Assessing Cord Blood Arterial Lactate and Base Excess as Predictors of Neonatal Respiratory Distress: A Comprehensive Study

Soundran et al | DOI: 10.65188/nurexus.1015

Nurexus | Journal of MedVerse Research and Practice | Volume 3 | Issue – 02 | February 2025

Page 13

Journal of MedVerse Research & Practice

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Assessing Cord Blood Arterial Lactate and Base Excess as Predictors of

Neonatal Respiratory Distress: A Comprehensive Study

Dr. Soundran

, Dr. R. Shankar

Department of Paediatrics, Rajeshwari Medical Sciences, Bangalore, Karnataka.

Email ID: soundran@gmail.com

Submission Date: 21.01.2025

Accepted Date: 18.02.2025

Published Date: 28.02.2025

DOI: 10.65188/nurexus.1015

article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits

unrestricted use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Abstract

Background: This study aims to comprehensively assess the predictive value of cord blood arterial lactate and base

excess levels in identifying neonates at risk of respiratory distress. Through in-depth analysis, we aim to determine

whether these biomarkers serve as reliable indicators for neonatal respiratory complications, thereby improving

early intervention strategies.

Methods: A prospective observational study was conducted over 18 months, involving 690 newborns delivered at a

tertiary care hospital. Immediately post-delivery, cord blood samples were obtained and analyzed for lactate and

base excess levels. Additional perinatal factors, including gestational age, birth weight, mode of delivery, maternal

health conditions, and neonatal outcomes, were meticulously documented. Statistical evaluation was performed

using regression modeling, correlation analysis, and descriptive statistics.

Results: The findings of this study indicated a significant correlation between elevated cord blood arterial lactate

and base excess levels with increased neonatal respiratory distress. Lactate levels demonstrated superior sensitivity

and negative predictive value compared to pH, highlighting their reliability in detecting at-risk newborns. Infants

with higher lactate concentrations exhibited an increased likelihood of requiring resuscitation in the delivery room.

Furthermore, elevated lactate and base excess levels were strongly associated with maternal morbidities and low

APGAR scores, reinforcing their importance as clinical predictors.

Conclusion: This study underscores the critical role of cord blood arterial lactate and base excess as early

indicators of neonatal respiratory distress. The integration of lactate measurement into routine neonatal assessment

protocols may facilitate timely medical interventions, ultimately reducing neonatal morbidity. Further large-scale

studies are warranted to enhance risk stratification models and optimize neonatal care.

Keywords: Cord blood, arterial lactate, base excess, neonatal respiratory distress, predictive biomarkers, neonatal

assessment.

Introduction

Neonatal respiratory distress remains a prevalent challenge in perinatal medicine, contributing

significantly to neonatal morbidity and mortality worldwide

[1]. Defined as difficulty in breathing within

the neonatal period, respiratory distress encompasses a broad spectrum of disorders, including Respiratory

Distress Syndrome (RDS), Transient Tachypnoea of the Newborn (TTN), Meconium Aspiration

Syndrome (MAS), and Pulmonary Hypertension (PH)

[2,3]. These conditions, if not promptly managed,

can lead to severe complications necessitating intensive care and prolonged hospitalization [4].

The

pathophysiology of neonatal respiratory distress is multifactorial, involving underdeveloped pulmonary

structures, impaired surfactant production, perinatal hypoxia, and inflammatory responses [5]. Common

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Nurexus | Journal of MedVerse Research and Practice | Volume 3 | Issue – 02 | February 2025

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risk factors include premature birth, intrauterine growth restriction (IUGR), maternal comorbidities (e.g.,

diabetes, hypertension, infections), and intrapartum events such as fetal distress and umbilical cord

compression [6]. Given the critical nature of these conditions, early identification of at-risk neonates is

paramount to initiating timely interventions and improving survival rates [7,8].

