Ventilation onset prior to umbilical cord clamping (physiological-based cord clamping) improves systemic and cerebral oxygenation in preterm lambs

Physiological-Based Cord Clamping: When the Baby Is Ready for Clamping

BACKGROUND

The timing of cord clamping has become a focal point for neonatal caregivers due to the promising outcomes associated with delayed cord clamping, which is a simple and cost-effective method to enhance the survival and well-being of preterm infants. While initially the rationale behind delaying clamping was to facilitate increased placental transfusion, research has unveiled additional hemodynamic benefits.

SUMMARY

Experimental studies have demonstrated improved circulatory transition when clamping is postponed until the lungs are adequately aerated. This suggests that infants requiring assistance during the transition phase may benefit from stabilization while still attached to the cord. The Aeration, Breathing, and then Clamping (ABC) project aimed to translate these experimental findings into clinical practice.

KEY MESSAGE

In this review, we will discuss the insights gained and lessons learned from the project's implementation.

Blood pressure and cerebral oxygenation with physiologically-based cord clamping: sub-study of the BabyDUCC trial

BACKGROUND

Cord-clamping strategies may modify blood pressure (BP) and cerebral tissue oxygen saturation (rStO2) immediately after birth.

METHODS

We conducted a sub-study nested within the Baby-Directed Umbilical Cord-Clamping trial. Infants ≥32+0 weeks' gestation assessed as requiring resuscitation were randomly allocated to either physiologically-based cord clamping (PBCC), where resuscitation commenced prior to umbilical cord clamping, or standard care where cord clamping occurred early (ECC). In this single-site sub-study, we obtained additional measurements of pre-ductal BP and rStO2. In a separate observational arm, non-randomised vigorous infants received 2 min of deferred cord clamping (DCC) and contributed data for reference percentiles.

RESULTS

Among 161 included infants, n = 55 were randomly allocated to PBCC (n = 30) or ECC (n = 25). The mean (SD) BP at 3-4 min after birth (primary outcome) in the PBCC group was 64 (10) mmHg compared to 62 (10) mmHg in the ECC group, mean difference 2 mmHg (95% confidence interval -3-8 mmHg, p = 0.42). BP and rStO2 were similar across both randomised arms and the observational arm (n = 106).

CONCLUSION

We found no difference in BP or rStO2 with the different cord clamping strategies. We report reference ranges for BP and rStO2 for late-preterm and full-term infants receiving DCC.

IMPACT

Among late-preterm and full-term infants receiving varying levels of resuscitation, blood pressure (BP, at 3-4 minutes and 6 min) and cerebral tissue oxygen saturation (rStO2) are not influenced by timing of cord clamping in relation to establishment of ventilation. Infants in this study did not require advanced resuscitation, where cord clamping strategies may yet influence BP and rStO2. The reference ranges for BP and rStO2 represent the first, to our knowledge, for vigorous late-preterm and full-term infants receiving deferred cord clamping. rStO2 > 90% (~90th percentile) may be used to define cerebral hyperoxia, for instance when studying oxygen supplementation after birth.

Physiological-based cord clamping stabilised cardiorespiratory parameters in very low birth weight infants

AIM

We investigated the influence of physiological-based cord clamping (PBCC) on cardiorespiratory stability in very low birth weight (VLBW) infants during the first 72 h of life.

METHODS

This retrospective study comprised VLBW infants born at <32 + 0 weeks of gestation and admitted to the neonatal intensive care unit of the Medical University of Graz, Austria, from December 2014 to April 2021. VLBW infants delivered with PBCC were matched by gestational age and birth weight to delayed cord clamping controls. The PBCC group was stabilised after birth with an intact cord. Routine monitoring parameters were compared between the groups.

RESULTS

We included 54 VLBW infants. The mean gestational ages of the PBCC group and controls were 27.4 ± 1.9 versus 27.4 ± 1.8 weeks (p = 0.87), and the mean birth weights were 912 ± 288 versus 915 ± 285 g (p = 0.96), respectively. The mean cord clamping time was 191 ± 78 s in the PBCC group. Heart rate was lower in the PBCC group during the first 3 days after birth, reaching significance by 10 h. Other monitoring parameters did not reveal any differences between the two groups.

CONCLUSION

PBCC stabilised cardiorespiratory parameters in VLBW infants. The lower heart rate in the PBCC group suggested higher blood volume following intact cord resuscitation.

Ventilatory Assistance Before Umbilical Cord Clamping in Extremely Preterm Infants: A Randomized Clinical Trial

Importance

Providing assisted ventilation during delayed umbilical cord clamping may improve outcomes for extremely preterm infants.

Objective

To determine whether assisted ventilation in extremely preterm infants (23 0/7 to 28 6/7 weeks' gestational age [GA]) followed by cord clamping reduces intraventricular hemorrhage (IVH) or early death.

Design, Setting, and Participants

This phase 3, 1:1, parallel-stratified randomized clinical trial conducted at 12 perinatal centers across the US and Canada from September 2, 2016, through February 21, 2023, assessed IVH and early death outcomes of extremely preterm infants randomized to receive 120 seconds of assisted ventilation followed by cord clamping vs delayed cord clamping for 30 to 60 seconds with ventilatory assistance afterward. Two analysis cohorts, not breathing well and breathing well, were specified a priori based on assessment of breathing 30 seconds after birth.

Intervention

After birth, all infants received stimulation and suctioning if needed. From 30 to 120 seconds, infants randomized to the intervention received continuous positive airway pressure if breathing well or positive-pressure ventilation if not, with cord clamping at 120 seconds. Control infants received 30 to 60 seconds of delayed cord clamping followed by standard resuscitation.

Main Outcomes and Measures

The primary outcome was any grade IVH on head ultrasonography or death before day 7. Interpretation by site radiologists was confirmed by independent radiologists, all masked to study group. To estimate the association between study group and outcome, data were analyzed using the stratified Cochran-Mantel-Haenszel test for relative risk (RR), with associations summarized by point estimates and 95% CIs.

Results

Of 1110 women who consented to participate, 548 were randomized and delivered infants at GA less than 29 weeks. A total of 570 eligible infants were enrolled (median [IQR] GA, 26.6 [24.9-27.7] weeks; 297 male [52.1%]). Intraventricular hemorrhage or death occurred in 34.9% (97 of 278) of infants in the intervention group and 32.5% (95 of 292) in the control group (adjusted RR, 1.02; 95% CI, 0.81-1.27). In the prespecified not-breathing-well cohort (47.5% [271 of 570]; median [IQR] GA, 26.0 [24.7-27.4] weeks; 152 male [56.1%]), IVH or death occurred in 38.7% (58 of 150) of infants in the intervention group and 43.0% (52 of 121) in the control group (RR, 0.91; 95% CI, 0.68-1.21). There was no evidence of differences in death, severe brain injury, or major morbidities between the intervention and control groups in either breathing cohort.

Conclusions and Relevance

This study did not show that providing assisted ventilation before cord clamping in extremely preterm infants reduces IVH or early death. Additional study around the feasibility, safety, and efficacy of assisted ventilation before cord clamping may provide additional insight.

Trial Registration

ClinicalTrials.gov Identifier: NCT02742454.

