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

Early treatment versus expectative management of patent ductus arteriosus in preterm infants

_Background:_ Much controversy exists about the optimal management of a patent ductus arteriosus (PDA) in preterm infants, especially in those born at a gestational age (GA) less than 28weeks. No causal relationship has been proven between a (haemodynamically significant) PDA and neonatal complications related to pulmonary hyperperfusion and/or systemic hypoperfusion. Although studies show conflicting results, a common understanding is that medical or surgical treatment of a PDA does not seem to reduce the risk of major neonatal morbidities and mortality. As the PDA might have closed spontaneously, treated children are potentially exposed to iatrogenic adverse effects. A conservative approach is gaining interest worldwide, although convincing evidence to support its use is lacking. _Methods:_ This multicentre, randomised, non-inferiority trial is conducted in neonatal intensive care units. The study population consists of preterm infants (GA1.5mm. Early treatment (between 24 and 72h postnatal age) with the cyclooxygenase inhibitor(COXi) ibuprofen (IBU) is compared with an expectative management (no intervention intended to close a PDA). The primary outcome is the composite of mortality, and/or necrotising enterocolitis (NEC) Bell stage ≥ IIa, and/or bronchopulmonary dysplasia (BPD) defined as the need for supplemental oxygen, all at a postmenstrual age (PMA) of 36weeks. Secondary outcome parameters are short term sequelae of cardiovascular failure, comorbidity and adverse events assessed during hospitalization and long-term neurodevelopmental outcome assessed at a corrected age of 2 years. Consequences regarding health economics are evaluated by cost effectiveness analysis and budget impact analysis. _Discussion:_ As a conservative approach is gaining interest, we investigate whether in preterm infants, born at a GA less than 28weeks, with a PDA an expectative management is non-inferior to early treatment with IBU regarding to the composite outcome of mortality and/or NEC and/or BPD at a PMA of 36weeks

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 (r(c)SO(2)) was measured by near-infrared spectroscopy on postnatal days 1, 2, 3, 4 and 5. Fractional tissue oxygen extraction (FTOE) was calculated using r(c)SO(2) and arterial oxygen saturation (SpO(2)) values:(SpO(2) - rcSO(2))/SpO(2). 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

Cerebrovascular Autoregulation in Preterm Infants During and After Surgical Ligation of the Ductus Arteriosus, a Comparison Between Two Surgical Approaches

Objective: During ligation of the ductus arteriosus, cerebrovascular autoregulation (CAR) may deteriorate. It is unknown whether different surgical approaches affect changes in CAR differently. The objective of this study was to compare the potential change in CAR in preterm infants during and after ligation comparing two surgical approaches: sternotomy and posterolateral thoracotomy.Design: This was an observational cohort pilot study.Setting: Level III NICU.Patients: Preterm infants (GA < 32 weeks) requiring ductal ligation were eligible for inclusion.Interventions: Halfway the study period, our standard surgical approach changed from a posterolateral thoracotomy to sternotomy. We analyzed dynamic CAR, using an index of autoregulation (COx) correlating cerebral tissue oxygen saturation and invasive arterial blood pressure measurements, before, during, and after ligation, in relation to the two approaches.Measurements and Main Results: Of nine infants, four were approached by thoracotomy and five by sternotomy. Median GA was 26 (range: 24.9-27.9) weeks, median birth weight (BW) was 800 (640-960) grams, and median post-natal age (PNA) was 18 (15-30) days, without differences between groups. COx worsened significantly more during and after thoracotomy from baseline (Delta rho from baseline: during surgery: Delta + 0.32, at 4 h: Delta + 0.36, at 8 h: Delta + 0.32, at 12 h: Delta + 0.31) as compared with sternotomy patients (Delta rho from baseline: during surgery: Delta + 0.20, at 4 h: Delta + 0.05, at 8 h: Delta + 0.15, at 12 h: Delta + 0.11) (F = 6.50; p = 0.038).Conclusions: In preterm infants, CAR reduced significantly during and up to 12 h after ductal ligation in all infants, but more evident during and after posterolateral thoracotomy as compared with sternotomy. These results need to be confirmed in a larger population

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. (C) 2011 Elsevier Ireland Ltd. All rights reserved

Supplementary Material for: Cerebral and Renal Oxygen Saturation Are Not Compromised in the Presence of Retrograde Blood Flow in either the Ascending or Descending Aorta in Term or Near-Term Infants with Left-Sided Obstructive Lesions

