Acid Base and Blood Gas Analysis in Term Neonates Immediately After Birth with Uncomplicated Neonatal Transition

doi:10.21203/rs.3.rs-858091/v1

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Acid Base and Blood Gas Analysis in Term Neonates Immediately After Birth with Uncomplicated Neonatal Transition

https://doi.org/10.21203/rs.3.rs-858091/v1

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Background: Acid base and blood gas measurements provide essential information, especially in critically ill neonates. After birth, rapidly changing physiology and difficulty to obtain blood samples represent unique challenges.

Objectives: The aim of the present study was to establish normal values of capillary acid base and blood gas analysis immediately after birth in term neonates after uncomplicated neonatal transition.

Method: This is a post-hoc- analysis of ancillary outcome parameter of a prospective observational study in term neonates immediately after caesarean section. Neonates were included after immediate neonatal transition without need of medical support and a capillary blood sample was taken by a heel-stick within 15-20 minutes after birth.

Result: 132 term neonates were included with mean (SD) gestational age of 38.7±0.7 weeks. The blood was drawn mean (SD) 16±1.7 minutes after birth. The mean (SD) values of the analyses were: pH 7.30±0.04, pCO₂52.6±6.4, base excess -0.9±1.7 and bicarbonate 24.8±1.6.

Conclusion: This is the first study describing acid base and blood gas analyses in term neonates immediately after birth with uncomplicated neonatal transition.

Pediatrics

acid base

blood gas

term neonate

neonatal transition

immediately after birth.

In 1957, a study group from New York, USA noticed that umbilical cord blood gas analysis may indicates preceding fetal hypoxic stress.[1] Since then, it is widely known that umbilical cord blood gas analysis might also provide important information concerning the neonate’s condition after birth.[2] Meanwhile, umbilical cord blood gas analysis is recommended in all high-risk deliveries[3, 4] and many obstetrics centers routinely perform cord blood gas analysis in all deliveries. In the last decades, there has been growing interest in research of umbilical blood gas analysis in neonates in different conditions[5, 6] – e.g. preeclamptic versus healthy preterm neonates or effect of delayed cord clamping versus early cord clamping. For precise interpretation, many study groups published normative data for umbilical cord blood gas values. [7, 8]

Umbilical cord blood gas analysis provides valuable information about the neonate’s condition immediately after birth. However, the neonates’ condition may change quickly after birth, depending on the pulmonary and cardio-circulatory adaptation. Besides pulse oximetry and/or electrocardiogram monitoring, the acid base and blood gas analysis of capillary blood enables a quick point-of care information. Immediately after birth the rapidly changing physiology, the difficulty of access to arterial blood samples and the small blood volumes present unique challenges.[9] Acid base and blood gas analysis as additional information might be helpful to assess the neonate’s condition, especially if they are in need of medical support. However, to guide interventions based on blood gas analysis immediately after birth, normal values are essential.

The aim of this study was to establish normal values of acid base and blood gas values during immediate transition in term neonates without need of any medical support.

This was a post-hoc-analysis of ancillary outcome parameter of a prospective observational study conducted at the Division of Neonatology, Department of Paediatrics and Adolescent Medicine, Medical University of Graz, from October 2015 to September 2018. The prospective observational study[10] was approved by the Regional Committee on Biomedical Research Ethics (EC Number: 27–465 ex 14/15.), the decision included a possible post-hoc analysis. Informed parental consent was obtained antenatally, before neonates were included in the study.

Data of term neonates ≥ 37^+ 0 gestational age born by caesarean section, who were included in the prospective observational study were eligible for this analysis. After the neonates were fully delivered, a stopwatch was started. After cord clamping, routinely performed after 30 seconds, neonates were brought to the resuscitation table and placed under an overhead heater in supine position. Routine monitoring of heart rate (HR) and arterial oxygen saturation (SpO₂) was performed by pulse-oximetry. The data of neonates without any medical support and capillary blood sampling during immediate transition were analyzed. The capillary blood sample was taken from the heel within 15–20 minutes after birth according to the study protocol before the neonates were brought to the parents. Stabilization was performed according to the latest neonatal life support guideline recommendations.[11] The capillary blood samples were analyzed with a blood gas analyzer (ABL 800 Flex; Fa.Drott, Wiener Neustadt, Austria). The following acid base and blood gas values were recorded and analyzed: pH, partial pressure of carbon dioxide (pCO₂), base excess and bicarbonate. As additional information hematocrit and lactate were recorded and analyzed. HR and SpO₂, and rectal body temperature at 15 minutes after birth were assessed.

