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Comparison of right atrial and pulmonary arterial pO2, pCO2, and pH in Gallus domesticus
Camp. Biochem. Physioi.. 1977, Vol.
%A,pp. 169 to
171. Pergamon Press. Printed
in Great Britain
COMPARISON OF RIGHT ATRIAL AND PULMONARY ARTERIAL pOz, pCOz, AND pH IN GALLUS DOMESTICUS THOMASE. NIGHTINGALEAND JOHN C. RICHARDI USDA Poultry Research Laboratory, RD 2, Box 600, Georgetown, DE 19947. U.S.A. (Received
4 May 1976)
Abstract-l.
Paired right atria1 and pulmonary arterial blood samples were examined to determine whether right atria1 p02, pCOz, and pH values could be used as an index of “mixed venous” values in the chicken. 2. Right atria1 blood pC0, was higher than pulmonary arterial blood pCOz by 2-3 mm Hg over the range of 30-50mm Hg whereas right atria1 blood pH was lower than pulmonary arterial blood
pH by 0.05WI.08 units. 3. pOz values over the range of 4&50 mm Hg were identical for the two sampling sites and differed by 7% or less over the range of 25-70 mm Hg. 4. Correction of right atria1 blood pC02 and pH by use of the derived regression equations should enable these values to be in agreement with “mixed venous” values whereas no correction should be necessary for ~0,‘s within the usual physiological range.
INTRODUCTION
through the lungs, and out to the atmosphere through the opened air sacs. The unidirectional ventilation procedure has been described by Fedde et al. (1969). A constant gas flow rate of 4 L/min was used. Concentrations of air, oxygen, nitrogen, and carbon dioxide in the ventilating gas stream were varied to produce arterial and, consequently, venous blood gas tensions over the range of 22-79 mm Hg for ~0, and 7.5-88.0 mm Hn for SO,. Paired l-ml blood samples w&e taken rom cannulae placed in the right atrium by way of a cannulated cutaneous ulnar vein and from a 20-gage needle and PE 90 catheter in the pulmonary artery. Clotting was prevented by frequent flushing with heparinized saline solution. Blood gas and pH were analyzed immediately on an Instrumentation Laboratories blood gas system (Model
Obtaining thoroughly mixed blood samples in mammals requires that the samples taken from the pulmonary artery. Venous blood gas tensions from individual organs or vascular beds are the product of local blood flow and respiratory quotients, so that the resulting mixed venous blood in man may differ from particular venous sampling sites by as much as 20 mm Hg for both p0, and pC0, (Rahn & Fenn, 1955). A comparable pO1 difference has been reported between jugular and brachial venous blood in the domestic chicken (Besch et al., 1971). Similarity of these mammalian and avian results would appear to indicate the need to sample a well-mixed venous blood site in the avian species rather than obtaining venous blood from a wing vein as is the common practice (Jukes, 1971). Obtaining pulmonary arterial blood is not always possible in avian studies because of either technical difficulties (Bredeck, 1960) or the need to avoid interfering with other measurements (Nightingale, 1977); thus many workers use right atria1 blood as an index of mixed venous blood (Besch et al., 1971; Jones & Holeton, 1972; Nightingale & Fedde, 1972). The present study was designed to compare blood gas tensions in right atria1 and pulmonary arterial blood of chickens and to determine whether right atria1 blood gas tensions could be considered to be accurate mixed venous samples.
60 -
MATERIALS AND METHODS
RIOHT ATRIAL
01’.
Eight adult male White Leghorn chickens weighing 1.7-2.7 kg were anesthetized with Equithesin (Jensen-Salsbury Labs.) at 2.5 ml/kg, given I.M. at 3 sites in both pectoral muscles. Each bird was secured in dorsal recumbency, its trachea cannulated mid-cervically, and its thoratic cavity opened to expose the heart and lungs. The thoratic and abdominal air sacs were incised and a warmed, humidified gas was passed into the tracheal cannula,
0
’
20
’
40
pCOe
60
(mm Hg)
80
t-
Fig. 1. Relationship between paired pulmonary artery and right ‘atria1 chicken blood pC0, values. r = correlation + SE. coefficient; X-Y = mean difference values ( ) = probability of mean difference. Dashed line % the line of unity (slope = 1); solid line is the calculated regression line. 169
170
THOMAS E. NIGHTINGALE AND JOHN C. RICHARDI Table
Y= 0.271*0.972X
zoo zoo
’
RIGHTATRIAL pH
I 220
Fig. 2. Relationship right atria1 chicken
’
I b40
’
I 160
’
I z80
artery
pOZ - right
pOz/pulmonary
artery
atria1 p02
x 100.
