Brain MRI Injury Patterns across Gestational Age among Preterm Infants with Perinatal Asphyxia.

INTRODUCTION: Brain injury patterns of preterm infants with perinatal asphyxia (PA) are underreported. We aimed to explore brain magnetic resonance imaging (MRI) findings and associated neurodevelopmental outcomes in these newborns. METHODS: Retrospective multicenter study included infants with gestational age (GA) 24.0-36.0 weeks and PA, defined as ≥2 of the following: (1) umbilical cord pH ≤7.0, (2) 5-min Apgar score ≤5, and (3) fetal distress or systemic effects of PA. Findings were compared between GA <28.0 (group 1), 28.0-31.9 (group 2), and 32.0-36.0 weeks (group 3). Early MRI (<36 weeks postmenstrual age or <10 postnatal days) was categorized according to predominant injury pattern, and MRI around term-equivalent age (TEA, 36.0-44.0 weeks and ≥10 postnatal days) using the Kidokoro score. Adverse outcomes included death, cerebral palsy, epilepsy, severe hearing/visual impairment, or neurodevelopment <-1 SD at 18-24 months corrected age. RESULTS: One hundred nineteen infants with early MRI (n = 94) and/or MRI around TEA (n = 66) were included. Early MRI showed predominantly hemorrhagic injury in groups 1 (56%) and 2 (45%), and white matter (WM)/watershed injury in group 3 (43%). Around TEA, WM scores were highest in groups 2 and 3. Deep gray matter (DGM) (aOR 15.0, 95% CI: 3.8-58.9) and hemorrhagic injury on early MRI (aOR 2.5, 95% CI: 1.3-4.6) and Kidokoro WM (aOR 1.3, 95% CI: 1.0-1.6) and DGM sub-scores (aOR 4.8, 95% CI: 1.1-21.7) around TEA were associated with adverse neurodevelopmental outcomes. CONCLUSION: The brain injury patterns following PA in preterm infants differ across GA. Particularly DGM abnormalities are associated with adverse neurodevelopmental outcomes.

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.

Early neonatal morbidities and neurological functioning of preterm infants 2 weeks after birth.

OBJECTIVE: To determine the association between potential neonatal risk factors and the quality of general movements (GMs) in preterm infants. STUDY DESIGN: Prospective cohort study in 67 preterm infants. From video recordings made on Days 8 and 15, we scored the GMs as normal/abnormal and detailed aspects using the general movement optimality score (GMOS). Risk factors included respiratory insufficiency requiring mechanical ventilation, patent ductus arteriosus (PDA), and abnormal blood glucose levels. We used multiple regression analyses. RESULT: On Day 8 after birth, the presence of a PDA remained in the multivariable model, explaining 17.1% of the variance in GMOS (beta, -0.414). On Day 15, duration of mechanical ventilation and frequency of hypoglycemic episodes explained 38.8% of the variance (betas, -0.382 and -0.466, respectively). CONCLUSION: In preterm infants, PDA, duration of mechanical ventilation, and frequency of hypoglycemic episodes were associated with poorer neurological functioning during the first 2 weeks after birth.

Measuring cerebrovascular autoregulation in preterm infants using near-infrared spectroscopy: an overview of the literature.

INTRODUCTION: The preterm born infant's ability to regulate its cerebral blood flow (CBF) is crucial in preventing secondary ischemic and hemorrhagic damage in the developing brain. The relationship between arterial blood pressure (ABP) and CBF estimates, such as regional cerebral oxygenation as measured by near-infrared spectroscopy (NIRS), is an attractive option for continuous non-invasive assessment of cerebrovascular autoregulation. Areas covered: The authors performed a literature search to provide an overview of the current literature on various current clinical practices and methods to measure cerebrovascular autoregulation in the preterm infant by NIRS. The authors focused on various aspects: Characteristics of patient cohorts, surrogate measures for cerebral perfusion pressure, NIRS devices and their accompanying parameters, definitions for impaired cerebrovascular autoregulation, methods of measurements and clinical implications. Expert commentary: Autoregulation research in preterm infants has reported many methods for measuring autoregulation using different mathematical models, signal processing and data requirements. At present, it remains unclear which NIRS signals and algorithms should be used that result in the most accurate and clinically relevant assessment of cerebrovascular autoregulation. Future studies should focus on optimizing strategies for cerebrovascular autoregulation assessment in preterm infants in order to develop autoregulation-based cerebral perfusion treatment strategies.

