Evaluating resuscitation practices on the basis of evidence: the findings at first glance may seem illogical

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.

Management of Multi Organ Dysfunction in Neonatal Encephalopathy

Neonatal Encephalopathy (NE) describes neonates with disturbed neurological function in the first post-natal days of life. NE is an overall term that does not specify the etiology of the encephalopathy although it often involves hypoxia-ischaemia. In NE, although neurological dysfunction is part of the injury and is most predictive of long-term outcome, these infants may also have multiorgan injury and compromise, which further contribute to neurological impairment and long-term morbidities. Therapeutic hypothermia (TH) is the standard of care for moderate to severe NE. Infants with NE may have co-existing immune, respiratory, endocrine, renal, hepatic, and cardiac dysfunction that require individualized management and can be impacted by TH. Non-neurological organ dysfunction not only has a negative effect on long term outcome but may also influence the efficacy of treatments in the acute phase. Post resuscitative care involves stabilization and decisions regarding TH and management of multi-organ dysfunction. This management includes detailed neurological assessment, cardio-respiratory stabilization, glycaemic and fluid control, sepsis evaluation and antibiotics, seizure identification, and monitoring and responding to biochemical and coagulation derangements. The emergence of new biomarkers of specific organ injury may have predictive value and improve the definition of organ injury and prognosis. Further evidence-based research is needed to optimize management of NE, prevent further organ dysfunction and reduce neurodevelopmental impairment.

Increasing Respiratory Effort With 100% Oxygen During Resuscitation of Preterm Rabbits at Birth

Background: Spontaneous breathing is essential for successful non-invasive respiratory support delivered by a facemask at birth. As hypoxia is a potent inhibitor of spontaneous breathing, initiating respiratory support with a high fraction of inspired O₂ may reduce the risk of hypoxia and increase respiratory effort at birth. Methods: Preterm rabbit kittens (29 days gestation, term ~32 days) were delivered and randomized to receive continuous positive airway pressure with either 21% (n = 12) or 100% O₂ (n = 8) via a facemask. If apnea occurred, intermittent positive pressure ventilation (iPPV) was applied with either 21% or 100% O₂ in kittens who started in 21% O₂, and remained at 100% O₂ for kittens who started the experiment in 100% O₂. Respiratory rate (breaths per minute, bpm) and variability in inter-breath interval (%) were measured from esophageal pressure recordings and functional residual capacity (FRC) was measured from synchrotron phase-contrast X-ray images. Results: Initially, kittens receiving 21% O₂ had a significantly lower respiratory rate and higher variability in inter-breath interval, indicating a less stable breathing pattern than kittens starting in 100% O₂ [median (IQR) respiratory rate: 16 (4-28) vs. 38 (29-46) bpm, p = 0.001; variability in inter-breath interval: 33.3% (17.2-50.1%) vs. 27.5% (18.6-36.3%), p = 0.009]. Apnea that required iPPV, was more frequently observed in kittens in whom resuscitation was started with 21% compared to 100% O₂ (11/12 vs. 1/8, p = 0.001). After recovering from apnea, respiratory rate was significantly lower and variability in inter-breath interval was significantly higher in kittens who received iPPV with 21% compared to 100% O₂. FRC was not different between study groups at both timepoints. Conclusion: Initiating resuscitation with 100% O₂ resulted in increased respiratory activity and stability, thereby reducing the risk of apnea and need for iPPV after birth. Further studies in human preterm infants are mandatory to confirm the benefit of this approach in terms of oxygenation. In addition, the ability to avoid hyperoxia after initiation of resuscitation with 100% oxygen, using a titration protocol based on oxygen saturation, needs to be clarified.

