Wim Baerts

BEHAVIOUR PROBLEMS OF VERY LOWBIRTHWEIGHT CHILDREN

Parent and clinician reports of behaviour problems among very low‐birthweight (VLBW) children at 3½ years of age were studied in relation to indicators of neonatal cerebral damage, cognition and social factors. VLBW children had more depressed behaviour and more internalizing problems by parent report, and also scored significantly more often within the clinical range on total problem scores, than children in the comparison group. Neither neonatal cerebral ultrasound nor neurological examinations were directly associated with behavioural outcome. Cerebral damage was related to cognitive development. Cognition directly influenced behaviour problems according to clinician report, while the home environment did so according to parent report. The authors suggest that depressed behaviour of preschool VLBW children might be associated with parental reactions to the birth of a VLBW child, and that their attention problems might be linked indirectly to brain damage via cognitive impairments.

Comparing near-infrared spectroscopy devices and their sensors for monitoring regional cerebral oxygen saturation in the neonate

Background:Near-infrared spectroscopy (NIRS) is an upcoming clinical method for monitoring regional cerebral oxygen saturation (rScO2) in neonates. There is a growing market offering different devices and sensors. Even though this technique is increasingly clinically applied, little is known about the similarities and/or differences in rScO2 values between the different devices and sensors. The aim of this study was to compare the rScO2 values obtained in (preterm) neonates with all available sensors of three frequently used NIRS devices.Methods:Fifty-five neonates admitted to our neonatal intensive care unit (NICU) were included in this study. rScO2 was simultaneously monitored bilaterally with two different NIRS sensors (left and right frontoparietal) for at least 1 h. Then, the sensors were switched, and measurements were collected for at least another hour.Results:We detected a rather close correlation between all investigated sensors from the three different NIRS devices, but absolute rScO2 values showed substantial differences: Bland–Altman analysis showed average differences from 10 to 15%.Conclusion:Although the rScO2 values correlated well between different NIRS sensors, sometimes there were substantial differences between the absolute rScO2 values, which may complicate clinical application.

Long-term neurodevelopmental outcome of monochorionic and matched dichorionic twins

Background Monochorionic (MC) twins are at increased risk for perinatal mortality and serious morbidity due to the presence of placental vascular anastomoses. Cerebral injury can be secondary to haemodynamic and hematological disorders during pregnancy (especially twin-to-twin transfusion syndrome (TTTS) or intrauterine co-twin death) or from postnatal injury associated with prematurity and low birth weight, common complications in twin pregnancies. We investigated neurodevelopmental outcome in MC and dichorionic (DC) twins at the age of two years. Methods This was a prospective cohort study. Cerebral palsy (CP) was studied in 182 MC infants and 189 DC infants matched for weight and age at delivery, gender, ethnicity of the mother and study center. After losses to follow-up, 282 of the 366 infants without CP were available to be tested with the Griffiths Mental Developmental Scales at 22 months corrected age, all born between January 2005 and January 2006 in nine perinatal centers in The Netherlands. Due to phenotypic (un)alikeness in mono-or dizygosity, the principal investigator was not blinded to chorionic status; perinatal outcome, with exception of co-twin death, was not known to the examiner. Findings Four out of 182 MC infants had CP (2.2%) - two of the four CP-cases were due to complications specific to MC twin pregnancies (TTTS and co-twin death) and the other two cases of CP were the result of cystic PVL after preterm birth - compared to one sibling of a DC twin (0.5%; OR 4.2, 95% CI 0.5–38.2) of unknown origin. Follow-up rate of neurodevelopmental outcome by Griffiths test was 76%. The majority of 2-year-old twins had normal developmental status. There were no significant differences between MC and DC twins. One MC infant (0.7%) had a developmental delay compared to 6 DC infants (4.2%; OR 0.2, 95% 0.0–1.4). Birth weight discordancy did not influence long-term outcome, though the smaller twin had slightly lower developmental scores than its larger co-twin. Conclusions There were no significant differences in occurrence of cerebral palsy as well as neurodevelopmental outcome between MC and DC twins. Outcome of MC twins seems favourable in the absence of TTTS or co-twin death.

