Perinatal adaptive response of the adrenal and carotid blood flow in sheep fetuses subjected to total cord occlusion

OBJECTIVE

To investigate the perinatal adaptive response of the adrenal blood flow/adrenal fractional moving blood volume (AFMBV) and carotid blood flow (CBF), in sheep fetuses subjected to severe acute intrauterine hypoxia/asphyxia induced by total cord occlusion.

METHODS

Adrenal blood flow velocity, AFMBV and CBF were measured in 13 exteriorized fetal sheep; eight of them underwent total umbilical cord occlusion to induce severe acute hypoxia/asphyxia. Five lambs were used as sham controls. Middle adrenal artery pulsatility index (MAAPI) and mean velocity (MAAMV) were recorded with pulsed Doppler ultrasound. AFMBV was estimated using power Doppler ultrasound. CBF was recorded with a transonic flowmeter. In the neonatal period, after resuscitation all lambs were followed for a 4-hour period and AFMBV and CBF were recorded. Mean arterial blood pressure (MABP) and fetal heart rate were recorded continuously. Arterial cortisol levels were measured at the beginning and at the end of the fetal and neonatal periods.

RESULTS

Following the total cord occlusion, there was a significant reduction in the CBF, MABP, and heart rate and adrenal flow/AFMBV after 2, 4 and 5 min, respectively. Cortisol levels in the asphyctic lambs at the end of the cord occlusion were significantly lower than those in controls. After resuscitation, the asphyctic lambs showed increased AFMBV and cortisol levels, and reduced MABP as compared to control lambs. No differences were found in CBF, MAAPI and MAAMV. Thereafter, no differences were observed between the two groups in any of the studied parameters. At the end of the cord occlusion period, there was a significant correlation between AFMBV and MABP (r=0.69), between AFMBV and CBF (r =0.65) and between CBF and MABP (r=0.89).

CONCLUSION

During severe acute intrauterine hypoxia, the fetal lamb is able to maintain the blood flow to the brain and the adrenal gland for 3-5 min. Changes in the AFMBV and the CBF were highly correlated to the changes in MABP. Adrenal FMBV and cortisol levels were higher in lamb neonates exposed to severe intrauterine asphyxia.

Nitric oxide in neonatal transposition of the great arteries

Three newborn infants with transposition of the great arteries (TGA) and intact ventricular septum (IVS) developed postnatal persistent pulmonary hypertension of the newborn (PPHN) and were successfully treated with inhaled nitric oxide (iNO). Intervention with balloon atrial septostomy (BAS) was performed in two of the infants before the iNO treatment, but they continued to be severely hypoxic with metabolic acidosis. However, the iNO immediately improved oxygenation and the clinical condition. The third neonate had a moderately large atrial communication and echocardiographic signs of PPHN. He received iNO before BAS with dramatic clinical improvement, which therefore postponed BAS.

CONCLUSION

Early diagnosis of PPHN and treatment with iNO may improve final outcome in neonates with TGA and IVS. In the presence of moderately large atrial communication and PPHN, treatment with iNO might be considered before BAS.

Role of cerebral function monitoring in the newborn

For many years, newborn infants admitted to neonatal intensive care units have had routine electrocardiography and been monitored for respiratory rate, heart rate, oxygen saturation, and blood pressure. Only recently has it also been considered important to monitor brain function using continuous electroencephalography. The role of cerebral function monitoring in sick full term and preterm infants is reviewed.

Electroencephalography and brain damage in preterm infants

Electroencephalography (EEG) is a sensitive method for detection of brain injury in preterm infants. Although the acute and chronic EEG changes are mainly non-specific regarding type of damage, they correlate with later neurological and cognitive function. In infants developing brain white matter damage, acute EEG findings include depression of background activity and presence of epileptic seizure activity. The chronic EEG changes associated with white matter injury and abnormal neurological development include delayed maturation, and presence of abundant Rolandic sharp waves. Cognitive limitations in preterm infants have been associated with changes in various sleep measures in EEG's recorded at full term. Continuous EEG-monitoring during neonatal intensive care shows that cerebral electrical activity during this vulnerable period can be affected by several extracerebral factors, e.g. cerebral blood flow, acidosis and some commonly used medications. For diagnosis of brain damage in preterm infants with neurophysiological methods, a combination of early continuous EEG monitoring during the initial intensive care period and full EEG, performed at later stages, is probably optimal.

VWF-cleaving protease (ADAMTS13) in premature infants

BACKGROUND

Patients with thrombotic thrombocytopenic purpura (TTP) are deficient in von Willebrand factor (VWF)-cleaving protease, called ADAMTS13, and are prone to develop abnormal intravascular platelet aggregation leading to focal cerebral ischaemia. We speculated that low levels of ADAMTS13 are present in premature infants. This might result in platelet aggregation with subsequent ischaemia, vessel rupture and haemorrhage, and thus contribute to intraventricular haemorrhage and periventricular leucomalacia (IVH and PVL).

PATIENTS AND METHODS

Nine preterm infants with gestational ages 23.7 to 30.9 (median 25.7) wk, and 10 healthy term control infants with gestational ages 36.9 to 39 (median 37.9) wk were included. Blood was sampled from the umbilical cord at delivery, and levels of ADAMTS13, VWF antigen and VWF collagen binding activity were analysed.

