jurnal

ARTERIAL BLOOD GASES AND ACID-BASE BALANCE INCYANOTIC CONGENITAL HEART DISEASE'BY MINERVA MORSE AND DONALD E. CASSELS 2

(From the Department of Pediatrics, University of Chicago Clinics, Chicago, Illinois)

(Submitted for publication April 16, 1953; accepted May 15, 1953)

The purpose of this report is to present dataconcerning the arterial blood gases and the acid-base balance in patients with cyanosis due to con-genital heart disease. Since the study is relatedto cyanosis and abnormalities of the blood con-sequent to this, no distinction is made betweenthe various anatomical defects producing cyanosis.

Compensatory or adaptive mechanisms in thepresence of cyanosis related to congenital heartdisease have been the subject of a number ofstudies (1-6). The present study was undertakento obtain further information concerning the ar-terial blood gases in this disease, especially in re-lation to age and in respect to the influence ofarterial unsaturation on the acid-base balance.

Sixty cyanotic patients were studied, varying inage from 1 to 36 years. The methods used havebeen described in a preceding report (7).

RESULTS

Because age has been found to affect the concen-trations of the blood gases (7), especially the HbO2capacity, the CO2 content and the alkaline reserve,it was necessary to evaluate the results for an indi-vidual of a given age in terms of deviations from themean values for that age. Normal values for chil-dren of different ages are given in the preceding re-port (7). Table I gives the results of single tests oneach of 60 patients with cyanotic congenital heartdisease, in terms both of absolute values and ofdeviations from the normal. In Figures 1 and 2deviations from the normal are plotted for eachage group against a background which representsthe range of variation found in normal, healthyindividuals of the same age group. Table II givesthe results of repeated tests on seven individuals.It includes cases of pulmonary stenosis in which

I This work was conducted under a grant from theDouglas Smith Foundation at the University of Chicago.2Present address: Bobs Roberts Memorial Hospital,

920 East 59th Street, Chicago, Ill.

pulmonary blood flow was increased by aortic-pulmonary artery anastomosis or pulmonaryvalvulotomy.

Certain differences in distribution with respectto age are evident in the data of Table I andFigures 1 and 2. Arterial oxygen saturation be-low 50 per cent was found only in children of 7years and younger. The fact that all but one ofthe adults had arterial saturations above 79 percent is misleading and an artifact of sampling.Of the adult group only one was believed to havepulmonary stenosis. It should be noted that inthe reports of Talbott et al. (1), Bing, Vandam,and Gray (8), and Suarez, Chiodi, Fasciolo, andTaquini (3), of 33 patients with cyanotic con-genital heart disease who were over 18 years ofage, 15 were found to have arterial saturationsbelow 75 per cent. However, only one of thesepatients had a saturation below 60 per cent. Thegreat majority of patients of our study who hadHbO2 capacities within the normal range wereyounger children. On the other hand, the ma-jority of very high HbO2 capacities, over 32 vol.per cent, were found in older children and adults.One child of 6 years was found to have a HbO2capacity of 32.5 vol. per cent. In regard to thealkaline reserve of the plasma there seems to be nospecial trend with age. The lowest values werefound in children of 7 and 8 years. It may besignificant that in spite of the fairly high arterialoxygen saturations found in the adults of thisstudy, all values for alkaline reserve were belowthe normal range of variation. In the case of thearterial pCO2, about a third of the children of 12years and younger had values above the normalmean, whereas in children above that age and inadults all values but one lay below the normalmean. The great majority of the lower thannormal pH. values were found in children between6 and 10 years.

Since the data of Table I are arranged in theorder of increasing arterial saturation, it can be

837

MINERVA MORSE AND DONALD E. CASSELS

TABLE IOxygen saturation, HbO2 capacity, pkssma CO2 T4o0* pCO2 and pH. of arterial blood of patients with

cyanotic congenital heart diseaseHbO2 capacity

Dev.Arterial Value from

Age Sex saturation found normalyr. per cent Vo. % Vol. %2 F 21.0 14.5 - 2.02 M 21.4 28.6 +12.11 F 21.6 18.0 + 1.56 M 40.5 28.6 + 10.27 M 40.6 31.1 +12.72 M 41.7 25.6 + 9.12 M 46.9 14.0 - 2.54 F 49.8 30.9 +13.2

14 M 52.0 33.8 +15.49 M 58.7 32.8 +14.415 M 59.1 35.1 +16.77 F 61.8 26.6 + 8.26 M 63.2 28.4 +10.036 F 63.4 35.1 +14.614 F 65.4 32.4 + 14.06 M 65.6 32.5 +14.110 F 65.7 25.0 + 6.63 F 68.3 19.7 + 2.04 M 68.6 29.9 +11.55 M 70.4 27.8 + 9.47 M 70.6 27.8 + 9.4