Cerebral oxygen saturation during the first 72h after birth in infants diagnosed prenatally with congenital heart disease.

BACKGROUND: Evidence suggests that hypoxic-ischemic brain injury in infants with congenital heart disease already occurs during early life. The aim of our study was, therefore, to assess the course of regional cerebral oxygen saturation (rcSO2) and fractional tissue oxygen extraction (FTOE) during the first 72h after birth in infants with prenatally diagnosed duct-dependent congenital heart disease. In addition, we identified clinical parameters that were associated with rcSO2. MATERIALS AND METHODS: We included 56 infants with duct-dependent congenital heart disease. We measured arterial oxygen saturation (SpO2) and rcSO2 during the first 72h after birth. Simultaneously, we calculated FTOE. RESULTS: We observed median rcSO2 values of approximately 60%, a decreasing FTOE from 0.34 on day 1 to 0.28 on day 3 and stable preductal SpO2 values around 90%. Several clinical variables were associated with rcSO2. In a multiple linear regression model only type of CHD and preductal SpO2 were significant predictors of rcSO2 during the first three days after birth. Infants with a duct-dependent pulmonary circulation had up to 12% lower rcSO2 values than infants with a duct-dependent systemic circulation. CONCLUSION: We demonstrated that, during the first three days after birth, cerebral oxygen saturation is low in infants with duct-dependent congenital heart disease. Furthermore, this study provides preoperative reference values of rcSO2 and FTOE in infants with duct-dependent CHD.

Children born preterm and full term have similar rates of feeding problems at three years of age.

AIM: We determined the prevalence of feeding problems and their association with perinatal risk factors in three-year-old children born preterm and compared them with a full-term reference group. METHODS: This pilot study assessed feeding problem scores in 35 preterm children, with a median gestational age of 30 weeks (range 26-32) and median birthweight of 1260 grams (730-2250), who were enrolled during their admission to a neonatal intensive care unit. These were compared with existing data on 248 term children from child healthcare centres at the age of three. We excluded children with severe perinatal complications from the reference group. The Screeningslijst Eetgedrag Peuters (SEP), a validated Dutch version of the Montreal Children's Hospital Feeding Scale, was used to identify feeding problems. RESULTS: We found no difference in SEP scores between the preterm children and the reference group (p = 0.217) and did not identify any perinatal risk factors for developing feeding problems. Only 23% of the parents of preterm or term children with moderate-to-severe feeding problems consulted a medical professional. CONCLUSION: Using a parental report instrument showed that the prevalence of feeding problems in three-year-old preterm children was low and similar to that of term children.

In preterm infants, ascending intrauterine infection is associated with lower cerebral tissue oxygen saturation and higher oxygen extraction.

BACKGROUND: Placental lesions are associated with neurological morbidity but the mechanism leading to morbidity is unclear. To provide insight into such a possible mechanism, we determined whether placental lesions were associated with regional cerebral tissue oxygen saturation (rcSO2) and fractional tissue oxygen extraction (FTOE) in preterm infants during their first 5 d after birth. We hypothesized that as a result of cerebral hypoperfusion, rcSO2 would be lower and FTOE would be higher. METHOD: In a prospective, observational study of 42 preterm infants (gestational age <32 wk), the infants' placentas were examined for histopathology. We measured rcSO2 and transcutaneous arterial oxygen saturation (SpO2) on days 1-5. FTOE was calculated as FTOE = (transcutaneous SpO2 - rcSO2)/transcutaneous SpO2. RESULTS: Only three placentas showed no pathology. Ascending intrauterine infection (AIUI) (n = 16) was associated with lower rcSO2 and higher FTOE values on days 2, 3, and 4 (P ≤ 0.05). Other placental lesions were not associated with rcSO2 and FTOE. CONCLUSION: AIUI is associated with lower rcSO2, and higher FTOE shortly after birth. The effect it has on cerebral oxygenation might be the mechanism leading to neurodevelopmental problems.