Thermoregulation for very preterm infants in the delivery room: a narrative review

Abnormal temperature in preterm infants is associated with increased morbidity and mortality. Infants born prematurely are at risk of abnormal temperature immediately after birth in the delivery room (DR). The World Health Organization (WHO) recommends that the temperature of newly born infants is maintained between 36.5-37.5oC after birth. When caring for very preterm infants, the International Liaison Committee on Resuscitation (ILCOR) recommends using a combination of interventions to prevent heat loss. While hypothermia remains prevalent, efforts to prevent it have increased the incidence of hyperthermia, which may also be harmful. Delayed cord clamping (DCC) for preterm infants has been recommended by ILCOR since 2015. Little is known about the effect of timing of DCC on temperature, nor have there been specific recommendations for thermal care before DCC. This review article focuses on the current evidence and recommendations for thermal care in the DR, and considers thermoregulation in the context of emerging interventions and future research directions. IMPACT: Abnormal temperature is common amongst very preterm infants after birth, and is an independent risk factor for mortality. The current guidelines recommend a combination of interventions to prevent heat loss after birth. Despite this, abnormal temperature is still a problem, across all climates and economies. New and emerging delivery room practice (i.e., delayed cord clamping, mobile resuscitation trolleys, early skin to skin care) may have an effect on infant temperature. This article reviews the current evidence and recommendations, and considers future research directions.

Extended period of ventilation before delayed cord clamping augments left-to-right shunting and decreases systemic perfusion at birth in preterm lambs

Previous studies have suggested that an extended period of ventilation before delayed cord clamping (DCC) augments birth-related rises in pulmonary arterial (PA) blood flow. However, it is unknown whether this greater rise in PA flow is accompanied by increases in left ventricular (LV) output and systemic arterial perfusion or whether it reflects enhanced left-to-right shunting across the ductus arteriosus and/or foramen ovale (FO), with decreased systemic arterial perfusion. Using an established preterm lamb birth transition model, this study compared the effect of a short (∼40 s, n = 11), moderate (∼2 min, n = 11) or extended (∼5 min, n = 12) period of initial mechanical lung ventilation before DCC on flow probe-derived perinatal changes in PA flow, LV output, total systemic arterial blood flow, ductal shunting and FO shunting. The LV output was relatively stable during initial ventilation but increased after DCC, with similar responses in all groups. Systemic arterial flow patterns displayed only minor differences during brief and moderate periods of initial ventilation and were similar after DCC. However, an increase in PA flow was augmented with an extended initial ventilation (P < 0.001), owing to an earlier onset of left-to-right ductal and FO shunting (P < 0.001), and was accompanied by a pronounced reduction in total systemic arterial flow (P = 0.005) that persisted for 4 min after DCC (P ≤ 0.039). These findings suggest that, owing to increased left-to-right shunting and a greater reduction in systemic arterial perfusion, an extended period of ventilation before DCC does not result in greater perinatal circulatory benefits than shorter periods of initial ventilation in the birth transition. KEY POINTS: Previous studies suggest that an extended period of initial ventilation before delayed cord clamping (DCC) augments birth-related rises in pulmonary arterial (PA) blood flow. It is unknown whether this greater rise in PA flow is accompanied by an increased left ventricular output and systemic arterial perfusion or whether it reflects enhanced left-to-right shunting across the ductus arteriosus and/or foramen ovale, with decreased systemic arterial perfusion. Anaesthetized preterm fetal lambs instrumented with central arterial flow probes underwent a brief (∼40 s), moderate (∼2 min) or extended (∼5 min) period of ventilation before DCC. Perinatal changes in left ventricular output were similar in all groups, but extended initial ventilation augmented both perinatal increases in PA flow, owing to earlier onset and greater left-to-right ductal and foramen ovale shunting, and perinatal reductions in total systemic arterial perfusion. Extended ventilation before DCC does not confer a greater perinatal circulatory benefit than shorter periods of initial ventilation.

Extrauterine Placental Perfusion and Oxygenation in Infants With Very Low Birth Weight: A Randomized Clinical Trial

Importance

An extrauterine placental perfusion (EPP) approach for physiological-based cord clamping (PBCC) may support infants with very low birth weight (VLBW) during transition without delaying measures of support.

Objective

To test whether EPP in resuscitation of infants with VLBW results in higher hematocrit levels, better oxygenation, or improved infant outcomes compared with delayed cord clamping (DCC).

Design, Setting, and Participants

This nonblinded, single-center randomized clinical trial was conducted at a tertiary care neonatal intensive care unit. Infants with a gestational age greater than 23 weeks and birth weight less than 1500 g born by cesarean delivery between May 2019 and June 2021 were included. Data were analyzed from October through December 2021.

Intervention

Prior to cesarean delivery, participants were allocated to receive EPP or DCC. In the EPP group, infant and placenta, connected by an intact umbilical cord, were detached from the uterus and transferred to the resuscitation unit. Respiratory support was initiated while holding the placenta over the infant. The umbilical cord was clamped when infants showed regular spontaneous breathing, stable heart rates greater than 100 beats/min, and adequate oxygen saturations. In the DCC group, cords were clamped 30 to 60 seconds after birth before infants were transferred to the resuscitation unit, where respiratory support was started.

Main Outcomes and Measure

The primary outcome was the mean hematocrit level in the first 24 hours after birth. Secondary prespecified outcome parameters comprised oxygenation during transition and short-term neonatal outcome.

Results

Among 60 infants randomized and included, 1 infant was excluded after randomization; there were 29 infants in the EPP group (mean [SD] gestational age, 27 weeks 6 days [15.0 days]; 14 females [48.3%]) and 30 infants in the DCC group (mean [SD] gestational age, 28 weeks 1 day [17.1 days]; 17 females [56.7%]). The mean (SD) birth weight was 982.8 (276.6) g and 970.2 (323.0) g in the EPP and DCC group, respectively. Intention-to-treat analysis revealed no significant difference in mean hematocrit level (mean difference [MD], 2.1 percentage points; [95% CI, -2.2 to 6.4 percentage points]). During transition, infants in the EPP group had significantly higher peripheral oxygen saturation as measured by pulse oximetry (adjusted MD at 5 minutes, 15.3 percentage points [95% CI, 2.0 to 28.6 percentage points]) and regional cerebral oxygen saturation (adjusted MD at 5 minutes, 11.3 percentage points [95% CI, 2.0 to 20.6 percentage points]). Neonatal outcome parameters were similar in the 2 groups.

Conclusions and Relevance

This study found that EPP resulted in similar hematocrit levels as DCC, with improved cerebral and peripheral oxygenation during transition. These findings suggest that EPP may be an alternative procedure for PBCC in infants with VLBW.

Trial Registration

ClinicalTrials.gov Identifier: NCT03916159.

Effect of delayed cord clamping on maternal and neonatal outcome in twin pregnancies: a retrospective cohort study

The objective of this study was to compare the maternal and neonatal outcomes following delayed cord clamping (DCC) versus immediate cord clamping (ICC) in twin pregnancies. This was a retrospective cohort study of 705 twin pregnancies who delivered at ≥ 24 weeks of gestation. Maternal and neonatal hemoglobin levels, blood transfusion, and neonatal outcomes were compared between DCC (n = 225) and ICC (n = 480) groups. Mean maternal predelivery and postpartum hemoglobin levels and the rate of postpartum hemoglobin drop ≥ 20% or maternal blood transfusion were comparable between the two groups. The DCC group had a significantly higher mean neonatal hemoglobin level (DCC vs. ICC: 17.4 ± 3.5 vs. 16.6 ± 2.7 g/dl, P = 0.010) but significantly lower rates of neonatal blood transfusion (DCC vs. ICC: 3.3% vs. 8.8%, P < 0.001) and respiratory distress syndrome (DCC vs. ICC: 6.7% vs. 15.2%, P < 0.001) than the ICC group. In conclusion, DCC compared with ICC in twin pregnancy was not associated with an increase of maternal postpartum bleeding complications, but it was associated with higher neonatal hemoglobin level and lower risks of neonatal blood transfusion and respiratory distress syndrome.