17 M 71.2 26.4 + 6.710 M 72.1 27.3 + 8.913 M 72.2 22.7 + 4.32 M 73.0 16.6 - 0.15 F 73.3 21.0 + 2.6

10 M 74.2 31.2 +12.88 M 74.3 28.1 + 9.72 M 74.9 19.1 + 2.65 F 75.4 22.7 + 4.34 M 76.8 24.6 + 6.910 M 77.0 36.5 +18.16 M 77.4 17.4 - 1.0

24 F 79.0 22.7 + 2.211 M 79.3 25.3 + 6.935 F 79.4 29.1 + 8.625 M 79.7 25.7 + 5.231 M 79.9 22.6t + 2.14 M 80.0 18.2 + 0.58 M 80.7 24.6 + 6.27 F 80.8 23.9 + 5.516 F 81.0 26.2 + 7.019 M 82.4 35.7 +15.28 M 82.8 22.5 + 4.15 F 83.6 23.8 + 5.4

23 F 83.8 25.2 + 4.712 M 84.9 22.5 + 4.19 M 85.9 21.6 + 3.210 F 87.1 20.0 + 1.612 M 88.0 21.6 + 3.231 M 89.0 28.5 + 8.012 F 89.8 17.2 - 1.225 M 89.9 24.4 + 3.916 M 90.1 27.9 + 8.29 F 90.5 18.4 0.09 M 90.8 18.4 0.010 M 91.7 21.1 + 2.74 F 91.7 17.2 - 0.54 M 91.9 18.6 + 0.29 M 92.7 26.1 + 7.7

Plasma C02 Tso*Dev.

Value fromfound normaloi. % Vol. %37.3 -11.137.4 -11.039.6 - 8.835.7 -18.934.6 -20.037.3 -11.142.6 - 5.841.5 -12.043.3 -12.233.6 -21.041.6 -13.945.3 - 9.340.8 -12.745.6 -12.641.2 -14.342.4 -11.150.6 - 4.043.6 - 4.846.4 - 7.149.4 - 4.145.9 - 8.749.5 - 6.349.0 - 5.654.2 - 1.349.1 + 0.745.9 - 7.646.2 - 8.448.9 - 5.743.6 - 4.845.5 - 8.042.5 -11.043.8 -10.849.6 - 3.955.5 - 2.946.1 - 9.448.0 -10.252.2 - 6.050.9 - 7.341.1 -12.448.6 - 6.943.7 -10.945.6 - 9.947.6 -10.649.3 - 5.349.2 - 4.351.5 - 6.747.6 - 7.050.9 - 3.746.6 - 8.155.6 + 1.051.6 - 6.652.7 - 2.854.3 - 3.950.0 - 5.548.7 - 5.952.3 - 2.453.0 - 1.653.0 - 0.547.1 - 6.448.6 + 0.2

Arterial pCO2Dev.

Value fromfound normalmm. mm.41.7 + 4.440.2 + 2.942.1 + 4.837.8 - 0.235.9 - 2.135.0 - 2.325.5 -11.839.3 + 2.040.8 - 0.538.3 + 0.331.6 - 9.737.9 - 0.132.9 - 4.430.2 -10.932.8 - 8.541.6 + 4.339.5 + 1.540.7 - 3.429.4 - 7.934.5 - 2.837.8 - 0.229.7 -11.633.4 - 4.627.5 -13.832.4 - 4.929.4 - 7.938.4 + 0.439.4 + 1.434.7 - 2.637.7 + 0.435.2 - 2.127.7 -10.344.7 + 7.428.5 -12.634.4 - 3.646.8 + 5.734.3 - 6.838.8 - 2.323.5 -13.834.5 - 6.833.1 - 4.934.4 - 6.737.2 - 3.929.5 - 8.534.7 - 2.633.7 - 7.430.0 - 8.035.9 - 2.142.2 + 4.226.5 -11.537.1 - 4.034.0 - 4.037.9 - 3.233.5 - 7.840.2 + 2.245.7 + 7.732.8 - 5.243.7 + 6.439.7 + 2.428.7 - 8.6

Arterial pHsDev.

