Bacigalupo et al., Influence o£ acidity on hematocrit and hemoglobin values 2Q5

J. Perinat. Med.l (1973) 205

The influence of acidity on hematocrit and hemoglobinvalues in newborn infants immediately after delivery

G. Bacigalupo, E. Z. Saling

Unit for Perinatal MedicineThe Free University of Berlin, Germany

Received March 30, 1973. Accepted April 20, 1973

In a previous work concerning the dependenceof the hemoconcentration on blood pH wedescribed significant increases of hematocrit andhemoglobin values in acidotic newborn infantsimmediately post partum [1], The pH values thenmeasured represented, of course, a measure ofthe momentary hydrogen ion concentrations inthe samples investigated; they gave, however,no Information about the proportion of organicacids (formed predominantly by glycolysis) inthe total acidity.The present study has two major objectives inview. On the one hand, it should clarify whetherand to what extent a conformity of the effectsof total acidity and metabolic acidity on thehemoconcentration in the neonate exists. Onthe other hand, it should answer the questionäs to whether the oxygen partial pressure inthe cord blood of the neonate correlates inany way with the hemoconcentration, sinceincreases in blood acidity leading to hemocon-centration are very frequently the consequenceof hypoxic episodes during labor.

1. Subjects and methodsIn the course of our study 314 term babies were examinedimmediately after delivery. They had all been born pervaginam. Neonates suffering from morbus haemolyticusfetalis were not included in the investigation.In all cases determinations of the pH, of the hematocritand of the hemoglobin in umbilical artery blood weremade. The hydrogen ion concentration was measured in aSALiNG-TuROWSKi-pH-meter. For hematocrit deter-minations the micro-method of STRUMIA, SAMPLE and HART[7] was used. Hemoglobin was colorimetrically determinedapplying the hemiglobin cyanide method of VAN KÄMPENand ZIJLSTRA [3].

Curriculum vitaeGIOVANNI BACIGALUPO,Priv.-Do^. Dr. med. habt l.1925: Born in Berlin, Ger-many, on February 23rd.1950: M. D. (Internal Me-dicine), Humboldt University,Berlin. 1950—1956: Clinicaleducation in infernal medicineat Berlin. 1956—1957: Post-doctoral researcb fellow (endo-crinology), University of Korne.1957—1962: Clinical re-searcb assistant and latersenior assistant, Tumor Clinic,Berlin-Buch, German Academy of Sciences. 1962—1969: Headof the Department of Infernal Medicine and Cancer Chemo-therapy, Clinical Division of the Institute of Cancer Research',Berlin-Buch', German cademy of Sciences. Since 1970 Headof Section "Metabolism and Endocrinolog}", Unit for PerinatalMedicine^ The Free University of Berlin.Main research interests: Pathophysiology of the human fetus inthe perinatal period. Hormone metaholism during pregnancy.

In 277 of the neonates examined the metabolic acidityin umbilical artery blood was estimated. The degree ofmetabolic acidity was assayed by pH measurement at astandardized CO2 pressure of 40 mmHg [6], In order toproduce this carbon dioxide pressure, the blood samplewas put into a small equilibration chamber thermostatedat 37°C, and a humidified mixture of 5.6 per cent carbondioxide and 94.4 per cent oxygen (v/v) was bubbled throughit for 3 minutes. Equilibration and subsequent pH measure-ment were made in the abovementioned type of pH-meter.The pH value being measured in the sample after in-vitro-normalization of the PCO2 — the so-called pHqu40 —depends largely on the amount of organic acids (chieflylactic acid) present in the fetal blood.In 281 cases the oxygen partial pressure in umbilicalartery blood was determined, The measurements were