RESULTS

The mean ADAMTS13 level in preterm infants was lower than in the term infants, but the difference between the groups was not statistically significant. However, in the preterm group there was a positive correlation between ADAMTS13 and both gestational age (r = 0.70, p = 0.035) and birthweight (r = 0.83, p = 0.005). Three preterm infants had ADAMTS13 of 18-20%. One of these developed a germinal matrix haemorrhage and PVL, and this infant had the lowest measured ADAMTS13 of all. The levels of VWF antigenand VWF collagen bindingactivity were higher in the preterm infants.

CONCLUSION

This pilot study showed that preterm infants have low levels of ADAMTS13. Enzyme substitution may be a therapeutic option if an association with IVH or PVL can be confirmed in larger patient groups.

Midazolam and amplitude-integrated EEG

Amplitude-integrated EEG (aEEG) is currently used in an increasing number of neonatal intensive care units. The method has been practised in newborn infants for more than 20 y. However, it was not until recently, when the method proved to be accurate for very early prediction of outcome in asphyxiated newborn infants, that it gained more widespread neonatal use. The use of aEEG in units for neonatal intensive care has increased the awareness that sick infants develop subclinical seizure activity, and that several medications affect the aEEG background.

Preterm male infants need more initial respiratory and circulatory support than female infants

AIM

The aim of this study was to investigate possible gender-related differences in clinical parameters during the first week of life that could explain the higher morbidity and mortality of preterm male infants.

METHODS

In total, 130 clinical variables were collected from 236 inborn infants (130 male and 106 female infants) with gestational age (GA) < 29 wk. A subgroup of 175 extremely low birthweight infants (ELBW) < 1000 g (n = 86 males; n = 89 females) was analysed separately.

RESULTS

At 6 postnatal h, 60.8% of the male infants needed mechanical ventilation versus 46.2% of the females (p = 0.026). Chronic lung disease (CLD) developed in 36.2% of males versus 9.8% of female infants (p = 0.004). Inotrope support with dopamine was used in more than 50% of the infants; additional inotrope support to dopamine was needed by 19.4% of male and 9.7% of female infants (p = 0.041). The gender-related difference in need for inotrope support was more evident among the ELBW infants; 67.1% of male infants needed inotrope support versus 50.6% of females (p = 0.028). At 12-24 h, male ELBW infants had lower minimum mean arterial blood pressure (mean (SD) 25(4) mmHg vs 28(6) mmHg, p = 0.004)) and lower minimum PaCO2 than females infants (4.3 (1.1) kPa vs 4.7 (0.9) kPa, p = 0.043).

CONCLUSIONS

There are early gender-related differences in need for ventilatory and circulatory support that may contribute to the worse long-term outcome in prematurely born male infants.

Different responses of myocardial and cerebral blood flow to cord occlusion in exteriorized fetal sheep

Type and duration of fetal asphyxial insult affect the distribution of blood flow to the heart and brain. The purpose of this study was to describe dynamic and quantitative changes in regional myocardial and cerebral blood flow (CBF) during fetal asphyxia induced by total occlusion of the umbilical cord. Eleven exteriorized fetal sheep were subjected to total umbilical cord occlusion and five fetal sheep served as sham controls. Regional blood flow (BF) to the brain and heart was quantified using radioactive microspheres before and after 5 min of occlusion and finally when fetal mean arterial blood pressure had decreased below 25 mm Hg, 9.8 (0.8) [mean (SD)] min after occlusion. Right coronary arterial (RCA) blood flow velocity and carotid BF were registered continuously. Mean values of arterial pH and oxygen content (mL O(2)/100 mL) were 7.08 (0.11) and 4.4 (2.9) before cord occlusion and decreased to 6.83 (0.05) and 1.4 (0.9) at 5 min after occlusion (p < 0.01, respectively). Carotid BF was significantly below preocclusion values by 2.5 min (p < 0.05), whereas RCA velocity time integral per minute remained above preocclusion values for 9 min. CBF decreased from 316 (24) before cord occlusion to 156 (30) mL/min/100 g at 5 min (p < 0.01), whereas right myocardial BF was maintained at 792 (125) and 751 (183) mL/min/100 g, respectively. CBF decreased rapidly after total cord occlusion whereas myocardial BF increased and was maintained until shortly before cardiac arrest, suggesting the myocardium to be better preserved during this type of insult in already partially asphyxiated fetuses.

Evaluation of screening procedures for congenital cataracts

AIM

To evaluate the efficacy of two different Swedish screening procedures for early detection of congenital cataracts in comparison with no screening.

METHODS

Children born between January 1992 and December 1998 in Swedish regions with an established eye-screening routine procedure, diagnosed with congenital cataract, and operated on before 1 y of age, were included in a retrospective study. Age at referral and age at time of the operation were compared between regions using different screening procedures: screening in the maternity wards (Region 1), at the well-baby clinics (Region 2) and one region without any screening (Region 3).