Value fromfound normal

7.227 -.1227.266 -.0837.257 -.0927.244 - .1557.244 -.1S57.279 -.0707.423 +.0747.297 - .0937.308 -.0737.203 -.2017.348 -.0337.334 -.0657.322 -.0777.399 -.0037.328 -.0537.283 -.1077.369 -.0347.289 -.0607.407 +.0177.392 +.0027.333 -.0667.434 +.0537.398 -.0067.502 +.1217.407 +.0587.401 +.0117.333 - .0717.351 - .0537.330 - .0197.328 - .0627.313 - .0777.391 +.0137.311 -.0927.496 +.0947.355 -.0497.296 - .1067.408 +.0067.367 -.0357.412 +.0227.379 - .0027.340 - .0017.351 - .0307.352 - .0297.429 +.0257.377 - .0227.407 +.0057.407 +.0037.387 -.0177.298 - .1057.519 +.1167.380 - .0227.421 +.0227.399 -.0037.394 +.0137.330 - .0747.323 - .0807.428 +.0257.340 -.0507.317 -.0737.420 +.016

No. Subject

1 S.D.2 R.E.3 P.S.4 R.B.5 J.M.6 J.A.7 H.R.8 J.G.9 M.P.10 J.W.11 S.X.12 V.S.13 W.B.14 M. M.15 L.C.16 C.F.17 J.R.18 V.J.19 N.H.20 A.F.21 B.G.22 L.S.23 J.S.24 B. M.25 C.L.26 P. M.27 S. D.28 R. B.29 R.J.30 P. K.31 R.F.32 R. D.33 R. M.34 L.Z.35 E.V.36 G.H.37 R.G.38 G. N.39 C.L.40 D. R.41 S.L.42 M.C.43 D. B.44 D. M.45 J.T.46 I. B.47 A.G.48 C. K.49 M. M.50 J. M.51 B.Z.52 M. D.53 P.T.54 B. N.55 P. B.56 W.G.57 B.V.58 P.C.59 R.W.60 T.A.

* Plasma C2 T40, or alkaline reserve, is defined as the CO2 content of plasma from fully oxygenated blood whichhas been equilibrated with CO2 at a tension of 40 mm. Hg.

t The moderately low HbO2 capacity in this case is due to repeated phlebotomy.

838

BLOOD GASES IN CYANOTIC CONGENITAL HEART DISEASE

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FIG. 1. ARTERIAL HbO, CONTENT, HbO, CAPACITY, AND PERCENTAGE OXYGEN SATURATION OF THEBLOOD OF PATIENTS WITH CYANOTIC CONGENITAL HEART DISEASE, SHOWN AS DISTRIBUTIONS OF THEDEVIATIONS FROM THE NORMAL MEAN FOR THE VARIOUS AGE GROUPS

seen that rough relationships exist between thedegree of arterial unsaturation and the extent ofthe deviations of the HbO2 capacity, alkaline re-serve and arterial pH. from the normal mean.These relationships are more clearly apparent inTable III which gives mean values for the threegroups into which the material was divided onthe basis of arterial unsaturation. The moremarked deviations from the normal tend to occurin patients with arterial saturations below 70 percent. In each group there are marked exceptions.The acid-base balance of the arterial blood of

patients with cyanotic congenital heart disease isshown in Figure 3, in which the individual datafor (HCO8)S, pCO2 and pH. are plotted ontriaxial charts according to the method of Hast-ings and Steinhaus (9) and of Shock and Hast-ings (10). The shaded area in each chart repre-sents the range of variation which we have foundfor normal healthy children of corresponding age

groups and for adults (7). It is evident that inthe great majority of cases the acid-base balancemay be described as that due to fixed acid excessor to a combination of fixed acid excess and CO2deficit.Data concerning serum chloride, protein and

lactic acid were obtained for 15 of the patientswith cyanotic congenital heart disease in the hopesof observing changes in the electrolyte balance ofthe serum which might compensate for the re-duced bicarbonate concentration. The data in-clude two independent determinations on three ofthe patients, in one case separated in time bythree years. The results in Table IV show thatin half of the cases the sum of the three ions whichconstitute the great part of the anion moiety ofthe serum electrolytes, bicarbonate, chloride, andproteinate, falls within the normal range of varia-tion, while in the other half the sum of the threemajor anions is below normal. The table shows

839

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clearly that the difference in the sum of the threeanions is due almost entirely to a difference in themean chloride level. Thus, in approximately halfof the cases a reduction in the bicarbonate level isalmost balanced by a rise in the serum chloridelevel, but in the other half there is no apparentrise in chloride concentration. Those in the groupwithout chloride compensation tend to have lowersaturations and higher HbO2 capacities, althoughthe values of the two groups overlap. The meanpH. of the group without chloride compensationis 7.332 as compared with a mean value of 7.382for the other group, but the low mean pH5 of theformer group is due to lower than normal valuesin only half of the group. The blood lactate con-centration of the group without chloride compen-sation is not significantly higher than in the othergroup.