J. Perinat. Mcd. l (1973)

206 Bacigalupo et al., Influence of acidity on hematocrit and hemoglobin values

made by potentiometry in an ASTRUP apparatus, producedby RADIOMETER Inc., Copenhagen.The blood samples were obtained from umbilical arteriesby puncture and blood aspiration, avoiding any contactwith the air. The interval of time between blood with-drawal and beginning of laboratory processing of thesamples did not usually exceed 5 minutes.The clinical condition of thenewborn infant immediatelyafter delivery was described by means of our modifiedscore System [5]. In this System 4 clinical signs are assessed:state of the umbilical vessels, skin color, muscle tone andmovements, and respiration during the first 90 secondsafter delivery. Each sign is given one of four scores,varying from 0 (the worst) to 3 (the best). Thus, the totalscore may ränge from 0 to 12 points.Based on the individual pH and pHqu40 values in umbilicalartery blood, the cases in this study were divided into5 groups (see Tabs. I and II). Cases showing pH orpHqu40 values between 7.25 and 7.39 were considerednormal or almost normal äs to their acidity; those withValues from 7.20 t o 7.24 were classified pre-acidotic;and those with values ranging from 7.00 to 7.19 wereregarded äs acidotic. As already suggested, the pHqu40values chiefly reflect the strength of metabolic aciditywhich is essentially determined by the blood concentra-tions of organic acids formed in the glycolytic pathway.By contrast, the "simple" pH values — measured withoutprevious in-vitro-normalization of the CO2 pressure inthe blood sample — comprise the total acidity in the bloodwith both of its chief components, the metabolic and therespiratory.

2. Results and commentsAs can be seen from Tabs. I and II, low pH andpHqu40 values are usually linked to decreasedoxygen partial pressures. While in infants bornwith normal acid base Status the mean Ö2 partialpressures in umbilical artery blood do not exceed22 mmHg, the corresponding oxygen values o£neonates suffering from preacidosis or acidosislie below this level.The insufficiently oxygenated fetus is forcedto reduce its oxidative metabolism. Obeying thePASTEUR reaction, its energy requirement willnow be met to a larger extent by anaerobiccarbohydrate catabolism, i. e. by a compensa-torily accelerated formation of lactic acidwhich represents the main source of metabolicacidity in the newborn infant immediatelyafter delivery.As a rule, rise of total and metabolic acidityleads to an advancing impairment of theneonate's clinical condition (see Tabs. I andII). The infants showing normal total and meta-

Tab. I Umbilical blood oxygen pressure and clinical stateof the newborri immediately after delivery in differentranges of total acidity.

pHuA No. Po2 UA (mmHg)

7.35—7.39

7.30—7.34

7.25—7.29

7.20—7.24

7.00—7.19

33

48

93

53

54

26.9±6.2

24.0±6.2

22.2±6.9

21.6±5.0

17.0±5.1

Sa S

9.7±1.6

9.3±2.5

9.4±1.2

7.8±3.2

7.5±2.3

pHuA =5= hydrogen ions concentration in umbilical arterybloodNo. = number of subjects examinedPo2uA = O2 pressure in umbilical artery blood, arithme-tical mean and Standard deviationSa S = SALING score, arithmetical mean in points andStandard deviation

Tab. II Umbilical blood oxygen pressure and clinical stateof the newborn immediately after delivery in differentranges of metabolic acidity.

pHqu40uA

7.35—7.39

7.30—7.34

7.25—7.29

7.20—7.24

7.00—7.19

No.

25

58

79

53

35

Po2uA (mmHg)

25.6±6.1

25.4±7.0

22.3±5.9

20.9±5.1

16.0±5.1

Sa S

9.7±1.9

9.8±1.2

9.4±1.3

8.7±2.3

6.7±2.4

pHqu40uA = metabolic acidity äs judged by measure-ment of hydrogen ions concentration in umbilical arteryblood, following in-vitro-normalization of carbon dioxidepressure.Other denotations äs in Tab. I.

bolic acidity (pH and pHqu40 above 7.25) areon the average born in good condition (meantotal scores above 9 points). In preacidosis andacidosis, however, the newborn infants aregenerally in poorer condition immediately afterbirth, äs is indicated by the mean values of theindividual total scores (mean total scores below9). Again, these findings prove the causal inter-

J. Perinat. Med. l (1973)

Bacigalupo et al., Influence of acidity on hematocrit and hemoglobin values 207

dependence o£ insufficient intrauterine oxygensupply, increase in acidity and impairment ofthe fetal and neonatal vitality.Tab. III demonstrates the changes of the hema-tocrit and hemoglobin values in several phys-iological and pathophysiological ranges of totalacidity. In newborn infants with normal pHvalues in umbilical artery blood the meanhematocrit values lie between 50 and 52 percent; in contrast to this with pathologically loweredpH values (< 7.25) the hematocrit values riseup to 54.7 per cent. Similar to the changes of thehematocrit values, the hemoglobin values alsoshow a tendency to rise with decreasing pH. Ininfants showing a normal total acidity imme-diately after delivery the hemoglobin values rängefrom 17.0 to 17.7 grams per 100 milliliters ofblood, while in the preacidotic and acidoticinfants the corresponding values rise to 18.0and 18.4 grams per 100 milliliters of blood.

globin values are higher in the subjects sufferingfrom metabolic preacidosis or acidosis (pHqu407.00 to 7.24) than in those suffering from preaci-dosis or acidosis äs a result of increased totalacidity (pH 7.00 to 7.24).