High vs. Low Initial Oxygen to Improve the Breathing Effort of Preterm Infants at Birth: Study Protocol for a Randomized Controlled Trial

Background: Although most preterm infants breathe at birth, their respiratory drive is weak and supplemental oxygen is often needed to overcome hypoxia. This could in turn lead to hyperoxia. To reduce the risk of hyperoxia, currently an initial low oxygen concentration (21-30%) is recommended during stabilization at birth, accepting the risk of a hypoxic period. However, hypoxia inhibits respiratory drive in preterm infants. Starting with a higher level of oxygen could lead to a shorter duration of hypoxia by stimulating breathing effort of preterm infants, and combined with subsequent titration based on oxygen saturation, prolonged hyperoxia might be prevented. Study design: This multi-center randomized controlled trial will include 50 infants with a gestational age between 24 and 30 weeks. Eligible infants will be randomized to stabilization with an initial FiO₂ of either 1.0 or 0.3 at birth. Hereafter, FiO₂ will be titrated based on the oxygen saturation target range. In both groups, all other interventions during stabilization and thereafter will be similar. The primary outcome is respiratory effort in the first 5 min after birth expressed as average minute volume/kg. Secondary outcomes include inspired tidal volumes/kg, rate of rise to maximum tidal volume/kg, percentage of recruitment breaths with tidal volumes above 8 mL/kg, duration of hypoxia and hyperoxia and plasma levels of markers of oxidative stress (8-iso-prostaglandin F2α). Discussion: Current resuscitation guidelines recommend oxygen titration if infants fail to achieve the 25th percentile of the SpO₂ reference ranges. It has become clear that, using this approach, most preterm infants are at risk for hypoxia in the first 5 min after birth, which could suppress the breathing effort. In addition, for compromised preterm infants who need respiratory support at birth, higher SpO₂ reference ranges in the first minutes after birth might be needed to prevent prolonged hypoxia. Enhancing breathing effort by achieving an adequate level of oxygenation could potentially lead to a lower incidence of intubation and mechanical ventilation in the delivery room, contributing to a lower risk on lung injury in high-risk preterm infants. Measuring 8-iso-prostaglandin F2α could lead to a reflection of the true amount of oxygen exposure in both study groups.

Gradually increased oxygen administration promoted survival after hemorrhagic shock

Gradually increased oxygen administration (GIOA) seems promising in hemorrhagic shock. However, the effects of GIOA on survival remain unclear, and details of GIOA are to be identified. After the induction of hemorrhagic shock, the rats were randomized into five groups (n = 9): normoxic group (Normo), hyperoxic group (Hypero), normoxic to hyperoxic group (GIOA1), long-time hypoxemic to hyperoxic group (GIOA2), and short-time hypoxemic to hyperoxic group (GIOA3). Survival was recorded for 96 h, plasma alanine transaminase, oxidative stress, hemodynamics, and blood gas were measured. The mean survival time of the GIOA3 was significantly longer than that of the Normo, Hypero, and GIOA2. Plasma alanine transaminase levels were significantly lower in the Normo, GIOA1, and GIOA3 compared to the Hypero and GIOA2 at 2 h post-resuscitation (PR). Plasma 3-nitrotyrosine levels at 2 h PR were significantly lower in the GIOA2 and GIOA3 compared to the Normo and Hypero. Central venous oxygen saturation at 2 h PR in the GIOA3 was significantly higher than the Normo; however, no significant difference was observed between GIOA1 and Normo. Besides, at 2 h PR, mean arterial pressure in the GIOA3 was significantly higher than the GIOA2; however, no significant difference was observed between GIOA1 and GIOA2. (1) GIOA could significantly prolong survival time compared to normoxemic resuscitation and hyperoxic resuscitation; (2) early moments of GIOA are critical to the benefits; and (3) hypoxemia at onset of resuscitation may be imperative, more works are needed to determine the optimal initial oxygen concentration of GIOA.

Oxygen administration for the resuscitation of term and preterm infants

Oxygen has been widely used in neonatal resuscitation for about 300 years. In October 2010, the International Liaison Committee on Neonatal Resuscitation released new guidelines. Based on experimental studies and randomized clinical trials, the recommendations on evaluation and monitoring of oxygenation status and oxygen supplementation in the delivery room were revised in detail. They include: inaccuracy of oxygenation clinical assessment (colour), mandatory use of pulse oximeter, specific saturation targets and oxygen concentrations during positive pressure ventilation in preterm and term infants. In this review, we describe oxygen management in the delivery room in terms of clinical assessment, monitoring, treatment and the gap of knowledge.

New concepts in neonatal resuscitation

PURPOSE OF REVIEW

There has been a substantial increase in the number of studies of neonatal resuscitation and it is timely to review the accumulating evidence.