Alternatives to neonatal intubation

Opportunities to learn and maintain competence in neonatal intubation have decreased. As many clinicians providing care to the newborn infant are not skilled in intubation, alternative strategies are critical. Most preterm infants breathe spontaneously, and require stabilisation rather than resuscitation at birth. Use of tactile stimulation, deferred cord clamping, and avoidance of hypoxia can help optimise breathing for these infants. Nasal devices appear a promising alternative to the face mask for early provision of respiratory support. In term and near-term infants, supraglottic airways may be the most effective initial approach to resuscitation. Use of supraglottic airways during resuscitation can be taught to a range of providers, and may reduce need for intubation. While face mask ventilation is an important skill, it is challenging to perform effectively. Identification of the best approach to training the use of these devices during neonatal resuscitation remains an important priority.

Optimizing transition: Providing oxygen during intact cord resuscitation

Delayed clamping and cutting of the umbilical cord at birth is standard practice for management for all newborns. Preterm infants may additionally benefit from a combination of ventilation and oxygen provision during intact cord resuscitation. This review highlights both the potential benefits of such a combined approach and the need for further rigorous studies, including randomized controlled trials, of delivery room management in this population.

Assisted ventilation prior to umbilical cord clamping: Potential benefits, challenges, and research studies

Delayed cord clamping (DCC) is beneficial for many infants, and the American College of Obstetrics and Gynecology recommends at least 30-60 seconds of DCC for both term and preterm vigorous infants. For newly born infants that are not vigorous, some evidence in animal models suggests that providing assisted ventilation prior to cord clamping (V-DCC) leads to a more stable transition of cerebral, pulmonary and systemic circulation and oxygenation and may confer not only short-term physiologic benefits but perhaps also improvement in clinically important outcomes. This review is based around 7 questions to help the reader understand the physiologic underpinnings and challenges of V-DCC as well as the published and ongoing research studies aimed at determining whether V-DCC is beneficial for preterm or term infants.

Cord management in non-vigorous newborns

Cord management in non-vigorous newborns remains up for debate, as limited studies have validated strategies in this high-risk population. While multiple national and international governing bodies now recommend the routine practice of delayed cord clamping (DCC) in vigorous neonates, these organizations have not reached a consensus on the appropriate approach in non-vigorous neonates.1 Benefits of placental transfusion are greatly needed amongst non-vigorous neonates who are at risk of asphyxiation-associated mortality and morbidities, but the need for immediate resuscitation complicates matters. This chapter discusses the physiological benefits of placental transfusion for non-vigorous neonates and reviews the available literature on different umbilical cord management strategies for this population.

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.

Resuscitation with Intact Cord Versus Clamped Cord in Late Preterm and Term Neonates: A Randomized Controlled Trial

OBJECTIVE

To compare the effect of intact cord versus clamped cord resuscitation on the physiologic transition of neonates receiving positive-pressure ventilation (PPV) at birth.

STUDY DESIGN

This open-label, parallel-group, randomized controlled superiority trial was conducted in a tertiary care hospital in India. Neonates born at ≥34 weeks of gestation after a complicated pregnancy or labor were randomized just before birth to receive resuscitation according to the Neonatal Resuscitation Program algorithm with either an intact cord (intact cord resuscitation group) or after early cord clamping (early cord clamping resuscitation group). The allocated study intervention was administered if the neonate needed PPV at birth. The primary outcome was expanded Apgar score at 5 minutes after birth.

RESULTS

Birth weight, gestational age, and the incidence of pregnancy complications were similar in the 2 study groups. The proportion of neonates who received PPV was lower in the intact cord resuscitation group (28.7% vs 36.5%, P = .05; relative risk, 0.79; 95% CI, 0.61-1.01). Among neonates who received PPV, the expanded Apgar score at 5 minutes was significantly higher in the intact cord resuscitation group (median, 15 [IQR, 14-15] vs 14 [IQR, 13-15]; P < .001). The expanded Apgar score at 10 minutes, Apgar scores at 5 and 10 minutes, and oxygen saturation at 1, 5, and 10 minutes were also higher in the intact cord resuscitation group.

CONCLUSION

In late preterm and term neonates, resuscitation with an intact cord results in better postnatal physiologic transition than the standard practice of resuscitation after immediate cord clamping.

TRIAL REGISTRATION

Clinical Trial Registry of India (www.ctri.nic.in); trial registration no. CTRI/2020/02/023379.

The Respiratory Management of the Extreme Preterm in the Delivery Room

The fetal-to-neonatal transition poses an extraordinary challenge for extremely low birth weight (ELBW) infants, and postnatal stabilization in the delivery room (DR) remains challenging. The initiation of air respiration and the establishment of a functional residual capacity are essential and often require ventilatory support and oxygen supplementation. In recent years, there has been a tendency towards the soft-landing strategy and, subsequently, non-invasive positive pressure ventilation has been generally recommended by international guidelines as the first option for stabilizing ELBW in the delivery room. On the other hand, supplementation with oxygen is another cornerstone of the postnatal stabilization of ELBW infants. To date, the conundrum concerning the optimal initial inspired fraction of oxygen, target saturations in the first golden minutes, and oxygen titration to achieve desired stability saturation and heart rate values has not yet been solved. Moreover, the retardation of cord clamping together with the initiation of ventilation with the patent cord (physiologic-based cord clamping) have added additional complexity to this puzzle. In the present review, we critically address these relevant topics related to fetal-to-neonatal transitional respiratory physiology, ventilatory stabilization, and oxygenation of ELBW infants in the delivery room based on current evidence and the most recent guidelines for newborn stabilization.

Umbilical cord milking-benefits and risks

The most common methods for providing additional placental blood to a newborn are delayed cord clamping (DCC) and umbilical cord milking (UCM). However, DCC carries the potential risk of hypothermia due to extended exposure to the cold environment in the operating room or delivery room, as well as a delay in performing resuscitation. As an alternative, umbilical cord milking (UCM) and delayed cord clamping with resuscitation (DCC-R) have been studied, as they allow for immediate resuscitation after birth. Given the relative ease of performing UCM compared to DCC-R, UCM is being strongly considered as a practical option in non-vigorous term and near-term neonates, as well as preterm neonates requiring immediate respiratory support. However, the safety profile of UCM, particularly in premature newborns, remains a concern. This review will highlight the currently known benefits and risks of umbilical cord milking and explore ongoing studies.

Lung aeration reduces blood pressure surges caused by umbilical cord milking in preterm lambs

Background

Umbilical cord milking (UCM) at birth causes surges in arterial blood pressure and blood flow to the brain, which may explain the high risk of intraventricular haemorrhage (IVH) in extremely preterm infants receiving UCM. This high risk of IVH has not been reported in older infants.

Objective

We hypothesized that lung aeration before UCM, reduces the surge in blood pressure and blood flow induced by UCM.

Methods

At 126 days' gestation, fetal lambs (N = 8) were exteriorised, intubated and instrumented to measure umbilical, pulmonary, cerebral blood flows, and arterial pressures. Prior to ventilation onset, the umbilical cord was briefly (2-3 s) occluded (8 times), which was followed by 8 consecutive UCMs when all physiological parameters had returned to baseline. Lambs were then ventilated. After diastolic pulmonary blood flow markedly increased in response to ventilation, the lambs received a further 8 consecutive UCMs. Ovine umbilical cord is shorter than the human umbilical cord, with ∼10 cm available for UCMs. Therefore, 8 UCMs/occlusions were done to match the volume reported in the human studies. Umbilical cord clamping occurred after the final milk.

Results

Both umbilical cord occlusions and UCM caused significant increases in carotid arterial blood flow and pressure. However, the increases in systolic and mean arterial blood pressure (10 ± 3 mmHg vs. 3 ± 2 mmHg, p = 0.01 and 10 ± 4 mmHg vs. 6 ± 2 mmHg, p = 0.048, respectively) and carotid artery blood flow (17 ± 6 ml/min vs. 10 ± 6 ml/min, p = 0.02) were significantly greater when UCM occurred before ventilation onset compared with UCM after ventilation.

