Abstract
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Objective
This study assessed the efficacy of electrocardiogram (ECG) compared to pulse oximetry (PO) in detecting heart rate (HR) during high-risk newborn resuscitation.
-
Methods
A prospective observational study was performed with high-risk delivery cases to measure the time required for HR detection. A conventional PO and a standard ECG monitor were used for HR assessment.
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Results
Forty-one infants were analyzed in the study, and 11 needed resuscitation. The study population was divided according to gestational age (GA): 9 were GA <32 weeks, 28 were GA 32–35 weeks, and 4 were GA ≥36 weeks. Time from ECG placement to HR detection (median, 30 seconds; interquartile range [IQR], 20–43.5 seconds) was significantly faster than that from PO placement (median, 125 seconds; IQR, 100–175 seconds; P<0.001). Time from ECG placement to HR detection was shortest in infants with GA <32 weeks at birth (19 seconds [IQR, 11.5–30.0] for GA <32 weeks vs. 34.5 seconds [IQR, 25.0–44.3] for GA 32–35 weeks vs. 39.5 seconds [IQR, 30.0–64.8] for GA ≥36 weeks; P=0.039).
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Conclusion
ECG effectively evaluated HR during neonatal resuscitation compared to PO. Low-GA infants who require resuscitation may benefit from HR evaluation with nearby standard ECG.
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Keywords: Heart rate; Newborn infant; Resuscitation; Electrocardiogram; Oxygen saturation monitor
Capsule Summary
What is already known
Newborn resuscitation guidelines recommend electrocardiogram heart rate monitoring.
What is new in the current study
The study demonstrates support for the use of any nearby standard electrocardiogram in resource-poor areas for efficient heart rate assessment during high-risk deliveries, especially in preterm birth before 32 weeks of gestational age.
INTRODUCTION
When a baby is born, the heart rate (HR) is used to assess the efficiency of spontaneous breathing and the need for interventions such as positive pressure ventilation. HR is the most important and sensitive indicator in neonatal resuscitation; thus, interventions are initiated based on HR, and increase in HR to the normal range is the first sign of a resuscitation response [
1,
2]. Therefore, fast and accurate estimation of HR is important in neonatal resuscitation. Neonatal resuscitation guidelines recommending a stethoscope and pulse oximetry (PO) ± electrocardiogram (ECG) assessment for HR determination are weak, based on limited, very low-quality evidence [
1–
4]. A stethoscope is initially useful in traditional resuscitation, but ongoing resuscitation requires a tool that continuously and accurately monitors HR.
Several studies suggest that ECG is faster and more accurate for HR assessment at birth relative to PO [
5–
8]. However, ECG monitoring is unavailable in many hospitals because the guideline does not specify such methods in the delivery room environment. Therefore, our study assessed the use of a nearby standard ECG monitor with standard newborn three-lead gel electrodes during high-risk deliveries. The primary outcome of the study was to examine the efficiency of HR assessment using ECG compared to PO in high-risk newborn resuscitation.
METHODS
Ethics statement
This study was reviewed and approved by the Institutional Review Board of Kangwon National University Hospital (No. KNUH-2020-02-001-001). Written informed parental consent was obtained prior to infant enrollment.
Study population
This prospective observational study was performed between March 2020 and February 2021. High-risk births needing physician attendance (preterm deliveries, deliveries of non-reassuring fetus such as fetal distress, severe fetal growth restriction, fetal anomalies, or deliveries of inappropriate antenatal care) were included in the study. Because informed consent was obtained before delivery and the attending team prepared study equipment that could record only one infant, the study only included cesarean section singleton delivery cases. The study population was divided according to gestational age (GA): 9 were GA <32 weeks, 28 were GA 32–35 weeks, and 4 were GA ≥36 weeks.