Visual field and grating acuity development in low-risk preterm infants during the first 2 1/2 years after term

The effect of early visual experience on visual field size and grating acuity development was studied longitudinally in 36 appropriate for gestational age (AGA) and 26 small for gestational age (SGA) low-risk preterm infants. These were selected out of 194 very low birth weight (VLBW) infants (birthweight less than 1500 g) born in 1985 and 1986. Criteria for inclusion as low-risk were the absence of neurological, respiratory, circulatory and alimentary problems in the neonatal period; no retinopathy of prematurity and no evidence of abnormality on the neonatal cranial ultrasound scans. Binocular field sizes were assessed using kinetic arc perimetry. Binocular grating acuity was tested by means of the prototype version of the acuity card procedure. Results were compared with norms obtained in control fullterms in earlier studies. Infants were tested at 6 weeks, 6, 6, 9 and 12 months of age from the expected term date. Twenty-two of these infants were retested at 2 1/2 years of corrected age. Visual field size and visual acuity estimates of (both AGA and SGA) low-risk, VLBW preterms and control fullterms overlapped at all test ages, except for a slight but significantly faster development of the upper and the lower visual field at 6 weeks corrected age in the preterm group. These results indicate that for clinical purposes visual experience before the expected term date has not only no measurable effect on the normal development of behavioural acuity, but also no accelerating effect on the development of peripheral vision.

Implementation of a nation-wide automated auditory brainstem response hearing screening programme in neonatal intensive care units

Aim: As part of a future national neonatal hearing screening programme in the Netherlands, automated auditory brainstem response (AABR) hearing screening was implemented in seven neonatal intensive care units (NICUs). The objective was to evaluate key outcomes of this programme: participation rate, first stage success rate, pass/referral rates, rescreening compliance, diagnostic referral rates, age of first diagnostic evaluation and prevalence of congenital hearing loss (CHL). Methods: This prospective cohort study collected data on 2513 survivors. NICU graduates with one or more risk factors according to the Joint Committee on Infant Hearing were included in a two‐stage AABR hearing screening programme. Conventional ABR was used to establish a diagnosis of CHL. Results: A total of 2513 newborns enrolled in the programme with a median gestational age of 31.6 (range 24–43) wk and a median birthweight of 1450 (range 510–4820) g. In 25 (1%) cases parents refused screening. Four out of 2513 newborns were initially lost; 2484 newborns have been tested initially. A final 98% participation rate (2465/2513) was obtained for the whole programme. After a median postmenstrual age at the first test of 33.7 (range 27–54) wk, a pass rate of 2284/2484 (92%) resulted at the first stage. The rescreening compliance after the first test was 92% (184/200). A referral rate for diagnostic ABR of 3.1% (77/2484) resulted. Of the 77 referrals 14 (18.2%) had normal screening thresholds, 15 (19.5%) had unilateral CHL and 48 (62.3%) had bilateral CHL. The prevalence of unilateral CHL was 0.6% (15/2484) and of bilateral CHL 1.9% (48/2484).

Neonatal cerebral ultrasound, neonatal neurology and perinatal conditions as predictors of neurodevelopmental outcome in very low birthweight infants

To determine the assessments before discharge from the intensive care unit, that will predict outcome most accurately, a prospective longitudinal study in a cohort of 79 high risk VLBW children was conducted from birth to 3.6 years of age. Birthweight, gestational age, obstetrical and neonatal optimality, neonatal neurological examinations and neonatal cerebral ultrasound were studied in relation to outcome. The best predictor for outcome was a simple cerebral ultrasound classification according to the presence or absence of ventriculomegaly and intraparenchymal damage of any cause. Infants with normal neonatal cerebral scans or abnormal scans without ventriculomegaly almost invariably had a normal neurological outcome. In infants with cerebral lesions with ventriculomegaly the incidence of normal neurological outcome decreased to less than 50%. Intraparenchymal damage was associated with cerebral palsy as well as other (mental and sensori) handicaps in over 85% of the cases. Neonatal neurological examinations at preterm age had additional value in predicting neurological outcome especially in the group with ventriculomegaly. Neither birthweight, nor gestational age, obstetrical or neonatal optimality were independent variables in the prediction of outcome in high risk VLBW children at 3.6 years of age.