RESULTS

Seventy-two children were included in the study. Concerning early diagnosis and surgery, Region 1 differed significantly from Regions 2 and 3, which were more similar and were combined for further analysis. The difference in detected cases was greatest at 21 d of age (55% vs 18%; p < 0.001), but persisted even at 100 d of age (78% vs 64%; p < 0.02). Region 1 screening resulted in more and earlier cases detected than the other two regions (22 vs 15 per 100,000 births). In 72% of all cases, surgery was performed in response to referrals from either the maternity wards (36%), or the well-baby clinics (36%). However, half of the cases from the well-baby clinics were detected too late, i.e. at > 100 d.

CONCLUSION

Eye screening in the maternity ward is preferable to well-baby clinic screening and to no screening at all, since it leads to early detection. Screening should also be performed routinely at well-baby clinics within the period when successful treatment is possible.

Tolerance to early human milk feeding is not compromised by indomethacin in preterm infants with persistent ductus arteriosus

AIM

Early human milk feeding is beneficial for gut and brain development. Persistent ductus arteriosus (PDA) and indomethacin may compromise enteral function in preterm infants. For many years enteral milk feedings have continued in preterm infants receiving indomethacin for PDA. The aim of this study was to investigate whether this strategy is efficient in terms of risks and tolerance to early enteral feeding.

METHODS

This retrospective study included 64 inborn infants of <29 wk gestational age (GA), 32 infants who received indomethacin for symptomatic PDA (case infants) and 32 matched controls. Case infants had a mean (SD) GA of 26.3 wk (1.3) and body weight 839 g (203) versus controls GA 26.4 wk (1.2) and body weight 896 g (213) (p = 0.82 and 0.27, respectively). Case infants had higher respiratory morbidity; 90.6% versus 50% of controls needed mechanical ventilation (p = 0.000).

RESULTS

Case infants received human milk from a median (range) age of 4.0 h (1.5-27.5), and controls from 5.3 h (2.0-38.0) (p = 0.092). The first dose of indomethacin was given at a mean age of 1.7 d (1.0). There were no differences between the two groups in feeding volumes or gastric residuals on days 1 to 7. Mean (SD) feeding volume on day 7 was 64 ml/kg (31) in case infants and 76 ml/kg (30) in controls (p = 0.23). Four infants developed necrotizing enterocolitis: two case infants and two controls (p = 1.00).

CONCLUSION

Early enteral feeding with human milk, starting within the first hours of life, seems to be as well tolerated in preterm infants treated with indomethacin for PDA as in their matched controls.

Amplitude-integrated encephalography in pyridoxine-dependent seizures and pyridoxine-responsive seizures

Pyridoxine-dependent seizures are rare in newborn infants, although recent data suggest that the prevalence probably is underestimated. In all newborn infants with recurrent epileptic seizures the general recommendation is to administer pyridoxine and simultaneously record an electroencephalogram (EEG).

CONCLUSION

One infant with pyridoxine-responsive seizures and another with pyridoxine-dependent seizures had different electroclinical responses on amplitude-integrated EEG monitoring (aEEG) when pyridoxine was administered.

Neonatal individualized care in practice: a Swedish experience

A family-centred, developmentally supportive approach to newborn intensive care referred to as NIDCAP (Newborn Individualized Developmental Care and Assessment Programme) has caught considerable interest during recent years. In this paper we review the scientific context behind its conceptual framework and summarize our experience from 10 years of training, implementation and research. We present the short- and long-term medical and developmental outcome of our Swedish NIDCAP studies as well as attitudes of nursing staff and neonatologists. Furthermore, ethical issues and scientific obstacles concerning this concept of care are discussed.

No indications of increased quiet sleep in infants receiving care based on the newborn individualized developmental care and assessment program (NIDCAP)

It has been proposed that the developmentally supportive care of very-low-birthweight (VLBW) infants provided by the Newborn Individualized Developmental Care and Assessment Program (NIDCAP) can improve the infants' opportunities for rest and sleep. The aim of the present study was to determine whether quiet sleep (QS) in VLBW infants is affected by NIDCAP care. Twenty-two infants with a gestational age of <32 wk at birth randomly received either NIDCAP (n = 11) or conventional care (n = 11). These two groups were comparable (mean (SD)) with respect to birthweight (1021 (240) vs 913 (362)g, respectively) and gestational age (27.1 (1.7) vs 26.4 (1.8) wk). The infants in the NIDCAP group were cared for in a separate room by a group of specially trained nurses and subjected to weekly NIDCAP observations until they reached a postconceptional age (PCA) of 36 wk. Quiet sleep (QS) was assessed from 24-h amplitude-integrated EEGs recorded at 32 and 36 wk of PCA. The percentage of time [mean (SD)] spent in QS at 32 wk of PCA was 33.5 (2.6) % for the NIDCAP group and 33.3 (6.9) % for the control infants (ns). At 36 wk, the corresponding values were 24.5 (3.2) % and 25.7 (4.7) %, respectively (ns). The number of QS periods/24 h decreased equally in both groups in association with maturation: from 24.6 (3.3) to 16.8 (1.8) and from 25.0 (5.8) to 17.5 (3.3), at 32 wk, and 36 wk of PCA, respectively (NS).

CONCLUSIONS

There were no indications of increased QS at 32 or 36 wk of postconceptional age among VLBW infants who received care based on NIDCAP.

