Respiratory function and near infrared spectroscopy recording during cardiopulmonary resuscitation in an extremely preterm newborn

Continuous chest compression during sustained inflation versus continuous compression with asynchronized ventilation in an infantile porcine model of severe bradycardia

Background

Recently, the American Heart Association released a statement calling for research examining the appropriate age to transition from the neonatal to pediatric cardiopulmonary resuscitation approach to resuscitation.

Aim

To compare neonatal and pediatric resuscitation approach by using either continuous chest compression with asynchronized ventilation (CCaV) or continuous chest compression superimposed with sustained inflation (CC + SI) during infant cardiopulmonary resuscitation. We hypothesized that CC + SI compared to CCaV would reduce time to return of spontaneous circulation (ROSC) in infantile piglets with asphyxia-induced bradycardic cardiac arrest.

Methods

Twenty infantile piglets (5-10 days old) were anesthetized and asphyxiated by clamping the endotracheal tube. Piglets were randomized to CC + SI or CCaV for resuscitation (n = 10/group). Heart rate, arterial blood pressure, carotid blood flow, cerebral oxygenation, intrathoracic pressure and respiratory parameters were continuously recorded throughout the experiment.

Main results

The median (IQR) time to ROSC with CC + SI compared to CCaV was 179 (104-447) vs 660 (189-660), p = 0.05. The number of piglets achieving ROSC with CC + SI and CCaV were 8/10 and 6/10, p = 0.628. Piglets resuscitated with CC + SI required less epinephrine compared to CCaV (p = 0.039). CC + SI increased the intrathoracic pressure throughout resuscitation (p = 0.025) and increased minute ventilation (p < 0.001), compared to CCaV. There was no difference in hemodynamic parameters between groups.

Conclusions

CC + SI improves resuscitative efforts of infantile piglets by increasing the intrathoracic pressure and minute ventilation, and thus reducing the duration of resuscitation, compared to CCaV.

Chest compressions and medications during neonatal resuscitation

Prolonged resuscitation in neonates, although quite rare, may occur in response to profound intractable bradycardia as a result of asphyxia. In these instances, chest compressions and medications may be necessary to facilitate return of spontaneous circulation. While performing chest compressions, the two thumb method is preferred over the two finger technique, although several newer approaches are under investigation. While the ideal compression to ventilation ratio is still uncertain, a 3:1 ratio remains the recommendation by the Neonatal Resuscitation Program. Use of feedback mechanisms to optimize neonatal cardiopulmonary resuscitation (CPR) show promise and are currently under investigation. While performing optimal cardiac compressions to pump blood, use of medications to restore spontaneous circulation will likely be necessary. Current recommendations are that epinephrine, an endogenous catecholamine be used preferably intravenously or by intraosseous route, with the dose repeated every 3-5 minutes until return of spontaneous circulation. Finally, while the need for volume replacement is rare, it may be considered in instances of acute blood loss or poor response to resuscitation.

Fetal to neonatal transition: what additional information can be provided by cerebral near infrared spectroscopy?

This narrative review focuses on the clinical use and relevance of cerebral oxygenation measured by NIRS during fetal to neonatal transition. Cerebral NIRS(cNIRS) offers the possibility of non-invasive, continuous, and objective brain monitoring in addition to the recommended routine monitoring. During the last decade, with growing interest in early and sensitive brain monitoring, many research groups worldwide have been working with cNIRS and verified the feasibility of cNIRS monitoring immediately after birth. Cerebral hypoxia during fetal to neonatal transition, defined as cerebral oxygenation values below10th percentile, seems to have an impact on neurological outcomes. Feasibility to guide clinical support using cNIRS to reduce the burden of cerebral hypoxia has been shown. It is well known that in some cases cerebral oxygenation follows different patterns than SpO2. Cerebral oxygenation does not only depend on systemic oxygenation, hemoglobin content and cerebral blood flow, but also on cardiocirculatory condition, ventilation, and metabolic parameters. Hence, measurement of cerebral oxygenation may uncover problems not detectable by standard monitoring. Therefore, applying NIRS can provide caregivers a more complete clinical overview, especially in critically ill neonates. In this review, we aim to describe the additional information which can be provided by cNIRS during fetal to neonatal transition. IMPACT: This narrative review focuses on the clinical use and relevance of cerebral oxygenation measured by near infrared spectroscopy (NIRS) during fetal to neonatal transition. During the last decade, interest on brain monitoring is growing continuously as the measurement of cerebral oxygenation may uncover problems which are not detectable by routine monitoring. Therefore, it will be crucial to have additional information to get a complete overview, especially in critically ill neonates in need of medical and respiratory support. In this review, we offer additional information which can be provided by cerebral NIRS during fetal to neonatal transition.