Conclusions

UCM after ventilation onset significantly reduces the increases in carotid blood flow and blood pressure caused by UCM.

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.

A newborn's "life line" - A review of umbilical cord management strategies

Literature supporting various umbilical management strategies have increased substantially over the past decade. Delayed cord clamping and umbilical cord milking are increasing embraced by obstetricians and neonatologists, and multiple international governing bodies now endorse these practices. This review summarizes the benefits and limitations of the different umbilical cord management strategies for term, near-term, and preterm neonates. Additional studies are underway to elucidate the safety profile of these practices, long term outcomes, and variations within these strategies that could potentially augment the benefits.

Physiological-based cord clamping in very preterm infants: the Aeration, Breathing, Clamping 3 (ABC3) trial-study protocol for a multicentre randomised controlled trial

BACKGROUND

International guidelines recommend delayed umbilical cord clamping (DCC) up to 1 min in preterm infants, unless the condition of the infant requires immediate resuscitation. However, clamping the cord prior to lung aeration may severely limit circulatory adaptation resulting in a reduction in cardiac output and hypoxia. Delaying cord clamping until lung aeration and ventilation have been established (physiological-based cord clamping, PBCC) allows for an adequately established pulmonary circulation and results in a more stable circulatory transition. The decline in cardiac output following time-based delayed cord clamping (TBCC) may thus be avoided. We hypothesise that PBCC, compared to TBCC, results in a more stable transition in very preterm infants, leading to improved clinical outcomes. The primary objective is to compare the effect of PBCC on intact survival with TBCC.

METHODS

The Aeriation, Breathing, Clamping 3 (ABC3) trial is a multicentre randomised controlled clinical trial. In the interventional PBCC group, the umbilical cord is clamped after the infant is stabilised, defined as reaching heart rate > 100 bpm and SpO₂ > 85% while using supplemental oxygen < 40%. In the control TBCC group, cord clamping is time based at 30-60 s. The primary outcome is survival without major cerebral and/or intestinal injury. Preterm infants born before 30 weeks of gestation are included after prenatal parental informed consent. The required sample size is 660 infants.

DISCUSSION

The findings of this trial will provide evidence for future clinical guidelines on optimal cord clamping management in very preterm infants at birth.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03808051. First registered on January 17, 2019.

Placental transfusion during neonatal resuscitation in an asphyxiated preterm model

BACKGROUND

Neonatal Resuscitation Program does not recommend placental transfusion in depressed preterm neonates.

METHODS

Our objectives were to study the effect of delayed cord clamping (DCC) with ventilation for 5 min (DCCV, n-5), umbilical cord milking (UCM) without ventilation (n-6), UCM with ventilation (UCMV, n-6), early cord clamping followed by ventilation (ECCV, n-6) on red cell volume (RCV), and hemodynamic changes in asphyxiated preterm lambs. Twenty-three preterm lambs at 127-128 days gestation were randomized to DCCV, UCM, UCMV, and ECCV. We defined asphyxia as heart rate <100/min.

RESULTS

The UCMV had the highest neonatal RCV as a percentage of fetoplacental volume compared to the other groups (UCMV 85.5 ± 10%, UCM 72 ± 10%, ECCV 65 ± 14%, DCCV 61 ± 10%, p < 0.01). The DCCV led to better ventilation (66 ± 1 mmHg) and higher pulmonary blood flow (75 ± 24 ml/kg/min). The carotid flow was significantly higher in UCM without ventilation. The fluctuations in carotid flow with milking were 25 ± 6% higher from baseline during UCM, compared to 6 ± 3% in UCMV (p < 0.01).

CONCLUSIONS

Cord milking with ventilation led to higher RCV than other interventions. Ventilation during cord milking reduced fluctuation in carotid flow compared to UCM alone. DCCV led to better ventilation and pulmonary blood flow but did not increase RCV.

IMPACT

The best practice of placental transfusion in a depressed preterm neonate remains unknown. Ventilation with an intact cord improves gas exchange and hemodynamics in an asphyxiated preterm model. Cord milking without ventilation led to lower red cell volume but higher carotid blood flow fluctuations compared to milking with ventilation. Our data can be translated to bedside and could impact preterm resuscitation.

Cardiopulmonary Resuscitation with an Intact Umbilical Cord

The body of literature supporting different umbilical management strategies has increased over the past decade as the role of cord management in neonatal transition is realized. Multiple international governing bodies endorse delayed cord clamping, and this practice is now widely accepted by obstetricians and neonatologists. Although term and preterm neonates benefit in some ways from delayed cord clamping, additional research on variations in this practice, including resuscitation with an intact cord, aim to find the optimal cord management practice that reduces mortality and major morbidities.

Divergent effects of initial ventilation with delayed cord clamping on systemic and pulmonary arterial flows in the birth transition of preterm lambs

A current view that delayed cord clamping (DCC) results in greater haemodynamic stability at birth than immediate cord clamping (ICC) is based on comparison of DCC vs. ICC followed by an asphyxial (∼2 min) cord clamp-to-ventilation (CC-V) interval. More recent data suggest that relatively minor perinatal differences in heart rate and blood pressure fluctuations exist between DCC and ICC with a non-asphyxial (<45 s) CC-V interval, but it is unknown how ventricular output and central arterial blood flow effects of DCC compare with those of non-asphyxial ICC. Anaesthetized preterm fetal lambs instrumented with flow probes on major central arteries were ventilated for 97 (7) s (mean (SD)) before DCC at birth (n = 10), or underwent ICC 40 (6) s before ventilation (n = 10). Compared to ICC, initial ventilation and DCC was accompanied by (1) redistribution of a similar level of ascending aortic flow away from cephalic arteries and towards the aortic isthmus after ventilation; (2) a lower right ventricular output after cord clamping that was redistributed towards the lungs, thereby maintaining the absolute contribution of this output to a similar increase in pulmonary arterial flow after birth; and (3) a lower descending thoracic aortic flow after birth, related to a more rapid decline in phasic right-to-left ductal flow only partially offset by increased aortic isthmus flow. However, systemic arterial flows were similar between DCC and non-asphyxial ICC within 5 min after birth. These findings suggest that compared to non-asphyxial ICC, initial ventilation with DCC transiently redistributed central arterial flows, resulting in lower perinatal systemic arterial, but not pulmonary arterial, flows. KEY POINTS: A current view that delayed cord clamping (DCC) results in greater haemodynamic stability at birth than immediate cord clamping (ICC) is based on comparison of DCC vs. ICC with an asphyxial (∼2 min) cord clamp-to-ventilation (CC-V) interval. Recent data suggest that relatively minor perinatal differences in heart rate and blood pressure fluctuations exist between DCC and ICC with a non-asphyxial (<45 s) CC-V interval, but how central arterial blood flow effects of DCC compare with those of non-asphyxial ICC is unknown. Anaesthetized preterm fetal lambs instrumented with central arterial flow probes underwent initial ventilation for ∼90 s before DCC at birth, or ICC for ∼40 s before ventilation. Compared to non-asphyxial ICC, initial ventilation with DCC redistributed central blood flows, resulting in lower systemic, but not pulmonary, arterial flows during this period of transition. This flow redistribution was transitory, however, with systemic arterial flows similar between DCC and non-asphyxial ICC within minutes after birth.

Effect of Delayed Umbilical Cord Clamping on Hemodynamic Instability in Preterm Neonates below 35 Weeks

INTRODUCTION

Delaying umbilical cord clamping facilitates postnatal transition in neonates but evidence on its effect in reducing hemodynamic instability in preterm neonates is inconclusive.

AIMS

To evaluate delayed cord clamping (DCC) in reducing the incidence of hemodynamic instability in preterm neonates below 35 weeks gestational age admitted to the neonatal intensive care unit.