Reference values of regional cerebral oxygen saturation during the first 3 days of life in preterm neonates

Background:Currently, reliable reference values of regional cerebral oxygen saturation (rScO2) for different gestational age (GA) groups are lacking, which hampers the implementation of near-infrared spectroscopy (NIRS) alongside monitoring arterial oxygen saturation (SaO2) and blood pressure in neonatal intensive care. The aim of this study was to provide reference values for rScO2 and cerebral fractional tissue oxygen extraction (cFTOE; (SaO2 − rScO2)/SaO2) for small adult and neonatal NIRS sensors.Methods:In this study, 999 infants born preterm (GA <32 wk) were monitored with NIRS during the first 72 h of life. Mixed modeling was used to generate reference curves grouped per 2 wk of GA. In addition, the influence of a hemodynamically significant patent ductus arteriosus, gender, and birth weight were explored.Results:Average rScO2 was ~65% at admission, increased with GA (1% per week) and followed a parabolic curve in relation to postnatal age with a peak at ~36 h. The cFTOE showed similar but inverse effects. On average, the neonatal sensor measured 10% higher than the adult sensor.Conclusion:rScO2 and cFTOE reference curves are provided for the first 72 h of life in preterm infants, which might support the broader implementation of NIRS in neonatal intensive care.

Effects of very low birth weight (VLBW) on visual development during the first year after term

Behavioural visual functions were assessed in 155 very low birth weight (VLBW) infants during the first 12 months after expected term. Visual development was examined (mainly cross-sectionally) at 6 weeks, 3, 6, 9, and 12 months of corrected age by assessment of visual acuity, visual fields, optokinetic nystagmus and visual threat response. Many VLBW infants showed visual impairments (54.2%). No single visual function appeared to be specifically susceptible to impairments, deficits were often apparent across a range of functions. Visual impairments were observed at all test ages, and could already be assessed at 6 weeks of corrected age. The highest incidence of visual impairments was scored at 6 months corrected age. Beyond 6 months, less deficits were observed, suggesting in many infants a delayed rather than a permanently impaired visual development. In some infants deficits became evident at a later stage, after an apparently normal initial development. The results suggest that VLBW infants are at risk for impaired visual development.

Effects of Neonatal Dexamethasone Treatment on the Cardiovascular Stress Response of Children at School Age

OBJECTIVE. The goal was to investigate cardiovascular responses to a psychosocial stressor in school-aged, formerly premature boys and girls who had been treated neonatally with dexamethasone or hydrocortisone because of chronic lung disease. METHODS. We compared corticosteroid-treated, formerly preterm infants with formerly preterm infants who had not been treated neonatally with corticosteroids (reference group). Children performed the Trier Social Stress Test for Children, which includes a public speaking task and a mental arithmetic task. Blood pressure was recorded continuously before, during, and after the stress test. Plasma norepinephrine levels were determined before the test, directly after the stress task, and after recovery. RESULTS. Overall, in response to stress, girls had significantly larger changes in systolic blood pressure and mean arterial pressure and in stroke volume and cardiac output, compared with boys. Boys exhibited larger total peripheral resistance responses, compared with girls. The hydrocortisone group did not differ significantly from the reference group in any of the outcome measures. However, dexamethasone-treated children had smaller stress-induced increases in systolic and mean arterial blood pressure than did hydrocortisone-treated children. In addition, the dexamethasone group showed smaller increases in stroke volume and blunted norepinephrine responses to stress, compared with children in the reference group. Correction for gender did not affect these results. CONCLUSIONS. The differences in cardiovascular stress responses between girls and boys are consistent with known gender differences in adult cardiovascular stress responses. Our data demonstrate that neonatal treatment with dexamethasone has long-term consequences for the cardiovascular and noradrenergic stress responses; at school age, the cardiovascular stress response was blunted in dexamethasone-treated children. Hydrocortisone-treated children did not differ from the reference group, which suggests that hydrocortisone might be a safe alternative to dexamethasone for treating chronic lung disease of prematurity.

Surfactant replacement therapy in neonates with respiratory failure due to bacterial sepsis

We describe four newborns (gestational ages 29‐37 weeks; birthweights 1380‐3040 grams) who were mechanically ventilated for respiratory insufficiency because of bacterial sepsis. A beneficial effect of bovine surfactant (Alvofact, dosages 50 or lOOmg/kg) was found, as shown by decreases in mean airway pressures and oxygen demands. No side effects were seen after instillation.