Low Cerebral Oxygenation in Preterm Infants Is Associated with Adverse Neurodevelopmental Outcome

Short apneas and periodic breathing in preterm infants in the neonatal intensive care unit-Effects of sleep position, sleep state, and age

This observational study investigated the effects of sleep position and sleep state on short apneas and periodic breathing in hospitalized preterm infants longitudinally, in relation to postmenstrual age. Preterm infants (25-31 weeks gestation, n = 29) were studied fortnightly after birth until discharge, in prone and supine positions, and in quiet sleep and active sleep. The percentage of time spent in each sleep state (percentage of time in quiet sleep and percentage of time in active sleep), percentage of total sleep time spent in short apneas and periodic breathing, respectively, the percentage of falls from baseline in heart rate, arterial oxygen saturation and cerebral tissue oxygenation index during short apneas and periodic breathing, and the associated percentage of total sleep time with systemic (arterial oxygen saturation < 90%) and cerebral hypoxia (cerebral tissue oxygenation index < 55%) were analysed using a linear mixed model. Results showed that the prone position decreased (improved) the percentage of falls from baseline in arterial oxygen saturation during both short apneas and periodic breathing, decreased the proportion of infants with periodic breathing and the periodic breathing-associated percentage of total sleep time with cerebral hypoxia. The percentage of time in quiet sleep was higher in the prone position. Quiet sleep decreased the percentage of total sleep time spent in short apneas, the short apneas-associated percentage of falls from baseline in heart rate, arterial oxygen saturation, and proportion of infants with systemic hypoxia. Quiet sleep also decreased the proportion of infants with periodic breathing and percentage of total sleep time with cerebral hypoxia. The effects of sleep position and sleep state were not related to postmenstrual age. In summary, when sleep state is controlled for, the prone sleeping position has some benefits during both short apneas and periodic breathing. Quiet sleep improves cardiorespiratory stability and is increased in the prone position at the expense of active sleep, which is critical for brain maturation. This evidence should be considered in positioning preterm infants.

A comparison of the effect of procedural pain on cerebral oxygen saturation between late preterm and term infants

OBJECTIVES

We prospectively compared cerebral oxygen saturation (CrSO2) and pain score changes during procedures in late preterm (LPT) versus term infants.

METHODS

Near-infrared spectroscopy, pulse oximetry, Neonatal Infant Pain Scale (NIPS) and Premature Infant Pain Profile-Revised (PIPP-R) scores were assessed and CrSO2 data analyzed.

RESULTS

Thirty infants in each group were evaluated. LPT infants displayed a milder significant drop in Minimum post-procedural CrSO2 and smaller Maximum-Minimum post-procedural CrSO2 disparity. CrSO2 minute changes between the groups were non-significant. Moderate correlations were observed in both groups between NIPS and Minimum post-procedural CrSO2, and a moderate correlation was found in the Maximum-Minimum post-procedural CrSO2 difference in LPT infants. No correlation between PIPP-R and CrSO2 values was noted.

CONCLUSION

LPT and term infants demonstrated decreased CrSO2 in response to painful procedures. Correlations between CrSO2 and PIPP-R or NIPS scores were poor to moderate, reflecting the complex nature of these associations relative to gestational age.

Cerebral tissue oxygen desaturations and increased fractional oxygen extraction events vary by gestational age in preterm infants

BACKGROUND AND OBJECTIVES

Cerebral tissue oxygen saturation (SctO2) and cerebral fractional tissue oxygen extraction (cFTOE) changes with GA in preterm infants. This study examines changes in frequency, duration, and severity of SctO2 desaturation and increased cFTOE with GA.

STUDY DESIGN

The lower limit of normal SctO2, the event threshold, was calculated using a tolerance interval method with 95% confidence interval (CI) and 90% probability. Cerebral desaturation events were defined as: 1) a drop below event threshold for at least 30 s (s), 2) preceded by a period above the event threshold for at least 30s, and 3) followed by a period above the threshold for at least 60s.

RESULTS

86% of infants <28 wk experienced one or more SctO2 desaturation event compared to 57% in >28 wk, odds ratios (OR) 4.5 (CI:1.3-15.3, p = 0.016). The severity of SctO2 desaturation events decreases at a rate of 77.9 units per wk increase in GA (p < 0.001). 39.3% of infants <28 wk experienced one or more increased cFTOE events compared to 28.6% in >28 wk, OR 1.6 (CI:0.6-4.4, p = 0.35). The severity of increasing cFTOE events decreased by 69.7 units per wk increase in GA (p < 0.001).

CONCLUSION

Cerebral tissue oxygen desaturation events decrease in frequency and severity with increasing GA. The severity of increased cFTOE episodes decrease with GA.

Oxygen in the neonatal ICU: a complicated history and where are we now?

Despite major advances in neonatal care, oxygen remains the most commonly used medication in the neonatal intensive care unit (NICU). Supplemental oxygen can be life-saving for term and preterm neonates in the resuscitation period and beyond, however use of oxygen in the neonatal period must be judicious as there can be toxic effects. Newborns experience substantial hemodynamic changes at birth, rapid energy consumption, and decreased antioxidant capacity, which requires a delicate balance of sufficient oxygen while mitigating reactive oxygen species causing oxidative stress. In this review, we will discuss the physiology of neonates in relation to hypoxia and hyperoxic injury, the history of supplemental oxygen in the delivery room and beyond, supporting clinical research guiding trends for oxygen therapy in neonatal care, current practices, and future directions.

Electrical Cardiometry during transition and short-term outcome in very preterm infants: a prospective observational study

The purpose of this study is to evaluate the association of Electrical Cardiometry (EC)-derived cardiac output indexed to weight (CO) and its changes during the first 48 h in relation to adverse short-term outcome in very preterm infants. In this prospective observational study of preterm infants < 32 weeks gestational age (GA), the combined adverse outcome was defined as mortality or abnormal cranial ultrasound (any grade intracranial hemorrhage (ICH) or periventricular leukomalacia) within the first 2 weeks postnatally. Logistic regression models were used to investigate the association between median CO and outcome and mixed-effects models for the time trajectory of CO. In the absence of device-specific thresholds for low or high CO, no thresholds were used in our analysis. Fifty-three infants (median (IQR) GA 29.0 (25.4-30.6) weeks, birthweight 1020 (745-1505) g) were included in the analysis. Median CO was 241 (197-275) mL/kg/min for the adverse outcome and 198 (175-227) mL/kg/min for normal outcome (odds ratio (OR) (95% confidence interval (95% CI)), 1.01 (1.00 to 1.03); p = 0.028). After adjustment for GA, the difference was not significant (adjusted OR (95% CI), 1.01 (0.99 to 1.02); p = 0.373). CO trajectory did not differ by outcome (p = 0.352). A post hoc analysis revealed an association between CO time trajectory and ICH ≥ grade 2.          Conclusions: EC-derived CO estimates within 48 h postnatally were not independently associated with brain injury (any grade) or mortality in the first 14 days of life. CO time trajectory was found to be associated with ICH ≥ grade 2. What is Known: • Bioreactance-derived cardiac output indexed to bodyweight (CO) in the transitional period has been associated with adverse short-term outcome in preterm infants. What is New: • Electrical Cardiometry (EC)-derived CO measurements in very preterm infants during the transitional period are not independently associated with adverse outcome (death or ultrasound detected brain damage) within 2 weeks postnatally. • In the first 48 h EC-derived CO increases over time and is higher in extremely preterm infants compared to very preterm and differs from previously reported bioreactance-derived CO values.