Is Chest Compression Superimposed with Sustained Inflation during Cardiopulmonary Resuscitation an Alternative to 3:1 Compression to Ventilation Ratio in Newborn Infants?

Approximately 0.1% for term and 10-15% of preterm infants receive chest compression (CC) in the delivery room, with high incidence of mortality and neurologic impairment. The poor prognosis associated with receiving CC in the delivery room has raised concerns as to whether specifically-tailored cardiopulmonary resuscitation methods are needed. The current neonatal resuscitation guidelines recommend a 3:1 compression:ventilation ratio; however, the most effective approach to deliver chest compression is unknown. We recently demonstrated that providing continuous chest compression superimposed with a high distending pressure or sustained inflation significantly reduced time to return of spontaneous circulation and mortality while improving respiratory and cardiovascular parameters in asphyxiated piglet and newborn infants. This review summarizes the current available evidence of continuous chest compression superimposed with a sustained inflation.

Asynchronous ventilation at 120 compared with 90 or 100 compressions per minute improves haemodynamic recovery in asphyxiated newborn piglets

OBJECTIVE

To determine whether different chest compression (CC) rates during continuous CC with asynchronous ventilations (CCaV) reduce time to return of spontaneous circulation (ROSC) and improved haemodynamic recovery in piglets aged 24-72 hours with asphyxia-induced asystole.

METHODS

Thirty piglets (aged 24-72 hours) were anaesthetised, intubated, instrumented and exposed to 30 min normocapnic hypoxia followed by asphyxia. Piglets were randomised into four groups: CCaV with CC rate of 90 (CCaV+90, n=8), 100 (CCaV+100, n=8) or 120 compressions per minute (CCaV+120, n=8), and a sham-operated group (n=6). Cardiac function, carotid blood flow, cerebral and renal oxygenation and respiratory parameters were continuously recorded. Cerebral cortical tissue was harvested and assayed for inflammatory and injury markers.

RESULTS

All three intervention groups had a similar number of piglets achieving ROSC (6/8, 5/8 and 5/8 for CCaV+120, CCaV+100 and CCaV+90, respectively) and mean ROSC time (120, 90 and 90 s for CCaV+120, CCaV+100 and CCaV+90, respectively). The haemodynamic recovery (indicated by carotid flow, cerebral and renal perfusion) was similar between CCaV+120 and sham by the end of experiment. In comparison, CCaV+90 and CCaV+100 had significantly reduced haemodynamic recovery compared with sham operated (p≤0.05). Inflammatory (interleukin [IL]-6 and IL-1β) and injury markers (lactate) were significantly higher in the frontoparietal cortex of CCaV+90 and CCaV+100 compared with sham, whereas brain injury markers were similar between CCaV+120 and sham.

CONCLUSIONS

Although there was no difference between the groups in achieving ROSC, the haemodynamic recovery of CCaV+120 was significantly improved compared with CCaV+90 and CCaV+100, which were also associated with higher cerebral inflammatory and brain injury markers.

Asphyxiated Female and Male Newborn Piglets Have Similar Outcomes With Different Cardiopulmonary Resuscitation Interventions

Background: Male newborns have a greater risk of poor cardiovascular and respiratory outcomes compared to females. The mechanisms associated with the "male disadvantage" remains unclear. We have previously shown no difference between male and female newborn piglets during hypoxia, asphyxia, resuscitation, and post-resuscitation recovery. However, it is unknown if there are differences in resuscitation outcomes between males and females during different cardiopulmonary resuscitation techniques. Intervention and Measurements: Secondary analysis of 184 term newborn mixed breed duroc piglets (1-3 days of age, weighing 2.0 (0.2) kg) from seven different studies, which were exposed to 30-50 min of normocapnic hypoxia followed by asphyxia until asystole. This was followed by cardiopulmonary resuscitation. For the analysis, piglets were divided into male and female groups, as well as resuscitation technique groups (sustained inflation, 3:1 compression-to-ventilation ratio, or asynchronous ventilations during chest compressions). Cardiac function, carotid blood flow, and cerebral oxygenation were continuously recorded throughout the experiment. Main results: Regardless of resuscitation technique, there was no significant difference between males and females in the number achieving return of spontaneous circulation (ROSC) [95/123 (77%) vs. 48/61 (79%)], the time to achieve ROSC [112 (80-185) s vs. 110 (77-186) s], and the 4-h survival rate [81/95 (85%) vs. 40/48 (83%)]. Levels of the injury markers interleukin (IL)-1ß, IL-6, IL-8, and tumor necrosis factor-α in frontoparietal cortex tissue homogenates were similar between males and females. Conclusions: Regardless of resuscitation technique, there was no significant effect of sex on resuscitation outcome, survival, and hemodynamic recovery in asphyxiated newborn piglets.