In Figures 1 and 2 the last column of eachgroup contains corresponding data for residents

at high altitude, taken from the reports of Dill etal. (11-13) and of Hurtado and Aste-Salazar(14). The triangles and squares of Figure 3 alsoshow these data. They are given for the purposeof comparison since both residents at high altitudeand patients with cyanotic congenital heart diseaserepresent hypoxic states to which the individualhas become acclimatized over a long period oftime. Both groups show approximately the samedegree of arterial unsaturation, although thespread of values in cyanotic congenital heart dis-ease is greater and much lower values are some-times found. Figure 2 shows that the alkalinereserve of the plasma tends to be lower in resi-dents at high altitude than in patients with cyanoticcongenital heart disease. Table III includesdata for residents at high altitude in terms of meandeviations from the normal. Of the three groupsof patients with cyanotic congenital heart diseasewhich are shown in this table, the second group,

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TABLE II

Results of repeated tests on the same individual

Arterial HbO Plasma* Arterial ArterialNo. Date Subject Age Notes saturation capacity CO2T4o pCO2 pHs

5 2-25-429- 8-4312- 3-464-22-47

Post-op.,5-14-473-10-49

17 10-14-47Post-op.,11-18-47

22 4-11-52Post-op.,10-15-52

27 6-12-4410-11-4610-17-4610-28-4612-12-469- 9-47

Post-op.,10- 8-4712- 8-473- 8-49

28 5- 5-47Post-op.,5-23-478-20-52

29 1-10-49Post-op.,2- 4-49

50 12-11-471-18-494- 2-51

Post-op.,6-29-51

J. Mu.

J. R.

L. S.

S. D.

R. B.

R. J.

Yr. Mo.2 74 27 47 97 109 8

Aortic-pulmonary arteryanastomosis, 4-24-47

9 8 Blalock anastomosis, 3-29-47Obliteration of anastomosis,

9 9 10-17-47

16 1017 48 010 410 410 510 611 311 411 612 98 08 113 22 0

2 1

J. Mr. 10 1011 1114 114 4

Pulmonary valvulotomy, 4-14-52

Phlebotomy, 10-24-46Iron medication begun 10-30-46Aortic-pulmonary artery

anastomosis, 9-14-47

Aortic-pulmonary arteryanastomosis, 5-47

Aortic-pulmonary arteryanastomosis, 1-11-49

Pulmonary valvulotomy, 6-13-51

per cent54.954.240.653.1

72.275.2

wl. %27.131.431.127.923.925.7

vol. %41.740.034.633.5

47.053.0

mm. Hg43.447.735.940.8

44.934.7

7.2667.2327.2447.186

7.2957.422

71.8 18.7 54.6 47.3 7.34065.7 25.0 50.6 39.5 7.369

71.2 26.4 49.5 29.7 7.43496.6 19.7 57.0 48.6 7.38768.870.874.262.666.177.184.383.883.2

31.531.131.127.429.427.924.025.426.0

47.142.746.249.342.847.052.451.453.4

34.736.338.439.035.233.933.531.432.4

7.3737.3147.3337.3657.3257.3727.4227.4317.438

74.3 28.1 48.9 39.4 7.35177.6 21.9 52.3 33.3 7.42674.1 24.2 47.6 30.2 7.40174.9 19.1 43.6 34.7 7.33076.8 16.4 47.5 31.1 7.40384.088.081.095.1

22.021.623.120.9

51.755.654.953.6

30.126.537.139.7

7.4477.5197.4157.375

* Plasma CO2 T40, or alkaline reserve, is defined as the CO2 content of plasma from oxygenated blood which hasbeen equilibrated with CO2 at a tension of 40 mm. Hg.

with arterial saturations of 70 to 88 per cent,compares well in arterial saturation with residentsat high altitude. It is evident that for comparabledegrees of arterial unsaturation the blood of resi-dents at high altitudes has a slightly higher HbO2capacity, a much lower alkaline reserve andarterial pCO2, and a slightly lower pH.. Theacid-base picture in Figure 3 is quite similar inboth groups, i.e., a combination of fixed acid ex-cess and CO2 deficit.The post-operative results in Table II give

information as to the effects of increased pul-monary blood flow on the arterial blood gases andthe acid-base balance. In four cases of Tetralogy

of Fallot, two, J. Mu. and S. D., showed markedimprovement in arterial saturation, but littlechange was observed in R. B. and R. J. Notshown in the table is the fact that R. J. showedmarked clinical improvement and little evidenceof cyanosis when seen four years later. L. S. andJ. Mr., who had diagnoses of pulmonary stenosisand atrial septal defect, showed arterial satura-tions of 96.6 and 95.0 per cent respectively follow-ing valvulotomy. A reduction of HbO2 capacityoccurred in all cases. Those patients who had amarked rise in arterial saturation also showed amarked rise in the alkaline reserve of the plasma.In the cases of J. Mu. and S. D. the alkaline re-

841


TABLE III

Relation of the degree of arterial unsaturation to the deviations from the normal of the Hb02 capacity and the acid base balanceof the blood of patients with cyanotic congenikal heart disease-a comparison of these deviations from

the normal with comparable values in native residents at high altitude*

Mean deviations from the normal meanArterial

No. of saturation HbO2 capacity Plasma C02 T4ot Arterial pCO2 Arterial pHscases per cent vol. % vl. % mm.