Cerebral oxygenation is associated with neurodevelopmental outcome of preterm children at age 2 to 3 years.

AIM: The aim of the study was to determine whether regional cerebral tissue oxygen saturation (r(c)SO2) and fractional tissue oxygen extraction (FTOE), using near-infrared spectroscopy, are associated with neurodevelopmental outcome of preterm infants. METHOD: We measured rc SO2 on days 1, 2, 3, 4, 5, 8, and 15 after birth in 83 preterm infants (<32wks gestational age), and calculated FTOE=(SpO2 -r(c)SO2)/SpO2. Cognitive, motor, neurological, and behavioural outcomes were determined at 2 to 3 years using the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III), an age-specific neurological examination, and the Child Behavior Checklist (CBCL) respectively. Multiple linear regression analyses were used to determine whether r(c)SO2 and FTOE contributed to outcome. RESULTS: We followed up 67 infants. The lower quartile (P(25-50)) and highest quartile (P(75-100)) of r(c)SO2 on day 1 were associated with poorer cognitive outcome (p=0.044 and p=0.008 respectively). A lower area under the curve (AUC; over 15d) of r(c)SO2 was associated with poorer cognitive outcome (p=0.014). The lower quartile (P(25-50)) AUC of r(c)SO2 was associated with poorer fine motor outcome (p=0.004). The amount of time r(c)SO2 <50% on day 1 was negatively associated with gross motor outcome (p=0.002). The highest quartile of FTOE on day 1 was associated with poorer total motor outcome (p=0.041). INTERPRETATION: Cerebral oxygen saturation during the first 2 weeks after birth is associated with neurodevelopmental outcome of preterm infants at 2 to 3 years. High and low r(c)SO2 on day 1 were associated with poorer neurodevelopmental outcome.

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.

Volume expansion does not alter cerebral tissue oxygen extraction in preterm infants with clinical signs of poor perfusion.

BACKGROUND: Preterm infants with signs of poor perfusion are often treated with volume expansion, although evidence regarding its effect on cerebral perfusion is lacking. Moreover, the effect is questionable in preterm infants with an adequate cerebrovascular autoregulation (CAR). A useful measure to assess perfusion is cerebral fractional tissue oxygen extraction (cFTOE). OBJECTIVES: To assess the effect of volume expansion on cFTOE in preterm infants with signs of poor perfusion. METHODS: In this observational study, we assessed cFTOE using near-infrared spectroscopy in preterm infants with signs of poor perfusion before, during and 1 h after volume expansion treatment. Simultaneously, we measured mean arterial blood pressure (MABP). We tested the effect of volume expansion on both cFTOE and MABP, using multi-level analyses. We intended to define a subgroup that responded to volume expansion with an increase in blood pressure and a decrease in cFTOE, suggesting absent CAR. RESULTS: In 14 preterm infants, with a median gestational age of 26.7 weeks (25.0-28.7 weeks) and a median birth weight of 836 g (615-1,290 g), we found a small increase in MABP during (1.4 ± 1.4 mm Hg, p = 0.003) and after (1.8 ± 1.7 mm Hg, p = 0.001) volume expansion, but no change in cFTOE during (-0.19 ± 0.1% p = 0.44) or after (-0.53 ± 0.1% p = 0.34) volume expansion. We were unable to define a subgroup lacking CAR. CONCLUSIONS: Cerebral perfusion, as assessed by cFTOE, does not improve in preterm infants with signs of poor perfusion following volume expansion. In these infants, either CAR is present or volume expansion is inadequate to affect cFTOE.

