Cerebral fractional tissue oxygen extraction (cFTOE) during immediate fetal-to-neonatal transition: a systematic qualitative review of the literature.

Cerebral monitoring during immediate fetal-to-neonatal transition is of increasing interest. The cerebral fractional tissue oxygen extraction (cFTOE) is a useful parameter to gain insight in the balance between tissue oxygen delivery and consumption during this complex process. The aim of this study was to review the literature on cFTOE during the first 15 min immediately after birth. A systematic qualitative literature research was last performed on 23 November 2023 of PubMed and EMBASE with the following search terms: neonate, infant, newborn, transition, after birth, delivery room, NIRS, near-infrared spectroscopy, spectroscopy, cFTOE, cerebral fractional tissue oxygenation extraction, cerebral oxygenation, and fractional oxygen extraction. Additional published reports were identified through a manual search of references in retrieved articles and in review articles. The methodological quality of the included studies was assessed by predefined quality criteria. Only human studies with data of cFTOE in the first 15 min after birth were included. Accordingly, exclusion criteria were defined as no measurement of cFTOE or no measurement within the first 15 min after birth. Across all studies, a total of 3566 infants (2423 term, 1143 preterm infants) were analysed. Twenty-five studies were identified describing cFTOE within the first 15 min after birth. Four studies established reference ranges for cFTOE and another four studies focused on the effect of pre-/perinatal circumstances on cFTOE in the first 15 min after birth. Six studies investigated the course of cFTOE after transition in infants without complications. Eleven studies analysed different potentially influencing parameters on cFTOE during transition. CONCLUSION: This systematic review provides a comprehensive insight on cFTOE during uncomplicated transition as well as the influence of perinatal circumstances, respiratory, haemodynamic, neurological, and laboratory parameters in preterm and term infants. WHAT IS KNOWN: • The NIRS-measured cerebral fractional tissue oxygen extraction (cFTOE) is a useful parameter to estimate the balance between oxygen delivery and consumption. • During normal transition, the cFTOE decreases in the first minutes after birth and then remains at a stable plateau. WHAT IS NEW: • The cFTOE is a promising parameter that gives additional information on cerebral oxygenation and perfusion in preterm and term infants. • Several hemodynamic, metabolic, respiratory, and perinatal factors are identified, influencing the oxygen extraction of the newborn's brain after birth.

Changes in regional tissue oxygen saturation values during the first week of life in stable preterm infants.

OBJECTIVES: Near infrared spectroscopy (NIRS) is a non-invasive method for monitoring regional tissue oxygen saturation (rSO2). The purpose of this study is to investigate the changes that occur in cerebral, splanchnic, and renal rSO2 and fractional tissue oxygen extraction (FTOE) in stable preterm infants in the first week of life. METHODS: Prospective observational study of infants born 30-34 weeks gestation at NYU Langone Health between November 2017 and November 2018. Cerebral, renal, and splanchnic rSO2 were monitored from 12 to 72 h of life, and at seven days. Subjects were divided into gestational age (GA) cohorts. Average rSO2, splanchnic cerebral oxygen ratio (SCOR), FTOE, and regional intra-subject variability was calculated at each location at five different time intervals: 0-12 h, 12-24 h, 24-48 h, 48-72 h, and one week of life. RESULTS: Twenty subjects were enrolled. The average cerebral rSO2 ranged from 76.8 to 92.8 %, renal rSO2 from 65.1 to 91.1 %, and splanchnic rSO2 from 36.1 to 76.3 %. The SCOR ranged from 0.45 to 0.94. The strongest correlation between the GA cohorts was in the cerebral region (R2=0.94) and weakest correlation was in the splanchnic region (R2=0.81). The FTOE increased in all three locations over time. Intra-subject variability was lowest in the cerebral region (1.3 % (±1.9)). CONCLUSIONS: The cerebral region showed the strongest correlation between GA cohorts and lowest intra-subject variability, making it the most suitable for clinical use when monitoring for tissue hypoxia. Further studies are needed to further examine rSO2 in preterm infants.