METHODS

Neonates between 25 weeks and 34 weeks and 6 days gestation were enrolled. Hemodynamic and respiratory parameters were monitored over 48 h. Hemodynamic instability was defined as persistent tachycardia and/or hypotension necessitating therapy.

RESULTS

The DCC cohort included 62 neonates with an equal number in the non-DCC group. The birth weight [mean ± standard deviation (SD)] was 1332.90 ± 390.05 g and the gestational age (mean ± SD) was 31.64 ± 2.52 weeks. Hemodynamic instability was noted in 18/62 (29%) neonates in the DCC cohort and 29/62 (46.7%) in the non-DCC group; relative risk (RR) 0.62 [95% confidence interval (CI) 0.38-0.99] (p = 0.023). The duration of inotrope requirement in the DCC cohort (mean ± SD) was 38.38 ± 16.99 h compared to 49.13 ± 22.90 h in the non-DCC cohort (p = 0.090). Significantly higher systolic, diastolic and mean arterial pressures were noted from 6 h to 48 h in the DCC cohort (p < 0.001). The severity of respiratory distress and FiO2 requirement was also less in the first 24 h. There was no difference in the incidence of patent ductus arteriosus, late-onset sepsis or mortality.

CONCLUSION

Delaying umbilical cord clamping at birth by 60 s resulted in significantly lower hemodynamic instability in the first 48 h and higher blood pressure parameters.

Oxygen saturation and heart rate in healthy term and late preterm infants with delayed cord clamping

Blood oxygen in the fetus is substantially lower than in the newborn infant. In the minutes after birth, arterial oxygen saturation rises from around 50-60% to 90-95%. Initial respiratory efforts generate negative trans-thoracic pressures that drive liquid from the airways into the lung interstitium facilitating lung aeration, blood oxygenation, and pulmonary artery vasodilatation. Consequently, intra- (foramen ovale) and extra-cardiac (ductus arteriosus) shunting changes and the sequential circulation switches to a parallel pulmonary and systemic circulation. Delaying cord clamping preserves blood flow through the ascending vena cava, thus increasing right and left ventricular preload. Recently published reference ranges have suggested that delayed cord clamping positively influenced the fetal-to-neonatal transition. Oxygen saturation in babies with delayed cord clamping plateaus significantly earlier to values of 85-90% than in babies with immediate cord clamping. Delayed cord clamping may also contribute to fewer episodes of brady-or-tachycardia in the first minutes after birth, but data from randomized trials are awaited. IMPACT: Delaying cord clamping during fetal to neonatal transition contributes to a significantly earlier plateauing of oxygen saturation and fewer episodes of brady-and/or-tachycardia in the first minutes after birth. We provide updated information regarding the changes in SpO2 and HR during postnatal adaptation of term and late preterm infants receiving delayed compared with immediate cord clamping. Nomograms in newborn infants with delayed cord clamping will provide valuable reference ranges to establish target SpO2 and HR in the first minutes after birth.

With or Without Nasal Continuous Positive Airway Pressure During Delayed Cord Clamping in Premature Infants <32 Weeks: A Randomized Controlled Trial Using an Intention-To-Treat Analysis

OBJECTIVE

To assess whether providing nasal continuous positive airway pressure (nCPAP) during delayed cord clamping is beneficial for preterm infants <32 weeks.

STUDY DESIGN

A randomized controlled trial was performed from March 2020 to May 2021. Premature infants (<32 weeks of gestational age; n = 160) were allocated to receive at least 60 s of delayed cord clamping with nCPAP (DCC+nCPAP; n = 80) or without nCPAP (DCC only; n = 80). For both groups, after the umbilical cord was clamped, the infants were carried immediately to the resuscitation room to continue receiving standard transition. The primary outcome was the mechanical ventilation (MV) rate within 24 h of life. The measurements related to early respiratory support effect before cord clamping including positive end-expiratory pressure (PEEP) and FiO₂ during transition/leaving the delivery room, intubation rate during transition, pulmonary surfactant (PS) administration ≥2 times after birth, extubation failure, and incidence of bronchopulmonary dysplasia (BPD) were collected as the secondary outcomes. Furthermore, other neonatal short-term outcomes and safety assessment were also included.

RESULTS

The measurements were calculated using intention-to-treat analysis. The median time for cord clamping were 60 s with interquartile range (IQR) (60.00-60.00 vs. 60.00-70.00) in both groups. There were no difference in the primary outcome of MV rate within 24 h of life (p = 0.184). The arterial blood gas pH at 1 h after birth in the DCC+nCPAP group was 7.28 ± 0.08 vs. 7.25 ± 0.07 in the control group (mean difference = 0.01, 95% CI: -0.01-0.05, p = 0.052), which approached statistical significance. There was no significant statistical difference in the other short-term neonatal outcomes and the safety indicators between the two groups.

CONCLUSIONS

Our study showed that delayed cord clamping with nCPAP was feasible and safe in preterm infants with gestational age <32 weeks. Although there was a trend toward a higher arterial blood gas pH at 1 h after birth in the DCC+nCPAP group, DCC+nCPAP neither resulted in a corresponding measurable clinical improvement nor did it reduce subsequent neonatal morbidity. A larger multi-center study including more infants with gestational age <28 weeks is needed to evaluate the full effects of DCC in combination with nCPAP in preterm infants.

Does physiological-based cord clamping improve cerebral tissue oxygenation and perfusion in healthy term neonates? - A randomized controlled trial

OBJECTIVES

To evaluate cerebral tissue oxygenation index (cTOI) during neonatal transition in a group of healthy full-term neonates receiving either a physiological-based approach of deferred cord clamping (CC) after the onset of stable regular breathing (PBCC group) or a standard approach of time-based CC < 1 min (control group). Secondary aim was to evaluate changes in cerebral blood volume (ΔCBV), peripheral arterial oxygen saturation (SpO2) and heart rate (HR) in those neonates.

MATERIALS AND METHODS

We conducted a randomized controlled trial (clinicaltrials.gov: NCT02763436) including vaginally delivered healthy full-term neonates. Continuous measurements of cTOI and ΔCBV using near-infrared spectroscopy, and of SpO2 and HR using pulse oximetry were performed within the first 15 min after birth. Data of each minute of the PBCC group were compared to those of the control group.

RESULTS

A total of 71 full-term neonates (PBCC: n = 35, control: n = 36) with a mean (SD) gestational age of 40.0 (1.0) weeks and a birth weight of 3,479 (424) grams were included. Median (IQR) time of CC was 275 (197-345) seconds and 58 (35-86) seconds in the PBCC and control group, respectively (p < 0.001). There were no significant differences between the two groups regarding cTOI (p = 0.319), ΔCBV (p = 0.814), SpO2 (p = 0.322) and HR (p = 0.878) during the first 15 min after birth.

CONCLUSION

There were no significant differences in the course of cTOI as well as ΔCBV, SpO2 and HR during the first 15 min after birth in a group of healthy full-term neonates, who received either deferred CC after the onset of stable regular breathing or standard CC < 1 min. Thus, deferring CC ≥ 1 min following a physiological-based approach offers no benefits regarding cerebral tissue oxygenation and perfusion after uncomplicated vaginal delivery compared to a time-based CC approach.

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.