RECENT FINDINGS

There have been major changes in the way that newly born infants are managed in the delivery room. Colour is no longer recommended as a useful indicator of oxygenation or effectiveness of resuscitation. Pulse oximetry provides rapid, continuous and accurate information on both oxygenation and heart rate. Resuscitation of term infants should begin with air, with the provision of blended oxygen to maintain oxygen saturations similar to those of term infants requiring no resuscitation. Positive end-expiratory pressure during initial ventilation aids lung aeration and establishment of functional residual capacity. Respiratory function monitoring allows operators to identify factors adversely affecting ventilation, including leak around the face mask and airway obstruction. Clamping of the umbilical cord should be delayed for at least 1 min for infants not requiring resuscitation.

SUMMARY

The International Liaison Committee on Resuscitation guidelines on the management of newborn infants were updated in 2010 and incorporate much of the newly available evidence. The use of intensive care techniques in the delivery room is promising but requires further evaluation. Monitoring techniques and interventions need to be adapted for use in developing countries.

Monitoring oxygen saturation and heart rate in the early neonatal period

Pulse oximetry is commonly used to assist clinicians in assessment and management of newly born infants in the delivery room (DR). In many DRs, pulse oximetry is now the standard of care for managing high risk infants, enabling immediate and dynamic assessment of oxygenation and heart rate. However, there is little evidence that using pulse oximetry in the DR improves short and long term outcomes. We review the current literature on using pulse oximetry to measure oxygen saturation and heart rate and how to apply current evidence to management in the DR.

Defining the reference range for oxygen saturation for infants after birth

OBJECTIVE

The goal was to define reference ranges for pulse oxygen saturation (Spo(2)) values in the first 10 minutes after birth for infants who received no medical intervention in the delivery room.

METHODS

Infants were eligible if a member of the research team was available to record Spo(2) immediately after birth. Infants were excluded if they received supplemental oxygen or any type of assisted ventilation. Spo(2) was measured with a sensor applied to the right hand or wrist as soon as possible after birth; data were collected every 2 seconds.

RESULTS

We studied 468 infants and recorded 61650 Spo(2) data points. The infants had a mean + or - SD gestational age of 38 + or - 4 weeks and birth weight of 2970 + or - 918 g. For all 468 infants, the 3rd, 10th, 50th, 90th, and 97th percentile values at 1 minute were 29%, 39%, 66%, 87%, and 92%, respectively, those at 2 minutes were 34%, 46%, 73%, 91%, and 95%, and those at 5 minutes were 59%, 73%, 89%, 97%, and 98%. It took a median of 7.9 minutes (interquartile range: 5.0-10 minutes) to reach a Spo(2) value of >90%. Spo(2) values for preterm infants increased more slowly than those for term infants. We present percentile charts for all infants, term infants of > or = 37 weeks, preterm infants of 32 to 36 weeks, and extremely preterm infants of <32 weeks.

CONCLUSION

These data represent reference ranges for Spo(2) in the first 10 minutes after birth for preterm and term infants.

Room air or 100% oxygen for resuscitation of infants with perinatal depression

PURPOSE OF REVIEW

The International Liaison Committee on Resuscitation (ILCOR) recommends initiating neonatal resuscitation with concentrations of oxygen between 21 and 100%. This wide range of oxygen concentrations recommended for resuscitation highlights the lack of evidence supporting either 21 or 100% O2. The purpose of this review is to analyze the efficacy of reoxygenation with 100% O2 or room air on rates of return of spontaneous circulation--the main goal of cardiopulmonary resuscitation.

RECENT FINDINGS

Clinical studies suggest that reoxygenation initiated with room air is effective in depressed neonates born with a preserved circulation. Reoxygenation with room air in these infants is associated with lower levels of circulating markers of oxidative stress than reoxygenation with 100% oxygen. However, there is no evidence that resuscitation with room air is as effective as that with 100% oxygen in restoration of an arrested circulation. In fact, animal studies indicate that, in comparison with 100% oxygen, reoxygenation with room air results in more sluggish restoration of depressed cerebral and systemic circulations.

SUMMARY

Prior to a revision of current neonatal resuscitation guidelines it must be determined whether resuscitation initiated with room air results in the same rate of return of spontaneous circulation as resuscitation initiated with 100% oxygen.