Tab. IV Dependence of hematocrit and hemoglobin valuesupon metabolic acidity.

pHqu40uA

7.35—7.39

7.30—7.34

7.25—7.29

7.20—7.24

7.00—7.19

No.

37

73

79

53

35

HctuA (%)

49.9±5.4

50.3±4.9

52.4±5.6

54.6±6.5

55.4±4.7

HbuA(g./100 ml.)

17.1±2.2

16.9± 1-8

18.0±2.2

18.4±2.2

18.8±2.0

Tab. III Dependence of hematocrit and hemoglobin valuesupon total acidity.

pHuA

7.35—7.39

7.30—7.34

7.25—7.29

7.20—7.24

7.00—7.19

No.

47

67

93

53

54

Hct UA (%)

50.0±5.3

50.3±5.3

52.0±6.0

53.3±5.9

54.7±5.5

HbÜA(g./lOOml.)

17.0±2.2

17.2±1.9

17.7±1-9

18.0±2.6

18.4±2.2

HctuA = hematocrit in umbilical artery bloodHbuA = hemoglobin content in umbilical artery blood

The influence of metabolic acidity on the hemato-crit and hemoglobin values of neonates imme-diately post partum is demonstrated in Tab.IV. Again, we can observe the characteristicincrease of hematocrit and hemoglobin valuesfrom 49.9 per cent and 17.0 grams per 100 milli-liters of blood in the lowest ränge of metabolicacidity to 55.4 per cent and 18.8 grams per100 milliliters of blood in the ränge of metabolicacidosis. Remarkably, the hematocrit and hemo-

Fig. 1. Correlation between total acidity (pHuA = x) andhematocrit (HctuA == y) in umbilical artery blood of 314newborn infants immediately after delivery. Regressionequation y = 174.9—16.9x; r = 0.24, v = 312,2<x< 0.001.

J. Perinat. Mcd. 1 (1973)

208 Bacigalupo et al., Influence of acidity on-hematocrit and hemoglobin values

70

65

60

50

i l

406,95 7,00 7,05 7,10 715 7,20 7,25 730 735 740

p H q u 4 0 U A — ^

Fig. 2. Correlation between metabolic acidity (pHqu 40uA= x) and hematocrit (HctuA = y) in umbilical arteryblood of 277 newborn infants immediately after delivery.Regression equation y = 244.7—26.5x; r = 0.31, v = 275,2α < 0.001.

Figs. l and 2 show the individual hematocritvalues in relation to the individual pH andpHqu40 values. From the 314 paired values ofpH and hematocrit and the 277 paired values ofpHqu40 and hematocrit, the appropriate correla-tion coefficients and regression equations werecomputed (see legends of Figs. l and 2). In con-sidering the large number o£ degrees o£ freedom,we find that the correlation between totalacidity and hematocrit s well s that betweenmetabolic acidity and hematocrit is statisti-cally highly significant (2oc < 0.001). Notably,the correlation between pHqu40 and hematocritis considerably closer than that between pH andhematocrit.The individual hemoglobin values in relation tothe individual pH and pHqu40 values are de-monstrated in Figs. 3 and 4. The correlationcoefficients and regression equations for thesepaired observations are quoted in the legends of

Figs. 3 and 4. The correlation between pH andhemoglobin concentration in the neonate's um-bilical artery blood is significant at the statisticallevel of 2oc < 0.01; the correlation betweenpHqu40 and hemoglobin concentration issignificant even at the level of 2oc < 0.001.From the regression equations of our randomsamples it can be derived that between the pHvalues of 7.40 and 7.00 a statistical rise of thehematocrit values from 49.2 to 56.9 per centand of the hemoglobin concentrations from17.1 to 19.1 grams per 100 milliliters of bloodoccurs. Accordingly, a decrease in blood pHof 0.1 units causes a statistical increase of1.7 per cent in hematocrit and of 0.5 grams

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Fig. 3. Correlation between total acidity (pHuA = tf andhemoglobin concentration (HbuA = y) in umbilicalartery blood of 314 newborn infants immediately afterdelivery. Regression equation y = 55.1 — 5.1x; t = 0.19,v = 312, 2oc < 0.01.