Enhanced monitoring during neonatal resuscitation

Immediately after birth through spontaneous breaths, infants' clear lung liquid replacing it with air, and gradually establishing a functional residual capacity to achieve gas exchange. Most infants start breathing independently after birth and ~3% of infants who require positive pressure ventilation. When newborns fail to start breathing the current neonatal resuscitation guidelines recommend initiatingpositive pressure ventilationusing a face mask and a ventilation device. Adequate ventilation is the cornerstone of successful neonatal resuscitation; therefore, it is mandatory that anybody involved in neonatal resuscitation is trained in mask ventilation techniques. One of the main problems with mask ventilation is that it is very subjective with direct feedback lacking and not uncommonly, the resuscitator does not realise that their technique is unsatisfactory. Many studies have shown that monitoring tidal volume and leak around the mask or endotracheal tube enables the resuscitator to identify the problem and adjust their technique to reduce the leak and deliver and appropriate tidal volume. This chapter discusses the currently available monitoring devices used during stabilization/resuscitation in the delivery room.

Chest Compressions in the Delivery Room

Annually, an estimated 13–26 million newborns need respiratory support and 2–3 million newborns need extensive resuscitation, defined as chest compression and 100% oxygen with or without epinephrine in the delivery room. Despite such care, there is a high incidence of mortality and neurologic morbidity. The poor prognosis associated with receiving chest compression alone or with medications in the delivery room raises questions as to whether improved cardiopulmonary resuscitation methods specifically tailored to the newborn could improve outcomes. This review discusses the current recommendations, mode of action, different compression to ventilation ratios, continuous chest compression with asynchronous ventilations, chest compression and sustained inflation optimal depth, and oxygen concentration during cardiopulmonary resuscitation.

Chest compression during sustained inflation versus 3:1 chest compression:ventilation ratio during neonatal cardiopulmonary resuscitation: a randomised feasibility trial

BACKGROUND

Current neonatal resuscitation guidelines recommend 3:1 compression:ventilation (C:V) ratio. Recently, animal studies reported that continuous chest compressions (CC) during a sustained inflation (SI) significantly improved return of spontaneous circulation (ROSC). The approach of CC during SI (CC+SI) has not been examined in the delivery room during neonatal resuscitation.

HYPOTHESIS

It is a feasibility study to compare CC+SI versus 3:1 C:V ratio during neonatal resuscitation in the delivery room. We hypothesised that during neonatal resuscitation, CC+SI will reduce the time to ROSC. Our aim was to examine if CC+SI reduces ROSC compared with 3:1 C:V CPR in preterm infants <33 weeks of gestation.

STUDY DESIGN

Randomised feasibility trial.

METHOD

Once CC was indicated all eligible infants were immediately and randomly allocated to either CC+SI group or 3:1 C:V group. A sequentially numbered, brown, sealed envelope contained a folded card box with the treatment allocation was opened by the clinical team at the start of CC.

STUDY INTERVENTIONS

Infants in the CC+SI group received CC at a rate of 90/min during an SI with a duration of 20 s (CC+SI). After 20 s, the SI was interrupted for 1 s and the next SI was started for another 20 s until ROSC. Infants in the '3:1 group' received CC using 3:1 C:V ratio until ROSC.

PRIMARY OUTCOME

Overall the mean (SD) time to ROSC was significantly shorter in the CC+SI group with 31 (9) s compared with 138 (72) s in the 3:1 C:V group (p=0.011).

CONCLUSION

CC+SI is feasible in the delivery room.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT02083705, pre-results.

