Interpretation of Cerebral Oxygenation Changes in the Preterm Infant

Effects of endotracheal suctioning duration cerebral oxygenation in preterm infants

AIM

This study evaluates the effects of endotracheal suctioning duration on cerebral oxygenation and physiological parameters in preterm infants in intensive care.

DESIGN

Prospective and observational study.

METHOD

In this study, 51 preterm infants born at 28-34 weeks of gestation in NICU were evaluated. Cerebral oxygenation was measured before, during, and after endotracheal suctioning with near-infrared spectroscopy. Pain levels of the infants were with N-PASS scale.

RESULTS

A negative correlation was found between the lowest cerebral oxygenation value during endotracheal suctioning and the duration of endotracheal suctioning. Cerebral oxygenation levels during endotracheal suctioning were lower than pre- and post-endotracheal suctioning levels. Higher cerebral oxygenation was observed in infants whose endotracheal aspiration time was less than 13 s. The duration of endotracheal suctioning was positively correlated with pain and cerebral oxygenation stabilization time.

CONCLUSION

Prolonged endotracheal suctioning duration negatively affects cerebral oxygenation in preterm infants. The study suggests an optimal endotracheal suctioning duration under 13 s.

IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE

Properly executed endotracheal suctioning, with the correct technique and knowledge, can alleviate the adverse physiological effects observed in preterm infants and contribute to routine nursing care in intensive care units.

REPORTING METHOD

This study has been reported in line with STROBE checklists.

PATIENT OR PUBLIC CONTRIBUTION

No patient or public contribution was required to design or undertake this research. Patients contributed only to the data collection.

IMPACT

This study contributes to defining the ideal endotracheal aspiration duration, as there is not enough data so far. It showed the effect of prolonged endotracheal aspiration time on cerebral oxygenation, pain and physiological parameters in preterm infants.

Cerebral Oxygenation during Neonatal Intubation with Nasal High Flow: A Sub-Study of the SHINE Randomized Trial

INTRODUCTION

Nasal high flow (nHF) improves the likelihood of successful neonatal intubation on the first attempt without physiological instability. The effect of nHF on cerebral oxygenation is unknown. The aim of this study was to compare cerebral oxygenation during endotracheal intubation in neonates receiving nHF and those receiving standard care.

METHODS

A sub-study of a multicentre randomized trial of nHF during neonatal endotracheal intubation. A subset of infants had near-infrared spectroscopy (NIRS) monitoring. Eligible infants were randomly assigned to nHF or standard care during the first intubation attempt. NIRS sensors provided continuous regional cerebral oxygen saturation (rScO2) monitoring. The procedure was video recorded, and peripheral oxygen saturation and rScO2 data were extracted at 2-second intervals. The primary outcome was the average difference in rScO2 from baseline during the first intubation attempt. Secondary outcomes included average rScO2 and rate of change of rScO2.

RESULTS

Nineteen intubations were analyzed (11 nHF; 8 standard care). Median (interquartile range [IQR]) postmenstrual age was 27 (26.5-29) weeks, and weight was 828 (716-1,135) g. Median change in rScO2 from baseline was -1.5% (-5.3 to 0.0) in the nHF group and -9.4% (-19.6 to -4.5) in the standard care group. rScO2 fell more slowly in infants managed with nHF compared with standard care: median (IQR) rScO2 change -0.08 (-0.13 to 0.00) % per second and -0.36 (-0.66 to -0.22) % per second, respectively.

CONCLUSIONS

In this small sub-study, regional cerebral oxygen saturation was more stable in neonates who received nHF during intubation compared with standard care.

Evaluation of the Hypotensive Preterm Infant: Evidence-Based Practice at the Bedside?

Choosing the appropriate management approach for the preterm infant with low blood pressure during the transition period generally involved intervening when the blood pressure drifted below a certain threshold. It is now clear that this approach is too simplistic and does not address the underlying physiology. In this chapter, we explore the many monitoring tools available for evaluation of the hypotensive preterm and assess the evidence base supporting or refuting their use. The key challenge relates to incorporating these outputs with the clinical status of the patient and choosing the appropriate management strategy.

Optical Monitoring in Neonatal Seizures

BACKGROUND

Neonatal seizures remain a significant cause of morbidity and mortality worldwide. The past decade has resulted in substantial progress in seizure detection and understanding the impact seizures have on the developing brain. Optical monitoring such as cerebral near-infrared spectroscopy (NIRS) and broadband NIRS can provide non-invasive continuous real-time monitoring of the changes in brain metabolism and haemodynamics.