Statistical significance at the 5% level or better determined by the t test for unpaired or paired data. RESULTS Comparison
was
DISCUSSION
pulmonary artery and values is shown in Fig. 1. Over
of 142 paired
right atria1 pC0,
rP
AND
Y=-4.94+1.123X r=0.937 x-5 -0.66f0.35mm
RlWf
Hg (ns)
No. of samples
2G24.9 25529.9 3G34.9 35539.9 4W44.9 4549.9 50-54.9 55-59.9 6G64.9 6569.9 7G74.9 75-79.9
3 8 10 22 21 30 16 21 6 4 0 2
Absolute difference* (mm Hg)
and
7; Difference
P value
0.47 0.64 1.22 0.63 0.72 0.54 0.71 0.83 0.84 3.04
-10 -3 -6 -1 -1 >-1 6 I 6 6 -
0.05 nst
9.3 + 1.10
12
-2.3 -0.9 -2.1 -2.5 -0.43 -0.02 3.36 3.83 3.93 4.08
+ + + + k * & + t_ 5
O.% ns 0% 0.001 0.01 ns
* Mean k SE. i ns = not significant.
between paired pulmonary artery and blood pH values. Statistical abbreviations as in Fig. 1.
= pulmonary
Pulmonary artery pOZ (mm Hg)
artery
Wts)
127) at 4o’C; Corning Model 160 digital meter was used for readout. Blood removed for analysis was returned to the bird after determinations were completed. Body temperature of the birds was monitored by a rectal thermistor and maintained at 40 f 1°C by a heating pad and i.r. lamp. Data were analyzed by linear regression of right atria1 data on pulmonary artery data and by difference analysis of each data pair. Percentage error for each right atria1 pOZ value was calculated as: % Error
1. Difference between paired pulmonary right atria1 pOZ values
’
ATRIAL POE (mm&l)
Fig. 3. Relationship between paired pulmonary artery and right atria1 chicken blood pO1 values. Statistical abbreviations as in Fig. 1. (ns) = not significant.
the range of 7.5-88.0 mm Hg, the relationship was linear, with a slope of 0.964, which was not significantly different from the line of unity (slope of 1). The average difference between the two sampling sites was 2.77 k 0.33 mm Hg; the right atria1 values were higher (P < 0.001). Regression analysis of pH data from the two sampling sites is shown in Fig. 2. The pulmonary artery pH was greater than the right atrial pH by an average of 0.062 & 0.005 units (P < O.OOl),with a regression equation of Y = 0.0271 + 0.972X. The slope was not significantly different from unity. Over the range of 22-79 mm Hg, pulmonary arterial and right atria1 pOz values differed by only 0.66 f 0.35 mm Hg, on the average; a regression equation of Y = 4.94 + 1.123X defined the relationship (Fig. 3). Because the slope of the regression line was significantly different from unity, and the mean difference between pulmonary arterial and right atria1 ~0~‘s was not significant, the difference between each paired data set was calculated, to determine the point beyond which the percentage error became excessive. As noted in Table 1, within pulmonary arterial values of 40 to 50 mm Hg, pulmonary artery and right atria1 ~0~‘s were within 1% of each other, and over the range of 25-70 mm Hg, the difference between the sampling sites was +7% or less. The results indicate that use of right atria1 pC02 would overestimate mixed venous pCOz by 3 to 2 mm Hg over the range of 30-50 mm Hg, whereas the use of pH values of right atria1 blood would underestimate mixed venous blood pH by 0.0550.08 units over the range of 7.4-7.6. Because both of these parameters were linearly and consistently different, application of a correction factor should present no problem within the usual physiological range that has been reported by others for avian studies (Piiper et al., 1970; Besch et al., 1971; Jones & Holeton, 1972). The nonsignificant difference in sample means for ~0,‘s between the two sites indicates that over the range studied, there was not a systematic difference. Within the range of 4G50 mm Hg, the values were identical, and within the range of 25-70 mm Hg, the maximum difference was 7%, which is considerably
Venous blood gases in chickens less than the difference between jugular and brachial venous blood pOz of 19 mm Hg reported by Besch et al. (1971) for chickens, or the 30 mm Hg difference between femoral and internal jugular venous blood p02 reported by Ernsting (1963) for humans. Right atria1 blood pC02 and pH values can be corrected to coincide with mixed venous blood values by use of the regression equations reported herein. Use of right atria1 blood p02 values in studies of birds should present no significant deviations from “true” mixed venous values within the normal physiological range.
