Respiratory transition in the newborn: a three-phase process

Neonatal outcomes and resuscitation practices following the addition of heart rate-guidance to basic resuscitation

AIM

To evaluate the impact of heart rate-guided basic resuscitation compared to Helping Babies Breathe on neonatal outcomes and resuscitation practices in the Democratic Republic of the Congo.

METHODS

We conducted a pre-post clinical trial comparing heart rate-guided basic resuscitation to Helping Babies Breathe in three facilities, enrolling in-born neonates ≥28 weeks gestation. We collected observational data during a convenience sample of resuscitations and extracted clinical data from the medical record for all participants. We evaluated our primary outcome of effective breathing at three minutes after birth among newborns not breathing well at 30 seconds after birth employing generalized linear models using maximum likelihood estimation.

RESULTS

Among 1,284 newborns with observational data, there was no difference in the proportion effectively breathing at three minutes (adjusted relative risk 1.08 [95% CI 0.81, 1.45]). Among 145 receiving bag mask ventilation, time to bag mask ventilation decreased 64.3 seconds during heart rate-guided resuscitation (p<0.001). Among 10,906 enrolled in the trial, perinatal mortality was unchanged (adjusted relative risk 1.19 [95% CI 0.96, 1.48]) and death before discharge increased (adjusted relative risk 1.43 [95% CI 1.03, 1.99]). Expert review of stillborn cases demonstrated a stillbirth misclassification rate of 33.3% during Helping Babies Breathe versus 5.9% in heart rate-guided resuscitation.

CONCLUSION

During heart rate-guided basic resuscitation, time to bag mask ventilation was reduced by greater than one minute. The increase in death before discharge and unchanged perinatal mortality may be due to resuscitation of newborns with a higher risk of mortality who were previously presumed stillborn. A cluster-randomized trial of heart rate-guided basic resuscitation is needed to evaluate its impact on neonatal mortality in low-resource settings.

Optimising CPAP and oxygen levels to support spontaneous breathing in preterm rabbits

BACKGROUND

Very preterm infants often require respiratory support after birth with current recommendations suggesting the use of continuous positive airway pressure (CPAP) of 4-8 cmH2O and an initial fraction of inspired oxygen (FiO2) of 0.21-0.3. We have examined the interaction of high and low CPAP and FiO2 levels on breathing rates and lung aeration in preterm rabbits.

METHODS

Prematurely delivered rabbits (29/32 days gestation) received CPAP of either 5cmH2O (5CPAP; n = 12) or 15 cmH2O (15CPAP; n = 14), and a FiO2 of either 0.3 (5CPAP/0.3, n = 6 or 15CPAP/0.3, n = 7) or 0.6 (5CPAP/0.6, n = 6 or 15CPAP/0.6, n = 7). Breathing rates, lung aeration (functional residual capacity; FRC), lung bulging and air accumulation in the stomach were measured using phase-contrast X-ray imaging.

RESULTS

Kittens receiving 0.6 FiO2 had higher breathing rates (5CPAP/0.6: 32.6±6.4 breaths/min; p = 0.0064 and 15CPAP/0.6: 36.9±3.5breaths/min; p = 0.0010) than 5CPAP/0.3 kittens (11.8±4.1breaths/min). Kittens receiving 15CPAP/0.6 tended to have higher FRC volumes (34.9±4 mL/kg) than kittens receiving 5 cmH2O CPAP (5CPAP/0.3: 13.1±6mL/kg; p = 0.0675 and 5CPAP/0.6: 13.5±6 mL/kg; p = 0.1720) and 15CPAP/0.3 (22.5 ± 6.6 mL/kg; p = 0.4245). Lung bulging and air accumulation in the stomach were not different between groups.

CONCLUSION

Preterm rabbits supported with both 15 cmH2O CPAP and 0.6 FiO2 increased spontaneous breathing rates and lung aeration without increasing the risk of air in the stomach or lung bulging.

IMPACT

While current guidelines recommend the use of low CPAP (4-8 cmH2O) and low FiO2 levels (0.21-0.3 FiO2) to support preterm infants at birth, the optimum levels are unknown. This study has shown that 15 cmH2O of CPAP and FiO2 of 0.6 improved lung aeration and breathing in preterm rabbits, compared with a CPAP of 4 cmH2O and FiO2 of 0.3. These results add to the evidence indicating that initial high CPAP and high FiO2 levels, followed by titration of both, enhance respiratory support for preterm newborns.

Respiratory metrics of neonatal positive pressure ventilation on different ventilatory rates: A simulation study

Background

Effective ventilation is the core of neonatal resuscitation (NR). T-piece resuscitators (TPR) and self-inflating bags (SIB) are the two most widely utilized resuscitation devices. Nevertheless, limited information is available regarding the respiratory metrics during NR with these devices.

Objectives

This study aimed to evaluate the respiratory metrics at different ventilatory rates (VR) using a TPR or SIB during NR training.

Methods

An observational, simulation study was conducted during a NR training course. The participants were instructed to perform positive pressure ventilation at predetermined pressures and varying rates using TPR and SIB. They were subsequently grouped into three categories based on their actual VR: 20-40 breaths per minute (bpm) (SlowVR), 40-60 bpm (StdVR), and 60-80 bpm (FastVR). Respiratory metrics were recorded and analyzed using a neonatal active lung model (NALM).

Results

Of the 71 participants in the training course, data from 66 were validated by analyzing 198 ventilations. In general, the participants manipulated the TPR slightly slower than the SIB. Notably, the positive end-expiratory pressure (PEEP) detected via TPR in the NALM was substantially higher, whereas the tidal volume (Tv) and minute volume (MV) with TPR were significantly smaller than those with SIB (p < 0.05). A significant decrease in the peak alveolar pressure (palva) was observed with faster TPR ventilation (p < 0.001), whereas no such reduction was observed with SIB (p = 0.103). Additionally, faster VR correlated positively with higher PEEP levels for both TPR (F = 7.543, p = 0.002) and SIB (F = 7.720, p = 0.002) and inversely with smaller Tv for both TPR (F = 19.239, p < 0.001) and SIB (F = 14.937, p < 0.001). However, no significant differences in MV were observed across the different VR for either TPR or SIB (both p > 0.05).

Conclusions

Faster VR were inversely associated with smaller Tv but increased PEEP in both devices. Despite the guidelines of NR, VR exceeding 60 bpm with TPR might sometimes be used, was associated with excessive PEEP in TPR, which may not be a safe in clinical practice. The effect of varying VR on MV was relatively minor for both TPR and SIB.

Resuscitation With Placental Circulation Intact Compared With Cord Milking: A Randomized Clinical Trial

Importance

Among preterm newborns undergoing resuscitation, delayed cord clamping for 60 seconds is associated with reduced mortality compared with early clamping. However, the effects of longer durations of cord clamping with respiratory support are unknown.

Objective

To determine whether resuscitating preterm newborns while keeping the placental circulation intact and clamping the cord after a long delay would improve outcomes compared with umbilical cord milking.

Design, Setting, and Participants

This randomized clinical trial (PCI Trial) was conducted at 8 Italian neonatal intensive care units from April 2016 through February 2023 and enrolled preterm newborns born between 23 weeks 0 days and 29 weeks 6 days of gestation from singleton pregnancies.

Interventions

Enrolled newborns were randomly allocated to receive at-birth resuscitation with intact placental circulation for 180 seconds or umbilical cord milking followed by an early cord clamping (within 20 seconds of life).

Main Outcomes and Measures

The primary outcome was the composite end point of death, grade 3 to 4 intraventricular hemorrhage, and bronchopulmonary dysplasia at 36 weeks of postconception age. Prespecified secondary end points were the single components of the composite primary outcome. An intention-to-treat analysis was conducted.

Results

Of 212 mother-newborn dyads who were randomized, 209 (median [IQR] gestational age, 27 [26-28] weeks; median [IQR] birth weight, 900 [700-1070] g) were enrolled in the intention-to-treat population; 105 were randomized to the placental circulation intact group, and 104 were randomized to the cord milking group. The composite outcome of death, grade 3 to 4 intraventricular hemorrhage, or bronchopulmonary dysplasia occurred in 35 of 105 newborns (33%) in the placental circulation intact group vs 39 of 104 newborns (38%) in the cord milking group (odds ratio, 0.83; 95% CI, 0.47-1.47; P = .53).

Conclusions and Relevance

In a randomized clinical trial of preterm newborns at 23 to 29 weeks' gestational age, intact placental resuscitation for 3 minutes did not lower the composite outcome of death, grade 3 to 4 intraventricular hemorrhage, or bronchopulmonary dysplasia compared with umbilical cord milking.

Trial Registration

Clinicaltrials.gov Identifier: NCT02671305.