AIM

To perform a systematic review of optical biomarkers to identify changes in cerebral haemodynamics and metabolism during the pre-ictal, ictal, and post-ictal phases of neonatal seizures.

METHOD

A systematic search was performed in eight databases. The search combined the three broad categories: (neonates) AND (NIRS) AND (seizures) using the stepwise approach following PRISMA guidance.

RESULTS

Fifteen papers described the haemodynamic and/or metabolic changes observed with NIRS during neonatal seizures. No randomised controlled trials were identified during the search. Studies reported various changes occurring in the pre-ictal, ictal, and post-ictal phases of seizures.

CONCLUSION

Clear changes in cerebral haemodynamics and metabolism were noted during the pre-ictal, ictal, and post-ictal phases of seizures in neonates. Further studies are necessary to determine whether NIRS-based methods can be used at the cot-side to provide clear pathophysiological data in real-time during neonatal seizures.

Does Early Cerebral Near-Infrared Spectroscopy Monitoring Predict Outcome in Neonates with Hypoxic Ischaemic Encephalopathy? A Systematic Review of Diagnostic Test Accuracy

INTRODUCTION

Hypoxic ischaemic encephalopathy (HIE) remains one of the top 10 contributors to the global burden of disease. Early objective biomarkers are required. Near-infrared spectroscopy (NIRS) may provide a valuable insight into cerebral perfusion and metabolism. We aimed to determine whether early NIRS monitoring (<6 h of age) can predict outcome as defined by grade of encephalopathy, brain MRI findings, and/or neurodevelopmental outcome at 1-2 years in infants with HIE.

METHODS

We searched PubMed, Scopus, Web of Science, Embase, and The Cochrane Library databases (July 2019). Studies of infants born ≥36+0 weeks gestation with HIE who had NIRS recording commenced before 6 h of life were included. We planned to provide a narrative of all the studies included, and if similar clinically and methodologically, the results would be pooled in a meta-analysis to determine test accuracy.

RESULTS

Seven studies were included with a combined total of 161 infants. Only 1 study included infants with mild HIE. A range of different oximeters and probes were utilized with varying outcome measures making comparison difficult. Although some studies showed a trend towards higher cSO2 values before 6 h in infants with adverse neurodevelopmental outcomes, in the majority, this was not significant until beyond 24 h of life.

CONCLUSION

Very little data currently exists to assess the use of early NIRS to predict outcome in infants with HIE. Further studies using a standardized approach are required before NIRS can be evaluated as a potential objective assessment tool for early identification of at-risk infants.

Cortical hemodynamic activity and pain perception during insertion of feeding tubes in preterm neonates: a randomized controlled cross-over trial

OBJECTIVE

The present study evaluated the pain perception in preterm neonates during insertion of orogastric (OG) vs. nasogastric (NG) tube by measuring the cerebral regional oxygen saturation (crSO2) and premature infant pain profile-revised (PIPP-R) score.

STUDY DESIGN

Randomized controlled cross-over trial.

RESULTS

Fifty infants of mean (SD) gestational age of 31.54(2) and 31.64(2.2) weeks, birth weight of 1362(354) and 1507(365) grams were randomized into OG/NG (n = 25) and NG/OG (n = 25) sequences. Mean post-menstrual age at assessment was 33(2.8) and 33(1.5) weeks, and the difference between two interventions was 1.08(0.5) and 1.12(0.5) days in OG-NG and NG-OG, respectively. Mean crSO2(%) during insertion was significantly lower with NG compared to OG route. Mean PIPP-R score, heart rate variability, time to normalize crSO2, and the duration of cry were also significantly higher with NG insertion.

CONCLUSIONS

Compared to OG, NG route of feeding tube insertion was associated with higher fluctuations in crSO2 and higher PIPP-R scores.

CLINICAL TRIAL REGISTRY OF INDIA (CTRI) REGISTRATION NO

CTRI/2020/03/023728.