Understanding Near-Infrared Spectroscopy: An Update

Near-infrared spectroscopy (NIRS) is a novel technology that uses infrared light to noninvasively and continuously measure regional oxygen extraction in real time at the bedside. Neonatal research using this device supports its use as an adjunct to routine cardiovascular monitoring because NIRS serves as a surrogate marker for end-organ perfusion and can detect minute changes in cerebral, intestinal, and kidney tissue beds. Multiple conditions affecting premature infants are frequently associated with hypoperfusion; therefore, methods to detect early tissue-specific perfusion alterations may substantially improve the clinician's ability to intervene and prevent further deterioration.

Preterm infants experience a nadir in cerebral oxygenation during sleep three months after hospital discharge

AIM

Preterm infants are at increased risk of Sudden Infant Death Syndrome (SIDS) and frequently experience short central apnoeas which can occur in isolation or a repetitive pattern (periodic breathing). We investigated the relationship between central apnoeas experienced before and over the 6 months after hospital discharge and cerebral oxygenation.

METHODS

Preterm infants born between 28 and 32 weeks gestational age (GA) were studied during supine daytime sleep at 32-36 weeks post menstrual age (PMA) (n = 40), 36-40 weeks PMA (n = 27), 3-months corrected age (CA) (n = 20) and 6-months CA (n = 26). Cerebral tissue oxygenation (TOI), peripheral oxygenation (SpO2 ) and heart rate were recorded continuously. The percentage total sleep time (%TST) spent having central apnoeas at each study and cerebral fractional oxygen extraction (SpO2 -TOI/SpO2 ) were calculated.

RESULTS

%TST spent with central apnoeas decreased with increasing age in both active sleep (AS) and quiet sleep (QS). TOI tended to be lower and cerebral fractional oxygen extraction higher at 3 months compared to the other studies and this reached statistical significance compared to 32-36 weeks in QS.

CONCLUSION

The nadir in cerebral tissue oxygenation at 3 months of age coincides with the peak risk period for SIDS and this may contribute to increased risk in these infants.

Developmental consequences of short apneas and periodic breathing in preterm infants

OBJECTIVE

We investigated the relationship between respiratory events experienced before and after hospital discharge and developmental outcomes at 6 months corrected age (CA).

STUDY DESIGN

Preterm infants born between 28-32 weeks gestational age (GA) were studied at 32-36 weeks postmenstrual age (PMA), 36-40 weeks PMA, 3- and 6-months CA. Percentage total sleep time (%TST) with respiratory events (isolated apneas, sequential apneas and periodic breathing (PB)) at each study was calculated. Stepwise multiple linear regressions determined significant predictors of developmental outcomes at 6 months.

RESULT

%TST with respiratory events at term were significant predictors of language (R2 = 0.165, β = -0.416) and motor (R2 = 0.180, β = -0.485) composite scores of the Bayley Scales of Infant Development at 6 months, independent of GA, birth weight and sex.

CONCLUSIONS

In clinically stable very preterm infants at term equivalent age, time spent having respiratory events, was related to a reduction in language and motor outcomes at 6 months.

Tissue Oxygenation Changes After Transfusion and Outcomes in Preterm Infants: A Secondary Near-Infrared Spectroscopy Study of the Transfusion of Prematures Randomized Clinical Trial (TOP NIRS)

Importance

Preterm infants with varying degrees of anemia have different tissue oxygen saturation responses to red blood cell (RBC) transfusion, and low cerebral saturation may be associated with adverse outcomes.

Objective

To determine whether RBC transfusion in preterm infants is associated with increases in cerebral and mesenteric tissue saturation (Csat and Msat, respectively) or decreases in cerebral and mesenteric fractional tissue oxygen extraction (cFTOE and mFTOE, respectively) and whether associations vary based on degree of anemia, and to investigate the association of Csat with death or neurodevelopmental impairment (NDI) at 22 to 26 months corrected age.

Design, Setting, and Participants

This was a prospective observational secondary study conducted among a subset of infants between August 2015 and April 2017 in the Transfusion of Prematures (TOP) multicenter randomized clinical trial at 16 neonatal intensive care units of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. Preterm neonates with gestational age 22 to 28 weeks and birth weight 1000 g or less were randomized to higher or lower hemoglobin thresholds for transfusion. Data were analyzed between October 2020 and May 2022.

Interventions

Near-infrared spectroscopy monitoring of Csat and Msat.

Main Outcomes and Measures

Primary outcomes were changes in Csat, Msat, cFTOE, and mFTOE after transfusion between hemoglobin threshold groups, adjusting for age at transfusion, gestational age, birth weight stratum, and center. Secondary outcome at 22 to 26 months was death or NDI defined as cognitive delay (Bayley Scales of Infant and Toddler Development-III score <85), cerebral palsy with Gross Motor Function Classification System level II or greater, or severe vision or hearing impairment.

Results

A total of 179 infants (45 [44.6%] male) with mean (SD) gestational age 25.9 (1.5) weeks were enrolled, and valid data were captured from 101 infants during 237 transfusion events. Transfusion was associated with a significant increase in mean Csat of 4.8% (95% CI, 2.7%-6.9%) in the lower-hemoglobin threshold group compared to 2.7% (95% CI, 1.2%-4.2%) in the higher-hemoglobin threshold group, while mean Msat increased 6.7% (95% CI, 2.4%-11.0%) vs 5.6% (95% CI, 2.7%-8.5%). Mean cFTOE and mFTOE decreased in both groups to a similar extent. There was no significant change in peripheral oxygen saturation (SpO2) in either group (0.2% vs -0.2%). NDI or death occurred in 36 infants (37%). Number of transfusions with mean pretransfusion Csat less than 50% was associated with NDI or death (odds ratio, 2.41; 95% CI, 1.08-5.41; P = .03).