Lung Ultrasound Assessment of Regional Distribution of Pulmonary Edema and Atelectasis in Infants with Evolving Bronchopulmonary Dysplasia

Background: Preterm infants are at risk for bronchopulmonary dysplasia (BPD) due to prolonged respiratory support. Studies have described differences in the regional distribution of lung ventilation (non-dependent (NDL) vs. dependent (DL)). The aim of this study was to use LUS to compare regional distribution of pulmonary edema and atelectasis in infants with evolving BPD. Methods: We prospectively performed LUS in premature infants with evolving BPD. On each side, three lung areas (NDL/anterior, lateral, and DL/posterior) were examined for the presence of pulmonary edema and atelectasis. Pulmonary edema scores were assigned based on the number of B-lines, and atelectasis scores were assigned based on the presence/absence of atelectasis. Results: 38 premature infants were enrolled. The NDL showed more pulmonary edema and atelectasis compared to the DL (p = 0.003, p = 0.049, respectively) and compared to the lateral lung (p =< 0.001, p = 0.004, respectively). There was no difference between the lateral and DL (p = 0.188, p = 0.156, respectively). There was no difference between the right and the left lung (p = 0.223, p = 0.656, respectively). Conclusions: In this cohort of preterm infants with evolving BPD, lung disease was unevenly distributed, with more pulmonary edema and atelectasis in the NDL regions compared to the DL or lateral regions.

Knee-to-chest flexion manoeuvre to reduce respiratory distress after planned caesarean birth: a feasibility study

BACKGROUND

Planned caesarean section (CS) is a risk factor for neonatal respiratory distress caused by a greater volume of airway liquid in the absence of uterine contractions.Performing a newly conceptualised knee-to-chest flexion (KCF) manoeuvre at birth, mimicking uterine contraction-induced flexion may aid in expelling excess lung liquid.

OBJECTIVES

To test whether performing a KCF manoeuvre at birth is feasible in infants born after planned CS and to test whether KCF leads to visible expulsion of lung liquid.

METHODS

Single-centre prospective interventional study in term infants born by planned CS at Leiden University Medical Centre, Netherlands. KCF was performed for a maximum of 45 s. Baseline characteristics were collected, primary outcome was ability to perform KCF and secondary outcome was any visible expulsion of fluid.

RESULTS

In 39 infants (mean (SD) gestational age 38.0 (0.7) weeks, birth weight 3537 (440) g), KCF could be performed in 21/39 (54%), whereas 18/39 (46.2%) starting vigorous breathing before KCF could be performed. Notably, visible lung liquid expulsion occurred in 9/21 (43%) infants. KCF duration averaged 29 (18) s. In 13/21 (62 %), KCF was not performed as per standard operating procedure. No adverse events were reported.

CONCLUSION

It is feasible to perform KCF at birth in a large proportion of term infants born by planned CS, with visible expulsion of liquid in a significant proportion of these infants. Training healthcare providers to perform a standardised KCF could increase feasibility and success. Further studies are needed to assess feasibility and effectiveness of KCF.

TRIAL REGISTRATION NUMBER

NL74285.058.20.

The cardiopulmonary benefits of physiologically based cord clamping persist for at least 8 hours in lambs with a diaphragmatic hernia

Introduction

Infants with congenital diaphragmatic hernia can suffer severe respiratory insufficiency and pulmonary hypertension after birth. Aerating the lungs before removing placental support (physiologically based cord clamping, PBCC) increases pulmonary blood flow (PBF) and reduces pulmonary vascular resistance (PVR) in lambs with a diaphragmatic hernia (DH). We hypothesized that these benefits of PBCC persist for at least 8 h after birth.

Methods

At ∼138 days of gestation age (dGA), 21 lambs with a surgically induced left-sided DH (∼86 dGA) were delivered via cesarean section. The umbilical cord was clamped either before ventilation onset (immediate cord clamping, ICC, n = 9) or after achieving a tidal volume of 4 ml/kg, with a maximum delay of 10 min (PBCC, n = 12). The lambs were ventilated for 8 h, initially with conventional mechanical ventilation, but were switched to high-frequency oscillatory ventilation after 30 min if required. Ventilatory parameters, cardiopulmonary physiology, and arterial blood gases were measured throughout the study.

Results

PBF increased after ventilation onset in both groups and was higher in the PBCC DH lambs than the ICC DH lambs at 8 h (5.2 ± 1.2 vs. 1.9 ± 0.3 ml/min/g; p < 0.05). Measured over the entire 8-h ventilation period, PBF was significantly greater (p = 0.003) and PVR was significantly lower (p = 0.0002) in the PBCC DH lambs compared to the ICC DH lambs. A high incidence of pneumothoraces in both the PBCC (58%) and ICC (55%) lambs contributed to a reduced sample size at 8 h (ICC n = 4 and PBCC n = 4).

Conclusion

Compared with ICC, PBCC increased PBF and reduced PVR in DH lambs and the effects were sustained for at least 8 h after ventilation onset.

From intra- to extra-uterine: early phase design of a transfer to extra-uterine life support through medical simulation

Introduction

Extra-uterine life support technology could provide a more physiologic alternative for the treatment of extremely premature infants, as it allows further fetal growth and development ex utero. Animal studies have been carried out which involved placing fetuses in a liquid-filled incubator, with oxygen supplied through an oxygenator connected to the umbilical vessels. Hence, by delaying lung exposure to air, further lung development and maturation can take place. This medical intervention requires adjustments to current obstetric procedures to maintain liquid-filled lungs through a so-called transfer procedure.

Methods

Our objective was to develop obstetric device prototypes that allow clinicians to simulate this birth procedure to safely transfer the infant from the mother's uterus to an extra-uterine life support system. To facilitate a user-centered design, implementation of medical simulation during early phase design of the prototype development was used. First, the requirements for the procedure and devices were established, by reviewing the literature and through interviewing direct stakeholders. The initial transfer device prototypes were tested on maternal and fetal manikins in participatory simulations with clinicians.

Results & discussion

Through analysis of recordings of the simulations, the prototypes were evaluated on effectiveness, safety and usability with latent conditions being identified and improved. This medical simulation-based design process resulted in the development of a set of surgical prototypes and allowed for knowledge building on obstetric care in an extra-uterine life support context.

Proportion of confluent B-Lines predicts respiratory support in term infants shortly after birth

OBJECTIVE

To develop and evaluate the predictive value of a simplified lung ultrasound (LUS) method for forecasting respiratory support in term infants.

METHODS

This observational, prospective, diagnostic accuracy study was conducted in a tertiary academic hospital between June and December 2023. A total of 361 neonates underwent LUS examination within 1 h of birth. The proportion of each LUS sign was utilized to predict their respiratory outcomes and compared with the LUS score model. After identifying the best predictive LUS sign, simplified models were created based on different scan regions. The optimal simplified model was selected by comparing its accuracy with both the full model and the LUS score model.

RESULTS

After three days of follow-up, 91 infants required respiratory support, while 270 remained healthy. The proportion of confluent B-lines demonstrated high predictive accuracy for respiratory support, with an area under the curve (AUC) of 89.1% (95% confidence interval [CI]: 84.5-93.7%). The optimal simplified model involved scanning the R/L 1-4 region, yielding an AUC of 87.5% (95% CI: 82.6-92.3%). Both the full model and the optimal simplified model exhibited higher predictive accuracy compared to the LUS score model. The optimal cut-off value for the simplified model was determined to be 15.9%, with a sensitivity of 76.9% and specificity of 91.9%.

CONCLUSIONS

The proportion of confluent B-lines in LUS can effectively predict the need for respiratory support in term infants shortly after birth and offers greater reliability than the LUS score model.

A critical appraisal of tools for delivery room assessment of the newborn infant

Assessment of an infant's condition in the delivery room represents a prerequisite to adequately initiate medical support. In her seminal paper, Virginia Apgar described five parameters to be used for such an assessment. However, since that time maternal and neonatal care has changed; interventions were improved and infants are even more premature. Nevertheless, the Apgar score is assigned to infants worldwide but there are concerns about low interobserver reliability, especially in preterm infants. Also, resuscitative interventions may preclude the interpretation of the score, which is of concern when used as an outcome parameter in delivery room intervention studies. Within the context of these changes, we performed a critical appraisal on how to assess postnatal condition of the newborn including the clinical parameters of the Apgar score, as well as selected additional parameters and a proposed new scoring system. The development of a new scoring system that guide clinicians in assessing infants and help to decide how to support postnatal adaptation is discussed. IMPACT: This critical paper discusses the reliability of the Apgar score, as well as additional parameters, in order to improve assessment of a newborn's postnatal condition. A revised neonatal scoring system should account for infant maturity and the interventions administered. Delivery room assessment should be directed toward determining how much medical support is needed and how the infant responds to these interventions.

Slowing lung deflation by increasing the expiratory resistance enhances FRC in preterm rabbits

BACKGROUND

As very preterm infants have surfactant-deficient and highly incompliant lungs, slowing lung deflation during expiration might help preserve functional residual capacity(FRC) during lung aeration. In this study, we investigated the effect of expiratory resistance(Re) on lung aeration during positive pressure ventilation in preterm rabbits immediately after birth.

METHODS

Preterm rabbit pups were delivered at 29 days gestation, mechanically ventilated from birth and simultaneously imaged to measure lung aeration using phase-contrast X-ray. Re was varied by altering the length (0, 60 or 1000 mm) of the expiratory circuit.

RESULTS

Increasing Re led to a decrease in lung deflation rates and both peak expiratory flows and flow rates at mid-deflation. As a result, the rate of de-acceleration(slowing) in lung deflation when approaching FRC was markedly reduced with increasing resistance. During lung aeration, FRC was significantly different between resistance groups and was significantly higher over time in the high compared to the low resistance group. While FRC values tended to be higher with higher Re, they were not significantly different at end-ventilation (t = 7 min).