Oxygen saturation in healthy infants immediately after birth

OBJECTIVE

Because the optimal concentration of oxygen (FiO2) required for stabilization of the newly born infant has not been established, the FiO2 is commonly adjusted according to the infant's oxygen saturation (SpO2). We aimed to determine the range of pre-ductal SpO2 in the first minutes of life in healthy newborn infants.

STUDY DESIGN

We applied an oximetry sensor to the infant's right palm or wrist of term and preterm deliveries immediately after birth. Infants who received any resuscitation or supplemental oxygen were excluded. SpO2 was recorded at 60 second intervals for at least 5 minutes and until the SpO2 was >90%.

RESULTS

A total of 205 deliveries were monitored; 30 infants were excluded from the study. SpO2 readings were obtained within 60 seconds of age from 92 of 175 infants (53%). The median (interquartile range) SpO2 at 1 minute was 63% (53%-68%). There was a gradual rise in SpO2 with time, with a median SpO2 at 5 minutes of 90% (79%-91%).

CONCLUSION

Many newborns have an SpO2 <90% during the first 5 minutes of life. This should be considered when choosing SpO2 targets for infants treated with supplemental oxygen in the delivery room.

Feasibility of and delay in obtaining pulse oximetry during neonatal resuscitation

Application of the sensor to newly born infants before connection to a pulse oximeter increases the reliability and speed with which data are displayed. Data are available in most infants within 90 seconds of birth. Oximetry may be useful in guiding interventions during resuscitation.

Use of supplementary equipment for resuscitation of newborn infants at tertiary perinatal centres in Australia and New Zealand

AIM

Neonatal resuscitation is a common and important intervention. International consensus statements advise how newborns should be resuscitated and suggest equipment to be used. Use of equipment not specifically recommended in these guidelines has been advocated. We wished to determine how widely this supplementary equipment is used in a geographically defined region.

METHODS

Each of the 25 tertiary perinatal centres with on-site deliveries in Australia and New Zealand was surveyed. The questionnaire asked about the use of the following items during delivery room resuscitation: pulse oximetry, exhaled carbon dioxide detection, polyethylene wrapping, oxygen blenders, laryngeal mask and oropharyngeal airways.

RESULTS

Data were obtained from all centres. Pulse oximetry is used at 12 (48%) centres. Exhaled CO2 detection is used to confirm endotracheal tube placement at three (12%) of the centres. Polyethylene wrapping is used to prevent heat loss in very-low-birthweight infants at delivery at 11 (44%) centres. Oxygen blenders are used to modify the amount of oxygen delivered at nine (36%) centres. Laryngeal mask airways are infrequently used at two (8%) centres. Oropharyngeal airways are infrequently used at five (20%) centres.

CONCLUSION

There is considerable variation in the equipment and techniques used to resuscitate newly born infants. Use of equipment not specifically recommended in international consensus statements is widespread. These are potentially effective tools to improve resuscitation. The evidence supporting their use is, however, limited. Urgent evaluation of their efficacy and safety is required before even more widespread use occurs.

[Air or oxygen for neonatal resuscitation in the delivery room?]

Most of the contemporary guidelines on newborn resuscitation are based on experience but lack scientific evidence. The use of 100% oxygen is one of the more evident. Today, these practices are questioned, particularly for the resuscitation of moderately depressed full term or near term newborns. Results of recent meta-analysis of trials that compared ventilation with air versus pure oxygen at birth suggests current practices should be revisited. On the basis of these data, air can be the initial gas to use for these babies. Large scale trials, including preterm and cause and/or severity of initial asphyxia, must now be undertaken before the publication of new guidelines for these populations. Particularly severely asphyxiated infants might require supplemental oxygen with titration of oxygen delivery and continuous monitoring of oxygen saturation.

Resuscitation of newborn infants with 100% oxygen or air: a systematic review and meta-analysis

BACKGROUND

International consensus statements for resuscitation of newborn infants recommend provision of 100% oxygen with positive pressure if assisted ventilation is required. However, 100% oxygen exacerbates reperfusion injury in animals and reduces cerebral perfusion in newborn babies. We aimed to establish whether resuscitation with air decreased mortality or neurological disability in newborn infants compared with 100% oxygen.