Study protocol
Resuscitation followed the 2015 Neonatal Resuscitation Program (NRP) guidelines [
1,
2]. Despite the introduction of new guidelines in 2020 [
3,
4], they had not yet been widely implemented, so the previous guidelines were used in the study. Resuscitation of all newborns started with 21% oxygen, and the fraction of inspired oxygen was adjusted every 30 seconds to meet the NRP recommended PO saturation goal.
A conventional PO (TruSat Pulse Oximeter, GE Datex-Ohmeda) with an adhesive oximeter sensor was used. A Mediana D500 ECG monitor (Mediana Co, Ltd) was used with disposable electrodes (Pro-Neo, Meridius Medical Europe Ltd). This ECG monitor is used as a monitor and a defibrillator in cardiopulmonary resuscitation events and is kept in every ward of our hospital next to the emergency cart. Disposable neonatal three-lead gel electrodes are commonly used in our neonatal intensive care unit. A researcher wore an action camera (GoPro 10, GoPro Inc) on her head throughout the study period. PO and ECG placement occurred at the time of delivery as a part of standard care for our study population. For standard care, at least three medical personnel (doctor, physician assistant nurse, and delivery nurse or resident doctor) participated in every high-risk birth during the study period. According to the NRP flow, the physician assistant and delivery nurse simultaneously attached the ECG and PO, respectively, just after initial care of the newborn infants.
Outcome measures
Two points were collected from the video of the action camera: (1) the time for PO and ECG placement and (2) the time for HR detection with recognizable PO monitor waves or recognizable QRS complexes on the ECG monitor. The accuracy of HR detection by PO or ECG was double-checked by manual HR detection using a stethoscope by physicians with verbalization according to the NRP flow.
Statistical analysis
The G*Power program calculator (Heinrich Heine University Düsseldorf) was used for sample size estimation. From one pilot newborn infant from our hospital, a twofold difference in ECG and PO HR detection time was estimated. Thus, assuming an α error of 0.05 and an effect size of 0.5, the minimum sample size was 34 with a power (1–β) of 0.8 in paired t-tests. Because the data were nonparametric, Wilcoxon tests were used for ECG versus PO comparisons and Kruskal-Wallis tests were used for comparisons according to GA groups. Statistical analyses were performed using IBM SPSS ver. 29.0 (IBM Corp). A P-value of <0.05 was considered significant.
RESULTS
During the study period, 83 cases were classified as high-risk births, 23 were vaginally delivered, and 18 were twins; all of these were excluded from the study. Consent was obtained in all remaining cases, one of which was excluded because the video was obscured. Finally, 41 cases were analyzed in the study (
Table 1).
Eleven newborns needed positive pressure ventilation, and one infant was intubated. None of the patients required chest compressions. The average Apgar score was 7 (interquartile range [IQR], 6–8) at 1 minute and 9 (IQR, 8–9) at 5 minutes. All studied infants were discharged alive.
The median time for both PO and ECG placement from birth was 22 seconds. The median time for PO and ECG HR detection after placement was 125 and 30 seconds, respectively. Time from ECG placement to HR detection was significantly faster than time from PO placement to HR detection (P<0.001). Initial HR with ECG detection was significantly lower than initial HR with PO detection (134.0 [IQR, 112.0–148.0] vs. 150.0 [IQR, 130.0–163.5], P<0.001) (
Table 2 and
Fig. 1).
When the study population was divided into three GA groups (<32, 32–35, and ≥36 weeks), the median time for ECG HR detection after placement was significantly fastest in the youngest GA group (19 seconds, P=0.039) (
Table 2 and
Fig. 2).
DISCUSSION
In this study, HR detection in high-risk infants at birth was faster with ECG monitoring than with PO. HR in preterm infants younger than GA 32 weeks who needed more frequent resuscitation at birth was more effectively evaluated by ECG than by PO monitoring.