Patients with cyanotic congenital heart disease10 93-88 + 2.9 4 1.21t -3.5 4 0.79 -1.4 4 1.81 -0.023 4 0.013631 88-70 + 5.8 i 1.31 -5.4 4 1.18 -4.6 4 1.29 -0.010 d 0.010412 70-40 +12.9 1 0.72 -13.8 4i 1.72 -3.1 1.44 -0.083 4 0.0185

Residents at high altitudes15 85-68 + 8.5 41 0.95 -13.2 :1 0.73 -8.4 :1= 1.19 -0.043 :1= 0.0106

* Data for residents at high altitude are taken from the reports of Dill et al. (11-13) and of Hurtada and Aste-Salazar(14).t Plasma CO2 T40, or alkaline reserve, is defined as the CO2 content of plasma from fully oxygenated blood which

has been equilibrated with CO2 at a tension of 40 mm. Hg.t The figures following the 4 signs represent the standard error of the mean.

serve of the plasma rose to levels within the nor-mal range in spite of the fact that their arterialblood still contained a considerable degree ofvenous admixture. Their pH. levels, which pre-viously had been consistently low, rose to normallevels after an aortic-pulmonary artery anastomo-sis had been made. In the case of J. R. the pre-operative values are comparable to the post-operative values in the other patients. A Blalockanastomosis had been performed some time beforebut cardiac decompensation followed. Subsequentsurgical obliteration of the anastomosis reducedthe arterial saturation, raised the HbO2 capacity,and decreased the alkaline reserve of the plasma.It also reduced the arterial pCO2 which presum-ably had been high because of pulmonary conges-tion.

DISCUSSION

The fact that the great majority of patients withcyanotic congenital heart disease have a normal orhigher than normal arterial oxygen content isdue to the fact that the great majority have a highHbO2 capacity. The high arterial oxygen con-tent loses much of its value in the presence of re-duced arterial saturation since the arterial oxygentension rather than its concentration determinesthe level of the mean capillary oxygen pressureand the resultant pressure gradient or diffusionpressure head between capillaries and tissues.Studies of cyanotic congenital heart disease byBing et al. (2) and Ermsting and Shephard (6)

have emphasized the great part played by thesigmoid shape of the oxygen dissociation curve inreducing the arterial-mean capillary oxygen ten-sion gradient, in contrast to the small effect of thegreatly increased HbO2 capacity. The latter ex-erts its effect on the mean capillary oxygen pres-sure by raising the venous level of saturation since,of two bloods equally saturated, the one with highHbO2 capacity will remain more highly saturatedafter equal quantities of oxygen per unit of bloodhave been transferred to the tissues.

It is of interest to find that 12 patients withcyanotic congenital heart disease, or 20 per centof the number studied, did not have an elevatedHbO2 capacity. Half of these had mild cyanosisand arterial saturations between 87 and 92 percent. The majority of the remainder were infantsnot over 2 years of age. The fact that bloodcounts in these infants showed elevated values,with red cell counts of 6.2 to 8.5 million per cu.mm., suggests that the low HbO2 capacity is dueto a nutritional deficiency. Administration of fer-rous sulfate to one infant raised his HbO2 ca-pacity. Talbott and associates' (1) summary ofthe literature shows several cases of congenitalheart disease in which the blood HbO2 capacitywas not elevated. Burchell, Taylor, Knutson, andWood (4) have also noted a case with 68 percent saturation and with an HbO2 capacity ofonly 15.2 vol. per cent.The arterial saturation found in patients with

cyanotic congenital heart disease covers a wide

842


range. Eight cases showed arterial saturationsbelow 50 per cent. It is probably significant thatsaturations below 25 per cent were found only ininfants and that no saturation below 50 per centwas observed in children over 7 years of age. Avery low arterial saturation suggests a poor prog-nosis unless remedial operative procedures canbe used. Operation was attempted in the case oftwo infants with arterial saturations below 25 percent but death followed. The third infant withthis low saturation survived only a few monthsafter she was studied. Autopsy revealed trans-position of the great vessels. There is suggestiveevidence that correction of the iron deficiencypresent in cyanotic infants with low HbO2 ca-pacity improves their status.We believe that many of the saturation values

found in arterial samples in children may rep-resent the lower limit of a variable quantity whichis determined by factors which regulate both the