Ventilation Strategies during Neonatal Cardiopulmonary Resuscitation

Approximately, 10-20% of newborns require breathing assistance at birth, which remains the cornerstone of neonatal resuscitation. Fortunately, the need for chest compression (CC) or medications in the delivery room (DR) is rare. About 0.1% of term infants and up to 15% of preterm infants receive these interventions, this will result in approximately one million newborn deaths annually worldwide. In addition, CC or medications (epinephrine) are more frequent in the preterm population (~15%) due to birth asphyxia. A recent study reported that only 6 per 10,000 infants received epinephrine in the DR. Further, the study reported that infants receiving epinephrine during resuscitation had a high incidence of mortality (41%) and short-term neurologic morbidity (57% hypoxic-ischemic encephalopathy and seizures). A recent review of newborns who received prolonged CC and epinephrine but had no signs of life at 10 min following birth noted 83% mortality, with 93% of survivors suffering moderate-to-severe disability. The poor prognosis associated with receiving CC alone or with medications in the DR raises questions as to whether improved cardiopulmonary resuscitation methods specifically tailored to the newborn could improve outcomes.

Management of Extremely Low Birth Weight Infants in Delivery Room

Extremely low birth weight (ELBW) infants are particularly vulnerable at birth, and stabilization in the delivery room (DR) remains challenging. After birth, ELBW infants are at high risk for the development of thermal dysregulation, respiratory insufficiency, and hemodynamic instability due to their immature physiology and anatomy. Although successful stabilization facilitates the transition and reduces acute morbidity, suboptimal care in the DR could cause long-term sequelae. This review addresses the challenges in stabilization in the DR and current neonatal resuscitation guidelines and recommendations.

Cerebral Tissue Oxygenation during Immediate Neonatal Transition and Resuscitation

This article provides a review of cerebral tissue oxygenation during immediate transition after birth in human neonates. Recommended routine monitoring, especially if resuscitation is needed, during this period includes arterial oxygen saturation and heart rate measured by pulse oximetry and electrocardiogram. However, there is increasing interest to monitor in addition with near-infrared spectroscopy (NIRS) the oxygenation of the brain. There is a different pattern of increase between cerebral tissue oxygenation and arterial oxygen saturation during the immediate transition, with cerebral tissue oxygenation reaching a plateau faster than arterial oxygen saturation. Differences can be explained, since cerebral tissue oxygenation is not only affected by arterial oxygen saturation but also by cerebral blood flow, hemoglobin content, and cerebral oxygen consumption. Normal values have already been established for different devices, gestational ages, and modes of delivery in neonates without any medical support. Cerebral hypoxia during immediate transition might cause brain damage. In preterm neonates with cerebral hemorrhage evolving in the first week after birth, the cerebral tissue oxygenation is already lower in the first minutes after birth compared to preterm neonates without cerebral hemorrhage. Using cerebral NIRS in combination with intervention guidelines has been shown to reduce the burden of cerebral hypoxia in preterm neonates. Cerebral tissue oxygenation during immediate transition seems to have an impact on outcome, whereby NIRS monitoring is feasible and has the advantage of continuous, non-invasive recording. The impact of NIRS monitoring and interventions on short- and long-term outcomes still need to be evaluated.

Optimal Chest Compression Rate and Compression to Ventilation Ratio in Delivery Room Resuscitation: Evidence from Newborn Piglets and Neonatal Manikins

Cardiopulmonary resuscitation (CPR) duration until return of spontaneous circulation (ROSC) influences survival and neurologic outcomes after delivery room (DR) CPR. High quality chest compressions (CC) improve cerebral and myocardial perfusion. Improved myocardial perfusion increases the likelihood of a faster ROSC. Thus, optimizing CC quality may improve outcomes both by preserving cerebral blood flow during CPR and by reducing the recovery time. CC quality is determined by rate, CC to ventilation (C:V) ratio, and applied force, which are influenced by the CC provider. Thus, provider performance should be taken into account. Neonatal resuscitation guidelines recommend a 3:1 C:V ratio. CCs should be delivered at a rate of 90/min synchronized with ventilations at a rate of 30/min to achieve a total of 120 events/min. Despite a lack of scientific evidence supporting this, the investigation of alternative CC interventions in human neonates is ethically challenging. Also, the infrequent occurrence of extensive CPR measures in the DR make randomized controlled trials difficult to perform. Thus, many biomechanical aspects of CC have been investigated in animal and manikin models. Despite mathematical and physiological rationales that higher rates and uninterrupted CC improve CPR hemodynamics, studies indicate that provider fatigue is more pronounced when CC are performed continuously compared to when a pause is inserted after every third CC as currently recommended. A higher rate (e.g., 120/min) is also more fatiguing, which affects CC quality. In post-transitional piglets with asphyxia-induced cardiac arrest, there was no benefit of performing continuous CC at a rate of 90/min. Not only rate but duty cycle, i.e., the duration of CC/total cycle time, is a known determinant of CC effectiveness. However, duty cycle cannot be controlled with manual CC. Mechanical/automated CC in neonatal CPR has not been explored, and feedback systems are under-investigated in this population. Evidence indicates that providers perform CC at rates both higher and lower than recommended. Video recording of DR CRP has been increasingly applied and observational studies of what is actually done in relation to outcomes could be useful. Different CC rates and ratios should also be investigated under controlled experimental conditions in animals during perinatal transition.

