Heart rate, respiratory rate, apnoeas and peripheral arterial oxygen saturation in healthy term neonates during quiet sleep

Heart rate in newborns is associated with age, sex and maternal levothyroxine therapy

AIM

To evaluate the definition and causes of neonatal bradycardias.

METHODS

This retrospective study included 135 term-born newborns referred for 24-hour Holter monitoring due to bradycardia. Bradycardia was defined as either a heart rate below 80 beats per minute (standard definition) or a heart rate below our recently published age-specific reference values for neonatal heart rate.

RESULTS

The mean (SD) age was 6.1 (1.3) days. With standard definition, 107 newborns (79%) had bradycardia, whereas only 20 (15%) had a minimum heart rate lower than the age-specific reference. Younger newborns had lower heart rates. Each day increased the minimum, mean and maximum heart rate by 1.8 (95% CI: 1.0, 2.6), 4.2 (95% CI: 3.0, 5.3) and 2.1 beats per minute (95% CI: 0.3, 3.8), respectively. Male sex and maternal levothyroxine medication were negatively associated with the mean and maximum heart rate. None of the newborns had a cardiac cause for low heart rate.

CONCLUSION

Among term newborns with bradycardias, younger age, male sex and maternal levothyroxine medication were associated with a lower heart rate on Holter monitoring. Given the age-related increase in heart rate, the 80 beats per minute limit as a universal threshold for abnormal heart rate in newborns appears inappropriate.

Younger postnatal age is associated with a lower heart rate on Holter monitoring during the first week of life

To evaluate heart rate (HR), the presence of extrasystoles and other Holter findings among healthy newborns, and to collect data for new normal limits for Holter parameters in newborns. For this cross-sectional study, 70 healthy term newborns were recruited to undergo 24-h Holter monitoring. Linear regression analysis was used in HR analyses. The age-specific limits for HRs were calculated using linear regression analysis coefficients and residuals. The mean (SD) age of the infants was 6.4 (1.7) days during the recording. Each consecutive day of age raised the minimum and mean HR by 3.8 beats per minute (bpm) (95% CI: 2.4, 5.2; P < .001) and 4.0 bpm (95% CI: 2.8, 5.2; P < .001), respectively. Age did not correlate with maximum HR. The lowest calculated limit for minimum HR ranged from 56 bpm (aged 3 days) to 78 bpm (aged 9 days). A small number of atrial extrasystoles and ventricular extrasystoles were observed in 54 (77%) and 28 (40%) recordings, respectively. Short supraventricular or ventricular tachycardias were found in 6 newborns (9%).

CONCLUSION

 The present study shows an increase of 20 bpm in both the minimum and mean HRs of healthy term newborns between the 3rd and 9th days of life. Daily reference values for HR could be adopted in the interpretation of HR monitoring results in newborns. A small number of extrasystoles are common in healthy newborns, and isolated short tachycardias may be normal in this age group.

WHAT IS KNOWN

• The current definition of bradycardia in newborns is 80 beats per minute. • This definition does not fit into the modern clinical setting of continuously monitored newborns, where benign bradycardias are commonly observed.

WHAT IS NEW

• A linear and clinically significant increase in heart rate was observed in infants between the ages of 3 and 9 days. • It appears as though lower normal limits for heart rate could be applied to the youngest newborns.

Extrasystoles or short bradycardias of the newborn seldom require subsequent 24-hour electrocardiographic monitoring

AIM

To retrospectively assess the indications for and findings on 24-hour electrocardiographic (Holter) monitoring in newborns, focussing on bradycardias and extrasystoles.

METHODS

Data included 337 term-born infants. Holter indications were categorised into bradycardias below 80 beats per minute, extrasystoles, any tachycardia and other. Heart rate below 60 beats per minute, pathological atrioventricular conduction, supraventricular or ventricular tachycardia, or either atrial premature contractions over 10% or ventricular premature contractions over 5% of total beats were defined as significant arrhythmia on Holter.