Anemia and Red Blood Cell Transfusions, Cerebral Oxygenation, Brain Injury and Development, and Neurodevelopmental Outcome in Preterm Infants: A Systematic Review

Background: Anemia remains a common comorbidity of preterm infants in the neonatal intensive care unit (NICU). Left untreated, severe anemia may adversely affect organ function due to inadequate oxygen supply to meet oxygen requirements, resulting in hypoxic tissue injury, including cerebral tissue. To prevent hypoxic tissue injury, anemia is generally treated with packed red blood cell (RBC) transfusions. Previously published data raise concerns about the impact of anemia on cerebral oxygen delivery and, therefore, on neurodevelopmental outcome (NDO). Objective: To provide a systematic overview of the impact of anemia and RBC transfusions during NICU admission on cerebral oxygenation, measured using near-infrared spectroscopy (NIRS), brain injury and development, and NDO in preterm infants. Data Sources: PubMed, Embase, reference lists. Study Selection: We conducted 3 different searches for English literature between 2000 and 2020; 1 for anemia, RBC transfusions, and cerebral oxygenation, 1 for anemia, RBC transfusions, and brain injury and development, and 1 for anemia, RBC transfusions, and NDO. Data Extraction: Two authors independently screened sources and extracted data. Quality of case-control studies or cohort studies, and RCTs was assessed using either the Newcastle-Ottawa Quality Assessment Scale or the Van Tulder Scale, respectively. Results: Anemia results in decreased oxygen-carrying capacity, worsening the burden of cerebral hypoxia in preterm infants. RBC transfusions increase cerebral oxygenation. Improved brain development may be supported by avoidance of cerebral hypoxia, although restrictive RBC transfusion strategies were associated with better long-term neurodevelopmental outcomes. Conclusions: This review demonstrated that anemia and RBC transfusions were associated with cerebral oxygenation, brain injury and development and NDO in preterm infants. Individualized care regarding RBC transfusions during NICU admission, with attention to cerebral tissue oxygen saturation, seems reasonable and needs further investigation to improve both short-term effects and long-term neurodevelopment of preterm infants.

Influence of altitude on cerebral and splanchnic oxygen saturation in critically ill children during air ambulance transport

Objective

The aim of the current study was to investigate how cerebral and splanchnic oxygen saturation (rSO₂-C and rSO₂-A) in critically ill children transported in air ambulance was affected by flight with cabin pressurization corresponding to ≥ 5000 feet. A second aim was to investigate any differences between cyanotic and non-cyanotic children in relation to cerebral and splanchnic oxygen saturation during flight ≥ 5000 feet. The variability of the cerebral and splanchnic Near Infrared Spectroscopy (NIRS) sensors was evaluated.

Design

NIRS was used to measure rSO₂-C and rSO₂-A during transport of critically ill children in air ambulance. rSO₂ data was collected and stored by the NIRS monitor and extracted and analyzed off-line after the transport. Prior to evaluation of the NIRS signals all zero and floor-effect values were removed.

Setting

The Pediatric Intensive Care Unit (PICU) at Astrid Lindgren Children’s Hospital, Karolinska University Hospital in Stockholm, Sweden.

Patients

In total, 44 critically ill children scheduled for inter-hospital transport by a specialized pediatric transport team were included in the study between January 2014 and January 2019 (convenience sampling).

Intervention

No interventions were conducted.

Measurements

All study patients were monitored with a cerebral NIRS-sensor placed over the forehead and an abdominal NIRS-sensor placed in the infra-umbilical area for cerebral and splanchnic regional oxygen saturation monitoring, rSO₂-C and rSO₂-A, respectively.

Main results

Complete rSO₂-C and rSO₂-A data was obtained in 39 patients. Median age was 12 days. Cyanotic congenital heart malformations were present in 9 patients (23%). In 22 patients (56%) rSO₂-C decreased at altitude ≥ 5000 feet and in 24 patients (61%) rSO₂-A decreased at altitude ≥ 5000 feet compared to baseline (p<0.0001). In 25 patients (64%) the rSO₂-C/rSO₂-A ratio was greater at altitude ≥ 5000 feet than at baseline. A ratio ≥ 1 was seen in 77% of patients at altitude ≥ 5000 feet compared to in 67% of patients at baseline.

Conclusion

Both cerebral and splanchnic oxygen saturation decreased at altitude ≥ 5000 feet compared to baseline. In most patients, both cyanotic and non-cyanotic, cerebral oxygen saturation was preserved more than splanchnic oxygen saturation.