Chest Compressions during Sustained Inflations Improve Recovery When Compared to a 3:1 Compression:Ventilation Ratio during Cardiopulmonary Resuscitation in a Neonatal Porcine Model of Asphyxia

BACKGROUND

Recently, sustained inflations (SI) during chest compression (CC) (CC+SI) have been suggested as an alternative to the current approach during neonatal resuscitation. No previous study compared CC+SI using CC rates of 90/min to the current 3:1 compression:ventilation ratio (C:V).

OBJECTIVE

To determine whether CC+SI versus a 3:1 C:V reduces the time to the return of spontaneous circulation (ROSC) and improves hemodynamic recovery in newborn piglets with asphyxia-induced bradycardia.

INTERVENTION AND MEASUREMENTS

Term newborn piglets were anesthetized, intubated, instrumented, and exposed to 45-min normocapnic hypoxia followed by asphyxia. Cardiopulmonary resuscitation (CPR) was initiated when the heart rate decreased to 25% of baseline. Piglets were randomized into 3 groups: CC during SI at a rate of 90 CC/min (SI+CC 90, n = 8), a 3:1 C:V using 90 CC and 30 inflations (3:1, n = 8), or a sham group (n = 6). Cardiac function, carotid blood flow, cerebral oxygenation, and respiratory parameters were continuously recorded throughout the experiment.

RESULTS

CC+SI significantly reduced the median (IQR) time of ROSC, i.e., 34 s (28-156 s) versus 210 s (72-300 s) in the 3:1 group (p = 0.048). CC+SI also significantly reduced the requirement for 100% oxygen, improved respiratory parameters, and resulted in a similar hemodynamic recovery.

CONCLUSIONS

CC+SI during CPR significantly improved ROSC in a porcine model of neonatal resuscitation. This is of considerable clinical relevance because improved respiratory and hemodynamic parameters potentially minimize morbidity and mortality in newborn infants.

A review of approaches to optimise chest compressions in the resuscitation of asphyxiated newborns

OBJECTIVE

Provision of chest compressions (CCs) and/or medications in the delivery room is associated with poor outcomes. Based on the physiology of perinatal asphyxia, we aimed to provide an overview of current recommendations and explore potential determinants of effective neonatal cardiopulmonary resuscitation (CPR): balancing ventilations and CC, CC rate, depth, full chest recoil, CC technique and adrenaline.

DESIGN

A search in the databases MEDLINE (Ovid) and EMBASE until 10 April 2015.

SETTING

Delivery room.

PATIENTS

Asphyxiated newborn infants.

INTERVENTIONS

CCs.

MAIN OUTCOME MEASURES

Haemodynamics, recovery and survival.

RESULTS

Current evidence is derived from mathematical models, manikin and animal studies, and small case series. No randomised clinical trials examining neonatal CC have been performed. There is no evidence to refute a CC to ventilation (C:V) ratio of 3:1. Raising the intrathoracic pressure, for example, by superimposing a sustained inflation on uninterrupted CC, and a CC rate >120/min may be beneficial. The optimal neonatal CC depth is unknown, but factors influencing depth and consistency include the C:V ratio. Incomplete chest wall recoil can cause less negative intrathoracic pressure between CC and reduced CPR effectiveness. CC should be performed with the two-thumb method over the lower third of the sternum. The optimal dose, route and timing of adrenaline administration remain to be determined.

CONCLUSIONS

Successful CPR requires the delivery of high-quality CC, encompassing optimal (A) C:V ratio (B) rate, (C) depth, (D) chest recoil between CC, (E) technique and (F) adrenaline dosage. More animal studies with high translational value and randomised clinical trials are needed.

Exhaled CO2 Parameters as a Tool to Assess Ventilation-Perfusion Mismatching during Neonatal Resuscitation in a Swine Model of Neonatal Asphyxia

Background

End-tidal CO₂ (ETCO₂), partial pressure of exhaled CO₂ (PECO₂), and volume of expired CO₂ (VCO₂) can be continuously monitored non-invasively to reflect pulmonary ventilation and perfusion status. Although ETCO₂ ≥14mmHg has been shown to be associated with return of an adequate heart rate in neonatal resuscitation and quantifying the PECO₂ has the potential to serve as an indicator of resuscitation quality, there is little information regarding capnometric measurement of PECO₂ and ETCO₂ in detecting return of spontaneous circulation (ROSC) and survivability in asphyxiated neonates receiving cardiopulmonary resuscitation (CPR).