Renal oximetry for early acute kidney injury detection in neonates with hypoxic ischemic encephalopathy receiving therapeutic hypothermia.

BACKGROUND: Neonates with hypoxic ischemic encephalopathy (HIE) receiving therapeutic hypothermia are at high risk of acute kidney injury (AKI). METHODS: We performed a two-site prospective observational study from 2018 to 2019 to evaluate the utility of renal near-infrared spectroscopy (NIRS) in detecting AKI in 38 neonates with HIE receiving therapeutic hypothermia. AKI was defined by a delayed rate of serum creatinine decline (< 33% on day 3 of life, < 40% on day 5, and < 46% on day 7). Renal saturation (Rsat) and systemic oxygen saturation (SpO2) were continuously measured for the first 96 h of life (HOL). Renal fractional tissue oxygen extraction (RFTOE) was calculated as (SpO2 - Rsat)/(SpO2). Using renal NIRS, urine biomarkers, and perinatal factors, logistic regression was performed to develop a model that predicted AKI. RESULTS: AKI occurred in 20 of 38 neonates (53%). During the first 96 HOL, Rsat was higher, and RFTOE was lower in the AKI group vs. the no AKI group (P < 0.001). Rsat > 70% had a fair predictive performance for AKI at 48-84 HOL (AUC 0.71-0.79). RFTOE ≤ 25 had a good predictive performance for AKI at 42-66 HOL (AUC 0.8-0.83). The final statistical model with the best fit to predict AKI (AUC = 0.88) included RFTOE at 48 HOL (P = 0.012) and pH of the infants' first postnatal blood gas (P = 0.025). CONCLUSIONS: Lower RFTOE on renal NIRS and pH on infant first blood gas may be early predictors for AKI in neonates with HIE receiving therapeutic hypothermia. A higher resolution version of the Graphical abstract is available as Supplementary information.

Cerebral and Renal Oxygenation in Infants Undergoing Laparoscopic Gastrostomy Tube Placement.

AIM: The aim of this study was to evaluate the effects of a carbon dioxide pneumoperitoneum on cerebral and renal oxygenation and oxygen extraction, in a cohort of infants from the neonatal intensive care unit, undergoing laparoscopic gastrostomy. METHODS: After institutional review board approval, between February 2018 and June 2019, infants 0-3 mo corrected age, undergoing laparoscopic gastrostomy tube placement, were included. Strict exclusion criteria created a homogeneous cohort. Cerebral and renal tissue oxygen saturation (rSO2) by near-infrared spectroscopy, skin surface oxygen saturation (SpO2), by pulse oximetry, and amplitude-integrated electroencephalography were measured. Monitoring was divided into preoperative, intraoperative and postoperative time periods. Cerebral and renal fractional tissue oxygen extraction was calculated using arterial (SpO2) and tissue oxygen saturation (rSO2): (SpO2-rSO2SpO2)X100. Data were averaged into one-minute epochs and significant changes from baseline during the intraoperative and postoperative periods were detected using one-way analysis of variance with repeated measures. RESULTS: This pilot study examined sixteen infants, born at a median gestational age of 34.2 wk (range: 23.0-40.6) with a median corrected age of 42.9 wk (range: 40.0-46.3) at operation. None had seizure activity or altered sleep-wake cycles. No statistically significant variations in cerebral and renal tissue oxygenation and extraction were observed. Pulse oximetry did demonstrate significant variation from baseline on analysis of variance, but post hoc analysis did not identify any one specific time point at which this difference was significant. CONCLUSIONS: During a short infant laparoscopic procedure, no significant alteration in cerebral or renal oxygenation or oxygen extraction was observed. No seizure activity or changes in infant sleep-wake cycles occurred.

The effect of enteral bolus feeding on regional intestinal oxygen saturation in preterm infants is age-dependent: a longitudinal observational study.