The timing of HR detection by ECG or PO in the study cohort was comparable to that of other studies. In our study, time from PO placement to HR detection was 125 seconds (IQR, 100–175 seconds), while a study conducted by Katheria et al. [
6], which included 40 preterm infants (mean GA, 28 weeks), showed a PO HR detection time of 114±39 seconds. Mizumoto et al. [
7] studied 20 newborn infants (mean GA, 36 weeks), finding a PO HR detection time of 122 seconds (IQR, 101–146 seconds), similar to our study results. Furthermore, their study showed an ECG HR detection time as 38 seconds (IQR, 34–43 seconds). A study including 30 very-low-birth weight infants (mean GA, 27 weeks), 28 of whom required resuscitation, reported a median ECG HR detection time of 26 seconds (IQR, 17–41 seconds) [
5]. Another study, which included a large number of preterm and term newborn infants (n=334), reported a median ECG HR detection time of 29 seconds (IQR, 5–60 seconds) [
8]. In our study, the ECG HR detection time was 30 seconds (IQR, 20–43.5 seconds), similar to those of the aforementioned studies.
Preterm infants younger than GA 32 weeks showed the fastest HR detection. Gulati et al. [
8] conducted a study similar to ours, and the results showed significantly faster ECG HR detection in preterm infants younger than GA 31 weeks than that in infants with GA 31 weeks and above (10 seconds [IQR, 2–40 seconds] vs. 30 seconds [IQR, 5–60 seconds]). Low-GA infants without skin vernix may not move excessively, decreasing motion artifacts. With increasing GA, thick skin vernix appears, attributing to the insufficient drying of infants, delaying HR detection by ECG.
The initial HR detection by ECG was significantly lower, as well as faster, than that of the PO in our study, which suggests that ECG is better at detecting lower HR than PO. A study by van Vonderen et al. [
9], which monitored 53 term and preterm infants simultaneously with ECG and PO after birth, showed significantly lower PO HR than ECG HR, implying that PO underestimates HR compared to ECG in the first minutes after birth. In addition, Iglesias et al. [
10] monitored 29 episodes of bradycardia in the delivery room of preterm infants (mean GA, 29.5 weeks) and found PO to detect the start and recovery of bradycardia events slower and less accurately than ECG during stabilization at birth. The discrepancy between PO and ECG may be due to hemodynamic instability and hypoperfusion interfering with PO function. Because of the relative superiority of ECG over PO in HR detection just after delivery, ECG seems to decrease intubation frequency and increase cardiac compression frequency [
11], while a randomized controlled study showed that ECG monitoring did not reduce time to stabilization during preterm resuscitation [
12]. The outcomes of ECG monitoring during newborn resuscitation need to be further studied.
Recently, new interfaces for ECG monitoring including dry-electrode ECG was introduced for rapid HR detection [
13–
15]. ECG monitoring with classical gel electrodes is sometimes difficult due to the damp skin of newborn infants. Thus, dry-electrode ECG was suggested for fast HR detection. In addition, a new ECG algorithm study reported rapid HR detection [
16]. Instead of the usual ECG monitor algorithm, which requires time for analysis of several beats before displaying HR, a novel ECG algorithm using statistical techniques to buffer HR values showed shortened HR detection time. However, in many hospitals, there is a practical inability to utilize advanced ECG devices, despite the recommendation of ECG by the NRP guidelines. Furthermore, the NRP guidelines do not provide specific methods for ECG in the delivery room environment. In the study cohort, a domestically manufactured ECG monitor, readily available as a defibrillator in a cardiopulmonary resuscitation cart, was used with standard newborn three-lead gel electrodes. The study methodology aims to improve the accessibility of ECG monitoring in the delivery room environment for newborns requiring resuscitation.
One limitation of the study was the low resuscitation rate. However, resuscitation rate was higher in neonates younger than GA 32 weeks, in whom HR detection by ECG was more effective. The other limitation of the study is that the sample size was small, and the distribution of infants was not even according to GA. Thus, effectiveness of ECG HR detection for high-risk deliveries should be further evaluated with larger numbers of preterm and term infants who require resuscitation from a larger, multicenter study.