Early prediction of outcome with aEEG in preterm infants with large intraventricular hemorrhages

BACKGROUND

The electrocortical background contains prognostic information in full-term asphyxiated newborn infants already during the first postnatal hours. In preterm infants with intra-ventricular hemorrhages (IVH) the background activity in EEG and amplitude-integrated EEG (aEEG) is depressed during the first days of life, and the extent of the depression correlates with the degree of IVH. However, it has not been previously evaluated whether very early aEEG can predict later outcome also in pre-term infants.

OBJECTIVE

To investigate if early prediction of outcome is possible from aEEG in preterm infants with large IVH.

METHODS

aEEG recordings from the first postnatal week were investigated in 64 preterm infants with IVH grade III - IV. For every 24-hour period the aEEG background pattern was classified, and the maximum and minimum numbers of bursts/h, respectively,were counted. Outcome was divided into three categories: died (n = 36), survived (n = 28) with "poor" outcome, i.e., severe cerebral palsy and not able to walk and/or mental retardation (n = 8), and survived with "fair" outcome, i.e., healthy or mild cerebral palsy (n = 19). One surviving child was lost in the follow-up.

RESULTS

There were significant differences in maximum bursts/h (MaxB) at 0-24 hours (p = 0.033), 24-48 hours (p = 0.011), 48-72 hours (p=0.049) and 72-96 hours (p=0.032), respectively, between the infants who died and the surviving infants. At 24-48 hours the median (range) MaxB in the surviving infants with "fair" outcome was 156 (103-179) versus 102 (73-156) in the surviving infants with "poor" outcome (p = 0.002). With the assumption that MaxB < 130 was predictive of death or survival with "poor" outcome, 68 % and 78% of infants were correctly predicted at 0-24 hours and 24-48 hours, respectively.

CONCLUSIONS

This study shows that outcome may be predicted with aEEG already during the first days of life in preterm infants with large IVH. The findings should be confirmed in prospective studies since they may have clinical implications if specific medical interventions become available.

Reduced postnatal cerebral glucose metabolism measured by PET after asphyxia in near term fetal lambs

The effects of fetal asphyxia on cerebral function and development, involve the transition from fetal to neonatal life. Changes in cerebral glucose metabolism may be an early postnatal indicator of fetal asphyxia. The objective is to develop an experimental lamb model involving the transition from fetal to neonatal life and to examine the effect of fetal asphyxia with cerebral hypoxic ischemia on early postnatal cerebral glucose metabolism. Fetal asphyxia was induced by total umbilical cord occlusion in eight near-term fetal lambs (134-138 days) with the ewe under isoflurane-opiate anesthesia. The mean occlusion time until cardiac arrest was 14.5 (4.2) min (SD). Lambs were immediately delivered and standardized resuscitation was instituted after 2 min asystole. At 4 hr postnatal age, [18-F]Fluoro-2-deoxy-glucose (18-FDG) was injected intravenously in eight asphyxiated lambs and in eight controls. Cerebral glucose metabolism was examined by positron emission tomography (PET). As a result the mean arterial blood pressure, acid-base values, blood glucose and serum lactate at 4 hr postnatal age did not differ significantly between lambs subjected to umbilical cord occlusion and controls. EEG was abnormal in all lambs subjected to cord occlusion and normal in the controls at 4 hr postnatal age. Global cerebral metabolic rate (CMRgl) as determined by PET was significantly lower in lambs subjected to cord occlusion mean/median (SD) 22.2/19.6 (8.4) micromol/min/100 g) than in controls mean/median (SD) 37.8/35.9 (6.1); P < 0.01). Global CMRgl is significantly reduced in newborn lambs 4 hr after fetal asphyxia induced by umbilical cord occlusion. A reduction in CMRgl is an early indicator of global hypoxic cerebral ischemia.

Long-distance transports of newborn infants with congenital heart disease

Little has been published about specific problems that may occur during long-distance transports of newborn cardiac patients. During a 4-year period after centralization of pediatric heart surgery in Sweden, 286 transports were prospectively investigated. A majority (77.3%) of the transports were carried out by nonspecialized teams. Ten severe adverse events, including the death of 1 infant, occurred during the 286 transports (3.5%). Another infant died later of cerebral complications from hypoxia, rendering a transport-related mortality of 0.7%. Twenty-two infants (7.7%) were severely hypoxic (oxygen saturation < or =65%) at arrival, and 12 of these infants suffered from transposition of the great arteries. During the second 2-year period increased use of intravenous prostaglandin E1 and transportation from tertiary-level units was associated with better transport outcome. During the same time period, overall 30-day postoperative mortality for pediatric cardiac surgery decreased from 4.0% to 1.2% in our hospital. When highly specialized treatment is centralized for quality reasons it is also important that risks associated with transport are considered and that the quality of transport is high. For some cardiac malformations antenatal diagnosis and referral of the mother for delivery to a center with pediatric cardiac surgery would probably further increase the chance of healthy survival in some infants.