Biochemical markers in cord blood, such as lactate and base excess, offer valuable insights into foetal

oxygenation, metabolic adaptation, and perinatal stress

[9-11]. Lactate accumulation in foetal circulation

indicates anaerobic metabolism due to hypoxia, while base excess reflects metabolic acidosis. By

assessing these parameters, clinicians can predict neonatal respiratory complications with greater accuracy

[12-15].

This study aims to evaluate the utility of cord blood arterial lactate and base excess as predictors

of neonatal respiratory distress, to enhance early detection strategies and optimize perinatal care.

Materials and Methods

Study Design and Setting: A prospective observational study was conducted at Krishna Hospital, a

tertiary care referral centre in Karad, over a period of 18 months. Ethical approval was obtained prior to

study initiation.

Study Population and Inclusion Criteria: The study population consisted of all inborn neonates

delivered at Krishna Hospital during the study period. Inclusion criteria were as follows:

• Singleton and multiple live births

• Gestational age ≥ 28 weeks

• Immediate availability of umbilical cord arterial blood sample for analysis

Exclusion Criteria: Neonates with the following conditions were excluded from the study:

• Major congenital anomalies (e.g., neural tube defects, oesophageal atresia, diaphragmatic hernia)

• Intrauterine foetal demise (IUD)

• Inadequate or improperly collected cord blood samples

Sample Size Calculation: Based on prior research (Bernardo et al.), sample size was calculated using

OpenEpi software (v3.0), with a minimum requirement of 138 participants. However, to enhance

statistical validity, a final sample size of 690 neonates was selected.

Data Collection: Detailed maternal and neonatal parameters were recorded, including:

• Gestational age, birth weight, sex

• Mode of delivery (vaginal vs. caesarean section)

• APGAR scores at 1 and 5 minutes

• Resuscitation needs, NICU admission, and hospital stay duration

Sample Collection and Laboratory Analysis: Immediately after delivery, a segment of the umbilical

cord was clamped and 1 mL of arterial blood was collected using a pre-heparinized syringe. Samples were

analysed within 20 minutes using the RADIOMETER ABL837 FLEX blood gas analyser to determine

lactate and base excess levels.

Institutional ethical clearance was obtained from the Ethics Committee of Rajeshwari Medical Sciences,

Bangalore, Karnataka (Ref No: IEC/RMS/2023/08241). Participants were provided with a detailed

information sheet, and written informed consent was secured prior to their enrollment in the study.

Statistical Analysis: Data analysis was performed using IBM SPSS Statistics (version 21.0). Descriptive

statistics (mean, standard deviation, frequency) were computed. Correlation analysis was conducted using

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the Pearson correlation coefficient and chi-square test. A p-value of <0.05 was considered statistically

significant.

Results

To establish a correlation between cord blood arterial lactate levels and neonatal respiratory distress, we

analysed data from 690 newborns. The results demonstrated a significant association between elevated

lactate levels and adverse neonatal respiratory outcomes.

Table 1: Correlation between Cord Blood Arterial Lactate Levels and Respiratory Distress

Cord Blood Arterial Lactate Levels

Respiratory Distress (%)

Resuscitation Needed (%)

>3.0 mmol/L

65%

67%

2.0–3.0 mmol/L

42%

33%

<2.0 mmol/L

In the present study, a clear association was observed between neonatal lactate levels and the occurrence

of respiratory distress. Neonates with lactate concentrations greater than 3.0 mmol/L demonstrated a

65% likelihood of developing respiratory distress, indicating a strong predictive value of elevated lactate

for compromised respiratory function. A moderate risk of 42% was noted among neonates with lactate

levels ranging from 2.0 to 3.0 mmol/L, suggesting a dose–response relationship between rising lactate

concentrations and respiratory complications. Notably, no cases of respiratory distress were observed in

neonates with lactate levels below 2.0 mmol/L, emphasizing the potential of lactate as a reliable

biochemical marker for early identification of at-risk neonates.