In conclusion, ECG provided earlier HR detection than PO, and the HR of preterm infants younger than GA 32 weeks was more effectively evaluated by ECG than by PO monitoring. The study findings support the use of any conventional ECG for high-risk preterm deliveries.
NOTES
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Author contributions
Conceptualization: ESK; Data curation: ESK; Formal analysis: KHC, HSL; Supervision: ESK; Writing–original draft: KHC; Writing–review & editing: all authors. All authors read and approved the final manuscript.
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Conflicts of interest
The authors have no conflicts of interest to declare.
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Funding
The authors received no financial support for this study.
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Acknowledgments
The authors thank Juhyun Bang (physician assistant nurse; Department of Pediatrics, Kangwon National University Hospital, Chuncheon, Korea) who helped with data acquisition.
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Data availability
Data analyzed in this study are available from the corresponding author upon reasonable request.
Fig. 1.Heart rate (HR) detection time after electrocardiogram (ECG) placement versus pulse oximetry (PO; P<0.001).
Fig. 2.Heart rate (HR) detection time by electrocardiogram according to gestational age (GA) groups (P=0.039).
Table 1.Characteristics of study infants
Table 1.
|
Characteristic |
Total (n=41) |
GA
|
|
<32 wk (n=9) |
32–35 wk (n=28) |
≥36 wk (n=4) |
|
GA (wk) |
33.68±2.34 |
30.29±0.94 |
34.19±0.89 |
37.75±2.17 |
|
Birth weight (kg) |
2.03±0.57 |
1.49±0.18 |
2.07±0.48 |
2.92±0.40 |
|
Male sex |
21 (51.2) |
4 (44.4) |
16 (57.1) |
1 (25.0) |
|
Apgar score |
|
|
|
|
|
At 1 min |
7 (6–8) |
4 (3–7.5) |
8 (7–8) |
7.5 (7–8) |
|
At 5 min |
9 (8–9) |
8 (7–9) |
9 (8.3–9) |
9 (9–9) |
|
Resuscitated |
11 (26.8) |
4 (44.4) |
7 (25.0) |
0 (0) |
Table 2.ECG- or PO-assessed HR results based on GA group
Table 2.
|
Variable |
Total (n=41) |
GA
|
P-value |
|
<32 wk (n=9) |
32–35 wk (n=28) |
≥36 wk (n=4) |
|
ECG |
|
|
|
|
|
|
PT (sec) |
22.0 (19.5–30.0) |
25.0 (20.0–36.5) |
21.5 (17.5–27.5) |
24.5 (16.0–32.3) |
0.462 |
|
DT (sec) |
60.0 (45.0–70.0) |
49.0 (37.5–65.0) |
60.0 (45.3–70.0) |
64.0 (48.8–94.3) |
0.253 |
|
DT-PT (sec) |
30.0 (20.0–43.5) |
19.0 (11.5–30.0) |
34.5 (25.0–44.3) |
39.5 (30.0–64.8) |
0.039 |
|
Initial HR (bpm) |
134.0 (112.0–148.0) |
127.0 (83.5–143.0) |
134.0 (113.3–147.3) |
141.0 (140.3–174.5) |
0.056 |
|
PO |
|
|
|
|
|
|
PT (sec) |
22.0 (20.0–30.0) |
23.0 (20.0–36.5) |
22.0 (20.0–29.0) |
20.0 (19.3–29.8) |
0.554 |
|
DT (sec) |
155.0 (125.0–200.0) |
180.0 (101.0–200.0) |
162.5 (125.0–207.5) |
131.5 (120.0–141.5) |
0.534 |
|
DT-PT (sec) |
125.0 (100.0–175.0) |
160.0 (78.0–170.0) |
137.5 (102.3–188.8) |
112.0 (100.0–122.5) |
0.705 |
|
Initial HR (bpm) |
150.0 (130.0–163.5) |
150.0 (140.0–167.0) |
150.0 (130.0–161.3) |
136.0 (141.3–163.8) |
0.685 |
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