Maternal antihypertensive drugs may influence cerebral oxygen extraction in preterm infants during the first days after birth.

OBJECTIVE: To determine whether maternal antihypertensive drugs influenced cerebral oxygenation in preterm infants during the first days after birth. METHODS: We included 49 preterm infants (median gestational age 30.3 weeks, (range 26.0-31.9), birth weight 1250 g (560-2250)). Regional cerebral oxygen saturation (rcSO2) was measured by near-infrared spectroscopy on postnatal days 1, 2, 3, 4 and 5. Fractional tissue oxygen extraction (FTOE) was calculated using rcSO2 and arterial oxygen saturation (SpO2) values:(SpO2 - rcSO2)/SpO2. RESULTS: Nine mothers were treated with labetalol and/or MgSO4 during pregnancy, three mothers with labetalol, MgSO4 and nifedipine, and 19 mothers with nifedipine only. Eighteen infants served as controls. Multivariate linear regression analysis showed that exposure to labetalol and/or MgSO4 during pregnancy decreased FTOE on day 1 after birth, while nifedipine did not. CONCLUSIONS: Treating pregnant women with labetalol and/or MgSO4 may influence cerebral oxygen extraction in their offspring shortly after birth.

Effect of balloon atrial septostomy on cerebral oxygenation in neonates with transposition of the great arteries.

BACKGROUND: The aim of this study was to determine the effect of balloon atrial septostomy (BAS) on cerebral oxygenation in neonates with transposition of the great arteries (TGA). METHODS: In term neonates with TGA, regional cerebral tissue oxygen saturation (r(c)SO(2)) was measured using near-infrared spectroscopy (NIRS) for a period of 2 h, before BAS, after BAS, and 24 h after BAS. In neonates who did not require BAS on clinical grounds, r(c)SO(2) was measured within 24 h of admission and 24 h later. RESULTS: BAS was performed in 12 of 21 neonates. r(c)SO(2) increased from a median of 42% (before) to 48% at 2 h after BAS (P < 0.05), as did transcutaneous arterial oxygen saturation (spO(2)) (from 72% to 85%, P < 0.01). r(c)SO(2) increased further during the next 24 h (from 48% to 64%, P < 0.05), whereas spO(2) remained stable. Although beginning from a lower baseline (42 vs. 51%, P < 0.01), r(c)SO(2) was higher in neonates treated with BAS, as compared with neonates not treated with BAS, 24 h after the procedure (64 vs. 58%, P < 0.05); spO(2) was, however, similar between the two groups. CONCLUSION: BAS improves cerebral oxygen saturation in neonates with TGA. Complete recovery of cerebral oxygen saturation occurred only 24 h after BAS.

The relationship between electrocerebral activity and cerebral fractional tissue oxygen extraction in preterm infants.

Impaired cerebral oxygen delivery may cause cerebral damage in preterm infants. At lower levels of cerebral perfusion and oxygen concentration, electrocerebral activity is disturbed. The balance between cerebral oxygen delivery and oxygen use can be measured by near-infrared spectroscopy (NIRS), and electrocerebral activity can be measured by amplitude-integrated EEG (aEEG). Our aim was to determine the relationship between regional cerebral tissue oxygen saturation (rcSO2), fractional tissue oxygen extraction (FTOE), and aEEG. We recorded longitudinal digital aEEG and rcSO2 prospectively in 46 preterm infants (mean GA 29.5 wk, SD 1.7) for 2 hr on the 1st to 5th, 8th, and 15th d after birth. We excluded infants with germinal matrix hemorrhage exceeding grade I and recordings of infants receiving inotropes. FTOE was calculated using transcutaneous arterial oxygen saturation (tcSaO2) and rcSO2 values: (tcSaO2 - rcSO2)/tcSaO2. aEEG was assessed by calculating the mean values of the 5th, 50th, and 95th centiles of the aEEG amplitudes. The aEEG amplitude centiles changed with increasing GA. FTOE and aEEG amplitude centiles increased significantly with postnatal age. More mature electrocerebral activity was accompanied by increased FTOE. FTOE also increased with increasing postnatal age and decreasing Hb levels.