Short-term effects of incubator covers on quiet sleep in stable premature infants

Incubator covers are increasingly being used in neonatal care as part of minimal disturbance strategies. The aim of this study was to examine possible effects of incubator covers on sleep patterns in stable premature infants. Quiet sleep (QS) can be investigated by amplitude-integrated electroencephalography (aEEG) at 32-34 wk gestational age. In nine premature infants (gestational ages 26-32 wk, median 29) QS periods were measured at a postconceptional age of 32-34 wk (median 34) during two consecutive 24 h periods, one period with a padded dark cover over the incubator and one period without the cover, in a randomized order. There were no significant differences between the two 24 h periods (with incubator cover and without cover, respectively) regarding the duration of the QS periods, the percentage of QS of the total recording time (%QS) or the duration of QS intervals. However, there was a positive correlation between postnatal age in days and the mean duration of QS periods when incubator covers were used (r = 0.90, p = 0.001). When the covers were used there was a difference between the girls and the boys in the duration of QS intervals (p = 0.032); the QS intervals increased in the five girls from median (range) 63.2 (49.4-94.6) min to 77.2 (59.3-100.9) min (p = 0.043). There was no difference in the duration of QS periods between girls and boys.

CONCLUSION

Incubator covers seem to have some short-term effects on sleep quality in premature infants but the clinical significance and possible long-term effects are not known.

Amplitude integrated EEG 3 and 6 hours after birth in full term neonates with hypoxic-ischaemic encephalopathy

AIM

To assess the prognostic value of amplitude integrated EEG (aEEG) 3 and 6 hours after birth.

METHODS

Seventy three term, asphyxiated infants were studied (from two different centres), using the Cerebral Function Monitor (CFM Lectromed). The different aEEG tracings were compared using pattern recognition (flat tracing mainly isoelectric (FT); continuous extremely low voltage (CLV); burst-suppression (BS); discontinuous normal voltage (DNV); continuous normal voltage (CNV)) with subsequent outcome.

RESULTS

Sixty eight infants were followed up for more than 12 months (range 12 months to 6 years). Twenty one out of 68 infants (31%) showed a change in pattern from 3 to 6 hours, but this was only significant in five cases (24%). In three this changed from BS to CNV with a normal outcome. One infant showed a change in pattern from CNV to FT and had a major handicap at follow up. Another infant showed a change in pattern from DNV to BS, and developed a major handicap at follow up. The other 16 infants did not have any significant changes in pattern: 11 infants had CLV, BS, or FT at 3 and 6 hours and died (n = 9) in the neonatal period or developed a major handicap (n = 2). Five infants had a CNV or DNV pattern at 3 and 6 hours, with a normal outcome. The sensitivity and specificity of BS, together with FT and CLV, for poor outcome at 3 hours was 0.85 and 0.77, respectively; at 6 hours 0.91 and 0.86, respectively. The positive predictive value (PPV) was 78% and the negative predictive value (NPV) 84% 3 hours after birth. At 6 hours the PPV was 86% and the NPV was 91%.

CONCLUSION

aEEG could be very useful for selecting those infants who might benefit from intervention after birth asphyxia.

Cerebral excitatory amino acids and Na+,K+-ATPase activity during resuscitation of severely hypoxic newborn piglets

We tested the hypothesis that early brain recovery in hypoxic newborn piglets is improved by resuscitating with an O2 supply close to the minimum level required by the newborn piglet brain. Severely hypoxic 2-5-d-old anaesthetized piglets were randomly divided into three resuscitation groups: hypoxaemic (n = 8), 21% O2 (n = 8), and 100% O2 groups (n = 8). The hypoxaemic group was mechanically ventilated with 12-18% O2 adjusted to achieve a cerebral venous O2 saturation of 17-23% (baseline; 45 +/- 1%, mean +/- SEM). During the 2h resuscitation period, extracellular aspartate and glutamate concentrations in the cerebral striatum were higher during hypoxaemic resuscitation (p = 0.044 and p = 0.055, respectively) than during resuscitation with 21% O2 or 100% O2, suggesting an unfavourable accumulation of potent excitotoxins during hypoxaemic resuscitation. The cell membrane Na+,K+-ATPase activity of cerebral cortical tissue after 2 h resuscitation was similar in the three groups (p = 0.30). In conclusion, hypoxaemic resuscitation did not normalize early cerebral metabolic recovery as efficiently as resuscitation with 21% O2 or 100% O2. Resuscitation with 21% O2 was as efficient as resuscitation with 100% O2 in this newborn piglet hypoxia model.

Early cerebral metabolic and electrophysiological recovery during controlled hypoxemic resuscitation in piglets

We tested the hypothesis that controlled hypoxemic resuscitation improves early cerebral metabolic and electrophysiological recovery in hypoxic newborn piglets. Severely hypoxic anesthetized piglets were randomly divided into three resuscitation groups: hypoxemic, 21% O2, and 100% O2 groups (8 in each group). The hypoxemic group was mechanically ventilated with 12-18% O2 adjusted to achieve a cerebral venous O2 saturation of 17-23% (baseline; 45 +/- 1%). Base excess (BE) reached -22 +/- 1 mM at the end of hypoxia. During a 2-h resuscitation period, no significant differences in time to recovery of electroencephalography (EEG), quality of EEG at recovery, or extracellular hypoxanthine concentrations in the cerebral cortex and striatum were found among the groups. BE and plasma hypoxanthine, however, normalized significantly more slowly during controlled hypoxemic resuscitation than during resuscitation with 21 or 100% O2. We conclude that early brain recovery during controlled hypoxemic resuscitation was as efficient as, but not superior to, recovery during resuscitation with 21 or 100% O2. The systemic metabolic recovery from hypoxia, however, was delayed during controlled hypoxemic resuscitation.