Demographic and clinical characteristics are presented as mean ± standard deviation (SD) for normally distributed continuous variables and medians with interquartile range (IQR) when the distribution was skewed. PH, pCO₂, base excess, bicarbonate, hematocrit and lactate are presented as mean ± standard deviation (SD). The statistical analyses were performed using IBM SPSS Statistics 26.0.0 (IBM Corporation, Armonk, NY, USA).

Data of 132 term neonates were analyzed. Demographic and clinical characteristics of the study population are presented in Table 1.

Table 1

Demographic and clinical characteristics of the study population at 15 minute after birth
	Study population (n = 132)
Gestational age (weeks) – mean (SD)	38.7 ± 0.7
Birth weight (g) – mean (SD)	3260 ± 472
Female sex – n (%)	57 (43.2)
Apgar score at 5 minutes –median (IQR)	10 (10–10)
Apgar score at 10 minutes –median (IQR)	10 (10–10)
Umbilical artery pH –mean (SD)	7.31 ± 0.04
Body temperature (°C) – mean (SD)	37.2 ± 0.34
Heart rate (beat per minute) – mean (SD)	156 ± 18
SpO₂ (%) – mean (SD)	96 ± 2.9

The blood samples were drawn mean (SD) 16 ± 1.8 minutes after birth.

The blood samples were drawn mean (SD) 16 ± 1.8 minutes after birth. Table 2 presents the data of the mean and standard deviation (SD) of pH, pCO₂, base excess bicarbonate, hematocrit and lactate of the capillary blood gas analyses in term infants after uncomplicated immediate neonatal transition.

Table 2

Capillary acid base and blood gas values within 15–20 minutes after birth in stable neonates without any medical support
	mean	SD
pH	7.30	0.04
pCO₂ (mmHg)	52.6	6,4
base excess (mmol/L)	-0,9	1,7
bicarbonate (mmol/L)	24,8	1,6
hematocrit (%)	57,4	8,1
lactate (mmol/l)	2,7	0,8

To the best of our knowledge, this is the first description of capillary acid base and blood gas values immediately after birth in stable neonates without any medical support.

Postnatal immediate transition is a vulnerable time period, where the neonates undergo complex changes affecting all vital organ systems. If disturbances occur during this period, this might lead to severe consequences. Non-invasive monitoring of HR and SpO₂ by pulse oximetry or electrocardiogram is recommended in neonates during stabilization immediately after birth. For this routine non-invasive monitoring, normative data are already established. [12, 13] But non-invasive monitoring often does not provide the whole information needed to judge on the cardio-respiratory status of a neonate. Acid base and blood gas analyses from capillary blood samples might give further information to guide the respiratory and medical support, especially in critically ill neonates.[14] Cousineaua et al. published reference values of capillary blood gases in term neonates at the age of 48 hours after birth. The mean pH was 7.39 and pCO₂ was 38.7mmHg. These values are comparable with reference values, which are considered as normal at clinical aspects. [14]

Within the present study, we observed lower pH and higher pCO2 values. Still, these neonates did not need any respiratory support and returned to their parents without any sign of respiratory distress.

Several studies compared blood gas values from arterial and capillary blood samples. [9, 15] Saili et al. observed in 51 neonates with moderate asphyxia 60 hours after birth, higher capillary pCO₂ compared to arterial pCO₂. This study group concluded, that the capillary pCO₂ is of little use to predict arterial pCO₂. [15] According to the literature caution should be used, when clinicians make decision based only on capillary blood gas analyses. [9, 15] However, in neonates and especially during immediate transition, arterial blood samples are often not available and capillary blood samples are the only way to get information of the blood gases to guide respiratory or cardio-circulatory support.

We recognize some limitations in our study. First, we analyzed only capillary blood samples. Second, all included neonates were term neonates, who were observed by a neonatologist for 10–15 minutes after cesarean section. Values after spontaneous vaginal delivery might differ. However, we included only neonates without any medical support during immediate transition suggesting similar values in healthy vaginally delivered neonates. Third, umbilical cord was clamped routinely after 30 seconds and values might differ in neonates with delayed umbilical cord clamping or physiological based cord clamping.

This is the first publication of capillary acid base and blood gas values immediately after the birth of healthy term neonates after uncomplicated neonatal transition after cesarian section. The presented acid base and blood gas values can be considered as normative values for a capillary blood sample about 15–20 minutes after birth. Major deviations from these values might be interpreted as potentially pathological and should lead to a re-evaluation of the newborn.