Conclusions and Relevance

In this secondary study of the TOP randomized clinical trial, Csat and Msat were increased after transfusion despite no change in SpO2. Lower pretransfusion Csat may be associated with adverse outcomes, supporting further investigation of targeted tissue saturation monitoring in preterm infants with anemia.

Trial Registration

ClinicalTrials.gov Identifier: NCT01702805.

Cerebral oxygenation immediately after birth and long-term outcome in preterm neonates-a retrospective analysis

BACKGROUND

Prematurity is associated with increased risk for morbidity and mortality. Aim of this study was to evaluate whether cerebral oxygenation during fetal-to-neonatal transition period was associated with long-term outcome in very preterm neonates.

METHODS

Preterm neonates ≤ 32 weeks of gestation and/or ≤ 1500 g with measurements of cerebral regional oxygen saturation (crSO₂) and cerebral fractional tissue oxygen extraction (cFTOE) within the first 15 min after birth were analysed retrospectively. Arterial oxygen saturation (SpO₂) and heart rate (HR) were measured with pulse oximetry. Long-term outcome was assessed at two years using "Bayley Scales of Infant Development" (BSID-II/III). Included preterm neonates were stratified into two groups: adverse outcome group (BSID-III ≤ 70 or testing not possible due to severe cognitive impairment or mortality) or favorable outcome group (BSID-III > 70). As the association between gestational age and long-term outcome is well known, correction for gestational age might disguise the potential association between crSO₂ and neurodevelopmental impairment. Therefore, due to an explorative approach the two groups were compared without correction for gestational age.

RESULTS

Forty-two preterm neonates were included: adverse outcome group n = 13; favorable outcome group n = 29. Median(IQR) gestational age and birth weight were 24.8 weeks (24.2-29.8) and 760 g (670-1054) in adverse outcome group and 30.6 weeks (28.1-32.0) (p = 0.009*) and 1250 g (972-1390) (p = 0.001*) in the favorable outcome group, respectively. crSO₂ was lower (significant in 10 out of 14 min) and cFTOE higher in adverse outcome group. There were no difference in SpO₂, HR and fraction of inspired oxygen (FiO₂), except for FiO₂ in minute 11, with higher FiO₂ in the adverse outcome group.

CONCLUSION

Preterm neonates with adverse outcome had beside lower gestational age also a lower crSO₂ during immediate fetal-to-neonatal transition when compared to preterm neonates with age appropriate outcome. Lower gestational age in the adverse outcome group would suggest beside lower crSO₂ also lower SpO₂ and HR in this group, which were however similar in both groups.

Periodic breathing in clinically stable very preterm infants

OBJECTIVE

We aimed to investigate the frequency and severity of periodic breathing (PB) in clinically stable very preterm infants and identify infant and maternal factors associated with increased time spent and severity of PB in these infants.

METHOD

Thirty-eight infants (28-32 weeks gestational age) who were ≥3 days off noninvasive respiratory support, were studied for 2-3 h with a daytime sleep study at 31-36 weeks postmenstrual age. Percent total sleep time spent in PB (%TSTPB) and time spent with SpO₂ <90%, <80%, and cerebral oxygenation <55% during PB were calculated. Infant and maternal characteristics were correlated with %TSTPB and hypoxia during PB.

RESULTS

The majority of infants (92%) had at least one episode of PB and infants spent a median 9.1 [interquartile range: 1.2, 15.5] %TSTPB. 80%, 37%, and 37% of infants experienced SpO₂ <90%, <80% and cerebral oxygenation <55%, respectively, during PB. Shorter duration of respiratory support, multigravida, multiparity, and maternal vitamin D deficiency were associated with higher %TSTPB. Multigravida, shorter duration on respiratory support, apnea of prematurity, and resuscitation at birth were associated with hypoxia during PB.

CONCLUSIONS

The majority of very preterm infants exhibited PB when they were off respiratory support and considered clinically stable. The time spent in PB was very variable between infants and was associated with significant hypoxia in some infants. Fewer days spent on respiratory support was associated with both increased frequency and severity of PB. However, the potential contribution of PB to neurocognitive outcomes remains uncertain and warrants further investigations.

Cerebral monitoring of very preterm infants with anterior cerebral artery resistive index and early NIRS

BACKGROUND

The prediction of adverse conditions in the preterm neonatal brain might be improved by cerebral monitoring using combined measures of cerebral function, including oxygenation and blood flow parameters. To perform the consecutive measurements of the resistive index (RI) from the anterior cerebral artery (ACA) within the first week of life and to evaluate the association of these measurements with cerebral oxygen saturation (Csat) detected by near-infrared spectroscopy (NIRS).

METHODS

This prospective cohort study enrolled very preterm infants, <32 weeks of gestational age, admitted to a tertiary neonatal intensive care unit. Csat levels were continuously monitored using NIRS for 72 h after birth. ACA RI measurements were obtained on the first, third, and seventh days of life by using transcranial Doppler ultrasound. These measurements were also compared between infants with and without unfavorable outcomes, including severe intraventricular hemorrhage (IVH) and early mortality.

RESULTS

A total of 96 preterm infants with Csat and ACA RI measurements were analyzed. Age at birth was 28.3 ± 1.9 weeks and birth weight was 1090 ± 305 g. The mean Csat of the infants was 77.1% ± 8.2% during the first 72 h of life. Mean ACA RI values were 0.76 ± 0.10, 0.75 ± 0.08, and 0.77 ± 0.08 on the first, third, and seventh days of life, respectively. RI on the first day of life was significantly higher in infants delivered by cesarian section than in those delivered vaginally (0.77 vs. 0.69; p = 0.017). Infants who died earlier had significantly higher ACA RI values on the first day than infants who survived beyond the first 7 postnatal days (0.83 vs. 0.76; p < 0.001).

DISCUSSION

There was no association between ACA RI and Csat in the early period of life. ACA RI values on the first postnatal day might be significant for predicting early mortality in very preterm infants.

Associations between neurological examination at term-equivalent age and cerebral hemodynamics and oxygen metabolism in infants born preterm

Background

Infants born at 29-36 weeks gestational age (GA) are at risk of experiencing neurodevelopmental challenges. We hypothesize that cerebral hemodynamics and oxygen metabolism measured by bedside optical brain monitoring are potential biomarkers of brain development and are associated with neurological examination at term-equivalent age (TEA).