REFERENCES
BESCHE. L., BURTONR. R. & SMITH A. H. (1971) Influence of chronic hypoxia on blood gas tensions and pH in domestic fowl. Am. J. Physiol. 220, 1379-1382. BREDECKH. E. (1960) Intraventricular blood pressures in the chicken. Am. J. Physiol. 198, 153154. ERNSTINCJ. (1963) The effect of brief profound hypoxia
171
upon the arterial and venous oxygen tensions in man. J. Physiol., Lond. 169, 292-311. FEDDE M. R., DE WET P. D. & KITCHELLR. L. (1969) Motor unit recruitment pattern and tonic activity in respiratory muscles of Gallus domesticus. J. Neurophysiol. 32, 995-1004. JONESD. R. & HOLETONG. F. (1972) Cardiovascular and respiratory responses of ducks to progressive hypocapnic hypoxia. J. exp. Biol. 56, 657-666. JUKESM. G. M. (1971) Transport of blood gases. In Physiology and Biochemistry of the Domestic Fowl (Edited by BELLD. J. & FREEMANB. M.) Vol. 1, pp. 187-196. Academic Press, New York. NIGHTINGALET. E. (1977) Acute isovolemic anemia in anesthetized chickens. Am. J. Physiol. (In press). NIGHTINGALE T. E. & FEDDEM. R. (1972) Determination of normal buffer line for chicken blood. Respir. Physiol. 14, 353-365. PIIPER J., DREESF., & SCHEID P. (1970) Gas exchange in the domestic fowl during spontaneous breathing and artificial ventilation. Respir. Physiol. 9, 234-245. RAHN H. & FENN W. 0. (1955) A Graphical Analysis of the Respiratory Gas Exchange. pp. 15-16. American Physiological Society, Washington, D.C.
%A,pp. 169 to
171. Pergamon Press. Printed
in Great Britain
COMPARISON OF RIGHT ATRIAL AND PULMONARY ARTERIAL pOz, pCOz, AND pH IN GALLUS DOMESTICUS THOMASE. NIGHTINGALEAND JOHN C. RICHARDI USDA Poultry Research Laboratory, RD 2, Box 600, Georgetown, DE 19947. U.S.A. (Received
4 May 1976)
Abstract-l.
Paired right atria1 and pulmonary arterial blood samples were examined to determine whether right atria1 p02, pCOz, and pH values could be used as an index of “mixed venous” values in the chicken. 2. Right atria1 blood pC0, was higher than pulmonary arterial blood pCOz by 2-3 mm Hg over the range of 30-50mm Hg whereas right atria1 blood pH was lower than pulmonary arterial blood
pH by 0.05WI.08 units. 3. pOz values over the range of 4&50 mm Hg were identical for the two sampling sites and differed by 7% or less over the range of 25-70 mm Hg. 4. Correction of right atria1 blood pC02 and pH by use of the derived regression equations should enable these values to be in agreement with “mixed venous” values whereas no correction should be necessary for ~0,‘s within the usual physiological range.