Prenatal tobacco exposure influences cerebral oxygenation in preterm infants.

AIM: Our aim was to determine the influence of prenatal tobacco exposure on regional cerebral tissue oxygen saturation (r(c)SO(2)) and fractional tissue oxygen extraction (FTOE) in preterm infants. We hypothesized that as a result of vasoconstriction caused by prenatal tobacco exposure r(c)SO(2) would be lower and FTOE would be higher during the first days after birth in infants exposed to tobacco during pregnancy. METHODS: Sixty preterms were included in this prospective, observational cohort study (median gestational age 29.9 weeks, range 26.0-31.8, median birth weight 1248 g, range 615-2250). Fourteen infants had been exposed to tobacco during pregnancy. All mothers smoked more than five cigarettes a day till delivery. We measured r(c)SO(2) and transcutaneous arterial oxygen saturation (tcSaO(2)) in all infants on days 1-5, 8, and 15. FTOE was calculated: FTOE=(tcSaO(2)-r(c)SO(2))/tcSaO(2). RESULTS: In preterm infants exposed to tobacco during pregnancy, r(c)SO(2) was lower during days 1, 2, and 8 after birth, median 73% versus 81%, 73% versus 80% and 71% versus 78% respectively. FTOE was higher during days 1 and 8 after birth, median 0.24 versus 0.15 and 0.26 versus 0.19 respectively. On the second day, FTOE tended to be higher, 0.18 versus 0.14. CONCLUSIONS: During the first two days and day 8 after birth cerebral oxygen saturation is lower and oxygen extraction higher in preterm infants following prenatal tobacco exposure. Our data suggest that prenatal tobacco exposure may have an effect on cerebral oxygenation of the infant.

Cerebral oxygenation in preterm infants with germinal matrix-intraventricular hemorrhages.

BACKGROUND AND PURPOSE: Preterm infants are at risk of developing germinal matrix hemorrhages-intraventricular hemorrhages (GMH-IVH). Disturbances in cerebral perfusion are associated with GMH-IVH. Regional cerebral tissue oxygen saturation (r(c)SO2), measured with near-infrared spectroscopy, and fractional tissue oxygen extraction (FTOE) were calculated to obtain an indication of cerebral perfusion. Our objective was to determine whether r(c)SO2 and FTOE were associated with GMH-IVH in preterm infants. METHODS: This case-control study included 17 preterm infants with Grade I to III GMH-IVH or periventricular hemorrhagic infarction (median gestational age, 29.4 weeks; range, 25.4 to 31.9 weeks; birth weight, 1260 g; range, 850 to 1840 g). Seventeen preterm infants without GMH-IVH, matched for gestational age and birth weight, served as control subjects (gestational age, 29.9 weeks; range, 26.0 to 31.6 weeks; birth weight, 1310 g; range, 730 to 1975 g). R(c)SO2 and transcutaneous arterial oxygen saturation were measured during 2 hours on Days 1 to 5, 8, and 15 after birth. FTOE was calculated as FTOE=(transcutaneous arterial oxygen saturation-r(c)SO2)/transcutaneous arterial oxygen saturation. RESULTS: Multilevel analyses showed that r(c)SO2 was lower and FTOE higher in infants with GMH-IVH on Days 1, 2, 3, 4, 5, 8, and 15. The largest difference occurred on Day 5 with r(c)SO2 median 64% in infants with GMH-IVH versus 77% in control subjects and FTOE median 0.30 versus 0.17. R(c)SO2 and FTOE were not affected by the grade of GMH-IVH. CONCLUSIONS: Preterm infants with GMH-IVH had lower r(c)SO2 and higher FTOE during the first 2 weeks after birth irrespective of the grade of GMH-IVH. This suggests that cerebral perfusion is decreased persistently for 2 weeks in infants with GMH-IVH, even in the presence of mild hemorrhages.