PH.40 Pft pHI

amount of right to left shunt and the venous oxy-gen level. Saturation levels determined by theear oximeter are usually higher because they aremeasured under conditions that are less disturbingto the patient than are arterial punctures.The finding of a low alkaline reserve of the

plasma in patients with cyanotic congenital heartdisease has been reported previously by Talbottet al. (1) and by Suarez, Chiodi, Fasciolo, andTaquini (3). It has also been suggested by thelow CO2 contents of arterial blood found in Tal-bott's summary of the literature (1), and in theserum of arterial blood as reported by Bing et al.(2).Talbott et al. (1) first described the analogy be-

tween the tissue anoxia of patients with cyanoticcongenital heart disease and that of persons livingunder the low oxygen pressure of high altitudes.He attributed the low alkaline reserve of the bloodin these patients to the effects of chronic hyperven-

7.40 pH, pHs 7.40 PHs

FIG. 3. ARTERIAL (HCO,) ., PCO2 AND pH. OF THE BLOOD OF PATIENTS WITH CYANOTIC CONGENITALHEART DISEASE, PLOTTED ON TRIAXIAL COORDINATES

The shaded areas represent the range of normal variation for the various age groups as determined by+ 2 standard deviations from the mean value of each group.

843


tilation, but he also recognized that some otherfactors caused the acidosis which was observed inthe patient he had studied so extensively and inseveral other cases reported in the literature.Bing et al. (2) found that the minute volume ofrespiration was increased above the normal in 29out of 30 cases of cyanotic congenital heart dis-ease, but the arterial pCO2 and the alkaline re-serve were reduced proportionately and the ar-terial pH. remained within normal limits.Suarez, Chiodi, Fasciolo, and Taquini (3) foundhyperventilation to be characteristic of the six pa-tients with this disease which they studied andarterial pH. in the normal range or slightly low.

Bing et al. (2) emphasized the difference inconditions under which tissue anoxia is producedin patients with congenital heart disease and inresidents at high altitudes. In the latter a lowalveolar oxygen pressure produces the low arterialPO2 and saturation. Hyperventilation is bene-ficial in that it raises the alveolar PO2. In patientswith cyanotic congenital heart disease on the otherhand low arterial PO2 and saturation levels arecaused by venous admixture through abnormalchannels. Beneficial effects of hyperventilationare questionable in such patients since the bloodthat passes through the lungs is exposed to a highoxygen tension and is well oxygenated, while the'blood shunted from the right to the left side ofthe heart does not pass through the lungs.

Presumably hyperventilation rises in response toan anoxic stimulus both in patients with cyanoticcongenital heart disease and in residents at high al-titude. Dill, Talbott and Consolazio (13) showedthat an essential process in acclimatization to highaltitude consists first of hyperventilation to increasealveolar oxygen pressure, followed later by a re-duction of the alkaline reserve of the plasma bykidney action to the point where the normal ratiobetween the pCO2 and the serum bicarbonate isreached. Both Dill, Talbott and Consolazio (13)and Hurtado and Aste-Salazar (14) found thatthe arterial blood serum of permanent residentsat high altitude is characterized by a lowering ofthe pCO2 proportional to that of the alkaline re-serve, with a normal or slightly low pH8, in con-trast to the elevated pH. of the arterial blood oftemporary residents at high altitude. Patients

with cyanotic congenital heart disease resembleresidents at high altitude in that they are ac-climatized to their state of anoxia. Our resultsshow that for a given degree of arterial unsatura-tion the blood of patients with cyanotic congenitalheart disease shows less of a depression of alkalinereserve than that of residents at high altitude.Since for equal degrees of alveolar hyperventila-tion the arterial pCO2 must remain higher in theblood of patients with cyanotic congenital heartdisease because of the venous admixture it con-tains, there is need for less decrease in the alkalinereserve of the blood in these patients in order tomaintain a normal arterial pHi.The case of cyanotic congenital heart disease

studied by Talbott et al. (1) was unusual becauseof the low arterial pH. which was observed. Thepresent report shows 32 per cent of pH8 valuesbelow the lower limit of normal. The great ma-jority of pH8 values below 7.30 were found insamples showing less than 60 per cent saturationand are therefore associated with large venous-arterial shunts. In such cases of severe hypoxia alow pH. offers compensation by raising arterialoxygen tension, hence mean capillary oxygenpressure, through the Bohr effect on the oxygendissociation curve.The low pH. of the arterial-blood and the lack

of balance in the common electrolytes of the serumin cases of severe hypoxia led Talbott to suggestthe presence of increased concentrations of organicacids in the blood. Since tissue metabolism ap-parently proceeds at relatively low levels of oxy-gen tension, it is conceivable that enzyme reactionsinvolved in muscle metabolism operate at a moreanaerobic level, with production of lactic acid inlarger quantities than normal. Our results agreewith those of Hallock (15), Bing et al. (2), andHavel and Watkins (5) in showing that in theresting state the lactic acid concentration in theblood of cyanotic patients with congenital heartdisease is not significantly higher than in thenormal person, and that the slightly elevated lacticacid levels that are occasionally found are notgreat enough to explain the deficiencies in theelectrolyte balance.