INTRODUCTION
through the lungs, and out to the atmosphere through the opened air sacs. The unidirectional ventilation procedure has been described by Fedde et al. (1969). A constant gas flow rate of 4 L/min was used. Concentrations of air, oxygen, nitrogen, and carbon dioxide in the ventilating gas stream were varied to produce arterial and, consequently, venous blood gas tensions over the range of 22-79 mm Hg for ~0, and 7.5-88.0 mm Hn for SO,. Paired l-ml blood samples w&e taken rom cannulae placed in the right atrium by way of a cannulated cutaneous ulnar vein and from a 20-gage needle and PE 90 catheter in the pulmonary artery. Clotting was prevented by frequent flushing with heparinized saline solution. Blood gas and pH were analyzed immediately on an Instrumentation Laboratories blood gas system (Model
Obtaining thoroughly mixed blood samples in mammals requires that the samples taken from the pulmonary artery. Venous blood gas tensions from individual organs or vascular beds are the product of local blood flow and respiratory quotients, so that the resulting mixed venous blood in man may differ from particular venous sampling sites by as much as 20 mm Hg for both p0, and pC0, (Rahn & Fenn, 1955). A comparable pO1 difference has been reported between jugular and brachial venous blood in the domestic chicken (Besch et al., 1971). Similarity of these mammalian and avian results would appear to indicate the need to sample a well-mixed venous blood site in the avian species rather than obtaining venous blood from a wing vein as is the common practice (Jukes, 1971). Obtaining pulmonary arterial blood is not always possible in avian studies because of either technical difficulties (Bredeck, 1960) or the need to avoid interfering with other measurements (Nightingale, 1977); thus many workers use right atria1 blood as an index of mixed venous blood (Besch et al., 1971; Jones & Holeton, 1972; Nightingale & Fedde, 1972). The present study was designed to compare blood gas tensions in right atria1 and pulmonary arterial blood of chickens and to determine whether right atria1 blood gas tensions could be considered to be accurate mixed venous samples.
60 -
MATERIALS AND METHODS
RIOHT ATRIAL
01’.
Eight adult male White Leghorn chickens weighing 1.7-2.7 kg were anesthetized with Equithesin (Jensen-Salsbury Labs.) at 2.5 ml/kg, given I.M. at 3 sites in both pectoral muscles. Each bird was secured in dorsal recumbency, its trachea cannulated mid-cervically, and its thoratic cavity opened to expose the heart and lungs. The thoratic and abdominal air sacs were incised and a warmed, humidified gas was passed into the tracheal cannula,
0
’
20
’
40
pCOe
60
(mm Hg)
80
t-
Fig. 1. Relationship between paired pulmonary artery and right ‘atria1 chicken blood pC0, values. r = correlation + SE. coefficient; X-Y = mean difference values ( ) = probability of mean difference. Dashed line % the line of unity (slope = 1); solid line is the calculated regression line. 169
170
THOMAS E. NIGHTINGALE AND JOHN C. RICHARDI Table
Y= 0.271*0.972X
zoo zoo
’
RIGHTATRIAL pH
I 220
Fig. 2. Relationship right atria1 chicken
’
I b40
’
I 160
’
I z80
artery
pOZ - right
pOz/pulmonary
artery
atria1 p02
x 100.
Statistical significance at the 5% level or better determined by the t test for unpaired or paired data. RESULTS Comparison
was
DISCUSSION
pulmonary artery and values is shown in Fig. 1. Over
of 142 paired
right atria1 pC0,
rP
AND
Y=-4.94+1.123X r=0.937 x-5 -0.66f0.35mm
RlWf
Hg (ns)
No. of samples
2G24.9 25529.9 3G34.9 35539.9 4W44.9 4549.9 50-54.9 55-59.9 6G64.9 6569.9 7G74.9 75-79.9
3 8 10 22 21 30 16 21 6 4 0 2
Absolute difference* (mm Hg)
and
7; Difference
P value
0.47 0.64 1.22 0.63 0.72 0.54 0.71 0.83 0.84 3.04
-10 -3 -6 -1 -1 >-1 6 I 6 6 -
0.05 nst
9.3 + 1.10
12
-2.3 -0.9 -2.1 -2.5 -0.43 -0.02 3.36 3.83 3.93 4.08
+ + + + k * & + t_ 5
O.% ns 0% 0.001 0.01 ns
* Mean k SE. i ns = not significant.
between paired pulmonary artery and blood pH values. Statistical abbreviations as in Fig. 1.
= pulmonary
Pulmonary artery pOZ (mm Hg)
artery
Wts)
127) at 4o’C; Corning Model 160 digital meter was used for readout. Blood removed for analysis was returned to the bird after determinations were completed. Body temperature of the birds was monitored by a rectal thermistor and maintained at 40 f 1°C by a heating pad and i.r. lamp. Data were analyzed by linear regression of right atria1 data on pulmonary artery data and by difference analysis of each data pair. Percentage error for each right atria1 pOZ value was calculated as: % Error
1. Difference between paired pulmonary right atria1 pOZ values
’
ATRIAL POE (mm&l)
Fig. 3. Relationship between paired pulmonary artery and right atria1 chicken blood pO1 values. Statistical abbreviations as in Fig. 1. (ns) = not significant.