Low risk of seizure recurrence after early withdrawal of antiepileptic treatment in the neonatal period

The risk of seizure recurrence within the first year of life was evaluated in infants with neonatal seizures diagnosed with a combination of clinical signs, amplitude-integrated electroencephalogram (EEG) monitoring, and standard EEG. Fifty eight of 283 (4.5%) neonates in tertiary level neonatal intensive care had seizures. The mortality in the infants with neonatal seizures was 36.2%. In 31 surviving infants antiepileptic treatment was discontinued after one to 65 days (median 4.5 days). Three infants received no antiepileptic treatment, two continued with prophylactic antiepileptic treatment. Seizure recurrence was present in only three cases (8.3%)--one infant receiving prophylaxis, one treated for 65 days, and in one infant treated for six days. Owing to the small number of infants with seizure recurrence, no clinical features could be specifically related to an increased risk of subsequent seizures. When administering antiepileptic treatment, one aim was to abolish both clinical and electrographical seizures. Another goal was to minimise the duration of treatment and to keep the treatment as short as possible. It is suggested that treating neonatal seizures in this way may not only reduce the risk of subsequent seizure recurrence, but may also minimise unnecessary non-specific prophylactic treatment for epilepsy.

OSCILLO-oscillating air mattress in neonatal care of very preterm babies

In this pilot study a new device for respiratory stimulation with undulating oscillations and high frequency vibrations via an air mattress was tested as an additional therapy in 12 preterm infants with recurrent apnoeic episodes. The mean birthweight of the study population was 1760 g and gestational age 31.1 weeks. it was shown that an oscillating air mattress is an effective additional mode of treatment for apnoeic episodes in preterm infants. There was a clear reduction in rate of apnoeas in all 12 infants being transitory in 2 and more persistent in 10 infants. Besides restlessness in a few cases no side effects were observed. Whether this mode of treatment could lessen the need for drug medication with xanthines will require a larger randomized investigation.

Predictive value of early continuous amplitude integrated EEG recordings on outcome after severe birth asphyxia in full term infants

The background pattern in single channel amplitude integrated EEG recordings (aEEG) was recorded in 47 infants within the first six hours after birth to see if this could predict outcome after birth asphyxia. The aEEG background pattern during the first six hours of life was continuous and of normal voltage in 26 infants. All these infants survived; 25 were healthy, one had delayed psychomotor development. A continuous but extremely low voltage pattern was present in two infants, both of whom survived with severe handicap. Five infants had flat (mainly isoelectric) tracings during the first six hours of life; four died in the neonatal period, and one survived with severe neurological handicap. Burst-suppression pattern was identified in 14 infants, of whom five died, six survived with severe handicap, and three were healthy at follow up. The type of background pattern recorded within the first six postnatal hours in the aEEG tracings predicted outcome correctly in 43 of 47 (91.5%) infants. Use of aEEG monitoring can predict outcome, with a high degree of accuracy, after birth asphyxia, within the first six hours after birth. The predictive value of a suppression-burst pattern was, however, somewhat lower than the other background patterns. The aEEG seems to be a feasible technique for identifying infants at high risk of subsequent brain damage who might benefit from interventionist treatment after asphyxia.

Comparison between tape-recorded and amplitude-integrated EEG monitoring in sick newborn infants

In 15 ill newborn infants a comparison between long-term multichannel and single-channel recordings of simultaneously tape-recorded (Medilog system) and amplitude-integrated EEG (Cerebral Function Monitor) was made. There was good agreement between the main type of background activity diagnosed with the tape-recorded and the amplitude-integrated EEG for all recordings. Two infants had repetitive subclinical and subtle seizure activity, lasting for several hours, which was detected by both techniques. Short, single seizures were diagnosed in the recordings of nine infants. When a single electrographic seizure appeared in an otherwise stable recording, it was identified by both the tape-recorded and the amplitude-integrated EEG. Very short (5-30 s) seizure patterns, which were diagnosed with the tape-recorded EEG, were not identified in the cerebral function monitor recordings. In the single-channel recordings of both the EEG and the cerebral function monitor there were, on some occasions, difficulties in distinguishing single seizures from interference due to external artefacts. In the multichannel recordings the diagnosis of seizure patterns was facilitated by comparison with the other channels. Both the Medilog EEG and the cerebral function monitor are feasible techniques for following cerebral electrical activity in sick neonates, although neither technique is specifically constructed for this purpose. For clinical use in the neonatal intensive care unit the advantage with the cerebral function monitor is the immediately available recording. The tape-recorded EEG offers possibilities of more channels and a higher reliability when diagnosing short subclinical seizures, however, only after offline analysis.

