Original Article
Pulse Oximetry Measures a Lower Heart Rate at Birth Compared with Electrocardiography

https://doi.org/10.1016/j.jpeds.2014.09.015Get rights and content

Objective

To examine the effect of time after birth on heart rate (HR) measured by pulse oximetry (PO) (HRPO) and electrocardiography (ECG) (HRECG).

Study design

HRECG and HRPO (collected at maximum sensitivity) were assessed in 53 term and preterm infants at birth. ECG electrodes and a PO sensor were attached as soon as possible and HRECG and HRPO were compared every 30 seconds from 1-10 minutes after birth. Data were compared using a Wilkinson signed-rank test. Clinical relevance (eg, HR <100 beats per minute [bpm] was tested using a McNemar test).

Results

Seven hundred fifty-five data pairs were analyzed. Median (IQR) gestational age was 37 (31-39) weeks. Mean (SD) starting time of PO and ECG data collection was 99 (33) vs 82 (26) seconds after birth (P = .001). In the first 2 minutes after birth, HRPO was significantly lower compared with HRECG (94 (67-144) vs 150 (91-153) bpm at 60 seconds (P < .05), 81 (60-109) vs 148 (83-170) bpm at 90 seconds (P < .001) and 83 (67-145) vs 158 (119-176) at 120 seconds (P < .001). A HR <100 bpm was more frequently observed with a PO than ECG in the first 2 minutes (64% vs 27% at 60 seconds (P = .05), 56% vs 26% at 90 seconds (P < .05) and 53% vs 21% at 120 seconds (P < .05). HR by ECG was verified by ultrasound for outflow from a subset of infants.

Conclusions

In infants at birth, HRPO is significantly lower compared with ECG with clinically important differences in the first minutes.

Section snippets

Methods

This prospective observational study was conducted in the Department of Neonatology of the Leiden University Medical Center, Leiden, The Netherlands, with approval from the institutional review board. Informed parental consent was asked before birth. In the event this was deemed not suitable (eg, because of the clinical condition of the mother), permission to use the data was asked after birth. Permission was acquired both verbally and in writing. Term and preterm infants born vaginally or by

Results

Data were collected from 52 infants, of which 4 infants were excluded because of technical problems with the PO or PO data that were not collected. Of the 48 infants included in the analyses, paired HR measurements were compared every 30 seconds (in total 755 data pairs). In 14 infants, the initiation of cardiac contraction was demonstrated by a Doppler flow profile over the left ventricular outflow tract assessed using ultrasonography following an ECG-complex. The mean (SD) time taken to

Discussion

We measured HRECG and HRPO in infants during the first 10 minutes after birth. Using Doppler measurements, we confirmed that each QRS complex, detected by ECG, was associated with a ventricular contraction and subsequent cardiac output. However, we observed that until 7 minutes after birth, HRPO was significantly lower than HRECG. As ECG is the gold standard, our findings imply that PO underestimates HR compared with ECG in the first minutes after birth. Although HRPO starts low and increased

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A.tP. is recipient of a Veni-grant, The Netherlands Organization for Health Research and Development (ZonMw), part of the Innovational Research Incentives Scheme Veni-Vidi-Vici (91612027). J.vV. is recipient of a Willem-Alexander Children's Foundation scholarship. The authors declare no conflicts of interest.

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