Methods

Preterm infants (N = 133) born 29-36 weeks GA and admitted in the neonatal intensive care unit were enrolled in this prospective cohort study. Combined frequency-domain near infrared spectroscopy (FDNIRS) and diffuse correlation spectroscopy (DCS) were used from birth to TEA to measure cerebral hemoglobin oxygen saturation and an index of microvascular cerebral blood flow (CBF _i ) along with peripheral arterial oxygen saturation (SpO₂). In combination with hemoglobin concentration in the blood, these parameters were used to derive cerebral oxygen extraction fraction (OEF) and an index of cerebral oxygen metabolism (CMRO_2i ). The Amiel-Tison and Gosselin Neurological Assessment was performed at TEA. Linear regression models were used to assess the associations between changes in FDNIRS-DCS parameters from birth to TEA and GA at birth. Logistic regression models were used to assess the associations between changes in FDNIRS-DCS parameters from birth to TEA and neurological examination at TEA.

Results

Steeper increases in CBF _i (p < 0.0001) and CMRO_2i (p = 0.0003) were associated with higher GA at birth. Changes in OEF, CBF _i , and CMRO_2i from birth to TEA were not associated with neurological examination at TEA.

Conclusion

In this population, cerebral FDNIRS-DCS parameters were not associated with neurological examination at TEA. Larger increases in CBF _i and CMRO_2i from birth to TEA were associated with higher GA. Non-invasive bedside FDNIRS-DCS monitoring provides cerebral hemodynamic and metabolic parameters that may complement neurological examination to assess brain development in preterm infants.

Cerebral oxygenation and body position in the preterm infant: A systematic review and meta-analysis

AIM

After preterm birth, supine head midline position is supported for stable cerebral blood flow (CBF) and prevention of intraventricular haemorrhage (IVH), while prone position supports respiratory function and enables skin-to-skin care. The prone compared to supine position could lead to a change in near-infrared derived cerebral tissue oxygen saturation (rScO2), which is a surrogate for cerebral blood flow (CBF). By monitoring rScO2 neonatologists aim to stabilise CBF during intensive care and prevent brain injury. In this systematic review and meta-analysis, we investigate the effect of the body position on rScO2.

METHODS

A comprehensive literature search was performed to identify all trials that included preterm infants in the first 2 weeks after birth and compared rScO2 in the prone versus supine head in midline position of the infant. A meta-analysis, including two subgroup analyses based on postnatal age (PNA) and gestational age (GA), was performed.

RESULTS

Six observational cohort studies were included. In the second, but not the first week after birth, a significant higher rScO2 in the prone position was found with a mean difference of 1.97% (95% CI 0.87-3.07). No rScO2 difference was observed between positions in the extremely preterm nor the preterm group.

CONCLUSION

No consistent evidence was found that body position influences rScO2 in the first 2 weeks after preterm birth. Subgroup analysis suggests that in the second week after birth, the prone position might result in higher cerebral rScO2 than the supine position with head in midline. Multiple factors determine the best body position in preterms.

Duration and Consequences of Periodic Breathing in Infants Born Preterm Before and After Hospital Discharge

OBJECTIVE

To investigate the amount of time spent in periodic breathing and its consequences in infants born preterm before and after hospital discharge.

METHODS

Infants born preterm between 28-32 weeks of gestational age were studied during daytime sleep in the supine position at 32-36 weeks of postmenstrual age (PMA), 36-40 weeks of PMA, and 3 months and 6 months of corrected age. The percentage of total sleep time spent in periodic breathing (% total sleep time periodic breathing) was calculated and infants were grouped into below and above the median (8.5% total sleep time periodic breathing) at 32-36 weeks and compared with 36-40 weeks, 3 and 6 months.

RESULTS

Percent total sleep time periodic breathing was not different between 32-36 weeks of PMA (8.5%; 1.5, 15.0) (median, IQR) and 36-40 weeks of PMA (6.6%; 0.9, 15.1) but decreased at 3 (0.4%; 0.0, 2.0) and 6 months of corrected age 0% (0.0, 1.1). Infants who spent above the median % total sleep time periodic breathing at 32-36 weeks of PMA spent more % total sleep time periodic breathing at 36-40 weeks of PMA (18.1%; 7.7, 23.9 vs 2.1%; 0.6, 6.4) and 6 months of corrected age 0.9% (0.0, 3.3) vs 0.0% (0.0, 0.0).

CONCLUSIONS

Percentage sleep time spent in periodic breathing did not decrease as infants born preterm approached term corrected age, when they were to be discharged home. High amounts of periodic breathing at 32-36 weeks of PMA was associated with high amounts of periodic breathing at term corrected age (36-40 weeks of PMA), and persistence of periodic breathing at 6 months of corrected age.

Association of early cerebral oxygen saturation and brain injury in extremely preterm infants

OBJECTIVE

To assess the association between cerebral saturation (crSO2) using Near-Infrared Spectroscopy (NIRS) and brain injury in extremely preterm infants.

STUDY DESIGN

This retrospective study includes 62 infants (<28 weeks gestation) who underwent continuous NIRS monitoring in the first 5 days after birth. Median crSO2 were compared in 12 h increments between infants with and without germinal matrix/intraventricular hemorrhage (GM/IVH). crSO2 was also compared by IVH severity, onset, and by grade of injury on term equivalent MRI.

RESULTS

After 48 h of life (HOL), infants with GM/IVH had significantly lower crSO2 than those without GM/IVH in analysis adjusted for potential confounding e.g., at 49-60 HOL (69.5 (66.2, 72.8) vs. 74.7 (71.8, 77.6), p = 0.023). There were no significant differences in crSO2 by IVH subcategory or injury severity on MRI.

CONCLUSION

Clinical use of NIRS has the potential to identify crSO2 patterns associated with development of GM/IVH.

Is low cerebral near infrared spectroscopy oximetry associated with neurodevelopment of preterm infants without brain injury?

OBJECTIVES

To evaluate the association between low regional cerebral oxygen saturation (rScO2) and neurodevelopment in preterm infants classified as no brain injury (NBI).

METHODS

We retrospectively reviewed data of rScO2 monitoring during the first 3 days of life of infants with a gestational age (GA)<28 weeks or birth weight (BW)<1,000 g, with and without brain injury (BI). BI was defined as intraventricular haemorrhage, cystic periventricular leukomalacia or cerebellar haemorrhage. Univariate and multivariate analyses were used to study the association of rScO2<55% for more than 10 h in the first 3 days of life (NIRS<55%^>10H) and the 24 months neurodevelopment.