[Near-infrared spectroscopy : Technique, development, current use and perspectives]

Near-infrared spectroscopy (NIRS) has been available in research and clinical practice for more than four decades. Recently, there have been numerous publications and substantial developments in the field. This article describes the clinical application of NIRS in relation to current guidelines, with a focus on pediatric and cardiac anesthesia. It discusses technical and physiological principles, pitfalls in clinical use and presents (patho)physiological influencing factors and derived variables, such as fractional oxygen extraction (FOE) and the cerebral oxygen index (COx). Recommendations for the interpretation of NIRS values in connection with influencing factors, such as oxygen transport capacity, gas exchange and circulation as well as an algorithm for cardiac anesthesia are presented. Limitations of the method and the lack of comparability of values from different devices as well as generally accepted standard values are explained. Technical differences and advantages compared to pulse oxymetry and transcranial Doppler sonography are illuminated. Finally, the prognostic significance and requirements for future clinical studies are discussed.

Findings From Somatic and Cerebral Near-Infrared Spectroscopy and Echocardiographic Monitoring During Ductus Arteriosus Ligation: Description of Two Cases and Review of Literature

Background: Preterm infants with hemodynamically significant patent ductus arteriosus (HsPDA) are exposed to low cerebral tissue oxygen saturation (rScO2) values. Additionally, infants requiring surgical ligation are at risk of further changes in cerebral oxygenation and postligation cardiac syndrome (PLCS). Previous studies have assessed the effect of PDA ligation on rScO2 with variable results. Cases description: In this report we analyse near-infrared spectroscopy (NIRS) and echocardiographic findings of two patients who underwent ligation of PDA and presented low cardiac output. Literature on regional tissue oxygenation saturation (rSO2) before and after PDA ligation was briefly reviewed. Discussion: Cerebral oxygenation values before and after PDA ligation may be influenced by gestational age, vasopressor use, ductal shunt volume, time of exposure HsPDA, chronological age and the presence of cerebral autoregulation. PLCS complicates 28-45% of all PDA ligations and is associated with higher mortality. Cerebral and somatic NIRS monitoring in the postoperative period may enhance the identification of PLCS at early stages. Conclusion: Cerebral oxygenation in the perioperative period of PDA ligation may be influenced by numerous clinical factors. Early detection of PLCS using multisite NIRS after ligation could prevent further alterations in cerebral hemodynamics and improve outcomes. A decrease in somatic-cerebral difference and/or a significant drop in somatic NIRS values may precede clinical signs of hypoperfusion. NIRS values should be interpreted as trends along with echocardiographic findings to guide goal directed interventions.

Metabolic brain measurements in the newborn: Advances in optical technologies

Neonatal monitoring in neonatal intensive care is pushing the technological boundaries of newborn brain monitoring in order to improve patient outcome. There is an urgent need of a cot side, real time monitoring for assessment of brain injury severity and neurodevelopmental outcome, in particular for term newborn infants with hypoxic-ischemic brain injury. This topical review discusses why brain tissue metabolic monitoring is important in this group of infants and introduces the currently used neuromonitoring techniques for metabolic monitoring in the neonatal intensive care unit (NICU). New optical techniques that can monitor changes in brain metabolism together with brain hemodynamics at the cot side are presented. Early studies from these emerging technologies have demonstrated their potential to deliver continuous information regarding cerebral physiological changes in sick newborn infants in real time. The promises of these new tools as well as their potential limitations are discussed.

Cardiovascular and cerebrovascular responses to cardio-respiratory events in preterm infants during the transitional period

KEY POINTS

Non-invasive simultaneous multiparametric monitoring allows the in vivo evaluation of cerebral and cardiovascular haemodynamic responses to different types of recurrent episodes of intermittent hypoxia and/or bradycardia, also defined as cardio-respiratory events (CRE), in preterm neonates during postnatal transition. By decreasing left cardiac output, bradycardia further contributes to cerebral hypoxia during CRE. The presence of a haemodynamically significant patent ductus arteriosus results in a deeper impairment of cerebral oxygen status in response to CRE, whereas the brain-sparing remodelling of the fetal circulation resulting from placental insufficiency is associated with more favourable haemodynamic responses to intermittent hypoxia. During transition, the haemodynamic impact of CRE is influenced not only by the event type, but also by specific clinical features; this highlights the importance of developing individualized approaches to reduce the hypoxic burden in this delicate phase.