BACKGROUND: The factors that determine the effect of enteral feeding on intestinal perfusion after preterm birth remain largely unknown. We aimed to determine the effect of enteral feeding on intestinal oxygen saturation (rintSO2) in preterm infants and evaluated whether this effect depended on postnatal age (PNA), postmenstrual age (PMA), and/or feeding volumes. We also evaluated whether changes in postprandial rintSO2 affected cerebral oxygen saturation (rcSO2). METHODS: In a longitudinal observational pilot study using near-infrared spectroscopy we measured rintSO2 and rcSO2 continuously for two hours on postnatal Days 2 to 5, 8, 15, 22, 29, and 36. We compared preprandial with postprandial values over time using multi-level analyses. To assess the effect of PNA, PMA, and feeding volumes, we performed Wilcoxon signed-rank tests or logistic regression analyses. To evaluate the effect on rcSO2, we also used logistic regression analyses. RESULTS: We included 29 infants: median (range) gestational age 28.1 weeks (25.1-30.7) and birth weight 1025 g (580-1495). On Day 5, rintSO2 values decreased postprandially: mean (SE) 44% (10) versus 35% (7), P = .01. On Day 29, rintSO2 values increased: 44% (11) versus 54% (7), P = .01. Infants with a PMA ≥ 32 weeks showed a rintSO2 increase after feeding (37% versus 51%, P = .04) whereas infants with a PMA < 32 weeks did not. Feeding volumes were associated with an increased postprandial rintSO2 (per 10 mL/kg: OR 1.63, 95% CI, 1.02-2.59). We did not find an effect on rcSO2 when rintSO2 increased postprandially. CONCLUSIONS: Our study suggests that postprandial rintSO2 increases in preterm infants only from the fifth week after birth, particularly at PMA ≥ 32 weeks when greater volumes of enteral feeding are tolerated. We speculate that at young gestational and postmenstrual ages preterm infants are still unable to increase intestinal oxygen saturation after feeding, which might be essential to meet metabolic demands. TRIAL REGISTRATION: For this prospective longitudinal pilot study we derived patients from a larger observational cohort study: CALIFORNIA-Trial, Dutch Trial Registry NTR4153 .

Early or delayed cord clamping during transition of term newborns: does it make any difference in cerebral tissue oxygenation?

BACKGROUND: According to the World Health Organization's recommendation, delayed cord clamping in term newborns can have various benefits. Cochrane metaanalyses reported no differences for mortality and early neonatal morbidity although a limited number of studies investigated long-term neurodevelopmental outcomes. The aim of our study is to compare the postnatal cerebral tissue oxygenation values in babies with early versus delayed cord clamping born after elective cesarean section. METHODS: In this study, a total of 80 term newborns delivered by elective cesarean section were included. Infants were randomly grouped as early (clamped within 15 s, n:40) and delayed cord clamping (at the 60th second, n:40) groups. Peripheral arterial oxygen saturation (SpO2) and heart rate were measured by pulse oximetry while regional oxygen saturation of the brain (rSO2) was measured with near-infrared spectrometer. Fractional tissue oxygen extraction (FTOE) was calculated for every minute between the 3rd and 15th minute after birth. (FTOE = pulse oximetry value-rSO2/pulse oximetry value). The measurements were compared for both groups. RESULTS: The demographical characteristics, SpO2 levels (except postnatal 6th, 8th, and 14th minutes favoring DCC p < 0.05), heart rates and umbilical cord blood gas values were not significantly different between the groups (p > 0.05). rSO2 values were significantly higher while FTOE values were significantly lower for every minute between the 3rd and 15th minutes after birth in the delayed cord clamping group (p < 0.05). CONCLUSION: Our study revealed a significant increase in cerebral rsO2 values and a decrease in FTOE values in the delayed cord clamping (DCC) group, indicating a positive impact on cerebral oxygenation and hemodynamics. Furthermore, the DCC group exhibited a higher proportion of infants with cerebral rSO2 levels above the 90th percentile. This higher proportion, along with a lower of those with such parameter below the 10th percentile, suggest that DCC may lead to the targeted/optimal cerebral oxygenetaion of these babies. As a result, we recommend measuring cerebral oxygenation, in addition to peripheral SpO2, for infants experiencing perinatal hypoxia and receiving supplemental oxygen.

