gasometer (Adams et al., 1967) and a low resistance valve. Rectal temperature was measured with an indwelling thermistor. Mean carboxyhemoglobin levels of 6, 10, 14, 23 and 36?,0 were produced in separate groups of dogs by giving them mixtures of l-6”;, carbon monoxide (CO) in air to breathe for 3 minutes. Blood samples, minute ventilation and cardiac outputs were obtained from each dog prior to and 7. 24, 40, 55, 70 and 85 minutes after CO administration. In several experiments additional blood samples were taken immediately following CO administration and 1, 2, 3, 5, 14 and 20 minutes after CO administration. During the course of 38 experiments more than 300 blood samples were analyzed for hemoglobin by the cyanomethemoglobin method and carbon monoxide content by the method of Dahms and Horvath (1974) which was periodically checked by Van Slyke analysis (Horvath and Roughton, 1942). Carboxyhemoglobin (COHb) levels in the blood were expressed as a percentage of the oxygen carrying capacity of hemoglobin (‘-,gCOHb). Correlation and regression techniques were used in the statistical analysis of the data.
-;
.
' -10 CcI 10 20 ;;w+;s Fig. 1. Changes of 1406 carbon
in arterial monoxide
blood percent for 3 minutes.
0.20, 0.18, 0.10, 0.15 and 0.16, respectively,
Cardiogreen,
kindly
supplied
by Hynson.
SO
60
70
80
90
carboxyhemoglobin (“,,COHb) vs. time following inhalation The coefficients of variation (S.D.F) for mean values were for groups levels. Westcott
with the lowest
and Dunning,
through
Inc.. Baltimore.
the highest
%COHb
CARBON
MONOXIDE
ELIMINATION
43
Results
Figure 1 presents the arterial blood jl