ABSTRACT

The present observational prospective study aimed to investigate cerebral and cardiovascular haemodynamic responses to different types of cardio-respiratory events (CRE) in preterm infants during postnatal transition, as well as evaluate the impact of relevant clinical characteristics. Infants with gestational age (GA) <32 weeks and/or birth weight <1500 g were enrolled after birth. Cerebral oxygenation index (cTOI), fractional oxygen extraction (cFTOE), cardiac output (CO), cardiac contractility (iCON) and systemic vascular resistances (sVR) were simultaneously monitored over the first 72 h by near-infrared spectroscopy and electrical velocimetry. CRE were clustered into isolated bradycardia (IB), isolated desaturation (ID) and combined desaturation/bradycardia (DB). For each parameter, percentage changes from baseline (%Δ) were calculated. The impact of different CRE types and clinical variables on %Δ was evaluated with generalized estimating equations. In total, 1426 events were analysed. %ΔcTOI significantly differed among ID, IB and DB (P < 0.001), with the latter showing the greatest drop. %ΔcFTOE decreased significantly during DB (P < 0.001) and ID (P < 0.001) compared to IB. DB and IB were associated with more negative %ΔCO (P < 0.001) and more positive %ΔsVR (P < 0.001) compared to ID. A slight iCON reduction was observed during DB compared to ID (P = 0.043). Antenatal umbilical Doppler impairment, GA and the presence of a haemodynamically significant patent ductus arteriosus had a significant independent impact on %ΔcTOI, %ΔcFTOE and %ΔCO. During the transitional period, the haemodynamic responses to CRE are influenced by the event type and by specific neonatal characteristics, suggesting the importance of targeted individualized approaches for minimizing the risk of cerebral injury in the preterm population.

Comparison of frequency-domain and continuous-wave near-infrared spectroscopy devices during the immediate transition

Background

Non-invasive monitoring of cerebral tissue oxygen saturation (rcSO₂) during transition is of growing interest. Different near-infrared spectroscopy (NIRS) techniques have been developed to measure rcSO₂. We compared rcSO₂ values during the immediate transition in preterm neonates measured with frequency-domain NIRS (FD-NIRS) with those measured with continuous-wave NIRS (CW-NIRS) devices in prospective observational studies.

Methods

We compared rcSO₂ values measured with an FD-NIRS device during the first 15 min after birth in neonates with a gestational age ≥ 30 weeks but < 37 weeks born at the Erasmus MC- Sophia Children’s Hospital, Rotterdam, the Netherlands, with similar values measured with a CW-NIRS device in neonates born at the Medical University of Graz, Austria. Mixed models were used to adjust for repeated rcSO₂ measurements, with fixed effects for time (non-linear), device, respiratory support and the interaction of device and respiratory support with time. Additionally, parameters such as total haemoglobin concentration and oxygenated and deoxygenated haemoglobin concentrations measured by FD-NIRS were analysed.

Results

Thirty-eight FD-NIRS measurements were compared with 58 CW-NIRS measurements. The FD-NIRS rcSO₂ values were consistently higher than the CW-NIRS rcSO₂ values in the first 12 min, irrespective of respiratory support. After adjustment for respiratory support, the time-dependent trend in rcSO₂ differed significantly between techniques (p < 0.01).

Conclusion

As cerebral saturation measured with the FD-NIRS device differed significantly from that measured with the CW-NIRS device, differences in absolute values need to be interpreted with care. Although FD-NIRS devices have technical advantages over CW-NIRS devices, FD-NIRS devices may overestimate true cerebral oxygenation and their benefits might not outweigh the usability of the more clinically viable CW-NIRS devices.

Defining "Haemodynamic Significance" of the Patent Ductus Arteriosus: Do We Have All the Answers?

Optimum management of the patent ductus arteriosus (PDA) in preterm infants remains one of the most debated topics within the field of neonatology. Despite numerous observational studies and over 60 randomized control trials, consensus on PDA management remains elusive. In order to make meaningful progress on the controversial issue of PDA management, several key factors must be thoroughly addressed; namely (1) accurate identification of infants at greatest risk of long-term morbidities from PDA exposure, (2) acceptance that the PDA is not a dichotomous entity and an individualised approach to its management is required for each neonate, (3) international consensus on what constitutes a haemodynamically significant PDA and (4) the incorporation of multi-organ assessment when evaluating the impact a PDA may pose on overall neonatal physiology. This review assesses the evidence base available supporting various therapeutic strategies for PDA, the deficits in our current knowledge on the definition of haemodynamic significance and future directions to pursue in order to more successfully address this contentious subject.