Regional tissue oxygenation in asymptomatic neonates at high risk for neonatal abstinence syndrome and impact of non-pharmacologic interventions: A case report.

BACKGROUND: Improving neonatal abstinence syndrome (NAS) management is an important concern, and objective measures of its physiologic impact remain elusive. We sought to determine whether near-infrared spectroscopy (NIRS)-derived tissue oxygenation (rSO2) and fractional tissue oxygen extraction (FTOE) demonstrated physiologically plausible changes correlating with standard NAS scoring. METHODS: Thirty subjects (mean 39 weeks' GA and 3 127 g BW) underwent cerebral and peripheral muscle NIRS monitoring on Days of Life (DOL) Three, Five, and Seven. We examined correlations between NAS scores and FTOE and assessed the impact of non-pharmacologic swaddling and cuddling. RESULTS: No statistically significant correlations between NAS scores and FTOE were observed; however, plausible trends were demonstrated between NAS scores and cerebral measurements. Buprenorphine-exposed babies (57%) showed significantly lower FTOE when swaddled (DOL7). CONCLUSIONS: Tissue oxygenation monitoring demonstrates potential to provide objective, clinically relevant physiologic information on infants at risk for NAS. Further study is required to determine whether NIRS-derived measures could assist in individualizing NAS care.

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.

Cerebral and peripheral regional oxygen saturation during postnatal transition in preterm neonates.

OBJECTIVE: To evaluate peripheral regional oxygen saturation (rpSO2) and cerebral regional oxygen saturation (rcSO2) during the immediate postnatal transition in late preterm infants with and without the need for respiratory support. STUDY DESIGN: This was a prospective observational study using near-infrared spectroscopy to evaluate changes in rpSO2 and rcSO2. These variables were measured during the first 15 minutes of life after elective cesarean delivery. Peripheral oxygen saturation (SpO2) and heart rate were measured continuously by pulse oximetry, and cerebral fractional tissue oxygen extraction (cFTOE) was calculated. Two groups were compared based on their need for respiratory support: a respiratory support group and a normal transition group. Positive-pressure ventilation was delivered with a T-piece resuscitator, and oxygen was adjusted based on SpO2 values. A Florian respiratory function monitor was used to record the ventilation variables. RESULTS: There were 21 infants in the normal transition group and 21 infants in the respiratory support group. Changes in heart rate over time were similar in the 2 groups. SpO2, rcSO2, and rpSO2 values were consistently higher in the normal transition group. In the respiratory support group, cFTOE values remained significantly elevated for a longer period. CONCLUSION: This systematic analysis of rpSO2, rcSO2, and cFTOE in late preterm infants found significantly lower oxygen saturation values in infants who received respiratory support compared with a normal transition group. We hypothesize that the elevated cFTOE values in the respiratory support group represent compensation for lower oxygen delivery.

Reference ranges for regional cerebral tissue oxygen saturation and fractional oxygen extraction in neonates during immediate transition after birth.

OBJECTIVE: To define reference ranges for regional cerebral tissue oxygen saturation (crSO2) and regional cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 minutes after birth in neonates requiring no medical support. STUDY DESIGN: The crSO2 was measured using near infrared spectroscopy (Invos 5100 cerebral/somatic oximeter monitor; Somanetics Corp, Troy, Michigan) during the first 15 minutes after birth for term and preterm neonates. The near infrared spectroscopy sensor was placed on the left forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry, and cFTOE was calculated. Neonates were excluded if they required any medical support. RESULTS: A total of 381 neonates were included: 82 term neonates after vaginal delivery, 272 term neonates after cesarean delivery, and 27 preterm neonates after cesarean delivery. In all neonates, median (10th-90th percentiles) crSO2 was 41% (23-64) at 2 minutes, 68% (45-85) at 5 minutes, 79% (65-90) at 10 minutes, and 77% (63-89) at 15 minutes of age. In all neonates, median (10th-90th percentiles) cFTOE was 33% (11-70) at 2 minutes, 21% (6-45) at 5 minutes, 15% (5-31) at 10 minutes, and 18% (7-34) at 15 minutes of age. CONCLUSION: We report reference ranges of crSO2 and cFTOE in neonates requiring no medical support during transition immediately after birth. The use of cerebral oxygenation monitoring and use of these reference ranges in neonates during transition may help to guide oxygen delivery and avoid cerebral hypo-oxygenation and hyperoxygenation.