RESULTS

Of the 185 patients who met the inclusion criteria, 31% were classified as BI infants and 69% NBI. BI compared to NBI infants had a significantly lower GA and a higher incidence of complications of prematurity. Mean rScO2 in the first 72 h of life was significantly lower in BI than NBI. NIRS<55%^>10H in NBI patients was negatively associated with neurodevelopmental scores both at the univariate and multivariate analysis (p<0.05). NBI infants with NIRS<55%^>10H were found to have lower systemic oxygenation than their counterparts with rScO2<55% for less than 10 h.

CONCLUSIONS

NIRS<55%^>10H in NBI small preterm infants was found to be an independent predictor of neurodevelopment at 24 months and it was associated with low systemic saturation values.

Association Analysis of the Cerebral Fractional Tissue Oxygen Extraction (cFTOE) and the Cerebral Oxygen Saturation (crSaO2) with Perinatal Factors in Preterm Neonates: A Single Centre Study

(1) Background: Near-infrared spectroscopy (NIRS) is a non-invasive, easily performed method of monitoring brain oxygenation. The regional cerebral oxygen saturation (crSaO2) and the cerebral fractional tissue oxygen extraction (cFTOE) evaluated by NIRS provide more accurate information on brain oxygenation than the blood oxygen saturation. We investigated the effect of perinatal factors on cerebral oxygenation of preterm newborns. (2) Methods: We conducted a longitudinal study with 48 preterm newborns <34 weeks of gestation who underwent NIRS registration during the first 72 h of life. crSaO2 was measured and cFTOE was calculated foreach patient. (3) Results: One-way ANOVA showed no significant main effect of IVH severity on crSaO2 and cFTOE (p > 0.05); there was a tendency toward statistical significance concerning the difference between the means of crSaO2 (p = 0.083) and cFTOE (p = 0.098). Patients with intraventricular haemorrhage (IVH) had a lower mean of crSaO2 and a higher mean of cFTOE (59.67 ± 10.37% vs. 64.92 ± 10.16% for crSaO2; 0.37 ± 0.11 vs. 0.32 ± 0.11 for cFTOE) compared to those with no IVH. Significantly lower values of crSaO2 and higher values of cFTOE were found in neonates receiving inotropic treatment (p < 0.0001). Episodes of apnoea also proved to influence the cerebral oxygen saturation of the study group (p = 0.0026). No significant association between the maternal hypertension treatment and the cerebral oxygenation of preterms was found. (4) Conclusions: This study showed a decreased cerebral oxygen saturation of preterms with IVH, inotrope support and apnoea episodes.

Utilizing near infra-red spectroscopy to identify physiologic variations during digital retinal imaging in preterm infants

OBJECTIVE

Evaluate physiologic changes during digital retinal imaging (DRI) using near infra-red spectroscopy (NIRS).

STUDY DESIGN

Prospective observational study of preterm infants undergoing retinopathy of prematurity screening via DRI using wide-field retinal camera. Cardiorespiratory (CR) and NIRS data were collected, trends correlated for changes and coefficient representing "slopes" of outcomes were plotted over time. The p value associated with each slope coefficient was tested to assess for slope differences from time of intervention (time = 0/or no slope).

RESULTS

Thirty-one preterm infants were included in the study. There were no significant changes in pre- and post-slopes for cerebral or mesenteric oxygenation, or CR indices with eye drop administration compared to baseline. DRI resulted in significant increase in post exam slope in cerebral oxygenation, mesenteric oxygenation and respiratory rate.

CONCLUSION

ROP examination using DRI was well tolerated with slight improvements in cerebral and mesenteric perfusion without significant safety concerns.

Early cerebral hypoxia in extremely preterm infants and neurodevelopmental impairment at 2 year of age: A post hoc analysis of the SafeBoosC II trial

BACKGROUND

The SafeBoosC II, randomised clinical trial, showed that the burden of cerebral hypoxia was reduced with the combination of near infrared spectroscopy and a treatment guideline in extremely preterm infants during the first 72 hours after birth. We have previously reported that a high burden of cerebral hypoxia was associated with cerebral haemorrhage and EEG suppression towards the end of the 72-hour intervention period, regardless of allocation. In this study we describe the associations between the burden of cerebral hypoxia and the 2-year outcome.

METHODS

Cerebral oxygenation was continuously monitored from 3 to 72 hours after birth in 166 extremely preterm infants. At 2 years of age 114 of 133 surviving children participated in the follow-up program: medical examination, Bayley II or III test and the parental Ages and Stages Questionnaire. The infants were classified according to the burden of hypoxia: within the first three quartiles (n = 86, low burden) or within in the 4th quartile (n = 28, high burden). All analyses were conducted post hoc.

RESULTS

There were no statistically significant differences between the quantitative assessments of neurodevelopment in the groups of infants with the low burden of cerebral hypoxia versus the group of infants with the high burden of cerebral hypoxia. The infants in the high hypoxia burden group had a higher-though again not statistically significant-rate of cerebral palsy (OR 2.14 (0.33-13.78)) and severe developmental impairment (OR 4.74 (0.74-30.49).

CONCLUSIONS

The burden of cerebral hypoxia was not significantly associated with impaired 2-year neurodevelopmental outcome in this post-hoc analysis of a feasibility trial.

Cerebral saturation reflects anterior cerebral artery flow parameters by Doppler ultrasound in the extremely premature newborn

BACKGROUND

Near-infrared spectroscopy measures cerebral saturation (Csat), although correlation with cerebral blood flow remains unclear in premature newborns at risk for intraventricular hemorrhage (IVH).

OBJECTIVES

Compare Doppler markers of anterior cerebral artery (ACA) flow with Csat obtained during head ultrasound (HUS).

METHOD

Newborns <29 weeks (2013-2017) underwent Csat monitoring with clinical acquisition of HUS. ACA Doppler markers were measured (with and without pressure) and Resistive Index (RI) was calculated. Mixed effects models evaluated the association between Csat and Doppler markers.

RESULTS

98 neonates with 175 Csat-HUS observations were analyzed. Age at birth was 26.2 ± 1.5 weeks, with post-menstrual age of 26.9 ± 1.7 weeks at HUS. Csat was associated with RI without pressure (p = 0.045), RI with pressure (p = 0.019), and peak systolic velocity with pressure (p = 0.036). Severe IVH (n = 27 [15%]) was associated with lower Csat (60 ± 11% vs 68 ± 9%, p = 0.01).

CONCLUSION

Csat was associated with ACA Doppler measurements in extremely premature neonates.

Predischarge cerebral oxygenation and psychomotor outcome in very preterm infants: is there an association?

