Biomedical subjects

G Greisen

Publications and source records attributed to G Greisen.

At least 19 recordsLinked to original sources

PubMed1992

[Surfactant treatment of newborn infants with respiratory distress syndrome primarily treated with nasal continuous positive air pressure. A pilot study].

In this pilot study, Curosurf (200 mg/kg) was administrated to 34 patients with the respiratory distress syndrome in nasal-CPAP therapy with FiO2 requirements greater than 0.60 and/or TcPCO2 greater than 8 kPa. The surfactant was instilled during a short period of intubation or in a few cases via an intratracheal catheter (Ch. 6). The age of the patients on surfactant treatment ranged from two to 72 hours. Eighteen patients could be maintained on nasal-CPAP after treatment with Curosurf and only a few complications were seen in these infants. The other 16 patients subsequently required artificial ventilation and had a higher incidence of pulmonary and extrapulmonary complications. On the basis of these observations, we plan a randomized trial to investigate whether, administration of surfactant reduces the need for ventilator treatment and improves the odds for uneventful recovery in this category of patients.

Biological Products↗

PubMed1992

Judging fetal growth from body proportions at birth.

Fetal growth velocity from 27 weeks until birth was calculated in 378 infants born after high risk pregnancies from at least three ultrasound measurements of estimated fetal weight and the weight at birth. Anthropometric measurements at birth (weight, head circumference, length, ponderal index and skinfolds), after correction for differences in gestational age, were significantly related to fetal growth velocity. The relation between fetal growth velocity and ponderal index was significant (correlation coefficient = 0.34, P < 0.001). However, the correlations between fetal growth velocity and each of the anthropometric measures disappeared when birth weight relative to gestational age was accounted for. This means that given the birth weight and the gestational age of a newborn infant, body proportions, e.g. ponderal index or skinfold thickness, do not contribute further to the judgment about fetal growth rate.

Anthropometry↗

PubMed1992

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.

Birth Weight↗

PubMed1992

Detection of small-for-gestational-age fetuses by ultrasound screening in a high risk population: a randomized controlled study.

OBJECTIVE: To assess the value of fetal weight estimation during routine third trimester ultrasound examinations for the identification of small-for-gestational-age (SGA) fetuses, to promote active pregnancy management and so reduce perinatal morbidity. DESIGN: A prospective controlled randomized study. SETTING: Outpatient clinic at the Department of Obstetrics, Herlev University Hospital, Denmark. SUBJECTS: One thousand pregnant women considered at risk were selected consecutively from April 1985 to September 1987 and randomized to either a revealed-results group or a withheld-results group. INTERVENTION: All the women had an early ultrasound examination for estimation of gestational age. Both groups had routine ultrasound estimates of fetal weight after 28 weeks and then every third week until delivery. The results were available for clinical use only in the revealed group. MAIN OUTCOME MEASURES: Number of interventions during pregnancy (admission to hospital, elective delivery), emergency intervention during labour, and fetal outcome. RESULTS: Revealing the results of ultrasound estimates of fetal weight for gestational age during the third trimester resulted in statistically significantly increased diagnosis of SGA fetuses, of elective deliveries based on this diagnosis, and of healthy preterm babies admitted to the neonatal care unit, but no detectable overall improvement in weight for gestational age at birth, or in neonatal morbidity or mortality. CONCLUSION: This method of screening improved the diagnosis of SGA fetuses, but this was not followed by improved fetal outcome.

Birth Weight↗

PubMed1992

Changes in cerebral oxygenation and cerebral blood volume during endotracheal suctioning in ventilated neonates.

The effect of endotracheal suctioning on cerebral haemodynamics was investigated in 29 newborn infants with a mean gestational age of 31 weeks (range 25-40 weeks). Prior to one of two suctioning procedures, the inspiratory fraction of oxygen was increased by 10%. Brain oxygenation and total haemoglobin concentration were estimated continuously by near infrared spectroscopy. Mean arterial blood pressure, arterial blood oxygen saturation and carbon dioxide tension were recorded simultaneously. Brain oxygenation decreased in parallel with arterial oxygen saturation during suctioning. Preoxygenation ameliorated the decrease in brain oxygenation and arterial oxygen saturation whereas there was no benefit with regard to the changes in total haemoglobin concentration, carbon dioxide tension or mean arterial pressure. Changes in total haemoglobin concentration were related closely to concomitant changes in carbon dioxide tension (p less than 0.0001) but unrelated to changes in mean arterial pressure or arterial oxygen saturation. Our findings suggest that cerebral blood volume may react to changes in carbon dioxide tension during endotracheal suctioning in mechanically ventilated neonates. Apparently, preoxygenation prior to suctioning does not ameliorate the stress in normoxic infants.