Near-Infrared Spectroscopy to Guide and Understand Effects of Red Blood Cell Transfusion.

This review is a summary of available evidence regarding the use of near-infrared spectroscopy (NIRS) to help better guide and understand the effects of red blood cell (RBC) transfusion in neonatal patients. We review recent literature demonstrating the changes that take place in regional tissue oxygen saturation (rSO2) resulting from RBC transfusion. We also discuss in detail if any correlation exists between rSO2 and hemoglobin values in neonates. Finally, we review studies that have evaluated the use of NIRS as a transfusion guide during neonatal intensive care.

A pilot study: Comparing a novel noninvasive measure of cerebrovascular stability index with an invasive measure of cerebral autoregulation in neonates with congenital heart disease.

Infants with congenital heart disease (CHD) may have impaired cerebral autoregulation (CA) associated with cerebral fractional tissue oxygen extraction (FTOE). We conducted a pilot study in nine CHD neonates to validate a noninvasive CA measure, cerebrovascular stability index (CSI), by eliciting responses to postural tilts. We compared CSI to an invasive measure of CA and to FTOE collected during tilts (FTOESpot). FTOESpot correlated with CSI, as did the change in FTOE during tilts, but CSI's correlation with impaired CA did not reach significance. Larger trials are indicated to validate CSI, allowing for noninvasive CA measurements and measurements in outpatient settings.

Noninvasive Monitoring to Demonstrate Postoperative Differences in Regional Hemodynamics in Newborn Infants With d-Transposition of the Great Arteries and Hypoplastic Left Heart Syndrome.

BACKGROUND: The adequacy of tissue O2 delivery in infants receiving intensive care is difficult to measure directly. Regional O2 (rSO2) and fractional tissue O2 extraction (FTOE), the ratio of O2 consumption to O2 delivery, obtained from newer noninvasive tools, such as near-infrared spectroscopy (INVOS) and microvascular tissue oximetry (T-Stat) can provide important information on the adequacy of tissue oxygenation and aid in managing critically ill infants. METHODS: We prospectively evaluated differences in rSO2 and FTOE in 26 infants with hypoplastic left heart syndrome (HLHS) (n = 12) or d-transposition of the great arteries (d-TGA) (n = 14). Continuous noninvasive monitoring of SpO2, heart rate, and perfusion index with pulse oximetry, cerebral-rSO2 and renal-rSO2 with INVOS, and buccal tissue oxygenation using T-Stat were performed during immediate postoperative period for 24 hours. RESULTS: The SpO2 and rSO2 in infants with d-TGA were higher compared with the infants with HLHS at all measured sites (buccal mucosa, cerebral, and renal). Significant regional differences were also observed in FTOE across all infants with the highest at the buccal mucosa tissue level, followed by cerebral and renal measurement sites. As compared with infants with d-TGA, infants with HLHS had higher regional FTOE and heart rate, with a lower arterial O2 content and perfusion index. CONCLUSIONS: Our study demonstrates the utility of noninvasive hemodynamic monitoring to assess regional oxygenation and perfusion, as evidenced by significant differences in infants with HLHS and d-TGA, conditions with different circulation physiologies. Such comprehensive monitoring can potentially aid in evaluating treatment strategies aimed at preventing organ damage from O2 insufficiency.

Fetal Hemoglobin and Cerebral Tissue Oxygenation during Immediate Postnatal Transition.