J. Perinat. Med. l (1973)

Bacigalupo et al., Influcncc of acidity on hcmatocrit and hemoglobin valucs 209

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Fig. 4. Correlation between metabolic acidity (pHqu 40uA= x) and hemoglobin concentration (HbuA = y) inum-bilical artery blood of 277 newborn infants immediatelyafter delivery. Regression equation y = 78.2—S.3x;r = 0.26, v = 275, 2α < 0.001.

per 100 milliliters of blood in hemoglobin.Between pHqu40 7.40 and 7.00 an increase from48.9 to 59.5 per cent in hematocrit and from16.7 to 20.0 grams in hemoglobin per 100 milli-liters of blood is to be expected. Diminution of0.1 units in pHqu40 is accompanied by a statisti-cal rise of 2.6 per. cent in hematocrit and of 0.8grams in hemoglobin per 100 milliliters of blood.It is likely that the nearly parallel increase inhematocrit and hemoglobin associated with theincrease in neonatal blood acidity can be explainedchiefly by hemoconcentration. This hemo-concentration seems to be a consequence of anincrease in capillary permeability produced byoxygen deficiency with an enhanced passage ofblood fluid into the interstitial space. Previous

experiments with anesthesized pigs had alreadydemonstrated that under conditions of controlledhypoxia a hemoconcentration can be provokedwithin a few minutes, the extent of which isdcpendent on the concomitant rise in acidity [2J.

Thcorctically it is also conceivable that, for instance, theconsiderablc increascs in hematocrit and hemoglobin foundin newborn infants suffering from acidosis are evidence ofan crythropoesis pathologically raised in response to achronically rcduced oxygen supply to the fetus. Thishypothesis, howevcr, does not appear to be very likely,sincc the acidotic nconatcs examined by us demonstratedno signs of rctardcd intrauterine growth, nor did theirplaccntas show any striking weight differences comparedto those of the non-acidotic neonates.

There are no significant correlations betweenoxygen partial pressures and hematocrit orhemaglobin concentrations in umbilical ar-tery blood (Figs. 5 and 6), although fetal oxy-gen deficiency, increase in acidity and hemo-concentration are closely connected. Fetal oxy-

70

65

60

S 55

50

45

10 15 20 25Hgl-

30 35 40

Fig. 5. Correlation between oxygen partial prcssure(PO2UA = x) and hematocrit (HctuA = y) in umbilicalartery blood of 291 newborn infants immediately afterdelivery. Regression equation y = 55.1—0.1 x; r = 0.12,v = 289, 2* < 0.1.

J. Pcrinat. Med. l (1973) 15

210 Bacigalupo et al., Influence of acidity on hematocrit and hemoglobin values

22

21

20

19

18

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5 10 15 20 25 30 35 40Po2uA ImmHg]—*~

Fig. 6. Correlation between oxygen partial pressure(PO2uA = x) and hemoglobin concentration (HbuA = y)in umbilical artery blood of 291 newborn infants immedi-ately after delivery. Regression equation y = 18.5—0.03x;r = 0.10, v· =289, 2 < 0.1.

genation during labor is temporarily and individ-ually radier variable, äs can be indirectly con-cluded from the large Standard deviations in themean Po2 values (Tabs. I and II). Naturally,ander these conditions our single determinationsof the momentary oxygen pressure in umbilical

cord blood of the newborn immediately afterdelivery will give us only incomplete indicationsof the degree of fetal oxygenation during thepreceding stage of labor, which profoundly in-fluences the degree of acidity. It can also be assum-ed that oxygen deficiency does not bring aboutthe increase in capillary permeability leading tohemoconcentration directly, but rather throughthe rise in acidity.