CONCLUSION

Increasing Re of the ventilation circuit during lung aeration in preterm rabbits immediately after birth decreased lung deflation rates and increased the accumulation of FRC over time.

IMPACT

The expiratory phase of the ventilatory cycle has been largely overlooked as an opportunity to improve ventilation in preterm infants after birth. Increasing the expiratory resistance of the ventilator circuit during lung aeration in preterm rabbits immediately after birth markedly decreased lung deflation rates and increased FRC accumulation, compared to a low expiratory resistance. This indicates that ventilation devices that reduce the "work of breathing" by reducing the expiratory resistance, may have the unintended effect of reducing FRC, particularly in extremely preterm infants that have surfactant deficient highly incompliant lungs.

Rescue nasopharyngeal tube for preterm infants non-responsive to initial ventilation after birth

BACKGROUND

Physiological changes during the insertion of a rescue nasopharyngeal tube (NPT) after birth are unclear.

METHODS

Observational study of very preterm infants in the delivery room. Data were extracted at predefined timepoints starting with first facemask placement after birth until 5 min after insertion of NPT. End-expiratory lung impedance (EELI), heart rate (HR) and SpO2/FiO2-ratio were analysed over time. Changes during the same time span of NIPPV via facemask and NIPPV via NPT were compared.

RESULTS

Overall, 1154 inflations in 15 infants were analysed. After NPT insertion, EELI increased significantly [0.33 AU/kg (0.19-0.57), p < 0.001]. Compared with the mask period, changes in EELI were not significantly larger during the NPT period [median difference (IQR) = 0.14 AU/kg (-0.14-0.53); p = 0.12]. Insertion of the NPT was associated with significant improvement in HR [52 (33-96); p = 0.001] and SpO2/FiO2-ratio [161 (69-169); p < 0.001] not observed during the mask period.

CONCLUSIONS

In very preterm infants non-responsive to initial facemask ventilation after birth, insertion of an NPT resulted in a considerable increase in EELI. This additional gain in lung volume was associated with an immediate improvement in clinical parameters. The use of a NPT may prevent intubation in selected non-responsive infants.

IMPACT

After birth, a nasopharyngeal tube may be considered as a rescue airway in newborn infants non-responsive to initial positive pressure ventilation via facemask. Although it is widely used among clinicians, its effect on lung volumes and physiological parameters remains unclear. Insertion of a rescue NPT resulted in a considerable increase in lung volume but this was not significantly larger than during facemask ventilation. However, insertion of a rescue NPT was associated with a significant and clinically important improvement in heart rate and oxygenation. This study highlights the importance of individual strategies in preterm resuscitation and introduces the NPT as a valid option.

Comparison of positive pressure ventilation devices during compliance changes in a neonatal ovine model

BACKGROUND

To compare tidal volume (VT) delivery with compliance at 0.5 and 1.5 mL/cmH2O using four different ventilation (PPV) devices (i.e., self-inflating bag (SIB), T-Piece resuscitator, Next Step (a novel Neonatal Resuscitator), and Fabian ventilator (conventional neonatal ventilator) using a neonatal piglet model.

DESIGN/METHODS

Randomized experimental animal study using 10 mixed-breed neonatal piglets (1-3 days; 1.8-2.4 kg). Piglets were anesthetized, intubated, instrumented, and randomized to receive positive pressure ventilation (PPV) for one minute with a SIB with or without a respiratory function monitor (RFM), T-Piece resuscitator with or without an RFM, Next Step, and Fabian Ventilator with both compliance levels. Compliance changes were achieved by placing a wrap around the piglets' chest and tightened it. Our primary outcome was targeted VT delivery of 5 mL/kg at 0.5 and 1.5 mL/cmH2O lung compliance.

RESULTS

At 0.5 mL/cmH2O compliance, the mean(SD) expired VT with the Next Step was 5.1(0.2) mL/kg compared to the Fabian 4.8(0.5) mL/kg, SIB 8.9(3.6) mL/kg, SIB + RFM 4.5(1.8) mL/kg, T-Piece 7.4(4.3) mL/kg, and T-Piece+RFM 6.4(3.1) mL/kg. At 1.5 mL/cmH2O compliance, the mean(SD) expired VT with the Next Step was 5.2(0.6) mL/kg compared to the Fabian 4.4(0.7) mL/kg, SIB 12.1(5.3) mL/kg, SIB + RFM 9.4(3.9) mL/kg, T-Piece 8.6(1.5) mL/kg, and T-Piece+RFM 6.5 (1.6) mL/kg.

CONCLUSION

The Next Step provides consistent VT during PPV, which is comparable to a mechanical ventilator.

IMPACT

Current guidelines recommend fixed peak inflation pressure in resuscitation, linked to lung and brain injury. The Next Step Neonatal Resuscitator, a cost-effective device, offers volume-targeted positive pressure ventilation with consistent tidal volumes. With two different compliances, the Next Step Neonatal Resuscitator delivered a consistent tidal volume which was similar to a mechanical ventilator. The Next Step Neonatal Resuscitator outperformed self-inflating bags and T-Pieces in delivering targeted tidal volumes. The Next Step Neonatal Resuscitator could be an alternative ventilation device for neonatal resuscitation.

Adverse respiratory patterns in near-term spontaneously breathing newborn lambs with elevated airway liquid volumes at birth

Introduction

Recent evidence indicates that respiratory distress (RD) in near-term infants is caused by elevated airway liquid (EL) volume at the beginning of air-breathing after birth. While the adverse effects EL volumes on newborn lung function are known, the effects on respiratory control and breathing patterns shortly after birth (<4 h) are unknown. We investigated the effects of EL volumes on cardiorespiratory function and breathing patterns in spontaneously breathing near-term newborn lambs in the first hours after birth.

Methods

At 137-8 days gestation (2-3 days prior to delivery; term ∼147 days), sterile surgery was performed on fetal sheep (n = 17) to implant catheters and blood flow probes. At 140 days, lambs were delivered via caesarean section under spinal anaesthesia. Airway liquid volumes were adjusted to mimic the level expected following vaginal delivery (∼10 ml/kg; Controls; n = 7), or elective caesarean section (∼30 ml/kg; elevated airway liquid group; EL; n = 10). Spontaneous breathing and cardiorespiratory parameters were recorded over four hours after birth. Non-invasive respiratory support with supplemental oxygen was provided if required.

Results

EL lambs required higher inspired oxygen levels (p = 0.0002), were less active (p = 0.026), fed less (p = 0.008) and had higher respiratory morbidity scores than Controls (p < 0.0001). EL lambs also displayed higher rates of breathing patterns associated with RD, such as expiratory braking and tachypnoea. These patterns were particularly evident in male EL lambs who displayed higher levels of severe respiratory morbidity (e.g., expiratory braking) than female EL lambs.

Conclusion

The study demonstrates that EL volumes at birth trigger respiratory behaviour and breathing patterns that resemble clinically recognised features of RD in term infants.

Positive end-expiratory pressure and surfactant administration mode influence function in ex-vivo premature sheep lungs

AIM

Respiratory distress syndrome often necessitates endotracheal surfactant administration in extremely preterm infants. Our study aimed to explore a multi-modal simulation tool for investigating treatment strategies in ex vivo sheep lungs during spontaneous breathing.

METHODS

An electromechanical lung simulator (xPULM) mimicking spontaneous breathing was coupled with a non-aerated premature sheep lung, replicating a premature respiratory system. Changes in tidal volume for different positive end-expiratory pressure (PEEP) levels prior to and after either bolus or nebulised surfactant administration were compared.

RESULTS

In two preterm sheep lungs, we observed a progressive decline in tidal volume with increasing PEEP levels prior to surfactant delivery from 0.30 ± 0.01 mL at zero PEEP to 0.04 ± 0.01 mL at 15 cmH2O PEEP. Our measurements showed that both bolus (p < 0.05) and nebulised (p < 0.05) surfactant administration resulted in a significant increase in tidal volume, with no significant difference (p = 0.71) between the two methods.

CONCLUSION

The experimental setup demonstrated the feasibility of xPULM for investigating the effectiveness of different PEEP levels and modes of surfactant administration with respect to tidal volume in premature sheep lungs. The lack of adequate lung water resorption in our model warrants further investigations.

Colorimetric CO2 Detector to Improve Effective Mask Ventilations in Very Preterm Infants: A Pilot Randomized Controlled Study

INTRODUCTION

End-tidal CO2 (ETCO2) detector is currently recommended for confirmation of endotracheal tube placement during neonatal resuscitation. Whether it is feasible to use ETCO2 detectors during mask ventilation to reduce risk of bradycardia and desaturations, which are associated with increased risk of death in preterm babies, is unknown.

METHODS

This is a pilot randomized controlled trial (NCT04287907) involving newborns 24 + 0/7 to 32 + 0/7 weeks gestation who required mask ventilation at birth. Infants were randomized into groups with or without colorimetric ETCO2 detectors. Combined duration of any bradycardia (<100 bpm) and time below prespecified target oxygen saturation (SpO2) as measured by pulse oximetry were compared.