It is important to note also that although Binget al. (2) found that the basal oxygen consump-

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TABLE IV

Serum electrolyte concentrations in the arterial blood of patients with cyanotic congenital heart disease

Oxygen (HCOs)s+satura- HbOi (Pro- (C1)a+(Pro-

Age tion capacity (HCOs), (Cl)5 teinate)s teinate)5 (Lactate), (Sodium).yr. Subject per cent Vol. % mEq./L. mEq./L. mEq./L. mEq./L. mEq./L. mEq.IL. pHs

Group I. Normal values for (HCOs). + (Cl). + (Proteinate).3 W. B. 63.4 23.2 18.8 110.0 16.6 145.4 1.9 7.4146 J. T. 83.6 23.8 20.0 106.3 18.1 144.4 2.9 7.3777 V. S. 61.8 26.6 19.8 105.6 19.6 145.0 1.2 7.234

10 J. S. 72.1 27.3 20.3 105.1 20.4 145.8 1.0 7.39816 B. N. 90.1 27.9 20.2 106.3 18.0 144.5 1.8 7.39416 M. C. 81.0 26.2 18.7 106.6 17.5 142.8 1.0 7.351

Adult R. G. 79.7 25.7 21.2 108.2 15.6 145.0 0.6 7.408Mean 76.0 25.8 19.9 106.9 18.0 144.7 1.5 7.382

Group II. Low values for (HCO,). + (Cl). + (Proteinate),3 N. H. 84.1 26.0 17.6 99.8 17.8 135.2 1.5 7.4324 J. M. 54.3 31.4 19.7 100.6 15.0 135.3 1.2 133.6 7.2325 A. F. 70.4 27.8 20.7 103.2 14.0 137.9 1.6 7.3926 R. B. 40.5 28.6 16.1 104.2 18.0 138.3 2.9 7.2446 R. B. 39.2 26.5 16.9 103.2 17.8 137.9 2.6 7.3007 J. M. 40.6 31.1 15.3 104.2 16.6 136.1 1.7 146.3 7.2447 W. G. 70.6 27.8 19.8 101.7 18.5 140.0 1.6 7.3338 D. M. 82.8 22.5 19.2 104.1 17.3 140.6 1.8 7.429

10 S. D. 66.1 29.4 18.1 98.3 19.5 135.9 2.1 139.8 7.32511 S. D. 77.1 35.7 19.3 101.5 16.4 137.2 1.7 7.372

Adult D. B. 82.4 35.7 20.2 103.3 16.3 139.8 1.1 7.352Mean 64.4 29.3 18.4 102.2 17.0 137.7 1.8 7.332

tion was usually below the normal mean in thesepatients, that finding has not been corroborated inour laboratory or by other investigators such asBurchell, Taylor, Knutson, and Wood (4),Suarez, Chiodi, Fasciolo, and Taquini (3) andErnsting and Shephard (6). We must concludethat metabolic requirements for the resting stateare met by adequate oxygen consumption in pa-tients with marked arterial unsaturation. Atpresent it is not known whether this is made pos-sible by modifications in the complex of enzymaticprocesses involved in tissue metabolism andwhether the production of organic acids other thanlactic acid are increased under these conditions.The problem requires further study. The pos-sibility of alterations in renal excretion also mustbe studied in this connection.

SUMMARY

The blood gases and acid-base balance of theblood were determined in arterial samples from60 patients with cyanotic congenital heart diseasewho varied in age from 1 to 36 years. The re-sults may be summarized as follows:

Arterial saturation varied from 21 to 93 percent. Saturations below 50 per cent were foundonly in children under 8 years of age.

In 80 per cent of the cases HbO2 capacities weremore than 2 vol. per cent higher than the normalmean for the appropriate age. Of those withnormal or below normal HbO2 capacities, halfwere cases with arterial saturation between 87and 92 per cent, and the majority of the remainderwere infants in whom a nutritional iron deficiencywas suspected. Very high HbO2 capacities, over32 vol. per cent, were usually found only in olderchildren and in adults.By means of high HbO2 capacities the oxygen

content of the arterial blood was maintained withinthe normal range in all but 15 per cent of thecases.