<p><b><i>Background:</i></b> In infants with left-sided obstructive lesions (LSOL), the presence of retrograde blood flow in either the ascending or descending aorta may lead to diminished cerebral and renal blood flow, respectively. <b><i>Objectives:</i></b> Our aim was to compare cerebral and renal tissue oxygen saturation (rSO₂) between infants with LSOL with antegrade and retrograde blood flow in the ascending aorta and with and without diastolic backflow in the descending aorta. <b><i>Methods:</i></b> Based on 2 echocardiograms, the study group was categorized according to the direction of blood flow in the ascending and descending aorta. We measured cerebral and renal rSO₂ using near-infrared spectroscopy and calculated fractional tissue oxygen extraction (FTOE). <b><i>Results:</i></b> Nineteen infants with LSOL, admitted to the NICU between 0 and 28 days after birth, were included. Infants with antegrade blood flow (<i>n </i>= 12) and infants with retrograde blood flow in the ascending aorta (<i>n</i> = 7) had similar cerebral rSO₂ and FTOE during both echocardiograms. Only during the first echocardiogram, infants with retrograde blood flow in the ascending aorta had lower renal FTOE (0.14 vs. 0.32,<i> p</i> = 0.04) and tended to have higher renal rSO₂ (80 vs. 65%,<i> p</i> = 0.09). The presence of diastolic backflow in the descending aorta was not associated with cerebral or renal rSO₂ and FTOE during the first (<i>n</i> = 8) as well as the second echocardiogram (<i>n</i> = 10). <b><i>Conclusions:</i></b> Retrograde blood flow in the ascending aorta was not associated with cerebral oxygenation, while diastolic backflow in the descending aorta was not associated with renal oxygenation in infants with LSOL.</p

Airway resistance measurements in pre-school children with asthmatic symptoms:The interrupter technique

SummaryMeasuring airway resistance in pre-school children with the interrupter technique has proven to be feasible and reliable in daily clinical practice and research settings. Whether it contributes to diagnosing asthma in pre-school children still remains uncertain. From the results of previous studies a need for standardisation of the technique has emerged. In this overview we will elaborate on research concerning the position of the interrupter technique in the difficult process of diagnosing asthma in pre-school children

Early treatment versus expectative management of patent ductus arteriosus in preterm infants: A multicentre, randomised, non-inferiority trial in Europe (BeNeDuctus trial)

Background: Much controversy exists about the optimal management of a patent ductus arteriosus (PDA) in preterm infants, especially in those born at a gestational age (GA) less than 28weeks. No causal relationship has been proven between a (haemodynamically significant) PDA and neonatal complications related to pulmonary hyperperfusion and/or systemic hypoperfusion. Although studies show conflicting results, a common understanding is that medical or surgical treatment of a PDA does not seem to reduce the risk of major neonatal morbidities and mortality. As the PDA might have closed spontaneously, treated children are potentially exposed to iatrogenic adverse effects. A conservative approach is gaining interest worldwide, although convincing evidence to support its use is lacking. Methods: This multicentre, randomised, non-inferiority trial is conducted in neonatal intensive care units. The study population consists of preterm infants (GA1.5mm. Early treatment (between 24 and 72h postnatal age) with the cyclooxygenase inhibitor(COXi) ibuprofen (IBU) is compared with an expectative management (no intervention intended to close a PDA). The primary outcome is the composite of mortality, and/or necrotising enterocolitis (NEC) Bell stage ≥ IIa, and/or bronchopulmonary dysplasia (BPD) defined as the need for supplemental oxygen, all at a postmenstrual age (PMA) of 36weeks. Secondary outcome parameters are short term sequelae of cardiovascular failure, comorbidity and adverse events assessed during hospitalization and long-term neurodevelopmental outcome assessed at a corrected age of 2 years. Consequences regarding health economics are evaluated by cost effectiveness analysis and budget impact analysis. Discussion: As a conservative approach is gaining interest, we investigate whether in preterm infants, born at a GA less than 28weeks, with a PDA an expectative management is non-inferior to early treatment with IBU regarding to the composite outcome of mortality and/or NEC and/or BPD at a PMA of 36weeks.SCOPUS: ar.jinfo:eu-repo/semantics/publishe