RESULTS

Fifty participants were randomized, 47 with outcomes analysed (2 incomplete data, 1 postnatal diagnosis of trachea-oesophageal fistula). Mean gestational age and birthweight were 28.5 ± 1.9 versus 29.4 ± 1.6 weeks (p = 0.1) and 1,252.7 ± 409.7 g versus 1,334.6 ± 369.1 g (p = 0.5) in the intervention and control arm, respectively. Mean combined duration of bradycardia and desaturation was 276.7 ± 197.7 s (intervention) and 322.7 ± 277.7 s (control) (p = 0.6). Proportion of participants with any bradycardia or desaturation at 5 min were 38.1% (intervention) and 56.5% (control) (p = 0.2). No chest compressions, epinephrine administration, or death occurred in the delivery room.

CONCLUSION

This pilot study demonstrates the feasibility of a trial to evaluate colorimetric ETCO2 detectors during mask ventilation of very preterm infants to reduce bradycardia and low SpO2. Further assessment with a larger population will be required to determine if ETCO2 detector usage at resuscitation reduces risk of adverse outcomes, including death and disability, in very preterm infants.

Deciphering Mechanisms of Respiratory Fetal-to-Neonatal Transition in Very Preterm Infants

Rationale: The respiratory mechanisms of a successful transition of preterm infants after birth are largely unknown. Objectives: To describe intrapulmonary gas flows during different breathing patterns directly after birth. Methods: Analysis of electrical impedance tomography data from a previous randomized trial in preterm infants at 26-32 weeks gestational age. Electrical impedance tomography data for individual breaths were extracted, and lung volumes as well as ventilation distribution were calculated for end of inspiration, end of expiratory braking and/or holding maneuver, and end of expiration. Measurements and Main Results: Overall, 10,348 breaths from 33 infants were analyzed. We identified three distinct breath types within the first 10 minutes after birth: tidal breathing (44% of all breaths; sinusoidal breathing without expiratory disruption), braking (50%; expiratory brake with a short duration), and holding (6%; expiratory brake with a long duration). Only after holding breaths did end-expiratory lung volume increase: Median (interquartile range [IQR]) = 2.0 AU/kg (0.6 to 4.3), 0.0 (-1.0 to 1.1), and 0.0 (-1.1 to 0.4), respectively; P < 0.001]. This was mediated by intrathoracic air redistribution to the left and non-gravity-dependent parts of the lung through pendelluft gas flows during braking and/or holding maneuvers. Conclusions: Respiratory transition in preterm infants is characterized by unique breathing patterns. Holding breaths contribute to early lung aeration after birth in preterm infants. This is facilitated by air redistribution during braking/holding maneuvers through pendelluft flow, which may prevent lung liquid reflux in this highly adaptive situation. This study deciphers mechanisms for a successful fetal-to-neonatal transition and increases our pathophysiological understanding of this unique moment in life. Clinical trial registered with www.clinicaltrials.gov (NCT04315636).

Positive Pressure Ventilation in Preterm Infants in the Delivery Room: A Review of Current Practices, Challenges, and Emerging Technologies

BACKGROUND

A major proportion of preterm neonates require positive pressure ventilation (PPV) immediately after delivery. PPV may be administered through a face mask (FM) or nasal prongs. Current literature indicates that either of these are associated with similar outcomes.

SUMMARY

Nonetheless, FM remains the most utilized and the best choice. However, most available FM sizes are too large for extremely preterm infants, which leads to mask leak and ineffective PPV. Challenges to providing effective PPV include poor respiratory drive, complaint chest wall, weak thoracic muscle, delayed liquid clearance, and surfactant deficiency in preterm infants. Mask leak, airway obstruction, poor technique, and inappropriate size are correctable causes of ineffective PPV. Visual assessment of chest rise is often used to assess the efficacy of PPV. However, its accuracy is debatable. Though end tidal CO2 may adjudge the effectiveness of PPV, clinical studies are limited. The compliance of a preterm lung is highly dynamic. The inflating pressure set on T-piece is constant throughout the resuscitation, but the lung volume and dynamics changes with every breath. This leads to huge fluctuations of tidal volume delivery and can trigger inflammatory cascade in preterm infants leading to brain and lung injury. Respiratory function monitoring in the delivery room has potential for guiding and optimizing delivery room resuscitation. This is, however, limited by high costs, complex information that is difficult to interpret during resuscitation, and absence of clinical trials.

KEY MESSAGES

This review summarizes the existing literature on PPV in preterm infants, the various aspects related to it such as the pathophysiology, interfaces, devices utilized to deliver it, appropriate technique, emerging technologies, and future directions.

Effect of Decision-to-Delivery Time of Emergency Cesarean Section on Adverse Newborn Outcomes at East Gojjam Zone Public Hospital, Ethiopia, March 2023: Multicenter Prospective Observational Study Design

Background

An emergency cesarean section requires prompt delivery to reduce the risk for a pregnant woman or newborn. Studies have been conducted to investigate the relationship between decision-to-delivery time and neonatal outcomes, but the findings are contradictory. Therefore, this study aimed to assess the average of decision-to-delivery time of an emergency cesarean section and its effect on adverse neonatal outcomes at East Gojjam Zone Public Hospital.

Methods

A multicenter prospective study design would be carried out between November 2022 and January 2023. Using the consecutive method, a sample of 352 mother-newborn pairs was studied. Direct observation and face-to-face interviews were undertaken to gather the data using a semi-structured questionnaire. For both data input and analysis, Epi Data version 4.6 and Stata version 14 software were used. Both the crude and adjusted odds ratios were computed. Measure of significance was based on the adjusted odds ratio with a 95% confidence interval and a p-value of less than 0.05.

Results

Decision-to-delivery time interval within 30 minute was seen in 21.9% of emergency cesarean delivery. The study found a significant relationship between the first-minute low Apgar score and the delayed decision-to-delivery time interval (OR = 2.6, 95% CI: 1.1-6, p = 0.03). In addition, determinant factors for poor 1st-minute Apgar scores include danger signs during pregnancy (AOR: 2.9, 95% CI: 1.1-7.8, p = 0.03), women referred from another facility (AOR: 2.6, 95% CI: 1.5-4.6, p = 001), and non-reassuring fetal heart rate (AOR: 4.2, 95% CI: 1.1-17, p = 0.04). A delayed decision-to-delivery time interval is not statistically significantly associated with a low 5th-minute Apgar score or neonatal intensive care unit (NICU) admission.

Conclusion

The study found unfavorable 1st-minute Apgar score and a longer decision-to-delivery period than recommended. This duration and negative newborn outcomes may be reduced by increasing and involving comprehensive obstetric and neonatal care facilities with skilled emergency obstetric surgeons, such as clinical midwife, integrated emergency surgeon officers, and physician.

Transferring an extremely premature infant to an extra-uterine life support system: a prospective view on the obstetric procedure

To improve care for extremely premature infants, the development of an extrauterine environment for newborn development is being researched, known as Artificial Placenta and Artificial Womb (APAW) technology. APAW facilitates extended development in a liquid-filled incubator with oxygen and nutrient supply through an oxygenator connected to the umbilical vessels. This setup is intended to provide the optimal environment for further development, allowing further lung maturation by delaying gas exposure to oxygen. This innovative treatment necessitates interventions in obstetric procedures to transfer an infant from the native to an artificial womb, while preventing fetal-to-neonatal transition. In this narrative review we analyze relevant fetal physiology literature, provide an overview of insights from APAW studies, and identify considerations for the obstetric procedure from the native uterus to an APAW system. Lastly, this review provides suggestions to improve sterility, fetal and maternal well-being, and the prevention of neonatal transition.

Sustained inflation improves initial lung aeration in newborn rabbits with a diaphragmatic hernia

BACKGROUND

Infants with a congenital diaphragmatic hernia (DH) have underdeveloped lungs and require mechanical ventilation after birth, but the optimal approach is unknown. We hypothesised that sustained inflation (SI) increases lung aeration in newborn kittens with a DH.

METHODS

In pregnant New Zealand white rabbits, a left-sided DH was induced in two fetal kittens per doe at 24-days gestation (term = 32 days); litter mates acted as controls. DH and control kittens were delivered by caesarean section at 30 days, intubated and mechanically ventilated (7-10 min) with either an SI followed by intermittent positive pressure ventilation (IPPV) or IPPV throughout. The rate and uniformity of lung aeration was measured using phase-contrast X-ray imaging.

RESULTS

Lung weights in DH kittens were ~57% of controls. An SI increased the rate and uniformity of lung aeration in DH kittens, compared to IPPV, and increased dynamic lung compliance in both control and DH kittens. However, this effect of the SI was lost when ventilation changed to IPPV.

CONCLUSION

While an SI improved the rate and uniformity of lung aeration in both DH and control kittens, greater consideration of the post-SI ventilation strategy is required to sustain this benefit.

IMPACT

Compared to intermittent positive pressure ventilation (IPPV), an initial sustained inflation (SI) increased the rate and uniformity of lung aeration after birth. However, this initial benefit is rapidly lost following the switch to IPPV. The optimal approach for ventilating CDH infants at birth is unknown. While an SI improves lung aeration in immature lungs, its effect on the hypoplastic lung is unknown. This study has shown that an SI greatly improves lung aeration in the hypoplastic lung. This study will guide future studies examining whether an SI can improve lung aeration in infants with a CDH.