RESULTS

The median age was 6 days (range: 2-62 days). Bradycardia (42%) or extrasystoles (32%) were the most common Holter indications. Fifty-three infants (16%) had significant arrhythmia on Holter. Heart disease or 12-lead electrocardiogram expressing extrasystoles or conduction abnormalities were associated with significant arrhythmias (p = 0.046 and p < 0.001, respectively). Twenty-seven of 109 infants (25%) with extrasystoles as a Holter indication had abnormal Holter results, but only seven (6.4%) had significant arrhythmia on Holter if the 12-lead electrocardiogram was normal. No pathology was found behind bradycardias below 80 beats per minute in the absence of heart disease.

CONCLUSION

Among term newborns with extrasystoles or bradycardias, Holter monitoring could be targeted to infants with heart disease or abnormal electrocardiograms.

Cardiorespiratory Events Following the Second Routine Immunization in Preterm Infants: Risk Assessment and Monitoring Recommendations

Due to frequent cardiorespiratory events (CREs) in response to the first routine immunization (rIM), current guidelines recommend readmitting and monitoring extremely preterm infants after the second rIM, though evidence on CREs in response to the second rIM is weak. In a prospective observational study, preterm infants with an increase in CREs after the first rIM were monitored for CREs before and after the second rIM. Seventy-one infants with a median gestational age of 26.4 weeks and a median weight of 820 g at birth were investigated at a median postnatal age of 94 days. All but seven infants showed an increase in CREs after the second rIM. The frequency of hypoxemias (p < 0.0001), apneas (p = 0.0003) and cardiorespiratory events requiring tactile stimulation (CRE-ts) (p = 0.0034) increased significantly. The 25 infants (35%) presenting with CRE-ts were significantly more likely to have been continuously hospitalized since birth (p = 0.001) and to receive analeptic therapy at the first rIM (p = 0.002) or some kind of respiratory support at the first (p = 0.005) and second rIM (p < 0.0001). At a postmenstruational age of 43.5 weeks, CRE-ts ceased. Our data support the recommendation to monitor infants who fulfil the above-mentioned criteria during the second rIM up to a postmenstruational age of 44 weeks.

Physiological vital sign reference ranges for well late preterm newborns calculated during a typical two-hour newborn period between 2 hours and 7 days of life

Objectives To calculate 95% reference ranges for heart rate, respiratory rate, oxygen saturation, temperature and blood pressure for well late preterm newborns between 34+0/7 and 36+6/7 weeks of gestation during typical neonatal behaviour. Approach A single site, prospective cohort study in a major Australian quaternary hospital between February and September 2019. A total of 120 late preterm newborns had their heart rate, respiratory rate and oxygen saturation measurements recorded every two seconds for up to two hours with unconditional 95% reference ranges determined using a linear mixed model with random intercept for total standard deviation calculation including repeated measures. Temperature and blood pressure measurements were collected twice - at the start and conclusion of the data recording period, with weighted 2.5th and 97.5th percentiles calculated using the mean value. Main results A total of 364,577 heart rate, 365,208 respiratory rate, 360,494 peripheral oxygen saturation, and 240 temperature and blood pressure values were obtained. The 95% reference ranges were: heart rate 102 - 164 bpm; respiratory rate 15 - 67 rpm; oxygen saturation 94 - 100%; temperature 36.4 - 37.6°C; systolic blood pressure 51 - 86 mmHg; diastolic blood pressure 28 - 61 mmHg; mean arterial pressure 35 - 68 mmHg. Significance Seven vital sign references ranges were reported for the late preterm population during a typical newborn period (such as crying, sleeping, feeding, awake and alert, and during nappy hygiene cares); internal and external validation should be completed prior to clinical use. Cut off points for escalation of care have previously been generalised to all newborns irrespective of gestational age which may result in over-treatment or a delay in recognising subtle signs of deterioration.