This observational study aimed to investigate whether predischarge cerebral oxygenation (CrSO₂), monitored by near-infrared spectroscopy, correlates with later psychomotor outcome in very preterm infants. Infants <32 weeks' gestation or <1500 g without evidence of major brain lesions underwent a 3-h continuous CrSO₂ monitoring before hospital discharge. Psychomotor development was assessed at 6, 12, 18, and 24 months using the Griffiths Mental Developmental Scales. The developmental quotients (DQ) at each follow-up appointment were correlated with predischarge CrSO₂. Significant correlations were adjusted for possible confounders. Sixty-three infants were enrolled. A significant correlation between CrSO₂ and DQ was observed at 6 months ca (p=0.010), but not at later psychomotor assessments. This correlation was confirmed significant (b=0.274, p=0.038) even after the adjustment for relevant covariates.   Conclusion: According to these preliminary findings, the association between predischarge CrSO₂ and psychomotor development over the first 24 months in preterm infants without major brain lesions is time-limited. Hence, this parameter may not represent an effective predictor for medium-term neurodevelopment. What is Known: • Prematurity is a major risk factor for adverse neurodevelopment. • The validation of clinical tools for psychomotor outcome prediction may aid to identify high-risk preterm infants who might benefit from early interventions. What is New: • In infants without major brain lesions, predischarge CrSO₂ correlates with psychomotor outcome at 6 months ca but not later, indicating a short time predictability.

Could Near Infrared Spectroscopy (NIRS) be the new weapon in our fight against Necrotising Enterocolitis?

There is no ideal single gut tissue or inflammatory biomarker available to help to try and identify Necrotising Enterocolitis (NEC) before its clinical onset. Neonatologists are all too familiar with the devastating consequences of NEC, and despite many advances in neonatal care the mortality and morbidity associated with NEC remains significant. In this article we review Near Infrared Spectroscopy (NIRS) as a method of measuring regional gut tissue oxygenation. We discuss its current and potential future applications, including considering its effectiveness as a possible new weapon in the early identification of NEC.

Normal regional tissue oxygen saturation in neonates: a systematic qualitative review

BACKGROUND

The aim of this systematic qualitative review was to give an overview of reference ranges defined as normal values or centile charts of regional tissue oxygen saturation measured by near-infrared spectroscopy (NIRS) in term and preterm neonates.

METHODS

A systematic search of MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials was performed. Additional articles were identified by manual search of cited references. Only human studies in neonates were included.

RESULTS

Nineteen studies were identified. Eight described regional tissue oxygen saturation during fetal-to-neonatal transition, six during the first 3 days after birth, four during the first 7 days after birth, and one during the first 8 weeks after birth. Nine described regional tissue oxygen saturation in term, nine in preterm neonates, and one in both. Eight studies published centile charts for cerebral regional tissue oxygen saturation, and only five included large cohorts of infants. Eleven studies described normal values for cerebral, muscle, renal, and abdominal regional tissue oxygen saturation, the majority with small sample sizes. Four studies of good methodological quality were identified describing centile charts of cerebral regional tissue oxygen saturation.

CONCLUSIONS

In clinical settings, quality centile charts are available and should be the preferred method when using NIRS monitoring.

IMPACT

Near-infrared spectroscopy (NIRS) enables a bed-side non-invasive continuous monitoring of tissue oxygenation. When using NIRS monitoring in a clinical setting, centile charts with good quality are available and should be preferred to normal values. High-quality reference ranges of regional tissue oxygenation in term and preterm born neonates are an important step toward routine clinical application of NIRS.

Cerebral oxygen saturation and autoregulation during hypotension in extremely preterm infants

BACKGROUND

The impact of the permissive hypotension approach in clinically well infants on regional cerebral oxygen saturation (rScO₂) and autoregulatory capacity (CAR) remains unknown.

METHODS

Prospective cohort study of blinded rScO₂ measurements within a randomized controlled trial of management of hypotension (HIP trial) in extremely preterm infants. rScO₂, mean arterial blood pressure, duration of cerebral hypoxia, and transfer function (TF) gain inversely proportional to CAR, were compared between hypotensive infants randomized to receive dopamine or placebo and between hypotensive and non-hypotensive infants, and related to early intraventricular hemorrhage or death.

RESULTS

In 89 potentially eligible HIP trial patients with rScO₂ measurements, the duration of cerebral hypoxia was significantly higher in 36 hypotensive compared to 53 non-hypotensive infants. In 29/36 hypotensive infants (mean GA 25 weeks, 69% males) receiving the study drug, no significant difference in rScO₂ was observed after dopamine (n = 13) compared to placebo (n = 16). Duration of cerebral hypoxia was associated with early intraventricular hemorrhage or death.  Calculated TF gain (n = 49/89) was significantly higher reflecting decreased CAR in 16 hypotensive compared to 33 non-hypotensive infants.

CONCLUSIONS

Dopamine had no effect on rScO₂ compared to placebo in hypotensive infants. Hypotension and cerebral hypoxia are associated with early intraventricular hemorrhage or death.

IMPACT

Treatment of hypotension with dopamine in extremely preterm infants increases mean arterial blood pressure, but does not improve cerebral oxygenation. Hypotensive extremely preterm infants have increased duration of cerebral hypoxia and reduced cerebral autoregulatory capacity compared to non-hypotensive infants. Duration of cerebral hypoxia and hypotension are associated with early intraventricular hemorrhage or death in extremely preterm infants. Since systematic treatment of hypotension may not be associated with better outcomes, the diagnosis of cerebral hypoxia in hypotensive extremely preterm infants might guide treatment.

Effects of Kangaroo Mother Care on Repeated Procedural Pain and Cerebral Oxygenation in Preterm Infants

OBJECTIVE

 The study aimed to investigate the effects of kangaroo mother care (KMC) on repeated procedural pain and cerebral oxygenation in preterm infants.

STUDY DESIGN

 Preterm infants of 31 to 33 weeks of gestational age were randomly divided into an intervention group (n = 36) and a control group (n = 37). Premature infant pain profile (PIPP) scores, heart rate, oxygen saturation, regional cerebral tissue oxygenation saturation (rcSO₂), and cerebral fractional tissue oxygen extraction (cFTOE) were evaluated during repeated heel stick procedures. Each heel stick procedure included three phases: baseline, blood collection, and recovery. KMC was given to the intervention group 30 minutes before baseline until the end of the recovery phase.

RESULTS

 Compared with the control group, the intervention group showed lower PIPP scores and heart rates, higher oxygen saturation, and rcSO₂ from the blood collection to recovery phases during repeated heel sticks. Moreover, there were significant changes in cFTOE for the control group, but not the intervention group associated with repeated heel stick procedures.