Miracles of science: Birth after uterus transplantation

AIM

The concept of regaining childbearing ability via uterus transplantation (UTx) motivates many infertile women to pursue giving birth to their own children. This article provides insight into maternal and neonatal outcomes of the procedure globally and facilitates quality of care in related medical fields.

METHODS

The authors searched ISI Web of Science, MEDLINE, non-PubMed-indexed journals, and common search engines to identify peer-review publications and unpublished sources in scientific reference databases.

RESULTS

The feasibility of the procedure has been proven with 46 healthy children in 88 procedures so far. Success relies upon dedicated teamwork involving transplantation surgery, obstetrics and reproductive medicine, neonatology, pediatrics, psychology, and bioethics. However, challenges exist owing to donor, recipient, and fetus. Fetal growth in genetically foreign uterine allograft with altered feto-maternal interface and vascular anatomy, immunosuppressive exposure, lack of graft innervation leading to "unable-to-feel" uterine contractions and conception via assisted reproductive technology create notable risks during pregnancy. Significant portion of women are complicated by at least one or more obstetric problems. Preeclampsia, gestational hypertension and diabetes mellitus, elevated kidney indices, and preterm delivery are common complications.

CONCLUSIONS

UTx has short- and long-term satisfying outcome. Advancements in the post-transplant management would undoubtedly lead this experimental procedure into mainstream clinical practice in the near future. However, both women and children of UTx need special consideration due to prematurity-related neonatal problems and the long-term effects of transplant pregnancy. Notable health risks for the recipient and fetus should be discussed with potential candidates for UTx.

Impact of tidal volume strategy at birth on initiating lung injury in preterm lambs

Tidal ventilation is essential in supporting the transition to air-breathing at birth, but excessive tidal volume (VT) is an important factor in preterm lung injury. Few studies have assessed the impact of specific VT levels on injury development. Here, we used a lamb model of preterm birth to investigate the role of different levels of VT during positive pressure ventilation (PPV) in promoting aeration and initiating early lung injury pathways. VT was delivered as 1) 7 mL/kg throughout (VTstatic), 2) begun at 3 mL/kg and increased to a final VT of 7 mL/kg over 3 min (VTinc), or 3) commenced at 7 mL/kg, decreased to 3 mL/kg, and then returned to 7 mL/kg (VTalt). VT, inflating pressure, lung compliance, and aeration were similar in all groups from 4 min, as was postmortem histology and lung lavage protein concentration. However, transient decrease in VT in the VTalt group caused increased ventilation heterogeneity. Following TMT-based quantitative mass spectrometry proteomics, 1,610 proteins were identified in the lung. Threefold more proteins were significantly altered with VTalt compared with VTstatic or VTinc strategies. Gene set enrichment analysis identified VTalt specific enrichment of immune and angiogenesis pathways and VTstatic enrichment of metabolic processes. Our finding of comparable lung physiology and volutrauma across VT groups challenges the paradigm that there is a need to rapidly aerate the preterm lung at birth. Increased lung injury and ventilation heterogeneity were identified when initial VT was suddenly decreased during respiratory support at birth, further supporting the benefit of a gentle VT approach.NEW & NOTEWORTHY There is little evidence to guide the best tidal volume (VT) strategy at birth. In this study, comparable aeration, lung mechanics, and lung morphology were observed using static, incremental, and alternating VT strategies. However, transient reduction in VT was associated with ventilation heterogeneity and inflammation. Our results suggest that rapidly aerating the preterm lung may not be as clinically critical as previously thought, providing clinicians with reassurance that gently supporting the preterm lung maybe permissible at birth.

Preterm lung and brain responses to mechanical ventilation and corticosteroids

Mechanical ventilation is necessary to maintain oxygenation and ventilation in many preterm infants. Unfortunately, even short periods of mechanical ventilation can cause lung and airway injury, and initiate the lung inflammation that contributes to the development of bronchopulmonary dysplasia (BPD). The mechanical stretch leads to airway cell differentiation and simplification of the alveoli, and releases cytokines that cause systemic response in other organs. Mechanical ventilation also leads to brain injury (IVH, white and gray matter) and neuronal inflammation that can affect the neurodevelopment of preterm infants. In efforts to decrease BPD, corticosteroids have been used for both prevention and treatment of lung inflammation. Corticosteroids have also been demonstrated to cause neuronal injury, so the clinician must balance the negative effects of both mechanical ventilation and steroids on the brain and lungs. Predictive models for BPD can help assess the infants who will benefit most from corticosteroid exposure. This review describes the lung and brain injury from mechanical ventilation in the delivery room and chronic mechanical ventilation in animal models. It provides updates on the current guidelines for use of postnatal corticosteroids (dexamethasone, hydrocortisone, budesonide, budesonide with surfactant) for the prevention and treatment of BPD, and the effects the timing of each steroid regimen has on neurodevelopment.

Monitoring of the Healthy Neonatal Transition Period with Serial Lung Ultrasound

Ultrasound has been used to observe lung aeration and fluid clearance during the neonatal transition period, but there is no consensus regarding the optimal timing of lung ultrasound. We aimed to monitor the trend of the serial lung ultrasound score (LUS) and extended LUS (eLUS) throughout the neonatal transition period (≤1, 2, 4, 8, 24, and 48 h after birth), assess any correlation to the clinical presentation (using the Silverman Andersen Respiratory Severity Score (RSS)), and determine the optimal time of the ultrasound. We found both LUS and eLUS decreased significantly after 2 h of life and had similar statistical differences among the serial time points. Although both scores had a positive, moderate correlation to the RSS overall (Pearson correlation 0.499 [p < 0.001] between LUS and RSS, 0.504 [p < 0.001] between eLUS and RSS), the correlation was poor within 1 h of life (Pearson correlation 0.15 [p = 0.389] between LUS and RSS, 0.099 [p = 0.573] between eLUS and RSS). For better clinical correlation, the first lung ultrasound for the neonate may be performed at 2 h of life. Further research is warranted to explore the clinical value and limitations of earlier (≤1 h of life) lung ultrasound examinations.

Aeration strategy at birth does not impact carotid haemodynamics in preterm lambs

BACKGROUND

The impact of different respiratory strategies at birth on the preterm lung is well understood; however, concerns have been raised that lung recruitment may impede cerebral haemodynamics. This study aims to examine the effect of three different ventilation strategies on carotid blood flow, carotid artery oxygen content and carotid oxygen delivery.

METHODS

124-127-day gestation apnoeic intubated preterm lambs studied as part of a larger programme primarily assessing lung injury were randomised to positive pressure ventilation with positive end-expiratory pressure (PEEP) 8 cmH2O (No-RM; n = 12), sustained inflation (SI; n = 15) or dynamic PEEP strategy (DynPEEP; maximum PEEP 14 or 20 cmH2O, n = 41) at birth, followed by 90 min of standardised ventilation. Haemodynamic data were continuously recorded, with intermittent arterial blood gas analysis.

RESULTS

Overall carotid blood flow measures were comparable between strategies. Except for mean carotid blood flow that was significantly lower for the SI group compared to the No-RM and DynPEEP groups over the first 3 min (p < 0.0001, mixed effects model). Carotid oxygen content and oxygen delivery were similar between strategies. Maximum PEEP level did not alter cerebral haemodynamic measures.

CONCLUSIONS

Although there were some short-term variations in cerebral haemodynamics between different PEEP strategies and SI, these were not sustained.

IMPACT

Different pressure strategies to facilitate lung aeration at birth in preterm infants have been proposed. There is minimal information on the effect of lung recruitment on cerebral haemodynamics. This is the first study that compares the effect of sustained lung inflation and dynamic and static positive end-expiratory pressure on cerebral haemodynamics. We found that the different ventilation strategies did not alter carotid blood flow, carotid oxygen content or carotid oxygen delivery. This preclinical study provides some reassurance that respiratory strategies designed to focus on lung aeration at birth may not impact cerebral haemodynamics in preterm neonates.

Increased risk of bradycardia in vigorous infants receiving early as compared to delayed cord clamping at birth

OBJECTIVE

To compare HR pattern of vigorous newborns during the first 180 s with early (≤60 s, ECC) or delayed (>60 s, DCC) cord clamping.

STUDY DESIGN

Observational study including dry-electrode ECG monitoring of 610 vaginally-born singleton term and late-preterm (≥34 weeks) who were vigorous after birth.

RESULTS

198 received ECC while 412 received DCC with median cord clamping at 37 s and 94 s. Median HR remained stable from 30 to 180 s with DCC (172 and 170 bpm respectively) but increased with ECC (169 and 184 bpm). The proportion with bradycardia was higher among ECC than DCC at 30 s and fell faster in the DCC through 60 s. After adjusting for factors affecting timing of cord clamping, ECC had significant risk of bradycardia compared to DCC (aRR 1.51; 95% CI; 1.01-2.26).

CONCLUSION

Early heart instability and higher risk of bradycardia with ECC as compared to DCC supports the recommended clinical practice of DCC.

Respiratory strategy at birth initiates distinct lung injury phenotypes in the preterm lamb lung

Background

A lack of clear trial evidence often hampers clinical decision-making during support of the preterm lung at birth. Protein biomarkers have been used to define acute lung injury phenotypes and improve patient selection for specific interventions in adult respiratory distress syndrome. The objective of the study was to use proteomics to provide a deeper biological understanding of acute lung injury phenotypes resulting from different aeration strategies at birth in the preterm lung.