3. ConclusionsOur investigätions demonstrate a definite de-pendence of the neonatal hemoconcentrationon the concentration of hydrogen ions in theränge from pH 7.00 to 7.39. In its strict meaning,this Statement implies that data concerning thenormal ranges of hematocrit and hemoglobin inneonatal blood immediately after delivery are fullyvalid only if the appropriate pH-values are alsocited. As a rule, acidotic neonates will showincreased hematocrit and hemoglobin values incomparison to non-acidotic neonates.In addition to these laboratory aspects, theacidity-induced hemoconcentration in the new-born infant may also be of clinical importance.Hemoconcentration, caused by enlarged capil-lary leakage and enhanced passage of blood fluidinto the exträväsculär space, results in a diminu-tion of the blood volume which in turn maynegatively affect pressure and blood flow in thecirculatory System. In addition, hemoconcen-tration is inevitably ässociated* with an elevationof blood viscosity; an increase in hematocritfrom 50 to 60 per cetit, for instance, is equivalentto a rise in blood viscosity of approximately lcentipoise [4]. Logically, both maüifestations,namely reduction of the circulating blood volumeand rise in blood viscosity, will .certainly notimprove the surviväl chances of an acidoticinfant born in a depressed condition.

Summary

In the present study we investigated whether and to whatextent the total acidity, the metabolic acidity and oxygenpartial pressure influence the hematocrit and hemo-globin levels of newborn infants immediately afterdelivery.314 term babies were examined immediately after delivery.In all subjects, determinations of hematocrit and hemo-

globin in umbilical artery blood were made, äs well äsassays of total acidity by potentiometric pH measurements.Furthermore, the metabolic acidity in umbilical arteryblood was assayed in 277 of the newborn infants studied;the degree of metabolic acidity was estimated by pHmeasurements at a Standard carbon dioxide pressure of40 mmHg (so-called pHqu40 values). In 281 subjects,

J. Pe±inat. Med. l (1973)

Bacigalupo et al, Influence of acidity on hcmatocrit and hemoglobin values 211

measurements of the oxygen partial pressurc in umbilicalartery blood were made.As can be shown (Figs. l and 2), there exist statisticallysignificant correlations between blood total acidityon the one band, and hematocrit and hemoglobinvalues on the other (p < 0.001 and 0.01). A definitedecrease in blood pH leads to a definite rise in hematocritand hemoglobin values. From the appropriate regressionequations it can be calculated that, for instance, at a bloodpH of 7.40 a hematocrit of 49.2 per cent and a hemoglobinvalue of 17.1 grams per 100 ml. of blood is to be expected.By contrast, at a blood pH of 7.00 the statistically mostprobable hematocrit and hemoglobin values will amountto 56.9 per cent and 19.1 grams per 100 ml. respectively.The correlations between metabolic acidity and hemato-crit o r hemoglobin values (Figs. 2 and 4) are also statisti-cally significant (p < 0.001). Between pHqu40 7.40 and7.00 an increase in hematocrit from 48.9 to 59.5 per centand in hemoglobin from 16.7 to 20.0 grams per 100 ml.

of umbilical artery blood is to be expected. Notably, thecorrelations between metabolic acidity and hemato-crit ot hemoglobin values respectively are considerablycloser than those between total acidity and hematocritor hemoglobin values respectively.In our random sample, no significant correlations be-tween oxygen partial pressure, hematocrit and hemo-globin content in umbilical artery blood immediatelyafter birth could be calculated (Figs. 5 and 6).The almost parallel increase in hematocrit and hemoglobinvalues of the newborn infant during the rise of bloodacidity can in all probability be explained by hemo-concentration due to increased capillary leakage andenhanced passage of blood fluid into the extravascularspace. The diminution in blood volume related to descend-ing blood pH values is inevitably associated with anincrease in blood viscosity. In acidotic neonates bornin poor condition, both manifestations may worsen thechances for survival.

Keywords: Newborn infant, umbilical cord blood, hematocrit, hemoglobin, acid-base equilibrium, oxygen deficiency,acidosis.