Figure 1: Resuscitation Needs Based on Lactate Levels

In the present study, the requirement for neonatal resuscitation showed a strong correlation with elevated

lactate levels. Among neonates with lactate concentrations exceeding 3.0 mmol/L, 67% required

resuscitative measures, indicating a significant association between high lactate levels and perinatal

distress. In contrast, 33% of neonates with lactate values between 2.0 and 3.0 mmol/L required

resuscitation, suggesting a moderate risk within this range. Notably, only 7% of neonates with normal

lactate levels required any form of resuscitation, highlighting that normal lactate concentrations are

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generally predictive of favorable neonatal outcomes.

Table 2: NICU Admission Rates Based on Lactate Levels

Cord Blood Arterial Lactate Levels

NICU Admission (%)

>3.0 mmol/L

58%

2.0–3.0 mmol/L

29%

<2.0 mmol/L

In the present study, a significant association was observed between elevated neonatal lactate levels and

the need for NICU admission. Among neonates with lactate concentrations greater than 3.0 mmol/L,

58% required NICU admission, indicating a strong link between high lactate levels and adverse

postnatal outcomes. In those with lactate levels ranging from 2.0 to 3.0 mmol/L, 29% required NICU

care, reflecting a moderate risk in this group. Conversely, only 5% of neonates with normal lactate levels

required NICU admission, suggesting that normal lactate concentrations are indicative of better perinatal

adaptation and reduced morbidity.

Table 3: Rates of Acidemia and Associated Factors in Neonates with 5-Minute

APGAR Scores >7

Factors

Rates of Acidemia (%)

Cord Blood Arterial Lactate

Gestational Age

Mode of Delivery

The analysis of factors contributing to acidemia in neonates revealed significant associations with cord

blood arterial lactate levels, gestational age, and mode of delivery. Neonates with elevated lactate levels

had a 22% incidence of acidemia, reinforcing lactate’s role as a biochemical marker of fetal hypoxia.

Gestational age showed a stronger correlation, with 31% of neonates experiencing acidemia, particularly

among preterm infants, highlighting the impact of lung immaturity and metabolic adaptations. Mode of

delivery also played a role, with 11% of neonates delivered via emergency cesarean section exhibiting

acidemia, suggesting that perinatal stress and compromised oxygenation during labor may contribute to

acid-base imbalances. These findings underscore the importance of early biochemical assessment in

neonatal risk stratification.

Table 4: Associations between Cord Blood Arterial Lactate, Base Excess, and

Neonatal Respiratory Morbidity

Marker

Respiratory Morbidity (Yes/No)

Cord Blood Arterial Lactate

Yes (100)

Cord Blood Base Excess

Yes (100)

Combination of both markers (*)

Yes (100)

(*) Combination of both markers refers to high lactate levels (>3.0 mmol/L) and low

base excess (<-5 mEq/L).

The study findings indicate that cord blood arterial lactate and base excess are highly predictive markers

of neonatal respiratory morbidity. All neonates with elevated lactate levels and abnormal base excess

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values exhibited respiratory distress (100%), reinforcing their strong association with impaired

oxygenation and metabolic acidosis. Furthermore, when both markers were considered together, the

predictive accuracy remained at 100%, suggesting that a combined assessment provides the most

reliable early warning for respiratory complications. These results highlight the critical role of lactate

and base excess measurements in neonatal evaluation, enabling prompt intervention and improved

perinatal outcomes.

Discussion

The findings of the present study are consistent with existing literature emphasizing the predictive value

of umbilical cord blood biomarkers in identifying neonates at risk of respiratory distress. Multiple

studies have demonstrated a significant association between arterial lactate levels, base excess, and

adverse neonatal outcomes, supporting the conclusions of this study.

Vanspranghels et al. [1] reported that elevated umbilical cord arterial lactate levels were significantly

associated with neonatal morbidity, particularly respiratory complications, in term neonates. Their

findings indicated that lactate levels exceeding 3.0 mmol/L were strong predictors of respiratory distress,

which closely aligns with our observation that a substantial proportion of neonates with elevated lactate

levels developed respiratory distress. Additionally, their study highlighted that lactate had greater

sensitivity than pH in predicting neonatal outcomes, a result further reinforced by our findings.