The alkaline reserve of the plasma tended to bereduced, for approximately two-thirds of the ob-served values were below tle lower limit of nor-mal. Arterial pCO2 was below the normal rangein only one-third of the cases. As a result, valuesfor arterial pH. were below the lower limit ofnormal in approximately one-third of the cases.A rough relationship was fQund to exist be-

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tween the degree of arterial unsaturation and theextent of the deviations of the HbO2 capacity,alkaline reserve and arterial pH. from the normalmean.

Deviations of the acid-base characteristics of theserum from the normal were found to be due inmost cases either to fixed acid excess or to a com-bination of fixed acid excess and CO2 deficit.

Calculation of a partial electrolyte balanceshowed that in some cases the reduced bicarbon-ate concentration of the serum was balanced by arise in serum chloride concentration. In othercases there was no evidence of replacement ofserum bicarbonate by chloride, nor by increasedlactate concentration. The question of a cor-responding reduction of total fixed base or anincrease in other organic acids has not been in-vestigated sufficiently.The determination of arterial blood gases in

samples drawn post-operatively, after pulmonaryblood flow had been increased by aortic-pulmonaryartery anastomosis or pulmonary valvulotomy,showed a marked rise in the alkaline reserve andthe arterial pH. of the blood, in addition to thewell-known increase in arterial saturation andreduction of HbO2 capacity.

ACKNOWLEDGMENTS

The authors acknowledge with gratitude the technicalassistance of Lottie Walaszek Pietrowski, June BreidijanDenemark, Melba Holder, Florence Numajiri Field, AxelSwanson and Edna O'Connell.

REFERENCES1. Talbott, J. H., Coombs, F. S., Castleman, B., Chamber-

lain, F. L., Consolazio,.W. V., and White, P. D.,A record case of the Tetralogy of Fallot, with com-ments on metabolic and pathologic studies. Am.Heart J., 1941, 22, 754.

2. Bing, R. J., Vandam, L. D., Handelsman, J. C.,Campbell, J. A., Spencer, R., and Griswold, H. E.,Physiological studies in congenital heart disease.VI. Adaptations to anoxia in congenital heart dis-

ease with cyanosis. Bull. Johns Hopkins Hosp.,1948, 83, 439.

3. Suarez, J. R. E., Chiodi, H., Fasciolo, J. C., andTaquini, A. C., Respiration and circulation inmorbus coeruleus. Acta cardiologica, 1949, 4, 439.

4. Burchell, H. B., Taylor, B. E., Knutson, J. R. B., andWood, E. H., Circulatory adjustments to the hy-poxemia of congenital heart disease of the cyanotictype. Circulation, 1950, 1, 404.

5. Havel, R. J., and Watkins, E., Jr., The metabolism oflactate and pyruvate in children with congenitalheart disease. Circulation, 1950, 2, 536.

6. Ernsting, J., and Shephard, R. J., Respiratory adap-tations in congenital heart disease. J. Physiol.,1951, 112, 332.

7. Cassels, D. E., and Morse, M., Arterial blood gasesand acid-base balance in normal children. J. Clin.Invest., 1953, 32, 824.

8. Bing, R. J., Vandam, L. D., and Gray, F. D., Jr.,Physiological studies in congenital heart disease.II. Results of preoperative studies in patients withTetralogy of Fallot. Bull. Johns Hopkins Hosp.,1947, 80, 121.

9. Hastings, A. B., and Steinhaus, A. H., A new chartfor the interpretation of acid-base changes and itsapplication to exercise. Am. J. Physiol., 1931, 96,538.

10. Shock, N. W., and Hastings, A. B., Studies of acid-base balance of the blood. IV. Characterizationand interpretation of displacement of the acid-basebalance. J. Biol. Chem., 1935, 112, 239.

11. Dill, D. B., Christensen, E. H., and Edwards, H. T.,Gas equilibria in the lungs at high altitudes. Am.J. Physiol., 1936, 115, 530.

12. Talbott, J. H., and Dill, D. B., Clinical observations athigh altitude. Observations on six healthy personsliving at 17,500 feet and a report of one case ofchronic mountain sickness. Am. J. M. Sc., 1936,192, 626.

13. Dill, D. B., Talbott, J. H., and Consolazio, W. V.,Blood as a physicochemical system. XII. Man athigh altitudes. J. Biol. Chem., 1937, 118, 649.

14. Hurtado, A., and Aste-Salazar, H., Arterial bloodgases and acid-base balance at sea level and at highaltitudes. J. Appl. Physiol., 1948, 1, 304.

15. Hallock, P., Lactic acid production during rest andafter exercise in subjects with various types ofheart disease with special reference to congenitalheart disease. J. Clin. Invest., 1939, 18, 385.

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