METHODS

We did a systematic review and meta-analysis of trials that compared resuscitation with air versus 100% oxygen, using the methods of the Cochrane Collaboration. We combined data for similar outcomes in the analysis where appropriate, using a fixed-effects model.

FINDINGS

Five trials (two masked and three unmasked), consisting of 1302 newborn infants, fulfilled the inclusion criteria. Most babies were born at or near term in developing countries. In the three unmasked studies, infants resuscitated with room air who remained cyanotic and bradycardic were switched to 100% oxygen at 90 s. The masked studies allowed crossover to the other gas during the first minutes of life. Although no individual trial showed a difference in mortality, the pooled analysis showed a significant benefit for infants resuscitated with air (relative risk 0.71 [95% CI 0.54 to 0.94], risk difference -0.05 [-0.08 to -0.01]). The effect on long-term development could not be reliably determined because of methodological limitations in the one study that followed up infants beyond 12 months of age.

INTERPRETATION

For term and near-term infants, we can reasonably conclude that air should be used initially, with oxygen as backup if initial resuscitation fails. The effect of intermediate concentrations of oxygen at resuscitation needs to be investigated. Future trials should include and stratify for premature infants.

The role of oxygen in neonatal resuscitation

New knowledge has accumulated in recent years making it prudent to ask questions regarding current oxygenation policies and guidelines. Because new-born resuscitation affects so many individuals, and because resuscitation procedures may have dramatic consequences on infant and child health, intensified discussion and research in this field are not only necessary but are a requirement. In particular, there is a lack of data on infants born before term. It is difficult to give absolute recommendations on which oxygen concentration should be applied for newborn resuscitation; however, it seems that ambient air is safe. It is easy to handle, is always at hand, and is inexpensive. Conversely, regarding 100% O2, I believe we have sufficient data to conclude that this should not be given routinely at birth to depressed infants; however, whether it is beneficial or harmful to start out resuscitation with 30%, 40%, or 60% O2 is not known. No data exist to answer this question. A call for more research in this area is timely. The effect of pure oxygen on cell growth and cell death, gene activation, and possibly DNA damage should be carefully investigated. Even before such data are collected, it is known that pure oxygen at birth triggers long-term and poorly understood effects. Oxygen obviously is more toxic than previously thought, and oxygen given to small infants has a 50-year history of uncertain benefits. Table 1 summarizes the pros and cons of using 21%versus 100% 02 for newborn resuscitation. Brain circulation as assessed by microspheres is restored as quickly with 21% O2 as it is with 100% O2; however, microcirculation is somewhat slower. Metabolism, pulmonary flow, and myocardial performance are normalized just as quickly by 21% and 100% O2. Brain injury as assessed by glycerol augmentation, matrix injury, and neonatal mortality is less in infants given 21% versus 100% O2.

Resuscitation of premature infants: what are we doing wrong and can we do better?

Neonatal resuscitation is based on experience with little evidence to support the methods advocated. Current guidelines make no distinction between the techniques for term and very premature infants. The guidelines support the use of 100%, cold, dry oxygen delivered with devices that provide variable peak inspiratory pressures and tidal volumes with no positive end-expiratory pressure (PEEP). It is possible that these techniques damage the lungs. Self-inflating resuscitation bags give no indication about leaks, produce variable inflating pressures, do not provide PEEP and cannot deliver prolonged inflations. Flow-inflating bags will not work if there is leak at the facemask and also have variable inflating pressures. Although they can provide PEEP and deliver prolonged inflations, they require considerable skill to use. The Neopuff is relatively easy to use, provides PEEP and steady inflating pressure and does not achieve the set pressures if there is a mask leak. Continuous positive airway pressure and PEEP are used in the neonatal intensive care unit to maintain lung volume. It is surprising they are not routinely recommended for resuscitation when establishing the lung volume is paramount. Volutrauma is a potential problem in neonatal resuscitation and yet none of the devices give any indication of the tidal volume delivered. There is considerable potential for improvement in techniques of neonatal resuscitation through the application of evidence already available and much scope for further research in this field.

Recomendaciones en reanimación neonatal

The recommendations for neonatal resuscitation are not always based on sufficient scientific evidence and thus expert consensus based on current research, knowledge, and experience are useful for formulating practical protocols that are easy to follow. The latest recommendations, in 2000, modified previously published recommendations and are included in the present text.