Blood Pressure↗

PubMed1992

Effect of cerebral blood flow and cerebrovascular autoregulation on the distribution, type and extent of cerebral injury.

Global cerebral blood flow (GCBF) is low in the human neonate compared to the adult. It is even lower in mechanically ventilated, preterm infants: 10-12 ml/100 g/minute, a level associated with brain infarction in adults. The reactivity, however, of global CBF to changes in cerebral metabolism, PaCO2, and arterial blood pressure is normal, except following severe birth asphyxia, or in mechanically ventilated preterm infants, who subsequently develop major germinal layer hemorrhage. The low level of cerebral blood flow (CBF) matches a low cerebral metabolism of glucose and a relatively small number of cortical synapses in the perinatal period. It has not been possible to define a threshold for GCBF below which electrical dysfunction or brain damage occurs (such as white matter and thalamic-basal ganglia necrosis). Three explanations for the lack of clear relation between GCBF and electrical brain activity of the preterm infant must be examined more closely: 1) low levels of CBF are adequate; 2) GCBF does not adequately reflect critically low perfusion of the white matter, and 3) acute white matter ischemia does not result in electrical silence. Two clinical patterns of brain damage following asphyxia may be explained by changes in the blood flow distribution induced by asphyxia: brainstem sparing and parasagittal cerebral injury. Hours to days after severe asphyxia, a state of marked global hyperperfusion may prevail. It is associated with poor neurological outcome and may be an entry point for trials of interventions aiming sat blocking the translation of asphyctic injury to cellular death and tissue damage.

Brain Ischemia↗

PubMed1992

Estimation of fetal weight by ultrasound.

Estimation of fetal size by ultrasound has supported two recent concepts of fetal growth. Firstly, the normal weight gain is constant from 28 weeks of gestation until several weeks after term; about 27 g/day. Secondly, the average weight of fetuses born preterm is lower than the average weight of fetuses of the same gestational age who remain in utero. This means that up to 40% of infants born at 28-30 weeks of gestation are small-for-gestational age, when related to the biological optimum. Unfortunately, the test-retest variation of fetal weight estimation is as much as 50% of the standard deviation of the gestational-age-specific fetal weight distribution. This means that fetal growth has to be followed for many weeks to document statistically significant deviations. No study has, as yet, demonstrated the value of this approach to distinguish between intrauterine growth retardation and growth along low centiles by fetuses of reduced growth potential.

Birth Weight↗

PubMed1992

Surfactant administration and the cerebral circulation.

We have used two main techniques to investigate the effect of surfactant therapy on the cerebral circulation in 34 babies. Twenty-one babies were studied using near infrared spectroscopy and 13 had cerebral blood flow measured using a xenon clearance technique. Other measures recorded included amplitude integrated EEG, mean arterial blood pressure and central venous or oesophageal pressure. There was a marked depression in EEG activity lasting for 10-20 min after surfactant administration. Cerebral blood volume and cerebral blood flow were maintained in most infants in spite of a fall in mean arterial blood pressure. We conclude that factors other than cerebral ischaemia cause the transient disturbance in electrophysiologic activity.

Biological Products↗

PubMed1992

Ischaemia of the preterm brain.

Much has been learned about the diagnosis and prognosis of periventricalar leucomalacia during the past 10 years. The understanding of its causation, however, has not advanced much. Still, the candidate for the principal role is focal ischaemia in the particularly vulnerable regions of the brain. It has been difficult to provide direct supportive evidence for this hypothesis. It has not been possible to define a threshold for (global) cerebral blood flow (CBF) under which brain damage or electrical dysfunction occurs. Three hypothetical explanations for the lack of clear relation between global CBF and electrical brain activity of the preterm infant must be examined more closely: (1) the very low levels of CBF are adequate, (2) global CBF does not reflect the perfusion of the white matter, or (3) acute white-matter ischaemia does not result in cerebro-electrical dysfunction. In view of the practical importance, more research is indicated.

Brain↗

PubMed1992

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.

Biological Products↗

PubMed1991

[The relationship between low pH in the umbilical cord artery in neonates and later development of cerebral paresis].