Mother's Bed Incline and Desaturation Episodes in Healthy Term Newborns during Early Skin-to-Skin Contact: A Multicenter Randomized Controlled Trial

INTRODUCTION

Early skin-to-skin contact (ESSC) is associated with rare, sudden, unexpected postnatal collapse episodes. Placing the newborn in ESSC closer to an upright position may reduce the risk of airway obstruction and improve respiratory mechanics. This study assessed whether a greater inclination of the mother's bed during ESSC would reduce the proportion of healthy term newborns (HTNs) who experienced episodes of pulse oximeter saturation (SpO2) <91%.

METHODS

We conducted a multicenter randomized controlled trial comparing the effect of the mother's bed incline, 45° versus 15°, on desaturation in HTNs during ESSC. Before delivery on 1,271 dyads, randomization was conducted, and stringent criteria to select healthy mothers and term newborns were monitored until after birth. Preductal SpO2 was continuously monitored between 10 min and 2 h after birth. The primary outcome was the occurrence of at least one episode of SpO2 <91%.

RESULTS

254 (20%) mother-infant dyads were eligible for analysis (45°, n = 126; 15°, n = 128). Overall, 57% (95% confidence interval [CI]: 51%-63%) of newborns showed episodes of SpO2 <91%. The proportion of infants with SpO2 <91% episodes was 52% in 45° and 62% in 15° (relative risk: 0.80; 95% CI: 0.6-1.07).

CONCLUSIONS

We did not show that a high mother bed inclination during ESSC led to significantly fewer HTNs who experienced episodes of SpO2 <91%. Desaturation episodes from 10 min to 2 h after birth occurred in more than half of HTNs.

How to Use Heart Rate Variability: Quantification of Vagal Activity in Toddlers and Adults in Long-Term ECG

Recent developments in noninvasive electrocardiogram (ECG) monitoring with small, wearable sensors open the opportunity to record high-quality ECG over many hours in an easy and non-burdening way. However, while their recording has been tremendously simplified, the interpretation of heart rate variability (HRV) data is a more delicate matter. The aim of this paper is to supply detailed methodological discussion and new data material in order to provide a helpful notice of HRV monitoring issues depending on recording conditions and study populations. Special consideration is given to the monitoring over long periods, across periods with different levels of activity, and in adults versus children. Specifically, the paper aims at making users aware of neglected methodological limitations and at providing substantiated recommendations for the selection of appropriate HRV variables and their interpretation. To this end, 30-h HRV data of 48 healthy adults (18–40 years) and 47 healthy toddlers (16–37 months) were analyzed in detail. Time-domain, frequency-domain, and nonlinear HRV variables were calculated after strict signal preprocessing, using six different high-frequency band definitions including frequency bands dynamically adjusted for the individual respiration rate. The major conclusion of the in-depth analyses is that for most applications that implicate long-term monitoring across varying circumstances and activity levels in healthy individuals, the time-domain variables are adequate to gain an impression of an individual’s HRV and, thus, the dynamic adaptation of an organism’s behavior in response to the ever-changing demands of daily life. The sound selection and interpretation of frequency-domain variables requires considerably more consideration of physiological and mathematical principles. For those who prefer using frequency-domain variables, the paper provides detailed guidance and recommendations for the definition of appropriate frequency bands in compliance with their specific recording conditions and study populations.

Home oxygen therapy after hospital discharge

Home oxygen therapy is increasingly prescribed for various conditions in the neonatal period, particularly for infants with bronchopulmonary dysplasia. Due to limited evidence on indication, minimal target oxygen saturation, monitoring, application and discontinuation of home oxygen therapy clinical practice varies widely throughout the world. International guidelines provide recommendations mostly on the basis of nonsystematic clinical observations. Most relevant points for the clinical management of home oxygen therapy include a minimal target oxygen saturation of equal to or greater than 93%, the provision of a home monitoring of oxygen saturation ideally with a memory function, and the conduct of continuous overnight oximetry or polysomnography during weaning from supplemental oxygen. This review summarizes relevant literature as well as existing guidelines and recommendations on home oxygen therapy to aid clinicians in the management of these patients and identifies areas for future research.