Acute changes in cerebral oxygenation and cerebral blood volume in preterm infants during surfactant treatment

Following administration of surfactant a marked depression in aEEG activity occurs for about 10 minutes; the mechanism of this depression is unknown. In view of this, twenty-nine preterm infants were investigated with near infrared spectroscopy (NIRS) to evaluate rapid changes in total cerebral haemoglobin concentration and cerebral oxyhaemoglobin concentration during rescue treatment with natural surfactant. During surfactant instillation there was a short-lasting hypoxaemia as demonstrated by pulseoximetry as well as a considerable fall in arterial blood pressure. With NIRS, tissue hypoxia was demonstrated by a drop in cerebral oxyhaemoglobin concentration. The marked drop in arterial blood pressure occurring immediately following surfactant was not matched by a drop in total cerebral haemoglobin concentration. This suggests that cerebral blood volume and hence cerebral blood flow was maintained. In the following minutes there was an improvement in cerebral oxygenation as indicated by the rise in cerebral oxyhaemoglobin concentration in nearly all the infants.

Cerebroelectrical depression following surfactant treatment in preterm neonates

During surfactant treatment of respiratory distress syndrome, 23 premature newborns were investigated with continuous amplitude-integrated electroencephalography (cerebral function monitors). Simultaneously, arterial blood pressure and transcutaneous blood gas values were recorded. A short (less than 10 minutes) but significant decrease in cerebral activity was seen in almost all neonates immediately after the surfactant instillation, in spite of an improved pulmonary function. In 21 of 23 neonates, a transient fall in mean arterial blood pressure of 9.3 mm Hg (mean) occurred coincidently with the cerebral reaction. Neonates in whom intraventricular hemorrhage developed tended to have lower presurfactant mean arterial blood pressure (P greater than .05), but they had a significantly lower mean arterial blood pressure after surfactant instillation (P less than .05). No other differences were found between neonates in whom intraventricular hemorrhage developed and those without intraventricular hemorrhage. The present findings demonstrate that an acute cerebral dysfunction may occur after surfactant instillation. In some vulnerable neonates with arterial hypotension and severe pulmonary immaturity, the fall in mean arterial blood pressure may increase the risk of cerebral complications and could be related to an unchanged rate of intraventricular hemorrhage after surfactant treatment.

Lidocaine for treatment of severe seizures in newborn infants. II. Blood concentrations of lidocaine and metabolites during intravenous infusion

The blood concentrations of lidocaine and its main active metabolites, methylethylglycinexylidide (MEGX) and glycinexylidide (GX), were measured in 24 newborn infants during anticonvulsive treatment with an iv infusion of lidocaine. After a bolus dose of 1.5-2.2 mg/kg and continuous infusion of lidocaine (4.7-6.3 mg/kg/h) there was accumulation of the drug and MEGX within 24 h. After termination of the iv infusion, both lidocaine and the metabolites were eliminated within 24-48 h. The anticonvulsive effectiveness--estimated by clinical observation and continuous amplitude integrated EEG monitoring (cerebral function monitor)--was immediate in 15 infants (nine term and six preterm). There was no correlation between blood concentrations of lidocaine and metabolites, and anticonvulsive effect (i.e. good, intermediate or no response). No differences in blood concentrations were found between full-term and preterm babies, or between infants with or without birth asphyxia. In combination with a fast withdrawal of the drug, few adverse reactions were seen with the dosages used, even though blood concentrations were high. Routine measurements of lidocaine concentrations during anticonvulsive treatment in neonates seem to be of little clinical value. For evaluation of the anticonvulsive effect and for early detection of seizure activity during lidocaine withdrawal, continuous EEG monitoring is preferable.

Cerebral function monitoring during the first week of life in extremely small low birthweight (ESLBW) infants

In order to evaluate the usefulness of early continuous EEG-monitoring in very preterm neonates, recordings with a Cerebral Function Monitor (CFM) were made prospectively in 31 ESLBW infants with birthweights below 901 grams, during their first week of life. The CFM background activity was, as expected from EEG studies, dominated by a suppression-burst pattern in 94% of the infants. Some infants had periods with more continuous EEG activity or suppression-burst changing into continuous. Patterns similar to sleep-wake cycling (SWC) were identified in infants with gestational ages as low as 24 weeks. The level of the CFM-background activity was mainly influenced by the presence and severity of intracranial hemorrhage (ICH), but also by medications such as phenobarbital. Epileptiform activity (EPA) was only found in infants with ICH, and was identified in 75% of these infants. Of the infants with EPA, 87% had periods with subclinical EPA, although 47% had both clinical and subclinical seizures. The presence of more continuous activity and SWC were indicators of a favourable outcome, whereas electrocerebral inactivity predicted an unfavorable outcome. The prognostic estimates of mortality and neurologic outcome were similar for early CFM recording (positive predictive value 69-100%) and cranial ultrasound scan (positive predictive value 71-100%). The monitoring of cerebral electrical activity also provided immediate and clinically useful information during the intensive care of these ESLBW infants. Further studies on the causal relation between EPA and the development of ICH should be performed before definite conclusions can be drawn concerning any preventive effect from anticonvulsive treatment of clinical/subclinical seizures.

Cerebral complications detected by EEG-monitoring during neonatal intensive care

The report describes the clinical use and value of continuous EEG-monitoring during different clinical circumstances that are not usually related to changes in EEG. Three infants with pneumothorax, hypoglycaemia, and severe hyaline membrane, respectively, are presented.