Cerebral hemodynamics during neonatal transition according to mode of delivery

Cerebral haemodynamics during the immediate transition period in neonates may differ depending on whether delivery is vaginal or by caesarean section. However, these differences have never been confirmed by near-infrared time-resolved spectroscopy (TRS). Therefore, the purpose of this study was to compare cerebral blood volume (CBV) and cerebral haemoglobin oxygen saturation (ScO₂) between healthy term neonates by mode of delivery. Subjects were 31 healthy term neonates who did not require resuscitation. Thirteen neonates were delivered vaginally (VD group) and 18 were delivered by elective caesarean section (CS group). Absolute oxyhaemoglobin, deoxyhaemoglobin, and total haemoglobin concentrations were measured continuously by TRS; oxyHb × 100/totalHb (ScO₂) (%) and CBV (mL/100 g brain tissue) were also calculated. Measurements were started as soon as possible after birth, obtained from 1 to 2 min after birth, and continued until 15 min after birth. CBV was significantly higher in the VD group than in the CS group in the 4 min after birth but not thereafter. There were no significant between-group differences in ScO₂ and SpO₂. These findings indicate that there is a difference in cerebral haemodynamic patterns in the first 4 min after delivery between term neonates by mode of delivery when CBV is monitored by TRS.

Cord Management of the Term Newborn

Keeping the umbilical cord intact after delivery facilitates transition from fetal to neonatal circulation and allows a placental transfusion of a considerable amount of blood. A delay of at least 3 minutes improves neurodevelopmental outcomes in term infants. Although regarded as common sense and practiced by many midwives, implementation of delayed cord clamping into practice has been unduly slow, partly because of beliefs regarding theoretic risks of jaundice and lack of understanding regarding the long-term benefits. This article provides arguments for delaying cord clamping for a minimum of 3 minutes.

Delayed cord clamping: Time for physiologic implementation

Delayed cord clamping has been shown to be beneficial in both preterm and term babies. Practice guidelines have not been consistent between centers and the practice of delayed cord clamping has not been standardized. The concept of physiologic-based cord clamping emerged into practice as well. Cord milking has different physiological effect and might be harmful in preterm babies.

Effect of maternal oxytocin on umbilical venous and arterial blood flows during physiological-based cord clamping in preterm lambs

BACKGROUND

Delayed umbilical cord clamping (UCC) after birth is thought to cause placental to infant blood transfusion, but the mechanisms are unknown. It has been suggested that uterine contractions force blood out of the placenta and into the infant during delayed cord clamping. We have investigated the effect of uterine contractions, induced by maternal oxytocin administration, on umbilical artery (UA) and venous (UV) blood flows before and after ventilation onset to determine whether uterine contractions cause placental transfusion in preterm lambs.

METHODS AND FINDINGS

At ~128 days of gestation, UA and UV blood flows, pulmonary arterial blood flow (PBF) and carotid arterial (CA) pressures and blood flows were measured in three groups of fetal sheep during delayed UCC; maternal oxytocin following mifepristone, mifepristone alone, and saline controls. Each successive uterine contraction significantly (p<0.05) decreased UV (26.2±6.0 to 14.1±4.5 mL.min-1.kg-1) and UA (41.2±6.3 to 20.7 ± 4.0 mL.min-1.kg-1) flows and increased CA pressure and flow (47.1±3.4 to 52.8±3.5 mmHg and 29.4±2.6 to 37.3±3.4 mL.min-1.kg-1). These flows and pressures were partially restored between contractions, but did not return to pre-oxytocin administration levels. Ventilation onset during DCC increased the effects of uterine contractions on UA and UV flows, with retrograde UA flow (away from the placenta) commonly occurring during diastole.

CONCLUSIONS

We found no evidence that amplification of uterine contractions with oxytocin increase placental transfusion during DCC. Instead they decreased both UA and UV flow and caused a net loss of blood from the lamb. Uterine contractions did, however, have significant cardiovascular effects and reduced systemic and cerebral oxygenation.

Differential Alveolar and Systemic Oxygenation during Preterm Resuscitation with 100% Oxygen during Delayed Cord Clamping

OBJECTIVE

 Delayed cord clamping (DCC) and 21 to 30% O₂ resuscitation is recommended for preterm infants but is commonly associated with low pulmonary blood flow (Qp) and hypoxia. 100% O₂ supplementation during DCC for 60 seconds followed by 30% O₂ may increase Qp and oxygen saturation (SpO₂).

STUDY DESIGN

 Preterm lambs (125-127 days of gestation) were resuscitated with 100% O₂ with immediate cord clamping (ICC, n = 7) or ICC + 30% O₂, and titrated to target SpO₂ (n = 7) or DCC + 100% O₂ for 60 seconds, which followed by cord clamping and 30% O₂ titration (n = 7). Seven preterm (23-27 weeks of gestation) human infants received continuous positive airway pressure (CPAP) + 100% O₂ for 60 seconds during DCC, cord clamping, and 30% O₂ supplementation after cord clamping.

RESULTS

 Preterm lambs in the ICC + 100% O₂ group resulted in PaO₂ (77 ± 25 mmHg), SpO₂ (77 ± 11%), and Qp (27 ± 9 mL/kg/min) at 60 seconds. ICC + 30% O₂ led to low Qp (14 ± 3 mL/kg/min), low SpO₂ (43 ± 26%), and PaO₂ (19 ± 7 mmHg). DCC + 100% O₂ led to similar Qp (28 ± 6 mL/kg/min) as ICC + 100% O₂ with lower PaO₂. In human infants, DCC + CPAP with 100% O₂ for 60 seconds, which followed by weaning to 30% resulted in SpO₂ of 92 ± 11% with all infants >80% at 5 minutes with 100% survival without severe intraventricular hemorrhage.

CONCLUSION

 DCC + 100% O₂ for 60 seconds increased Qp probably due to transient alveolar hyperoxia with systemic normoxia due to "dilution" by umbilical venous return. Larger translational and clinical studies are warranted to confirm these findings.

KEY POINTS

· Transient alveolar hyperoxia during delayed cord clamping can enhance pulmonary vasodilation.. · Placental transfusion buffers systemic oxygen tension and limits hyperoxia.. · Use of 100% oxygen for 60 seconds during DCC was associated with SpO2 ≥80% by 5 minutes..

Changes in heart rate from 5 s to 5 min after birth in vaginally delivered term newborns with delayed cord clamping

OBJECTIVE

To determine heart rate centiles during the first 5 min after birth in healthy term newborns delivered vaginally with delayed cord clamping.

DESIGN

Single-centre prospective observational study.

SETTING

Stavanger University Hospital, Norway, March-August 2019.

PATIENTS

Term newborns delivered vaginally were eligible for inclusion. Newborns delivered by vacuum or forceps or who received any medical intervention were excluded.

INTERVENTIONS

A novel dry electrode electrocardiography monitor (NeoBeat) was applied to the newborn's chest immediately after birth. The newborns were placed on their mother's chest or abdomen, dried and stimulated, and cord clamping was delayed for at least 1 min.

MAIN OUTCOME MEASURES

Heart rate was recorded at 1 s intervals, and the 3rd, 10th, 25th, 50th, 75th, 90th and 97th centiles were calculated from 5 s to 5 min after birth.

RESULTS

898 newborns with a mean (SD) birth weight 3594 (478) g and gestational age 40 (1) weeks were included. The heart rate increased rapidly from median (IQR) 122 (98-146) to 168 (146-185) beats per minute (bpm) during the first 30 s after birth, peaking at 175 (157-189) bpm at 61 s after birth, and thereafter slowly decreasing. The third centile reached 100 bpm at 34 s, suggesting that heart rates <100 bpm during the first minutes after birth are uncommon in healthy newborns after delayed cord clamping.

CONCLUSION

This report presents normal heart rate centiles from 5 s to 5 min after birth in healthy term newborns delivered vaginally with delayed cord clamping.

