Elsevier

Resuscitation

Volume 130, September 2018, Pages 105-110
Resuscitation

Clinical paper
Respiratory changes in term infants immediately after birth

https://doi.org/10.1016/j.resuscitation.2018.07.008Get rights and content

Abstract

Introduction

Over 5% of infants worldwide receive breathing support immediately after birth. Our goal was to define references ranges for exhaled carbon dioxide (ECO2), exhaled tidal volume (VTe), and respiratory rate (RR) immediately after birth in spontaneously breathing, healthy infants born at 36 weeks’ gestational age or older.

Methods

This was a single-centre, observational study at the Royal Women’s Hospital in Melbourne, Australia, a busy perinatal referral centre. Immediately after the infant’s head was delivered, we used a face mask to measure ECO2, VTe, and RR through the first ten minutes after birth. Respiratory measurements were repeated at one hour.

Results

We analysed 14,731 breaths in 101 spontaneously breathing infants, 51 born via planned caesarean section and 50 born vaginally with a median (IQR) gestational age of 391/7 weeks (383/7–395/7). It took a median of 7 (4–10) breaths until ECO2 was detected. ECO2 quickly increased to peak value of 48 mmHg (43–53) at 143 s (76–258) after birth, and decreased to post-transitional values, 31 mmHg (28–24), by 7 min. VTe increased after birth, reaching a plateau of 5.3 ml/kg (2.5–8.4) by 130 s for the remainder of the study period. Maximum VTe was 19 ml/kg (16–22) at 257 s (82–360). RR values increased slightly over time, being higher from minute five to ten as compared to the first two minutes after birth.

Conclusions

This study provides reference ranges of exhaled carbon dioxide, exhaled tidal volumes, and respiratory rate for the first ten minutes after birth in term infants who transition without resuscitation.

Introduction

Over 5% of infants worldwide receive breathing support immediately after birth [[1], [2], [3], [4]]. More than 800,000 infants die annually of birth asphyxia; many of these deaths may be avoided through simple resuscitation techniques [2,[5], [6], [7]]. Rising heart rate and oxygen saturation (SpO2) values are used as indicators of adequate ventilation [1,[8], [9], [10]]. Studies have shown that exhaled carbon dioxide (ECO2) levels correlate with lung aeration and that increasing ECO2 precedes increases in heart rate and SpO2 in effectively resuscitated infants [[11], [12], [13]].

The presence of ECO2 indicates airway patency, establishment of lung aeration, pulmonary blood flow, and pulmonary gas exchange. Lung aeration leads to a reduction of pulmonary vascular resistance which in turn leads to an increase in pulmonary blood flow, now serving as the preload of the left ventricle [[14], [15], [16], [17], [18]]. Schmӧlzer and colleagues have reported a median of three breaths before any ECO2 could be detected, supporting that functional residual capacity needs to be established before gas exchange begins [19].

Monitoring exhaled carbon dioxide and exhaled tidal volume (VTe) may guide ventilation of the compromised newborn [11,12,[20], [21], [22], [23], [24]]. However, studies defining reference ranges of ECO2, VTe, and respiratory rate (RR) in the delivery room in spontaneously breathing infants are limited [19,25]. This study aims to fill that gap by describing the respiratory changes in term infants immediately after birth.

Section snippets

Methods

This is a single centre, prospective, observational study of spontaneously breathing term infants in the birth suites and operating theatres at The Royal Women’s Hospital in Melbourne, Australia, a regional referral hospital with a high-risk perinatal service averaging >7500 deliveries per year. The study was approved by The Royal Women’s Hospital Human Ethics Committee and registered with the Australia New Zealand Trials Registry (TRN: 12615000380594).

Study population

We enrolled 108 infants in the study. Seven infants received respiratory support immediately after birth and were excluded. The population characteristics and timing of events for the remaining 101 patients are summarised in Table 1. Comparing modes of delivery, there were no statistically significant differences in gestational age at birth, umbilical cord arterial and venous pH, first temperature, and time to apply the face mask, time to first breath, time to first cry, and time to umbilical

Discussion

This is the first study measuring ECO2, VTe, and RR in spontaneously breathing infants from birth through neonatal adaption. Establishment of the expected ranges for ECO2, VTe, and RR may facilitate the of use respiratory monitoring during neonatal resuscitation. After birth the infant establishes functional residual capacity and pulmonary blood flow increases, shifting the elimination of CO2 from the placenta to the lung [14,18]. We could detect ECO2 after a median of seven breaths, indicating

Conclusions

We demonstrated that exhaled carbon dioxide increases quickly in spontaneously breathing term infants to peak values at 2–3 min after birth followed by a slow but steady descent to post-transitional levels. Exhaled tidal volumes and respiratory rate increased after birth, then plateaued in the minutes after birth. Large tidal volumes were observed throughout the first ten minutes after birth. This study may ultimately contribute to improved interventions in non-breathing infants after birth by

Conflicts of interest

None.

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    A Spanish translated version of the abstract of this article appears as Appendix in the final online version at https://doi.org/10.1016/j.resuscitation.2018.07.008.

    1

    These authors contributed equally to this work.

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