Methods

Changes in protein abundance against an unventilated group (n = 7) were identified via mass spectrometry in a biobank of gravity dependent and non-dependent lung tissue from preterm lambs managed with either a Sustained Inflation (SI, n = 20), Dynamic PEEP (DynPEEP, n = 19) or static PEEP (StatPEEP, n = 11). Ventilation strategy-specific pathways and functions were identified (PANTHER and WebGestalt Tool) and phenotypes defined using integrated analysis of proteome, physiological and clinical datasets (MixOmics package).

Results

2372 proteins were identified. More altered proteins were identified in the non-dependent lung, and in SI group than StatPEEP and DynPEEP. Different inflammation, immune system, apoptosis and cytokine pathway enrichment were identified for each strategy and lung region. Specific integration maps of clinical and physiological outcomes to specific proteins could be generated for each strategy.

Conclusions

Proteomics mapped the molecular events initiating acute lung injury and identified detailed strategy-specific phenotypes. This study demonstrates the potential to characterise preterm lung injury by the direct aetiology and response to lung injury; the first step towards true precision medicine in neonatology.

Bridging the gap in neonatal resuscitation in Zambia

Neonatal resuscitation has been poorly instituted in many parts of Africa and most neonatal resuscitation algorithms are adapted from environments with abundant resources. Helping Babies Breathe (HBB) is an algorithm designed for resource-limited situations and most other algorithms are designed for resource-rich countries. However, there are neonatal referral centers in resource-limited countries who may provide more advanced resuscitation. Thus, we developed a neonatal resuscitation algorithm for a resource-limited country (Zambia) which considers more advanced interventions in situations where they can be provided. The algorithm described in this paper is based on the Newborn Life Support algorithm from the UK as well as the HBB algorithm and accounts for all situations in a resource-limited country. Most importantly, it focuses on non-invasive ventilation but includes advice on more advanced resuscitation including intravenous access, fluid management, chest compressions and adrenaline for resuscitation. Although intubation skills are included in neonatal training workshops, it is not the main focus of the algorithm as respiratory support equipment is scarce or lacking in most health facilities in Zambia. A home-grown neonatal resuscitation algorithm for a resource-limited country such as Zambia is likely to bridge the gap between limited situations requiring only bag and mask ventilation and better equipped institutions where more advanced resuscitation is possible. This algorithm will be rolled out in all training institutions and delivery facilities across Zambia over the next months.

Prophylactic surfactant nebulisation for the early aeration of the preterm lung: a randomised clinical trial

OBJECTIVE

The effect of prophylactic surfactant nebulisation (SN) is unclear. We aimed to determine whether prophylactic SN improves early lung aeration.

DESIGN

Parallel, randomised clinical trial, conducted between March 2021 and January 2022.

SETTING

Delivery room (DR) of a tertiary neonatal centre in Zurich, Switzerland.

PATIENTS

Preterm infants between 26 ^0/7 and 31 ^6/7 weeks gestation INTERVENTIONS: Infants were randomised to receive positive distending pressure alone or positive distending pressure and additional SN (200 mg/kg; poractant alfa) using a customised vibrating membrane nebuliser. SN commenced with the first application of a face mask immediately after birth.

MAIN OUTCOME MEASURES

Primary outcome was the difference in end-expiratory lung impedance from birth to 30 min after birth (∆EELI_30min). EELI correlates well with functional residual capacity. Secondary outcomes included physiological and clinical outcomes.

RESULTS

Data from 35 infants were collected, and primary outcome data were analysed from 32 infants (n=16/group). Primary outcome was not different between intervention and control group (median (IQR): 25 (7-62) vs 10 (0-26) AU/kg, p=0.21). ∆EELI was slightly higher in the intervention group at 6 and 12 hours after birth, particularly in the central areas of the lung. There were no differences in cardiorespiratory and clinical parameters. Two adverse events were noted in the intervention group.

CONCLUSIONS

Prophylactic SN in the DR did not significantly affect ∆EELI_30min and showed only minimal effects on lung physiology. Prophylactic SN in the DR was feasible. There were no differences in clinical outcomes.

TRIAL REGISTRATION NUMBER

NCT04315636.

Positive pressure ventilation at birth

OBJECTIVE

To review the current state of the art of positive pressure ventilation (PPV) during resuscitation FINDINGS: The frequency of PPV during delivery room resuscitation varies across settings and gestational age subgroups. Goal targets and parameters for delivery room PPV remain undefined. The T-piece resuscitator provides the most consistent pressures during PPV and may improve clinical outcomes. The laryngeal mask may be an important alternative interface for PPV, but more data are needed to identify the optimal role of the supraglottic airway during PPV. No objective monitors of PPV have conclusively demonstrated improved outcomes to date.

CONCLUSION

More information, including real-world data from population-based studies, is needed to provide data-driven guidelines for positive pressure ventilation during neonatal transition after birth.

Technology in the delivery room supporting the neonatal healthcare provider's task

Very preterm infants are a unique and highly vulnerable group of patients that have a narrow physiological margin within which interventions are safe and effective. The increased understanding of the foetal to neonatal transition marks the intricacy of the rapid and major physiological changes that take place, making delivery room stabilisation and resuscitation an increasingly complex and sophisticated activity for caregivers to perform. While modern, automated technologies are progressively implemented in the neonatal intensive care unit (NICU) to enhance the caregivers in providing the right care for these patients, the technology in the delivery room still lags far behind. Diligent translation of well-known and promising technological solutions from the NICU to the delivery room will allow for better support of the caregivers in performing their tasks. In this review we will discuss the current technology used for stabilisation of preterm infants in the delivery room and how this could be optimised in order to further improve care and outcomes of preterm infants in the near future.

Preliminary study of automated oxygen titration at birth for preterm infants

OBJECTIVE

To study the feasibility of automated titration of oxygen therapy in the delivery room for preterm infants.

DESIGN

Prospective non-randomised study of oxygenation in sequential preterm cohorts in which FiO₂ was adjusted manually or by an automated control algorithm during the first 10 min of life.

SETTING

Delivery rooms of a tertiary level hospital.

PARTICIPANTS

Preterm infants <32 weeks gestation (n=20 per group).

INTERVENTION

Automated oxygen control using a purpose-built device, with SpO₂ readings input to a proportional-integral-derivative algorithm, and FiO₂ alterations actuated by a motorised blender. The algorithm was developed via in silico simulation using abstracted oxygenation data from the manual control group. For both groups, the SpO₂ target was the 25th-75th centile of the Dawson nomogram.

MAIN OUTCOME MEASURES

Proportion of time in the SpO₂ target range (25th-75th centile, or above if in room air) and other SpO₂ ranges; FiO₂ adjustment frequency; oxygen exposure.

RESULTS

Time in the SpO₂ target range was similar between groups (manual control: median 60% (IQR 48%-72%); automated control: 70 (60-84)%; p=0.31), whereas time with SpO₂ >75th centile when receiving oxygen differed (manual: 17 (7.6-26)%; automated: 10 (4.4-13)%; p=0.048). Algorithm-directed FiO₂ adjustments were frequent during automated control, but no manual adjustments were required in any infant once valid SpO₂ values were available. Oxygen exposure was greater during automated control, but final FiO₂ was equivalent.

CONCLUSION

Automated oxygen titration using a purpose-built algorithm is feasible for delivery room management of preterm infants, and warrants further evaluation.

Evaluating Clinical Outcomes and Physiological Perspectives in Studies Investigating Respiratory Support for Babies Born at Term With or at Risk of Transient Tachypnea: A Narrative Review

Respiratory distress in the first few hours of life is a growing disease burden in otherwise healthy babies born at term (>37 weeks gestation). Babies born by cesarean section without labor (i.e., elective cesarean section) are at greater risk of developing respiratory distress due to elevated airway liquid volumes at birth. These babies are commonly diagnosed with transient tachypnea of the newborn (TTN) and historically treatments have mostly focused on enhancing airway liquid clearance pharmacologically or restricting fluid intake with limited success. Alternatively, a number of clinical studies have investigated the potential benefits of respiratory support in newborns with or at risk of TTN, but there is considerable heterogeneity in study designs and outcome measures. A literature search identified eight clinical studies investigating use of respiratory support on outcomes related to TTN in babies born at term. Study demographics including gestational age, mode of birth, antenatal corticosteroid exposure, TTN diagnosis, timing of intervention (prophylactic/interventional), respiratory support (type/interface/device/pressure), and study outcomes were compared. This narrative review provides an overview of factors within and between studies assessing respiratory support for preventing and/or treating TTN. In addition, we discuss the physiological understanding of how respiratory support aids lung function in newborns with elevated airway liquid volumes at birth. However, many questions remain regarding the timing of onset, pressure delivered, device/interface used and duration, and weaning of support. Future studies are required to address these gaps in knowledge to provide evidenced based recommendations for management of newborns with or at risk of TTN.

Higher CPAP levels improve functional residual capacity at birth in preterm rabbits

BACKGROUND

Preterm infants are commonly supported with 4-8 cm H₂O continuous positive airway pressures (CPAP), although higher CPAP levels may improve functional residual capacity (FRC).

METHODS

Preterm rabbits delivered at 29/32 days (~26-28 weeks human) gestation received 0, 5, 8, 12, 15 cm H₂O of CPAP or variable CPAP of 15 to 5 or 15 to 8 cm H₂O (decreasing ~2 cm H₂O/min) for up to 10 min after birth.