Zusammenfassung

Der Einfluß der Azidität auf die Hämatokrit- undHämoglobinwerte bei Neugeborenen unmittelbar nachder Geburt

In der vorliegenden Arbeit wurde untersucht, ob und inwelchem Ausmaß die Gesamtazidität, die metabolischeAzidität und der Sauerstoff-Partialdruck die Hämato-krit- und Hämoglobinwerte von Neugeborenen un-unmittelbar nach der Geburt beeinflußt.314 ausgetragene Kinder wurden unmittelbar nach derGeburt untersucht. In allen Fällen wurden Hämatokrit-und Hämoglobinbestimmungen im Nabelarterienblutdurchgeführt, sowie Bestimmungen der Gesamtaziditätdurch potentiometrische pH-Messung. Außerdem wurdebei 277 der untersuchten Neugeborenen die metabolischeAzidität im Nabelarterienblut bestimmt; der Grad dermetabolischen Azidität wurde mittels pH-Messungen beieinem Standard-CO2-Druck von 40 mm Hg ermittelt(sogenannte pHqu40-Werte). In 281 Fällen wurdenMessungen des Sauerstoffpartialdruckes im Nabelarterien-blut vorgenommen.Es konnte gezeigt werden (Abb. l und 3), daß zwischender Blut-Gesamtazidität einerseits und den Hämatokrit-bzw. Hämoglobinwerten andererseits statistisch signi-fikante Korrelationen bestehen (p < 0.001 und 0.01).Abfall des Blut-pH um einen bestimmten Betrag führtzu einem definierten Anstieg der Hämatokrit- und Hämo-globinwerte. So kann zum Beispiel aus den zugehörigenRegressionsgleichungen berechnet werden, daß bei einemBlut-pH von 7.40 ein Hämatokrit von 49.2% und ein

Hämoglobinwert von 17.1 g/100 ml Blut zu erwarten ist.Bei einem Blut-pH von 7.00 würden die statistisch wahr-scheinlichsten Hämatokrit- und Hämoglobinwerte da-gegen 56.9% und 19.1 g/100 ml Blut betragen.Die Korrelationen zwischen metabolischer Azditätund Hämatokrit- bzw. Hämoglobin werten (Abb. 2und 4) sind ebenfalls statistisch signifikant (p < 0.001).Zwischen pHqu40 7.40 und 7.00 ist ein Anstieg des Häma-tokrits von 48.9 auf 59.5% und des Hämoglobins von16.7 auf 20.0 g/100 ml Nabelschnurblut zu erwarten.Bemerkenswerterweise sind die Korrelationen zwischenmetabolischer Azidität und Hämatokrit- bzw. Hämo-globinwerten beträchtlich enger als jene zwischen Ge-samtazidität und Hämatokrit- bzw. Hämoglobinwerten.Bei unserem Stichprobenumfang konnten keine signi-fikanten Korrelationen zwischen Sauerstoff-Partial-druck, Hämatokrit und Hämoglobingehalt des Nabel-arterienblutes unmittelbar nach der Geburt berechnetwerden (Abb. 5 und 6).Der nahezu parallele Anstieg der Hämatokrit- und Hämo-globinwerte beim Neugeborenen während des Anstiegesder Blutazidität ist aller Wahrscheinlichkeit nach durcheine Hämokonzentration zu erklären, die durch er-höhte Kapillardurchlässigkeit und vermehrten Übertrittvon Blutflüssigkeit in den extravaskulären Raum zustandekommen mag. Verminderung des Blutvolumens bei Ab-fall der Blut-pH-Werte führt unweigerlich zu einemAnstieg der Blutviskosität. Bei azidotischen Neugebore-nen in- schlechtem Zustand können beide Erscheinungendie Überlebenschancen der Kinder verschlechtern.

Schlüsselwörter: Neugeborenes, Nabelschnurblut, Hämatokrit, Hämoglobin, Säure-Basen-Gleichgewicht, Sauerstoff-mangel, Azidose.