CONCLUSION

 The analgesic effect of KMC is sustained over repeated painful procedures in preterm infants, and it is conducive to stabilizing cerebral oxygenation, which may protect the development of brain function.

KEY POINTS

· KMC stabilizes cerebral oxygenation during repeated heel sticks in preterm infants.. · The analgesic effect of KMC is sustained over repeated painful procedures in preterm infants.. · KMC may protect the development of brain function..

Neuroprotection of the Perinatal Brain by Early Information of Cerebral Oxygenation and Perfusion Patterns

Abnormal patterns of cerebral perfusion/oxygenation are associated with neuronal damage. In preterm neonates, hypoxemia, hypo-/hypercapnia and lack of cerebral autoregulation are related to peri-intraventricular hemorrhages and white matter injury. Reperfusion damage after perinatal hypoxic ischemia in term neonates seems related with cerebral hyperoxygenation. Since biological tissue is transparent for near infrared (NIR) light, NIR-spectroscopy (NIRS) is a noninvasive bedside tool to monitor brain oxygenation and perfusion. This review focuses on early assessment and guiding abnormal cerebral oxygenation/perfusion patterns to possibly reduce brain injury. In term infants, early patterns of brain oxygenation helps to decide whether or not therapy (hypothermia) and add-on therapies should be considered. Further NIRS-related technical advances such as the use of (functional) NIRS allowing simultaneous estimation and integrating of heart rate, respiration rate and monitoring cerebral autoregulation will be discussed.

Neonatal Hemoglobin Levels in Preterm Infants Are Associated with Early Neurological Functioning

BACKGROUND

Neonatal anemia may compromise oxygen transport to the brain. The effects of anemia and cerebral oxygenation on neurological functioning in the early neonatal period are largely unknown.

OBJECTIVE

This study aimed to determine the association between initial hemoglobin levels (Hb) and early neurological functioning in preterm infants by assessing their general movements (GMs).

METHODS

A retrospective analysis of prospectively collected data on preterm infants born before 32 weeks of gestation was conducted. We excluded infants with intraventricular hemorrhage > grade II. On day 8, we assessed infants' GMs, both generally as normal/abnormal and in detail using the general movement optimality score (GMOS). We measured cerebral tissue oxygen saturation (rcSO2) on day 1 using near-infrared spectroscopy.

RESULTS

We included 65 infants (median gestational age 29.9 weeks [IQR 28.2-31.0]; median birth weight 1,180 g [IQR 930-1,400]). Median Hb on day 1 was 10.3 mmol/L (range 4.2-13.7). Lower Hb on day 1 was associated with a higher risk of abnormal GMs (OR = 2.3, 95% CI: 1.3-4.1) and poorer GMOSs (B = 0.9, 95% CI: 0.2-1.7). Hemoglobin strongly correlated with rcSO2 (rho = 0.62, p < 0.01). Infants with lower rcSO2 values tended to have a higher risk of abnormal GMs (p = 0.06). After adjusting for confounders, Hb on day 1 explained 44% of the variance of normal/abnormal GMs and rcSO2 explained 17%. Regarding the explained variance of the GMOS, this was 25% and 16%, respectively.

CONCLUSIONS

In preterm infants, low Hb on day 1 is associated with impaired neurological functioning on day 8, which is partly explained by low cerebral oxygenation.

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.

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

Cerebrovascular pressure autoregulation promotes stable cerebral blood flow (CBF) across a range of arterial blood pressures. Cerebral autoregulation (CA) is a developmental process that reaches maturity around term gestation and can be monitored prenatally with both Doppler ultrasound and magnetic resonance imaging (MRI) techniques. Postnatally, there are key advantages and limitations to assessing CA with Doppler ultrasound, MRI, and near-infrared spectroscopy. Here we review these CBF monitoring techniques as well as their application to both fetal and neonatal populations at risk of perturbations in CBF. Specifically, we discuss CBF monitoring in fetuses with intrauterine growth restriction, anemia, congenital heart disease, neonates born preterm and those with hypoxic-ischemic encephalopathy. We conclude the review with insights into the future directions in this field with an emphasis on collaborative science and precision medicine approaches.

Association between early cerebral oxygenation and neurodevelopmental impairment or death in premature infants

OBJECTIVE

To assess the relationship between cerebral oxygenation in the first 72 h of life and neurodevelopmental impairment (NDI) at 2 years corrected age in former premature infants.

STUDY DESIGN

Prospective observational cohort study of 127 infants <32 weeks GA at birth with cerebral oxygenation monitoring using NIRS in the first 72 h of life.

RESULTS

Using a threshold cutoff for cerebral hypoxia, infants with NDI or death had increased duration of hypoxia (4 vs 2.3%, p = 0.001), which was more pronounced in the 23-27 week subgroup (7.6 vs 3.2%, p < 0.001). Individual generalized estimating equations to adjust for repeated measures were modeled in this subgroup for the physiologic parameters including StO₂. StO₂ < 67% was a predictor for death or NDI (OR 2.75, 95% CI 1.006, 7.5132, p = 0.049).

CONCLUSION

An increased duration of cerebral hypoxia is associated with NDI or death in infants born <32 weeks GA.

In Phantom Validation of Time-Domain Near-Infrared Optical Tomography Pioneer for Imaging Brain Hypoxia and Hemorrhage

The neonatal brain is a vulnerable organ, and lesions due to hemorrhage and/or ischemia occur frequently in preterm neonates. Even though neuroprotective therapies exist, there is no tool available to detect the ischemic lesions. To address this problem, we have recently designed and built the new time-domain near-infrared optical tomography (TD NIROT) system - Pioneer. Here we present the results of a phantom study of the system performance. We used silicone phantoms to mimic risky situations for brain lesions: hemorrhage and hypoxia. Employing Pioneer, we were able to reconstruct accurately both position and optical properties of these inhomogeneities.

Cerebral Oxygenation and Autoregulation in Preterm Infants (Early NIRS Study)

OBJECTIVE

To determine if decreased cerebral oxygenation or altered cerebral autoregulation as measured by near-infrared spectroscopy (NIRS) in the first 96 postnatal hours is associated with an increased risk of death or severe neuroradiographic abnormalities in very preterm infants.

STUDY DESIGN

The Early NIRS prospective, multicenter study enrolled very preterm infants with a birth weight of <1250 g from 6 tertiary neonatal intensive care units. Mean arterial blood pressure and cerebral oxygen saturation (Csat) were continuously monitored using a neonatal sensor until 96 hours of age. Moving window correlations between Csat and mean arterial blood pressure determined time periods with altered cerebral autoregulation, and percentiles of correlation were compared between infants with and without the adverse outcome of mortality or severe neuroradiographic abnormalities by early cranial ultrasound.