Resuscitation with an Intact Cord Enhances Pulmonary Vasodilation and Ventilation with Reduction in Systemic Oxygen Exposure and Oxygen Load in an Asphyxiated Preterm Ovine Model

(1) Background: Optimal initial oxygen (O₂) concentration in preterm neonates is controversial. Our objectives were to compare the effect of delayed cord clamping with ventilation (DCCV) to early cord clamping followed by ventilation (ECCV) on O₂ exposure, gas exchange, and hemodynamics in an asphyxiated preterm ovine model. (2) Methods: Asphyxiated preterm lambs (127-128 d) with heart rate <90 bpm were randomly assigned to DCCV or ECCV. In DCCV, positive pressure ventilation (PPV) was initiated with 30-60% O₂ and titrated based on preductal saturations (SpO₂) with an intact cord for 5 min, followed by clamping. In ECCV, the cord was clamped, and PPV was initiated. (3) Results: Fifteen asphyxiated preterm lambs were randomized to DCCV (N = 7) or ECCV (N = 8). The inspired O₂ (40 ± 20% vs. 60 ± 20%, p < 0.05) and oxygen load (520 (IQR 414-530) vs. 775 (IQR 623-868), p-0.03) in the DCCV group were significantly lower than ECCV. Arterial oxygenation and carbon dioxide (PaCO₂) levels were significantly lower and peak pulmonary blood flow was higher with DCCV. (4) Conclusion: In asphyxiated preterm lambs, resuscitation with an intact cord decreased O₂ exposure load improved ventilation with an increase in peak pulmonary blood flow in the first 5 min.

European Resuscitation Council Guidelines 2021: Newborn resuscitation and support of transition of infants at birth

The European Resuscitation Council has produced these newborn life support guidelines, which are based on the International Liaison Committee on Resuscitation (ILCOR) 2020 Consensus on Science and Treatment Recommendations (CoSTR) for Neonatal Life Support. The guidelines cover the management of the term and preterm infant. The topics covered include an algorithm to aid a logical approach to resuscitation of the newborn, factors before delivery, training and education, thermal control, management of the umbilical cord after birth, initial assessment and categorisation of the newborn infant, airway and breathing and circulation support, communication with parents, considerations when withholding and discontinuing support.

Impact of Acute and Chronic Hypoxia-Ischemia on the Transitional Circulation

The transition from intrauterine life to extrauterine existence encompasses significant cardiorespiratory adaptations. These include rapid lung aeration and increase in pulmonary blood flow (PBF). Perinatal asphyxia and fetal growth restriction can severely hamper this transition. Hypoxia is the common denominator in these 2 disease states, with the former characterized by acute insult and the latter by utero-placental insufficiency and a chronic hypoxemic state. Both may manifest as hemodynamic instability. In this review, we emphasize the role of physiologic-based cord clamping in supplementing PBF during transition. The critical role of lung aeration in initiating pulmonary gas exchange and increasing PBF is discussed. Physiologic studies in animal models have enabled greater understanding of the mechanisms and effects of various therapies on transitional circulation. With data from sheep models, we elaborate instrumentation for monitoring of cardiovascular and pulmonary physiology and discuss the combined effect of chest compressions and adrenaline in improving transition at birth. Lastly, physiologic adaptation influencing management in human neonatal cohorts with respect to cardiac and vascular impairments in hypoxic-ischemic encephalopathy and growth restriction is discussed. Impairments in right ventricular function and vascular mechanics hold the key to prognostication and understanding of therapeutic rationale in these critically ill cohorts. The right ventricle and pulmonary circulation seem to be especially affected and may be explored as therapeutic targets. The role of comprehensive assessments using targeted neonatal echocardiography as a longitudinal, reliable, and easily accessible tool, enabling precision medicine facilitating physiologically appropriate treatment choices, is discussed.

[Newborn resuscitation and support of transition of infants at birth]

The European Resuscitation Council has produced these newborn life support guidelines, which are based on the International Liaison Committee on Resuscitation (ILCOR) 2020 Consensus on Science and Treatment Recommendations (CoSTR) for Neonatal Life Support. The guidelines cover the management of the term and preterm infant. The topics covered include an algorithm to aid a logical approach to resuscitation of the newborn, factors before delivery, training and education, thermal control, management of the umbilical cord after birth, initial assessment and categorisation of the newborn infant, airway and breathing and circulation support, communication with parents, considerations when withholding and discontinuing support.

Impact of stimulation among non-crying neonates with intact cord versus clamped cord on birth outcomes: observation study

BACKGROUND

Stimulation of non-crying neonates after birth can help transition to spontaneous breathing. In this study, we aim to assess the impact of intact versus clamped umbilical cord on spontaneous breathing after stimulation of non-crying neonates.

METHODS

This is an observational study among non-crying neonates (n=3073) born in hospitals of Nepal. Non-crying neonates born vaginally at gestational age ≥34 weeks were observed for their response to stimulation with the cord intact or clamped. Obstetric characteristics of the neonates were analysed. Association of spontaneous breathing with cord management was assessed using logistic regression.

RESULTS

Among non-crying neonates, 2563 received stimulation. Of these, a higher proportion of the neonates were breathing in the group with cord intact as compared with the group cord clamped (81.1% vs 68.9%, p<0.0001). The use of bag-and-mask ventilation was lower among those who were stimulated with the cord intact than those who were stimulated with cord clamped (18.0% vs 32.4%, p<0.0001). The proportion of neonates with Apgar Score ≤3 at 1 min was lower with the cord intact than with cord clamped (7.6% vs 11.5%, p=0.001). In multivariate analysis, neonates with intact cord had 84% increased odds of spontaneous breathing (adjusted OR, 1.84; 95% CI: 1.48 to 2.29) compared with those with cord clamped.

CONCLUSIONS

Stimulation of non-crying neonates with intact cord was associated with more spontaneous breathing than among infants who were stimulated with cord clamped. Intact cord stimulation may help establish spontaneous breathing in apnoeic neonates, but residual confounding variables may be contributing to the findings. This study provides evidence for further controlled research to evaluate the effect of initial steps of resuscitation with cord intact.

Ductal Flow Ratio as Measure of Transition in Preterm Infants After Birth: A Pilot Study

Background: Cardiovascular changes during the transition from intra- to extrauterine life, alters the pressure gradient across the ductus arteriosus (DA). DA flow ratio (R-L/L-R) has been suggested to reflect the infant's transitional status and could potentially predict neonatal outcomes after preterm birth. Aim: Determine whether DA flow ratio correlates with oxygenation parameters in preterm infants at 1 h after birth. Methods: Echocardiography was performed in preterm infants born <32 weeks gestational age (GA), as part of an ancillary study. DA flow was measured at 1 h after birth. DA flow ratio was correlated with FiO₂, SpO₂, and SpO₂/FiO₂ (SF) ratio. The DA flow ratio of infants receiving physiological-based cord clamping (PBCC) or time-based cord clamping (TBCC) were compared. Results: Measurements from 16 infants were analysed (median [IQR] GA 29 [27-30] weeks; birthweight 1,176 [951-1,409] grams). R-L DA shunting was 16 [17-27] ml/kg/min and L-R was 110 [81-124] ml/kg/min. The DA flow ratio was 0.18 [0.11-0.28], SpO₂ 94 [93-96]%, FiO₂ was 23 [21-28]% and SF ratio 4.1 [3.3-4.5]. There was a moderate correlation between DA flow ratio and SpO₂ [correlation coefficient (CC) -0.415; p = 0.110], FiO₂ (CC 0.384; p = 0.142) and SF ratio (CC -0.356; p = 0.175). There were no differences in DA flow measurements between infants where PBBC or TBCC was performed. Conclusion: In this pilot study we observed a non-significant positive correlation between DA flow ratio at 1 h after birth and oxygenation parameters in preterm infants.

Delayed vs Immediate Cord Clamping Changes Oxygen Saturation and Heart Rate Patterns in the First Minutes after Birth

OBJECTIVE

To build arterial oxygen saturation (SpO₂) and heart rate (HR) percentiles for the first 10 minutes after birth in term infants born after an uneventful gestation, vaginal delivery, and delayed cord clamping (DCC) for ≥60 seconds, and to compare our results with previous ones constructed after immediate cord clamping.