J. Perinat. Mcd. l (1973) 15*

212 Bacigalupo et al., Influence of acidity on hematocrit and hemoglobin values

Resume

Influence de Tacidito sur les valeurs d'homatocrite etd'hemoglobine chez les nouveaux-nes aussitot apres lanaissance.Le travail present analyse l'influence de Pacidite totale,de l'acidito metabolique et de la pression partielled'oxygene sur les valeurs d'hematocrite et d'h^moglo-bine chez les nouveaux-nes aussitot apres la naissance.314 enfants venus ä terme ont 6te examines aussitotapres la naissance. Dans tous les cas, on a efFectue desdosages d'hematocrite et d'hemoglobine dans le sangarteriel ombilical et analyse Tacidite totale par le mesuragepotentiometrique du pH. En outre, chez 277 de cesnouveaux-nes, on a mesure Facidite metabolique dans lesang arteriel ombilical au moyen de mesurages du pHpour une pression Standard de CO2 de 40 mm Hg (valeursdites pHqu40). Dans 281 cas, on a egalement procedeä des mesures de la pression partielle d'oxygene dans lesang arteriel ombilical.,Les resultats ont montre l'existence de correlations sta-tistiquement significatives (p < 0.001 et 0.01) entrePacidite totale du sang d'une part et les valeurs respectivesd'hematocrite et d'hemoglobine d'autre part. La baissedu pH du sang provoque une hausse correspondante desvaleurs d'hematocrite et d'hemoglobine. C'est ainsi, parexemple, que peut calculer a partir des equations deregression correlatives qu'ä un pH du sang de 7.40correspond en general un hematocrite de 49.2 pour cent-et un taux d'hemoglobine .de 17.i-g/100 tnl de sang." Parcontre, pour un pH du sang de 7.00, les valeurs d'hemato-crite et d'hemoglobine les plus probables selon les statisti-

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ques monteraient ä 56.9 pour cent ä 19.1 g/100 ml de sang.Les correlations entre Facidite metabolique et lesvaleurs respectives d'homatocrite et d'hemoglobinesont, de meme, statistiquement significatives (p< 0.001).Entre pH qu 40 7.40 et 7.00, on a observe une hausse dePhematocrite de 48.9 ä 59.5 pur cent et de l'homoglobinede 16.7 ä 20.0 g/100 ml de sang du cordon ombilical. Uest interessant de noter que les correlations entre l'acl··dito motabolique et les valeurs d'homatocrite etd'hemoglobine sont beaucoup plus otroites qu'entrePacidite totale et les valeurs d'hematocrite et d'hemo-globine.Les analyses effiectuees sur nos specimens prdleves auhasard n'ont reVele aucune correlation significativeentre, d'une part, la pression partielle d'öxygfcne et,d'autre part, Phematocrite et le taux d'hemoglobinedu sang arteriel ombilical aussitot apres la naissance.La hausse quasiment parallele chez le nouveau-ne desvaleurs d'hematocrite et d'hemoglobine d'une part et dePaciditd du sang d'autre part s'explique selon toute vrai-semblance par une hemoconcentration resultant sansdoute d'une permeabilite capillaire accrue et du passagerenforce de liquide sanguin dans le Zone extravasculaire.Une diminution du volume sanguin consecutive ä unebaisse des valeurs pH du sang provoque inevitablementune augmentation de la viscosite du sang. Chez lesnouveaiix-nes acidosiques en .mauväis 6tat, ces deuxsymptömes peuvent reduire les chances de survie desenfants.

Mots-cles: Nouveau-ne, sang du cordon ombilical, hematocrite, hemoglobine, equilibre basacidique, hypoxygenie,acidose.

Bibliography

[1] BACIGALUPO, G., E. SALING: Hämatokrit- und Hämo-globinwerte im Nabelschnurblut nicht-azidotischer undazidotischer Neugeborener. In: DUDENHAUSEN, J. W.,E. SALING: Perinatale Medizin Band IV. Thieme,Stuttgart 1973

[2] BACIGALUPO, G., M. MÜLLING, H. J. HENNING, G.KRESSIN, K. WAGNER: Über einige Fragen des Adenyl-säuresystems des Blutes bei kontrollierter Hypoxie(Modellversuche am Schwein). In: SALING, E., J. W.DUDENHAUSEN: Perinatale Medizin Band III. Thieme,Stuttgart 1972

[3] VAN KÄMPEN, E. J., W. G. ZIJLSTRA: Standardizationof hemiglobinometry: II. The hemiglobincyanidemethod. Clin. Chim. Acta 6 (1961) 538

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[7] STRUMIA, M. M., A. B. SAMPLE, E. D. HART: Improvedmicrohematocrit method. Amer. J. Clin. Pathol. 24(1954) 1016; Correction: Amer. J. Clin. Pathol. 25(1955) 298

Priv.-Doz. Dr. med. habil. G. BacigalupoArbeitsgruppe für perinatale Medizinder Freien Universität BerlinD-1000 Berlin 44Mariendorfer Weg 28—38Germany

J. Perinat. Med. 2 (1973