Neonatal outcome of extremely small low birthweight liveborn infants below 901 g in a Swedish population

In a regional population of 32,120 liveborn newborn infants 65 (0.2%) had a birthweight less than or equal to 900 g (extremely small low birthweight = ESLBW) with mean gestational age 26.4 (range 22-31) completed weeks of gestation. The total 0-1 year survival rate was 48%. For the 42 infants treated in the Level III regional neonatal intensive care unit (NICU) the 0-1 year survival rate was 55% versus 34% for 23 infants not transferred to the Level III unit. In the ESLBW infants treated in the regional NICU the major complications were respiratory disorders requiring artificial ventilation (73%), bronchopulmonary dysplasia (26%), intracranial haemorrhages (40%), symptomatic persistent ductus arteriosus (36%) and sepsis (14%), persistent retinopathy of prematurity (8%). Duration of NICU treatment was 51 days (range 10-95) for survivors. Mode of delivery and rate of perinatal complications did not differ between survivors and non-survivors. Previous legal abortion occurred in 24%, fertility problems in 29% and 21% of the mothers were immigrants. Otherwise no significant abnormalities were found in maternal or socioeconomic conditions. Factors deciding neonatal outcome in the tiniest babies seem to be a combination of prenatal circumstances and neonatal minute fine care procedures.

Lidocaine for treatment of severe seizures in newborn infants. I. Clinical effects and cerebral electrical activity monitoring

The anticonvulsive effect of lidocaine was evaluated in 46 newborn infants with severe, recurrent seizures. Before the lidocaine all infants were being given phenobarbital, and 22 infants were also treated with diazepam. Different dosages of lidocaine were tested. A loading dose of 2 mg/kg followed by i.v. infusion of 6 mg/kg/hour was the most effective dosage and had an immediate anticonvulsive effect in 18 of 25 infants; within 30 min the same effect was attained in another five of the infants, with an overall seizure control in 92% of the sample population. During the lidocaine treatment cerebral electrical activity was followed continuously with a cerebral function monitor (CFM), which also enabled evaluation of the treatment. No serious side effects on blood-pressure, heart-rate or cerebral electrical activity were registered. For newborn infants with severe recurrent seizures not responding to other drugs, lidocaine is an effective additional mode of treatment.

EEG depression and germinal layer haemorrhage in the newborn

Amplitude integrated EEG (aEEG) recordings from 32 mechanically ventilated infants, gestational age 32 weeks or less, were analysed. All recordings were started within 24 h of birth and continued for at least 50 h. Germinal layer haemorrhage (GLH) was diagnosed by repeated ultrasonography. In six infants neither GLH nor hypocalcaemia were diagnosed; aEEG in these infants rapidly became more active after birth: at 30 h of age continuous background activity was present for more than 20% of the time, and a seizure-like pattern was exceptional. In seven infants without GLH but with hypocalcaemia and other signs of metabolic derangement, continuous background activity appeared later and seizure-like activity was frequent. In the infants with GLH, depression of the background activity was apparent. This finding was particularly distinct in the presence of severe haemorrhages. Four infants developed GLH after 30 h of age. All these infants had depressed aEEG before the development of GLH, with less than 20% continuous activity at 30 h of age. In ten infants an analysis of the aEEG during the occurrence of GLH was possible. In six of these, cortical electrical activity decreased. Due to the limitation of GLH timing, it was not possible to decide whether this decrease closely preceded or followed GLH. We suggest that GLH primarily occurs in brains with a preceding metabolic and neurophysiologic abnormality, and that further functional deterioration is caused by the most severe haemorrhages.

Silent seizures in sick infants in early life. Diagnosis by continuous cerebral function monitoring

Cerebral electric activity was surveilled with a Cerebral Function Monitor (CFM) technique in 87 newborn infants under neonatal intensive care. A total of 26 infants had electrographical signs of repeated seizure activity. Among these infants 14 had periods of one hour or more of silent seizures activity. Among these infants 14 had periods of one hour or more of silent seizures, i.e. typical pattern of ictal epileptic activity on CFM without clinical symptoms or signs of convulsions. The occurrence of silent seizures and their pattern in relation to the clinical condition and management was unpredictable in most cases. Besides general limpness or flaccidity in an outward quiet baby these infants showed no clinical fits or clonic convulsions. The findings indicate that anticonvulsive therapy in small infants may be insufficient and need re-evaluation, since the long-term effect of silent seizures on cerebral function and activity is still uncertain.

Monitoring of cerebral function after severe asphyxia in infancy

Thirty nine infants with severe asphyxia (28 affected perinatally and 11 later) were studied by electrophysiological cerebral function monitoring (CFM) for periods varying from a half to 49 days. Nineteen infants died while still in intensive care and two died later from sequelae. Eighteen survived and were followed up when aged between 8 and 36 months. The initial electroencephalogram (EEG) and the first 12 hours of CFM tracing correlated well. The type of background activity, whether continuous or interrupted, proved to be of high prognostic importance unlike the presence of seizure activity, which bore no distinct correlation to outcome in these severely asphyxiated infants.