STUDY DESIGN

Preductal SpO₂, HR, and timing of DCC immediately after complete fetal body expulsion were recorded. The pulse-oximeter was adjusted in the right wrist/hand and set at maximal intensity and measurements performed every 2 seconds.

RESULTS

A total of 282 term newborn infants were included. The definitive data set comprised of 70 257 SpO₂ and 79 746 HR measurements. Median and IQR of SpO₂ (%) at 1, 5, and 10 minutes after birth were 77 (68-85), 94 (90-96), and 96 (93-98), respectively. HR (beats per minute) median and IQR at 1, 5, and 10 minutes after birth were 148 (84-170), 155 (143-167), and 151 (142-161), respectively. We found significantly higher SpO₂ for the 10th, 50th, and 90th percentiles compared with the previous reference ranges for the first 5 minutes and HR for the first 1-2 minutes after birth.

CONCLUSIONS

Spontaneously breathing term newborn infants born by vaginal delivery who underwent DCC ≥60 seconds achieved higher SpO₂ and HR in the first 5 minutes after birth compared with term neonates born under the same conditions but with immediate cord clamping. Further studies in neonates undergoing cesarean delivery are under way.

Randomized Study of Delayed Cord Clamping of 30 to 60 Seconds in the Larger Infant Born Preterm

In a randomized study of infants born preterm (gestational age 28-34 6/7 weeks), we evaluated delayed cord clamping for 30 (n = 50) vs 60 (n = 55) seconds. The primary outcome of initial hematocrit differed by 2.8% (P = .006), being greater with 60 seconds. There were no differences in secondary outcomes and no adverse consequences between groups. These findings should serve as a stimulus to many centers that are reluctant to implement delayed cord clamping in this targeted larger premature population.

Respiratory Support of the Preterm Neonate: Lessons About Ventilation-Induced Brain Injury From Large Animal Models

Many preterm neonates require mechanical ventilation which increases the risk of cerebral inflammation and white matter injury in the immature brain. In this review, we discuss the links between ventilation and brain injury with a focus on the immediate period after birth, incorporating respiratory support in the delivery room and subsequent mechanical ventilation in the neonatal intensive care unit. This review collates insight from large animal models in which acute injurious ventilation and prolonged periods of ventilation have been used to create clinically relevant brain injury patterns. These models are valuable resources in investigating the pathophysiology of ventilation-induced brain injury and have important translational implications. We discuss the challenges of reconciling lung and brain maturation in commonly used large animal models. A comprehensive understanding of ventilation-induced brain injury is necessary to guide the way we care for preterm neonates, with the goal to improve their neurodevelopmental outcomes.

Cardiopulmonary Resuscitation of Asystolic Newborn Lambs Prior to Umbilical Cord Clamping; the Timing of Cord Clamping Matters!

Background: Current guidelines recommend immediate umbilical cord clamping (UCC) for newborns requiring chest compressions (CCs). Physiological-based cord clamping (PBCC), defined as delaying UCC until after lung aeration, has advantages over immediate UCC in mildly asphyxiated newborns, but its efficacy in asystolic newborns requiring CC is unknown. The aim of this study was to compare the cardiovascular response to CCs given prior to or after UCC in asystolic near-term lambs.

Methods: Umbilical, carotid, pulmonary, and femoral arterial flows and pressures as well as systemic and cerebral oxygenation were measured in near-term sheep fetuses [139 ± 2 (SD) days gestation]. Fetal asphyxia was induced until asystole ensued, whereupon lambs received ventilation and CC before (PBCC; n = 16) or after (n = 12) UCC. Epinephrine was administered 1 min after ventilation onset and in 3-min intervals thereafter. The PBCC group was further separated into UCC at either 1 min (PBCC₁, n = 8) or 10 min (PBCC₁₀, n = 8) after return of spontaneous circulation (ROSC). Lambs were maintained for a further 30 min after ROSC.

Results: The duration of CCs received and number of epinephrine doses required to obtain ROSC were similar between groups. After ROSC, we found no physiological benefits if UCC was delayed for 1 min compared to immediate cord clamping (ICC). However, if UCC was delayed for 10 min after ROSC, we found significant reductions in post-asphyxial rebound hypertension, cerebral blood flow, and cerebral oxygenation. The prevention of the post-asphyxial rebound hypertension in the PBCC₁₀ group occurred due to the contribution of the placental circulation to a low peripheral resistance. As a result, left and right ventricular outputs continued to perfuse the placenta and were evidenced by reduced mean pulmonary blood flow, persistence of right-to-left shunting across the ductus arteriosus, and persistence of umbilical arterial and venous blood flows.

Conclusion: It is possible to obtain ROSC after CC while the umbilical cord remains intact. There were no adverse effects of PBCC compared to ICC; however, the physiological changes observed after ROSC in the ICC and early PBCC groups may result in additional cerebral injury. Prolonging UCC after ROSC may provide significant physiological benefits that may reduce the risk of harm to the cerebral circulation.

Perinatal stabilisation of infants born with congenital diaphragmatic hernia: a review of current concepts

Congenital diaphragmatic hernia (CDH) is associated with high mortality rates and significant pulmonary morbidity, mainly due to disrupted lung development related to herniation of abdominal organs into the chest. Pulmonary hypertension is a major contributor to both mortality and morbidity, however, treatment modalities are limited. Novel prenatal and postnatal interventions, such as fetal surgery and medical treatments, are currently under investigation. Until now, the perinatal stabilisation period immediately after birth has been relatively overlooked, although optimising support in these early stages may be vital in improving outcomes. Moreover, physiological parameters obtained from the perinatal stabilisation period could serve as early predictors of adverse outcomes, thereby facilitating both prevention and early treatment of these conditions. In this review, we focus on the perinatal stabilisation period by discussing the current delivery room guidelines in infants born with CDH, the physiological changes occurring during the fetal-to-neonatal transition in CDH, novel delivery room strategies and early predictors of adverse outcomes. The combination of improvements in the perinatal stabilisation period and early prediction of adverse outcomes may mitigate the need for specific postnatal management strategies.

Early or delayed umbilical cord clamping? Experiences and perceptions of nurse-midwives and obstetricians at a regional referral hospital in Tanzania

Background

Umbilical cord clamping is a crucial step during the third stage of labour that separates the newborn from the placenta. Despite the available evidence that delayed umbilical cord clamping is more beneficial to infants, as well as the existence of 2014 WHO recommendation that the umbilical cord should be clamped between 1 and 3 minutes, its implementation is still low in many countries including Tanzania.

Objective

This study describes the experiences and perceptions of nurse-midwives`and obstetricians`about the timing of umbilical cord clamping at a regional referral hospital in Tanzania.

Methods

A descriptive qualitative study design that adopted a purposeful sampling strategy to recruit 19 participants was used. Nine semi-structured interviews with six nurse-midwives`and three obstetricians`, as well as one focus group discussion with ten nurse-midwives`were conducted. Thematic analysis guided the analysis of data.

Results

Three main themes generated from the data, each having 2 to 5 subthemes. 1. Experiences about the timing of umbilical cord clamping. 2. Perceptions about the umbilical cord clamping. 3. Factors influencing the practice of delayed umbilical cord clamping to improve newborn health outcomes.

Conclusion

Although the nurse-midwives`and obstetricians`commonly practiced clamping the umbilical cord immediately after delivery, they understood that delayed cord clamping has a potential benefit of oxygenation to the newborn in the event of the need for resuscitation. To move forward with the good practice in maternal and newborn care, proper pre-service and providers training on matters underlying childbirth is essential to address the gap of knowledge. Delayed cord clamping should be practiced widely to improve the health outcomes of the newborn.