RESULTS

Of 103 subjects with mean gestational age of 26 weeks, 21 (20%) died or had severe neuroradiographic abnormalities. Infants with adverse outcomes had a lower mean Csat (67 ± 9%) compared with those without adverse outcomes (72 ± 7%; P = .02). A Csat of <50% was identified as a cut-point for identifying infants with adverse outcome (area under the curve, 0.76). Infants with adverse outcomes were more likely to have significant positive or negative correlations between Csat and mean arterial blood pressure, indicating impaired cerebral autoregulation (P = .006).

CONCLUSIONS

Early NIRS monitoring may detect periods of lower cerebral oxygenation and altered cerebral autoregulation, identifying preterm infants at risk for mortality or neuroradiographic injury. An improved understanding of the relationship between altered hemodynamics and cerebral oxygenation may inform future strategies to prevent brain injury.

A wireless, skin-interfaced biosensor for cerebral hemodynamic monitoring in pediatric care

The standard of clinical care in many pediatric and neonatal neurocritical care units involves continuous monitoring of cerebral hemodynamics using hard-wired devices that physically adhere to the skin and connect to base stations that commonly mount on an adjacent wall or stand. Risks of iatrogenic skin injuries associated with adhesives that bond such systems to the skin and entanglements of the patients and/or the healthcare professionals with the wires can impede clinical procedures and natural movements that are critical to the care, development, and recovery of pediatric patients. This paper presents a wireless, miniaturized, and mechanically soft, flexible device that supports measurements quantitatively comparable to existing clinical standards. The system features a multiphotodiode array and pair of light-emitting diodes for simultaneous monitoring of systemic and cerebral hemodynamics, with ability to measure cerebral oxygenation, heart rate, peripheral oxygenation, and potentially cerebral pulse pressure and vascular tone, through the utilization of multiwavelength reflectance-mode photoplethysmography and functional near-infrared spectroscopy. Monte Carlo optical simulations define the tissue-probing depths for source-detector distances and operating wavelengths of these systems using magnetic resonance images of the head of a representative pediatric patient to define the relevant geometries. Clinical studies on pediatric subjects with and without congenital central hypoventilation syndrome validate the feasibility for using this system in operating hospitals and define its advantages relative to established technologies. This platform has the potential to substantially enhance the quality of pediatric care across a wide range of conditions and use scenarios, not only in advanced hospital settings but also in clinics of lower- and middle-income countries.

[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.

What Inotrope and Why?

Primary function of cardiovascular system is to meet body's metabolic demands. The aim of inotrope therapy is to minimise adverse impact of cardiovascular compromise. Current use of inotropes is primarily guided by the pathophysiology of cardiovascular compromise and anticipated actions of inotropes. Lack of significant reduction in morbidity and mortality associated with cardiovascular compromise despite inotrope use, highlights major gaps in our understanding of circulatory targets, thresholds and choices of inotrope therapy. Thus far, prevention of cardiovascular compromise remains the most effective strategy to optimize outcomes. Studies of alternative design are needed for further advancement in cardiovascular therapy in neonates.

Cerebral Oxygenation in Preterm Infants With Necrotizing Enterocolitis

BACKGROUND AND OBJECTIVES

Preterm infants with necrotizing enterocolitis (NEC) are known to have worse neurodevelopmental outcomes, but there is no substantial evidence to support an underlying pathophysiology. We aimed to examine whether cerebral oxygenation differs in those infants who develop NEC compared to cerebral oxygenation in those who do not.

METHODS

We examined 48 infants <30 weeks' gestation admitted to a tertiary level NICU from October 2016 to May 2018. Infants with birth weight less than or equal to the second percentile, abnormal antenatal dopplers or twin-to-twin-transfusion-syndrome were excluded. Cerebral oximetry measurements were performed by using a near-infrared spectroscopy (NIRS) monitor weekly for 60 minutes, allowing measurement of cerebral tissue oxygenation index from the first week of life to 36 weeks postconceptional age. Weekly clinical status was also recorded. NEC was defined as greater than or equal to Bell stage 2.

RESULTS

The median birth weight was 884 g (range of 460-1600 g), the median weeks' gestational age was 26 + 3/7 (23 + 0/7 to 29 + 6/7), and 52% were girls. In total, 276 NIRS measurements were completed, and 7 infants developed NEC. NIRS measurements from 1 infant with NEC and 4 infants without NEC who developed hemorrhagic parenchymal infarcts were excluded from analysis. Infants who developed NEC had significantly lower cerebral tissue oxygenation index than those who did not (P = .011), even when adjusted for confounders, including gestational age, birth weight, patent ductus arteriosus, enteral feeds, sex, ethnicity, and hemoglobin.

CONCLUSIONS

Infants with NEC have significantly lower cerebral tissue oxygenation throughout their neonatal intensive care stay in comparison with those who did not develop NEC. This is a novel finding and could explain their worse neurodevelopmental outcome.

When does prone sleeping improve cardiorespiratory status in preterm infants in the NICU?

Study Objectives

Preterm infants undergoing intensive care are often placed prone to improve respiratory function. Current clinical guidelines recommend preterm infants are slept supine from 32 weeks’ postmenstrual age, regardless of gestational age at birth. However, respiratory function is also related to gestational and chronological ages and is affected by sleep state. We aimed to identify the optimal timing for adopting the supine sleeping position in preterm infants, using a longitudinal design assessing the effects of sleep position and state on cardiorespiratory stability.

Methods

Twenty-three extremely (24–28 weeks’ gestation) and 33 very preterm (29–34 weeks’ gestation) infants were studied weekly from birth until discharge, in both prone and supine positions, in quiet and active sleep determined by behavioral scoring. Bradycardia (heart rate ≤100 bpm), desaturation (oxygen saturation ≤80%), and apnea (pause in respiratory rate ≥10 s) episodes were analyzed.

Results

Prone positioning in extremely preterm infants reduced the frequency of bradycardias and desaturations and duration of desaturations. In very preterm infants, prone positioning only reduced the frequency of desaturations. The position-related effects were not related to postmenstrual age. Quiet sleep in both preterm groups was associated with fewer bradycardias and desaturations, and also reduced durations of bradycardia and desaturations in the very preterm group.

Conclusions

Cardiorespiratory stability is improved by the prone sleep position, predominantly in extremely preterm infants, and the improvements are not dependent on postmenstrual age. In very preterm infants, quiet sleep has a more marked effect than the prone position. This evidence should be considered in individualizing management of preterm infant positioning.