Cerebral tissue oxygen saturation and extraction in preterm infants before and after blood transfusion.

OBJECTIVE: Preterm infants often need red blood cell (RBC) transfusions. The aim of this study was to determine whether haemoglobin levels before transfusion were associated with regional cerebral tissue oxygen saturation (r(c)SO(2)) and fractional tissue oxygen extraction (FTOE) and whether RBC transfusions were associated with r(c)SO(2) and FTOE during the 24-h period thereafter. DESIGN: Prospective observational cohort study. SETTING: Third level neonatal intensive care unit. PATIENTS: Thirty-three preterm infants (gestational age 25-34 weeks, birth weight 605-2080 g) were included. INTERVENTIONS: None. MAIN OUTCOME MEASURES: R(c)SO(2) was measured during a 1-h period, before, 1 h after and 24 h after a 15 ml/kg RBC transfusion in 3 h. Using r(c)SO(2) and transcutaneous arterial oxygen saturation (tcSaO(2)) values, FTOE was calculated: FTOE=(tcSaO(2)-r(c)SO(2))/tcSaO(2). Results Forty-seven RBC transfusions were given. R(c)SO(2) and FTOE correlated strongly with haemoglobin before transfusion (r=0.414 and r=-0.462, respectively, p<0.005). TcSaO(2) did not correlate with haemoglobin before transfusion. 24 h after transfusion, r(c)SO(2) increased from a weighted mean of 61% to 72% and FTOE decreased from a weighted mean of 0.34 to 0.23. The decrease in FTOE was strongest in the group with haemoglobin below 6.0 mmol/l (97 g/l). The decrease in FTOE was already present 1 h after transfusion and remained unchanged at 24 h after transfusion. CONCLUSION: Following RBC transfusion, cerebral tissue oxygen saturation increases and FTOE decreases. The data suggest that cerebral oxygenation in preterm infants may be at risk when haemoglobin decreases under 6 mmol/l (97 g/l).

Cerebral oxygen saturation and extraction in preterm infants with transient periventricular echodensities.

OBJECTIVE: Our aim was to determine regional cerebral tissue oxygen saturation and fractional tissue oxygen extraction in preterm infants with transient periventricular echodensities. We hypothesized that as a result of reduced cerebral perfusion, regional cerebral tissue oxygen saturation will be lower and fractional tissue oxygen extraction will be higher during the first days after birth. PATIENTS AND METHODS: This was a prospective, observational study of 49 preterm infants (gestational age median: 30.1 weeks [26.0-31.8 weeks]; birth weight median: 1220 g [615-2250 g]). We defined transient periventricular echodensities as echodensities that persisted for >7 days. Regional cerebral tissue oxygen saturation was measured on days 1-5, 8, and 15 after birth. Fractional tissue oxygen extraction was calculated as (transcutaneous arterial oxygen saturation--regional cerebral tissue oxygen saturation)/transcutaneous arterial oxygen saturation. RESULTS: Transient periventricular echodensities were found in 25 of 49 infants. During the first week we found no difference between the 2 groups for cerebral tissue oxygen saturation and fractional tissue oxygen extraction values. On day 15 after birth, cerebral tissue oxygen saturation was lower in preterm infants with transient periventricular echodensities (66%) compared with infants without echodensities (76%) (P = .003). Fractional tissue oxygen extraction in infants with transient periventricular echodensities (0.30) was higher than fractional tissue oxygen extraction in infants without transient periventricular echodensities (0.20) (P < .001). The differences could not be explained by confounding variables. CONCLUSIONS: Persistent transient periventricular echodensities may be associated with increased cerebral oxygen demand after the first week after birth, which is contrary to our hypothesis. Cerebral oxygenation may be involved in the recovery of perinatal white matter damage.