RESULTS

FRC was lower in the 0 (6.8 (1.0-11.2) mL/kg) and 5 (10.1 (1.1-16.8) mL/kg) compared to the 15 (18.8 (10.9-22.4) mL/kg) cm H₂O groups (p = 0.003). Fewer kittens achieved FRC > 15 mL/kg in the 0 (20%), compared to 8 (36%), 12 (60%) and 15 (73%) cm H₂O groups (p = 0.008). While breathing rates were not different (p = 0.096), apnoea tended to occur more often with CPAP < 8 cm H₂O (p = 0.185). CPAP belly and lung bulging rates were similar whereas pneumothoraces were rare. Lowering CPAP from 15 to 5, but not 15 to 8 cm H₂O, decreased FRC and breathing rates.

CONCLUSION

In all, 15 cm H₂O of CPAP improved lung aeration and reduced apnoea, but did not increase the risk of lung over-expansion, pneumothorax or CPAP belly immediately after birth. FRC and breathing rates were maintained when CPAP was decreased to 8 cm H₂O.

IMPACT

Although preterm infants are commonly supported with 4-8 cm H₂O CPAP at birth, preclinical studies have shown that higher PEEP levels improve lung aeration. In this study, CPAP levels of 15 cm H₂O improved lung aeration and reduced apnoea in preterm rabbit kittens immediately after birth. In all, 15 cm H₂O CPAP did not increase the risk of lung over-expansion (indicated by bulging between the ribs), pneumothorax, or CPAP belly. These results can be used when designing future studies on CPAP strategies for preterm infants in the delivery room.

Increased airway liquid volumes at birth impairs cardiorespiratory function in preterm and near-term lambs

Respiratory distress is relatively common in infants born at or near-term, particularly in infants delivered following elective cesarean section. The pathophysiology underlying respiratory distress at term has largely been explained by a failure to clear airway liquid, but recent physiological evidence has indicated that it results from elevated airway liquid at the onset of air-breathing. We have investigated the effect of elevated airway liquid volumes at birth on cardiorespiratory function in preterm and near-term lambs. Preterm (130 ± 0 days gestation, term ~147 days gestation; n=13) and near-term (139 ± 1 days gestation; n=13) lambs were instrumented (to measure blood pressure, blood flow and blood gas status) and at delivery airway liquid volumes were adjusted to mimic levels expected following vaginal delivery (Controls; ~7mL/kg) or elective caesarean section with no labour (elevated liquid; EL; 37mL/kg). Lambs were delivered, mechanically ventilated and monitored for blood gas status, oxygenation, ventilator requirements, blood flows (carotid artery and pulmonary artery) and blood pressure during the first few hours of life. Preterm and near-term EL lambs had poorer gas exchange and required greater ventilatory support to maintain adequate oxygenation. Pulmonary blood flow was reduced and carotid artery blood flow, mean arterial blood pressure and heart rate were reduced in EL near-term but not preterm lambs. These data provide further evidence that greater airway liquid volumes at birth adversely effects newborn cardiorespiratory function, with the effects being greater in near-term newborns.

Quantifying lung aeration in neonatal lambs at birth using lung ultrasound

BACKGROUND

Lung ultrasound (LUS) is a safe and non-invasive tool that can potentially assess regional lung aeration in newborn infants and reduce the need for X-ray imaging. LUS produces images with characteristic artifacts caused by the presence of air in the lung, but it is unknown if LUS can accurately detect changes in lung air volumes after birth. This study compared LUS images with lung volume measurements from high-resolution computed tomography (CT) scans to determine if LUS can accurately provide relative measures of lung aeration.

METHODS

Deceased near-term newborn lambs (139 days gestation, term ∼148 days) were intubated and the chest imaged using LUS (bilaterally) and phase contrast x-ray CT scans at increasing static airway pressures (0-50 cmH₂O). CT scans were analyzed to calculate regional air volumes and correlated with measures from LUS images. These measures included (i) LUS grade; (ii) brightness (mean and coefficient of variation); and (iii) area under the Fourier power spectra within defined frequency ranges.

RESULTS

All LUS image analysis techniques correlated strongly with air volumes measured by CT (p < 0.01). When imaging statistics were combined in a multivariate linear regression model, LUS predicted the proportion of air in the underlying lung with moderate accuracy (95% prediction interval ± 22.15%, r ² = 0.71).

CONCLUSION

LUS can provide relative measures of lung aeration after birth in neonatal lambs. Future studies are needed to determine if LUS can also provide a simple means to assess air volumes and individualize aeration strategies for critically ill newborns in real time.

A novel low-cost bubble continuous positive airway pressure device with pressure monitoring and controlling system for low resource settings

Background

Currently bubble continuous positive airway pressure (bCPAP) is commonly used in low resource settings to treat respiratory distress. However, the accumulation of condensate in the patient's exhalation limb during operation could significantly increase pressure delivered to the body, which can lead to severe respiratory failure in the infant. The objective of this research was to develop a novel low-cost bCPAP device that can monitor and control the pressure delivered to infants.

Methods

When the neonate expires, the pressure sensor inside the expiratory limb measures the instant positive end-expiratory pressure. The microcontroller decides whether to turn the relay to switch the path of expiration between the two expiratory tubes connected to the valve outlets. This depends on the pressure reading and the cutoff pressure value inserted by the physician.

Results

The system was tested for accuracy, safety, cost, ease of use, and durability. The prototype was accurate in eight iterations at eight different depths of water that were made to monitor and control the pressure. It was safe and provided suitable pressure for the neonate, and the prototype was built in less than 193 USD.

Conclusions

The performance testing of the device demonstrated accurate and safe control and monitoring of continuous positive air pressure (CPAP) and oxygen levels with humidity levels safe for infants. The device provides humidified, blended, and pressurized gas for the patient. It allows physicians to easily monitor and control the accumulation of condensate in the exhalation limb of the CPAP machine accurately and safely.

Gravity-induced loss of aeration and atelectasis development in the preterm lung: a serial sonographic assessment

OBJECTIVE

To assess the impact of gravity and time on the changes in the distribution patterns of loss of aeration and atelectasis development in very preterm infants.

STUDY DESIGN

Preterm infants less than 32 weeks gestation were included in this prospective, observational study. Infants were assessed via serial lung ultrasound (LUS) score in four lung zones, performed on days 7, 14, 21, and 28 after birth.

RESULT

Eighty-eight patients were enrolled. There was a significant main effect of gravity (P < 0.001) and time (P = 0.01) on the LUS score between gravity-dependent lungs and non-dependent lungs. Moreover, there was a significant main effect of gravity (P = 0.003) on atelectasis development between the lungs.

CONCLUSION

Gravity and time have an impact on the changes in the distribution patterns of gravity-induced lung injuries in preterm infants.

Respiratory monitoring during neonatal resuscitation using a supraglottic airway device vs. a face mask

OBJECTIVE

To evaluate the respiratory function of asphyxiated infants resuscitated with i-gel supraglottic airway (SGA) vs. face mask (FM) in a low-resource setting.

METHODS

In this sub-study from the NeoSupra trial, respiratory function during the first 60 inflations was evaluated in 46 neonates (23 with SGA and 23 with FM) at the Mulago National Referral Hospital, Uganda. The primary outcome was the mask leak (%). The secondary outcomes included inspired (VTi) and expired (VTe) tidal volumes, and heart rate response to ventilation.

RESULTS

Median mask leak was 40% (IQR 22-52) with SGA and 39% (IQR 26-62) with FM (p = 0.38). Median VTe was 7.8 ml/kg (IQR 5.6-10.2) with SGA and 7.3 ml/kg (IQR 4.8-11.9) with FM (p = 0.84), while median VTi was 15.4 ml/kg (IQR 11-4-17.6) with SGA and 15.9 ml/kg (IQR 9.0-22.6) with FM (p = 0.68). A shorter time was needed to achieve heart rate > 100 bpm in SGA (median 13 s IQR 9-15) with respect to FM arm (median 61, IQR 33-140) (p = 0.0002).

CONCLUSION

Respiratory function was not statistically different between neonates resuscitated with SGA vs. FM. SGA was associated with faster heart rate recovery compared to FM in the subgroup of neonates with bradycardia. Further research is needed to investigate possible advantages of SGA on respiratory function at birth.

Stimulating and maintaining spontaneous breathing during transition of preterm infants

Most preterm infants breathe at birth, but need additional respiratory support due to immaturity of the lung and respiratory control mechanisms. To avoid lung injury, the focus of respiratory support has shifted from invasive towards non-invasive ventilation. However, applying effective non-invasive ventilation is difficult due to mask leak and airway obstruction. The larynx has been overlooked as one of the causes for obstruction, preventing face mask ventilation from inflating the lung. The larynx remains mostly closed at birth, only opening briefly during a spontaneous breath. Stimulating and supporting spontaneous breathing could enhance the success of non-invasive ventilation by ensuring that the larynx remains open. Maintaining adequate spontaneous breathing and thereby reducing the need for invasive ventilation is not only important directly after birth, but also in the first hours after admission to the NICU. Respiratory distress syndrome is an important cause of respiratory failure. Traditionally, treatment of RDS required intubation and mechanical ventilation to administer exogenous surfactant. However, new ways have been implemented to administer surfactant and preserve spontaneous breathing while maintaining non-invasive support. In this narrative review we aim to describe interventions focused on stimulation and maintenance of spontaneous breathing of preterm infants in the first hours after birth.