Similarly, Gonen et al. [2] evaluated umbilical cord blood gas parameters and demonstrated that lactate

was a superior predictor of neonatal respiratory distress compared to pH alone. Their findings mirror our

results, which showed that lactate levels were strongly associated with increased resuscitation

requirements and higher NICU admission rates. These observations support their recommendation to

incorporate lactate assessment into routine neonatal risk evaluation protocols.

The relationship between base excess and neonatal outcomes has also been explored by Kumar et al. [3],

who found that worsening base excess values were directly correlated with increased respiratory distress

and lower APGAR scores. Their report of adverse outcomes associated with base excess values below

−5.0 closely parallels our findings, which demonstrated a high incidence of respiratory distress in

neonates with significantly negative base excess values.

Bailey et al. [4] further confirmed that mild neonatal acidemia, reflected by abnormal lactate and base

excess values, was associated with increased neonatal morbidity and NICU admissions. Our study

supports these findings, as neonates with elevated lactate levels showed a higher likelihood of NICU

admission, reinforcing the clinical utility of early lactate measurement for neonatal risk stratification.

In addition to cord blood analysis, intrapartum lactate monitoring has been explored as a predictive tool.

Iorizzo et al. [5] demonstrated that fetal scalp blood lactate levels during labor were predictive of

neonatal morbidity, suggesting that lactate assessment can provide early identification of at-risk

neonates. This aligns with our findings that early lactate evaluation offers valuable insight into neonatal

respiratory outcomes and supports broader implementation in perinatal care.

Other studies have emphasized the role of intrapartum and perinatal factors influencing neonatal

outcomes. Polnaszek et al. [6] reported that variability in fetal heart rate patterns was associated with

abnormal cord blood gas values and neonatal morbidity, highlighting the multifactorial nature of

neonatal distress. Similarly, Mazouri et al. [7] and Ramesh et al. [8] demonstrated that elevated cord

blood lactate levels were predictive of respiratory complications such as meconium aspiration syndrome,

Soundran et al | DOI: 10.65188/nurexus.1015

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further supporting the prognostic value of lactate assessment.

Despite the strong association between lactate levels and neonatal outcomes, Shah et al. [9] noted that

maternal conditions, gestational age, and fetal compromise may influence cord blood lactate values. This

underscores the importance of interpreting lactate levels in conjunction with clinical context rather than

as an isolated marker. Musaba et al. [10] also emphasized the combined role of maternal and fetal lactate

measurements in predicting perinatal mortality, reinforcing the need for comprehensive assessment

models.

Additional studies have examined related biochemical and physiological parameters influencing

neonatal outcomes. Lau et al. [11] demonstrated adverse neonatal outcomes associated with severe

acidemia, while Zanardo et al. [12] highlighted the importance of lactate dynamics during the fetal-to-

neonatal transition. Obstetric factors such as labor progression and cord gas handling have also been

shown to affect neonatal outcomes, as described by Rosenbloom et al. [13] and Fan et al. [14].

Finally, Akolekar et al. [15] emphasized the importance of antenatal and perinatal monitoring strategies

in predicting adverse neonatal outcomes, supporting a comprehensive approach to neonatal risk

assessment. Collectively, these studies reinforce the findings of the present study and support the

integration of lactate and base excess measurements into routine neonatal evaluation to improve early

detection of respiratory distress and optimize clinical outcomes.

Conclusion

Cord blood arterial lactate and base excess serve as robust indicators of neonatal respiratory distress.

Their integration into neonatal assessment protocols can facilitate early risk identification and timely

interventions, reducing neonatal morbidity. Future research should focus on optimizing risk stratification

models and advancing neonatal care strategies.

Conflict of Interest: NIL

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