Ethics approval and consent to participate

The study was conducted according to the guidelines of the Declaration of Helsinki, and the study protocol was approved by the Regional Committee on Biomedical Research Ethics (EC Number: 27-465 ex 14/15), Medical University of Graz.

Consent for publication

Not applicable

Availability of data and materials

The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no competing interests

Funding

None

Authors’ contributions

Conception and design: NBS, BS, BU, GP
Administrative support: CW, MB
Provision of study materials or patients: NBS, MB, BS, CW
Collection and assembly of data: NBS, MB, CW, GP
Data analysis and interpretation: NBS, GP, BU
Manuscript writing: All authors
Final approval of manuscript: All authors

Acknowledgement

We would like to thank the parents for allowing us to study their infants, as well as all the midwives, nurses and physicians involved in the treatment of these neonates.

1 JAMES LS, WEISBROT IM, PRINCE CE, HOLADAY DA, APGAR V: The acid-base status of human infants in relation to birth asphyxia and the onset of respiration. J Pediatr 1958;52:379-394.
2 Armstrong L, Stenson BJ: Use of umbilical cord blood gas analysis in the assessment of the newborn. Arch Dis Child Fetal Neonatal Ed 2007;92:F430-4.
3 ACOG Committee on Obstetric Practice: ACOG Committee Opinion No. 348, November 2006: Umbilical cord blood gas and acid-base analysis. Obstet Gynecol 2006;108:1319-1322.
4 Ferreira CS, Melo Â, Fachada AH, Solheiro H, Nogueira Martins N: Umbilical Cord Blood Gas Analysis, Obstetric Performance and Perinatal Outcome. Rev Bras Ginecol Obstet 2018;40:740-748.
5 Sheikh M, Zoham MH, Hantoushzadeh S, Shariat M, Dalili H, Amini E: Umbilical blood gas analysis in preeclamptic versus healthy pregnancies with preterm birth. J Matern Fetal Neonatal Med 2016;29:2549-2554.
6 De Paco C, Florido J, Garrido MC, Prados S, Navarrete L: Umbilical cord blood acid-base and gas analysis after early versus delayed cord clamping in neonates at term. Arch Gynecol Obstet 2011;283:1011-1014.
7 Victory R, Penava D, Da Silva O, Natale R, Richardson B: Umbilical cord pH and base excess values in relation to adverse outcome events for infants delivering at term. Am J Obstet Gynecol 2004;191:2021-2028.
8 Thorp JA, Rushing RS: Umbilical cord blood gas analysis. Obstet Gynecol Clin North Am 1999;26:695-709.
9 Courtney SE, Weber KR, Breakie LA, Malin SW, Bender CV, Guo SM, Siervogel RM: Capillary blood gases in the neonate. A reassessment and review of the literature. Am J Dis Child 1990;144:168-172.
10 Bresesti I, Bruckner M, Mattersberger C, Baik-Schneditz N, Schwaberger B, Mileder L, Avian A, Urlesberger B, Pichler G: Feasibilty of Transcutaneous pCO(2) Monitoring During Immediate Transition After Birth-A Prospective Observational Study. Front Pediatr 2020;8:11.
11 Wyllie J, Bruinenberg J, Roehr CC, Rudiger M, Trevisanuto D, Urlesberger B: European Resuscitation Council Guidelines for Resuscitation 2015: Section 7. Resuscitation and support of transition of babies at birth. Resuscitation 2015;95:249-263.
12 Dawson JA, Kamlin COF, Wong C, Te Pas AB, Vento M, Cole TJ, Donath SM, Hooper SB, Davis PG, Morley CJ: Changes in heart rate in the first minutes after birth. Archives of Disease in Childhood: Fetal and Neonatal Edition Invalid date;95:F177-F181.
13 Pichler G, Cheung PY, Binder C, O'Reilly M, Schwaberger B, Aziz K, Urlesberger B, Schmölzer GM: Time course study of blood pressure in term and preterm infants immediately after birth. PLoS One 2014;9:e114504.
14 Cousineau J, Anctil S, Carceller A, Gonthier M, Delvin EE: Neonate capillary blood gas reference values. Clin Biochem 2005;38:905-907.
15 Saili A, Dutta AK, Sarna MS: Reliability of capillary blood gas estimation in neonates. Indian Pediatr 1992;29:567-570.

No competing interests reported.

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Acid Base and Blood Gas Analysis in Term Neonates Immediately After Birth with Uncomplicated Neonatal Transition

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