INTRODUCTION: Concentration of fetal hemoglobin (HbFc) in human neonates determines oxygen-carrying capacity of blood and the position of oxyhemoglobin dissociation curve. Near-infrared spectroscopy enables the measurement of regional cerebral tissue oxygen saturation (rScO2) and in combination with measurements of pulsatile arterial oxygen saturation (SpO2), the calculation of cerebral fractional tissue oxygen extraction (cFTOE). METHODS: We aimed to investigate the impact of HbFc on rScO2, cFTOE, and SpO2 in preterm and term neonates during the first 15 min after birth. Blood analyses provided total blood hemoglobin (Hb) and HbFc measurements. Correlations between HbFc, Hb and rScO2, cFTOE, and SpO2 in each minute were analyzed. RESULTS: Ninety term and 19 preterm neonates without medical support were included. HbFc was significantly higher in preterm neonates, whereas there were no significant differences in Hb between the groups. In preterm neonates, we found positive correlations of both HbFc and Hb with rScO2 and negative correlations of HbFc and Hb with cFTOE in the first minutes after birth. In contrast, there were no significant correlations between the same parameters in term neonates. Correlations between HbFc or Hb and SpO2 were either insignificant, negligible, or very low in both groups. DISCUSSION/CONCLUSION: In preterm neonates, higher HbFc was associated with higher rScO2 and lower cFTOE in the first minutes after birth. This phenomenon could not be confirmed in term neonates and might reflect immature autoregulation of oxygen delivery to the brain or lower oxygen consumption in preterm neonates in the first minutes of immediate postnatal transition.

Regional tissue oxygenation and conventional indicators of red blood cell transfusion in anaemic preterm infants.

Background: It is unresolved whether low haemoglobin (Hb) and symptoms of anaemia reflect oxygen delivery-consumption imbalances (fractional tissue oxygen extraction [FTOE]). Here, we test whether pre-transfusion Hb and symptoms of anaemia correlate with pre-transfusion cerebral and splanchnic FTOE. Methods: This prospective cohort study was carried out between Sept 1, 2014 and Nov 30, 2016 at Nepean Hospital, Sydney, Australia. The study enroled haemodynamically stable preterm infants: gestation <32 weeks; birth weight <1500 gs; postmenstrual age <37weeks, who received 15 mL/kg packed red blood cell transfusion (PRBCT) based on low Hb and symptoms of anaemia. FTOE was determined using simultaneous monitoring of near-infrared spectroscopy and pulse oximetry for 4 h before PRBCT. Findings: The study enroled 29 infants born with a median gestation of 26.4 weeks (IQR 25.4-28.1), birth weight 922 g (655-1064), at postmenstrual age 33.6 weeks (31.7-34.9), and weight 1487 g (1110-1785). There was no significant correlation between Hb (median 97 g/L, IQR 87-100) and cerebral FTOE (r=-0.12, 95% CI -0.47 to 0.27; p = 0.54, n = 29) as well as splanchnic FTOE (r=-0.09, 95% CI -0.45 to 0.29; p = 0.64, n = 29). Median cerebral FTOE (p = 0.67) and splanchnic FTOE (p = 0.53) did not differ between symptomatic and asymptomatic groups. Interpretation: Our preliminary findings suggest that pre-transfusion Hb and symptoms of anaemia might not accurately reflect oxygen delivery-consumption imbalances in both the brain and the gut. A lack of correlation with cerebral FTOE might be presumed to be due to the brain-sparing effect. However, the lack of correlation with splanchnic FTOE is more concerning. Hence, these results warrant larger studies incorporating FTOE along with the conventional criteria in the transfusion algorithm. Funding: The study was funded (for the purchase of NIRS sensors) by the Australian Women and Children's Research Foundation.

Potential Relationship between Cerebral Fractional Tissue Oxygen Extraction (FTOE) and the Use of Sedative Agents during the Perioperative Period in Neonates and Infants.