Tidal Breathing Parameters Measured by Structured Light Plethysmography in Newborns: Is It Feasible in Neonatal Intensive Care Unit?

OBJECTIVE

Structured light plethysmography (SLP) is a novel and noncontact respiratory assessment technique. It provides tidal breathing measurement in patients difficult to cooperate. In this study, we aimed to determine data for tidal breathing parameters measured by SLP in newborns.

STUDY DESIGN

Infants between 2 and 5 days of life without having any respiratory symptoms were eligible for this observational study. In total, 5 minutes of tidal breathing was recorded using SLP (Thora-3Di, PneumaCare Ltd, Cambridge, U.K.) in each infant. Various tidal breathing parameters including timing indices, flow-based parameters, and regional parameters were obtained from SLP data.

RESULTS

A total of 57 infants underwent measurements in the study. Evaluable recordings from 42 term and 11 late preterm infants were analyzed. Median gestational age and birthweight of the infants were 38 (37-39) weeks and 3,195 (2,790-3,585) g, respectively. In terms of flow-based parameters, "tidal inspiratory flow at 50% of inspiratory volume divided by tidal expiratory flow at 50% of expiratory volume" was 1.29 (1.13-1.53). Relative contribution of the thorax to each breath in percentage was measured as 38.67 (28.21-43.60). Median values of left-right hemithoracic asynchrony and thoraco-abdominal asynchrony were 6.92 (5.35-9.04) and 17.96 (12.98-36.44) degrees in the study population, respectively. There were no differences in tidal breathing parameters except "hemithoracic asynchrony" between term and late preterm infants. Hemithoracic asynchrony was significantly lower in term neonates than late preterms.

CONCLUSION

SLP was found to be feasible to obtain measures of tidal breathing parameters in newborns and it could be performed successfully even in the first days of life.

Open or closed: Changes in ductus arteriosus flow patterns at birth using 4D flow MRI in newborn piglets

The ductus arteriosus (DA) functionally closes during the transition from fetal to postnatal life because of lung aeration and corresponding cardiovascular changes. The thorough and explicit measurement and visualization of the right and left heart output during this transition has not been previously accomplished. We combined 4D flow MRI (dynamic volumetric blood flow measurements) and T2 relaxometry (oxygen delivery quantification) in surgically instrumented newborn piglets to assess the DA. This was performed in Large White-Landrace-Duroc piglets (n = 34) spanning four age groups: term-9 days, term-3, term+1, and term+5. Subject's DA status was classified using 4D flow: closed DA, forward DA flow, reversed DA flow, and bidirectional DA flow. Over all states, vessel diameters and flows normalized to body weight increased with age (for example in the ascending aorta flow-term-9: 126.6 ± 45.4; term+5: 260.2 ± 80.0 ml/min per kg; p = 0.0005; ascending aorta diameter-term-9: 5.2 ± 0.8; term+5: 7.7 ± 0.4 mm; p = 0.0004). In subjects with reversed DA blood flow there was lower common carotid artery blood flow (forward: 37.5 ± 9.0; reversed: 20.0 ± 7.4 ml/min per kg; p = 0.032). Linear regression revealed that as net DA flow decreases, common carotid artery flow decreases (R2  = 0.32, p = 0.004), and left (R2  = 0.33, p = 0.003) and right (R2  = 0.34, p = 0.003) pulmonary artery flow increases. Bidirectional DA blood flow changed oxygen saturation as determined by MRI between the ascending and descending aorta (ascending aorta: 90.1% ± 8.4%; descending aorta: 75.6% ± 14.2%; p < 0.05). Expanded use of these techniques in preterm animal models will aid in providing new understandings of normal versus abnormal DA transition, as well as to test the effectiveness of related clinical interventions.

Increased end-expiratory pressures improve lung function in near-term newborn rabbits with elevated airway liquid volume at birth

Approximately 53% of near-term newborns admitted to intensive care experience respiratory distress. These newborns are commonly delivered by cesarean section and have elevated airway liquid volumes at birth, which can cause respiratory morbidity. We investigated the effect of providing respiratory support with a positive end-expiratory pressure (PEEP) of 8 cmH₂O on lung function in newborn rabbit kittens with elevated airway liquid volumes at birth. Near-term rabbits (30 days; term = 32 days) with airway liquid volumes that corresponded to vaginal delivery (∼7 mL/kg, control, n = 11) or cesarean section [∼37 mL/kg; elevated liquid (EL), n = 11] were mechanically ventilated (tidal volume = 8 mL/kg). The PEEP was changed after lung aeration from 0 to 8 to 0 cmH₂O (control, n = 6; EL, n = 6), and in a separate group of kittens, PEEP was changed after lung aeration from 8 to 0 to 8 cmH₂O (control, n = 5; EL, n = 5). Lung function (ventilator parameters, compliance, lung gas volumes, and distribution of gas within the lung) was evaluated using plethysmography and synchrotron-based phase-contrast X-ray imaging. EL kittens initially receiving 0 cmH₂O PEEP had reduced functional residual capacities and lung compliance, requiring higher inflation pressures to aerate the lung compared with control kittens. Commencing ventilation with 8 cmH₂O PEEP mitigated the adverse effects of EL, increasing lung compliance, functional residual capacity, and the uniformity and distribution of lung aeration, but did not normalize aeration of the distal airways. Respiratory support with PEEP supports lung function in near-term newborn rabbits with elevated airway liquid volumes at birth who are at a greater risk of suffering respiratory distress.NEW & NOTEWORTHY Term babies born by cesarean section have elevated airway liquid volumes, which predisposes them to respiratory distress. Treatments targeting molecular mechanisms to clear lung liquid are ineffective for term newborn respiratory distress. We showed that respiratory support with an end-expiratory pressure supports lung function in near-term rabbits with elevated airway liquid volumes at birth. This study provides further physiological understanding of lung function in newborns with elevated airway liquid volumes at risk of respiratory distress.

Optimizing initial neonatal resuscitation to reduce neonatal encephalopathy around the world

One million two hundred thousand neonatal lives are lost each year due to intrapartum-related events; 99% of these deaths occur in low- and lower middle-income countries. Neonates exposed to intrapartum-related events present with failure to breathe at birth. Quick and effective delivery room management of these neonates is critical in the prevention of brain injury. Given the prominent role of lung aeration in the cardiopulmonary transition at birth, the mainstay of neonatal resuscitation is effective ventilation. Basic neonatal resuscitation focuses on simple stimulation, airway positioning and clearing, and bag-mask ventilation. Although principles for basic neonatal resuscitation remain the same for high- and low-resource settings, guidelines may differ based on available human and material resources. Formal training in basic resuscitation reduces intrapartum-related neonatal mortality in low-resource settings. However, there remain opportunities to improve provider performance for increased impact with other strategies such as regular practice and continuous quality improvement.

The Term Newborn: Delivery Room Triage and Transitions of Care

Term newborn infants without significant medical problems usually transition from fetal to newborn life without medical assistance. Infants requiring therapy often need care in a neonatal intensive care unit as opposed to a well-baby unit. Infants with unclear physiologic status or disease that may require therapies in the immediate newborn period may benefit from a period of observation with close monitoring before admission to a well-baby unit. Whenever possible, providing care for a newborn infant in an area that provides care for the newborn and mother together in the same room facilitates adaptation to normal breastfeeding and family bonding.

Cardiorespiratory monitoring in the delivery room using transcutaneous electromyography

OBJECTIVE

To assess feasibility of transcutaneous electromyography of the diaphragm (dEMG) as a monitoring tool for vital signs and diaphragm activity in the delivery room (DR).

DESIGN

Prospective observational study.

SETTING

Delivery room.

PATIENTS

Newborn infants requiring respiratory stabilisation after birth.

INTERVENTIONS

In addition to pulse oximetry (PO) and ECG, dEMG was measured with skin electrodes for 30 min after birth.

OUTCOME MEASURES

We assessed signal quality of dEMG and ECG recording, agreement between heart rate (HR) measured by dEMG and ECG or PO, time between sensor application and first HR read-out and agreement between respiratory rate (RR) measured with dEMG and ECG, compared with airway flow. Furthermore, we analysed peak, tonic and amplitude diaphragmatic activity from the dEMG-based respiratory waveform.

RESULTS

Thirty-three infants (gestational age: 31.7±2.8 weeks, birth weight: 1525±661 g) were included.18%±14% and 22%±21% of dEMG and ECG data showed poor quality, respectively. Monitoring HR with dEMG was fast (median 10 (IQR 10-11) s) and accurate (intraclass correlation coefficient (ICC) 0.92 and 0.82 compared with ECG and PO, respectively). RR monitoring with dEMG showed moderate (ICC 0.49) and ECG low (ICC 0.25) agreement with airway flow. Diaphragm activity started high with a decreasing trend in the first 15 min and subsequent stabilisation.

CONCLUSION

Monitoring vital signs with dEMG in the DR is feasible and fast. Diaphragm activity can be detected and described with dEMG, making dEMG promising for future DR studies.