Methods

Seventeen newborn piglets were anesthetized, intubated, instrumented, and exposed to 45-minute normocapnic hypoxia followed by apnea to induce asphyxia. Protocolized resuscitation was initiated when heart rate decreased to 25% of baseline. Respiratory and hemodynamic parameters including ETCO₂, PECO₂, VCO₂, heart rate, cardiac output, and carotid artery flow were continuously measured and analyzed.

Results

There were no differences in respiratory and hemodynamic parameters between surviving and non-surviving piglets prior to CPR. Surviving piglets had significantly higher ETCO₂, PECO₂, VCO₂, cardiac index, and carotid artery flow values during CPR compared to non-surviving piglets.

Conclusion

Surviving piglets had significantly better respiratory and hemodynamic parameters during resuscitation compared to non-surviving piglets. In addition to optimizing resuscitation efforts, capnometry can assist by predicting outcomes of newborns requiring chest compressions.

Rescuer fatigue during simulated neonatal cardiopulmonary resuscitation

OBJECTIVE

To assess development of fatigue during chest compressions (CCs) in simulated neonatal cardiopulmonary resuscitation (CPR).

STUDY DESIGN

Prospective randomized manikin crossover study. Thirty neonatal healthcare professionals who successfully completed the Neonatal Resuscitation Program performed CPR using (i) 3:1 compression:ventilation (C:V) ratio, (ii) continuous CC with asynchronous ventilation (CCaV) at a rate of 90 CC per min and (iii) CCaV at 120 CC per min for a duration of 10 min on a neonatal manikin. Changes in peak pressure (a surrogate of fatigue) and CC rate were continuously recorded and fatigue among groups was compared. Participants were blinded to pressure tracings and asked to rate their level of comfort and fatigue for each CPR trial.

RESULT

Compared with baseline, a significant decrease in peak pressure was observed after 72, 96 and 156 s in group CCaV-120, CCaV-90 and 3:1 C:V, respectively. CC depth decreased by 50% within the first 3 min during CCaV-120, 30% during CCaV-90 and 20% during 3:1 C:V. Moreover, 3:1 C:V and CCaV were similarly preferred by healthcare professionals.

CONCLUSION

Similarly, 3:1 C:V and CCaV CPR were also fatiguing. We recommend that rescuers should switch after every second cycle of heart rate assessment during neonatal CPR.

Cerebral oxygenation during intermittent hypoxemia and bradycardia in preterm infants

BACKGROUND

Episodes of hypoxemia and bradycardia frequently occur with apnea of prematurity in preterm infants. Little is known about the impact of different event types on the brain.

OBJECTIVES

To describe the influence of hypoxemia and bradycardia, either isolated or in combination, on cerebral oxygenation.

METHODS

In 16 preterm infants with intermittent hypoxemia and/or bradycardia, cerebral tissue oxygen saturation (StO2, as measured by near-infrared spectroscopy), heart rate and pulse oximetric saturation (SpO2) were recorded simultaneously for 16 h. Events were classified as isolated bradycardia (type 1), isolated hypoxemia (type 2) or combined (simultaneous, type 3; bradycardia first, type 4; hypoxemia first, type 5). Primary outcome was a score representing the area below baseline for cerebral StO2 desaturation during an event. Secondary outcomes were duration and depth of cerebral desaturation.

RESULTS

Patients had a median (range) gestational age of 25.9 (22.6-30.4) weeks and a postnatal age of 32.5 (7-58) days. The median (quartiles) number of events was 49 (34-58). Isolated hypoxemias were the most frequent events (24; 9-36) and isolated bradycardias the least common (0; 0-1). Cerebral StO2 baseline was not different between event types. Cerebral desaturation score, duration of event and depth of cerebral desaturation were smallest for isolated bradycardias and largest for combined events, especially for those starting with hypoxemia followed by bradycardia. Regardless of event type, 12/16 infants maintained cerebral StO2 >60% despite severe SpO2 desaturations.

CONCLUSIONS

Isolated bradycardias had the lowest impact on cerebral desaturation, and combined events had the highest. Most infants preserved cerebral oxygenation >60% during events.