Fractional tissue oxygen extraction (FTOE) by means of cerebral near-infrared spectroscopy (NIRS) provides information about oxygen uptake in the brain. Experimental animal data suggest that sedative agents decrease cerebral oxygen demand. The aim of the present study was to investigate the association between the cerebral FTOE and the use of pre and intraoperative sedative agents in infants aged 1-90 days. Cerebral NIRS was continuously applied during open major non-cardiac surgery in 46 infants. The main outcomes were the mean intraoperative FTOE and the percentage (%) of time of intraoperative hyperoxiaFTOE relative to the total duration of anesthesia. HyperoxiaFTOE was defined as FTOE ≤ 0.1. Cumulative doses of sedative agents (benzodiazepines and morphine), given up to 24 h preoperatively, correlated with the mean intraoperative FTOE (Spearman's rho = -0.298, p = 0.0440) and were predictive for the % of time of intraoperative hyperoxiaFTOE (ß (95% CI) 47.12 (7.32; 86.92)) when adjusted for the patients' age, type of surgery, preoperative hemoglobin, intraoperative sevoflurane and fentanyl dose, mean intraoperative arterial blood pressure, and end-tidal CO2 by multivariate 0.75 quantile regression. There was no association with 0.5 quantile regression. We observed the suggestive positive association of decreased fractional cerebral tissue oxygen extraction and the use of sedative agents in neonates and infants undergoing surgery.

Near-infrared spectroscopy to detect absence of cerebrovascular autoregulation in preterm infants.

OBJECTIVE: Our aim was to explore clinical parameters that might predict the absence of cerebrovascular autoregulation (CAR) assessed by a negative relationship between mean arterial blood pressure (MABP) and fractional tissue oxygen extraction (FTOE) as measured by near-infared spectroscopy (NIRS) in preterm infants. METHODS: We included preterm infants (gestational age (GA) <32 weeks). Within 72 h after birth, we recorded the infants' NIRS parameters and MABP for a 24-h period. Fractional tissue oxygen extraction (FTOE) was calculated. For each infant we calculated Spearman rank (rho) correlations. A statistically significant negative correlation between MABP and FTOE indicated the absent CAR. We related the absent CAR to clinical parameters. RESULTS: Ten (40%) out of 25 infants (median GA 29.1 weeks, range 25.4-31.7, birth weight 1245 g, 560-1780) had a statistically significant negative correlation between MABP and FTOE (rho -0.432 to -0.156), suggesting the absence of CAR. None of the clinical variables predicted the absence of CAR. CONCLUSIONS: We were unable to predict the absence of CAR in terms of clinical variables. Nevertheless, we found a statistically significant negative correlation between MABP and FTOE using NIRS, suggesting the absence of CAR in almost half of the preterm infants studied. SIGNIFICANCE: NIRS could be a helpful tool to assess the presence or absence of CAR.

Deep hypothermic circulatory arrest during the arterial switch operation is associated with reduction in cerebral oxygen extraction but no increase in white matter injury.

OBJECTIVE: Deep hypothermic circulatory arrest may be associated with increased neural injury. We investigated whether short periods of deep hypothermic circulatory arrest are associated with altered neurophysiologic recovery or greater risk of injury. METHODS: Eighteen term infants with transposition of the great arteries undergoing the arterial switch operation were enrolled. Deep hypothermic circulatory arrest was used in 11, and bypass alone in 7. Near-infrared spectroscopy and amplitude-integrated electroencephalography were recorded with standard monitoring during and from 4 to 16 h after surgery. Fractional tissue oxygen extraction was determined from arterial oxygen saturation and venous weighted intracerebral oxygenation. Magnetic resonance imaging was performed before and 5 to 7 days after surgery. RESULTS: There were no significant differences between patients requiring deep hypothermic circulatory arrest (median, 5 min; range, 3-6 min) or cardiopulmonary bypass only at the beginning of surgery. At the end of surgery, amplitude-integrated electroencephalography minimum amplitude was significantly lower in the deep hypothermic circulatory arrest group (P < .05), and fractional tissue oxygen extraction tended to be lower (P = .068). After surgery, deep hypothermic circulatory arrest was associated with significantly higher tissue oxygenation index, lower fractional tissue oxygen extraction, and lower core temperature (P < .05). Magnetic resonance imaging-defined white matter injuries before and after surgery were similar between groups. CONCLUSIONS: In this prospective, observational study, brief deep hypothermic circulatory arrest during arterial switch was associated with reduced cerebral oxygen uptake during recovery, with transient electroencephalographic suppression but no increase in risk of white matter injury.