the range of 7.5-88.0 mm Hg, the relationship was linear, with a slope of 0.964, which was not significantly different from the line of unity (slope of 1). The average difference between the two sampling sites was 2.77 k 0.33 mm Hg; the right atria1 values were higher (P < 0.001). Regression analysis of pH data from the two sampling sites is shown in Fig. 2. The pulmonary artery pH was greater than the right atrial pH by an average of 0.062 & 0.005 units (P < O.OOl),with a regression equation of Y = 0.0271 + 0.972X. The slope was not significantly different from unity. Over the range of 22-79 mm Hg, pulmonary arterial and right atria1 pOz values differed by only 0.66 f 0.35 mm Hg, on the average; a regression equation of Y = 4.94 + 1.123X defined the relationship (Fig. 3). Because the slope of the regression line was significantly different from unity, and the mean difference between pulmonary arterial and right atria1 ~0~‘s was not significant, the difference between each paired data set was calculated, to determine the point beyond which the percentage error became excessive. As noted in Table 1, within pulmonary arterial values of 40 to 50 mm Hg, pulmonary artery and right atria1 ~0~‘s were within 1% of each other, and over the range of 25-70 mm Hg, the difference between the sampling sites was +7% or less. The results indicate that use of right atria1 pC02 would overestimate mixed venous pCOz by 3 to 2 mm Hg over the range of 30-50 mm Hg, whereas the use of pH values of right atria1 blood would underestimate mixed venous blood pH by 0.0550.08 units over the range of 7.4-7.6. Because both of these parameters were linearly and consistently different, application of a correction factor should present no problem within the usual physiological range that has been reported by others for avian studies (Piiper et al., 1970; Besch et al., 1971; Jones & Holeton, 1972). The nonsignificant difference in sample means for ~0,‘s between the two sites indicates that over the range studied, there was not a systematic difference. Within the range of 4G50 mm Hg, the values were identical, and within the range of 25-70 mm Hg, the maximum difference was 7%, which is considerably
Venous blood gases in chickens less than the difference between jugular and brachial venous blood pOz of 19 mm Hg reported by Besch et al. (1971) for chickens, or the 30 mm Hg difference between femoral and internal jugular venous blood p02 reported by Ernsting (1963) for humans. Right atria1 blood pC02 and pH values can be corrected to coincide with mixed venous blood values by use of the regression equations reported herein. Use of right atria1 blood p02 values in studies of birds should present no significant deviations from “true” mixed venous values within the normal physiological range.
REFERENCES
BESCHE. L., BURTONR. R. & SMITH A. H. (1971) Influence of chronic hypoxia on blood gas tensions and pH in domestic fowl. Am. J. Physiol. 220, 1379-1382. BREDECKH. E. (1960) Intraventricular blood pressures in the chicken. Am. J. Physiol. 198, 153154. ERNSTINCJ. (1963) The effect of brief profound hypoxia
171
upon the arterial and venous oxygen tensions in man. J. Physiol., Lond. 169, 292-311. FEDDE M. R., DE WET P. D. & KITCHELLR. L. (1969) Motor unit recruitment pattern and tonic activity in respiratory muscles of Gallus domesticus. J. Neurophysiol. 32, 995-1004. JONESD. R. & HOLETONG. F. (1972) Cardiovascular and respiratory responses of ducks to progressive hypocapnic hypoxia. J. exp. Biol. 56, 657-666. JUKESM. G. M. (1971) Transport of blood gases. In Physiology and Biochemistry of the Domestic Fowl (Edited by BELLD. J. & FREEMANB. M.) Vol. 1, pp. 187-196. Academic Press, New York. NIGHTINGALET. E. (1977) Acute isovolemic anemia in anesthetized chickens. Am. J. Physiol. (In press). NIGHTINGALE T. E. & FEDDEM. R. (1972) Determination of normal buffer line for chicken blood. Respir. Physiol. 14, 353-365. PIIPER J., DREESF., & SCHEID P. (1970) Gas exchange in the domestic fowl during spontaneous breathing and artificial ventilation. Respir. Physiol. 9, 234-245. RAHN H. & FENN W. 0. (1955) A Graphical Analysis of the Respiratory Gas Exchange. pp. 15-16. American Physiological Society, Washington, D.C.