Routine determination of the pH in umbilical arterial blood immediately after delivery is a commonly employed variable for assessing the risk of subsequent cerebral paresis caused by hypoxia. Opinions differ regarding the lower limit for normal NS-pH (acidosis limit) and this is due mainly to variable conceptions of what a normal delivery is. Lower limits from 7.04 to 7.14 are thus observed if the limit -2 SD is chosen. Even if the limit of 7.04 is chosen, only very few of the infants who are acidotic on delivery subsequently develop cerebral paresis. The most important reason for this is that the prevalence of cerebral paresis developed as a result of hypoxia during delivery is very low and that a low NS-pH value most probably originates from a neonate who recovers without cerebral paresis. Another reason is that the relationship between the pH value and the degree of hypoxia is far from perfect and this holds also true for the relationship between the degree of hypoxia and cerebral paresis. It is therefore concluded that in connection with cerebral paresis, NS-pH does not fulfill the requirements of a diagnostic test. Determination of NS-pH may, on the other hand, be of significance for neonatal treatment as the combination of a low Apgar score and NS-pH is a reasonable predictor for the neonatal morbidity.

Cerebral Palsy↗

PubMed1991

The relation between perinatal conditions and developmental outcome in low birthweight infants. Comparison of two cohorts.

We have compared the relations between perinatal conditions and developmental outcomes at age four years for two cohorts of children with birthweights 2,300 g or less, who did not develop cerebral palsy--one from Southeastern Wisconsin (children born 1975-76) and the other from Copenhagen (children born 1980-82). We examined the general effects of parental education and socioeconomic status, the use of Cesarean section, the degree of prematurity and neonatal complications on outcome. The methods of latent path structural analysis were used to form two models among 15 latent variables: one for children from Copenhagen and a similar model for children from Wisconsin. The impact of parental education and socioeconomic status was somewhat greater in Wisconsin. Several neonatal complications were related to outcome in Wisconsin: the early condition of the infant, use of a respirator, pneumothorax, and anemia/apnea. The only neonatal complication with a significant relation to outcome in Copenhagen was pneumothorax and to a much lesser degree major germinal layer haemorrhage. The degree of prematurity per se had a greater impact in Copenhagen. The use of Cesarean section and mechanical ventilation in the smallest infants was much more frequent in Denmark, but no association could be shown between this increased use and improved developmental outcome.

Child Development↗

PubMed1991

Estimating cerebral blood flow in newborn infants: comparison of near infrared spectroscopy and 133Xe clearance.

A new method of measuring cerebral blood flow (CBF) in newborn infants by means of near infrared spectroscopy (CBFnirs) was compared with the i.v. 133Xe clearance technique (CBFxe). Forty CBFnirs measurements were obtained during 19 133Xe measurements in 16 infants; 79 other CBFnirs data sets were discarded because the assumptions for their use were not fulfilled. The test-retest variation of repeated near infrared-measurements during each 133Xe clearance was 17.5%. CBFnirs was closely related to CBFxe (r2 = 0.84, p less than 0.0001), with a slope of 0.75 (SEM = 0.064) and a intercept of 1.58 mL/100 g/min (SEM = 0.51). The difference between the measurements obtained by the two methods (CBFnirs-CBFxe) was negative in the high range of CBF, whereas the difference was close to zero in the low range. We conclude that CBF measured with near infrared spectroscopy was in good agreement with the CBF measured with the 133Xe method. The near infrared spectroscopy method has the advantage of being noninvasive, and it does not involve ionizing radiation. Because of methodologic constraints, however, it may underestimate CBF in the high range of flow, and it may have limitations of application in clinical research.

Blood Flow Velocity↗

PubMed1990

Normal fetal growth evaluated by longitudinal ultrasound examinations.

Fetal weight estimation was evaluated using the equations of Warsof, Shepard and Hadlock in 192 patients, less than 3 days before delivery. Warsof's and Hadlock's equations resulted in significantly better weight estimates compared to Shepard's equation. No systematic error was found below 2500 g by use of Warsof's equation, whereas Shepard's and Hadlocks's equations resulted in significant over-estimation in the low weight group. In a study of 5 fetuses, of 27-38 weeks gestational age, the intra-observer variation was calculated to 4.6%, whereas the coefficient of variation among observer means was 2.9%. The mixed intra- and inter-observer coefficient of variation was 6.5%. Thirty-five low-risk, uncomplicated pregnancies with reliable last menstrual dates were investigated longitudinally with ultrasound measurements of fetal weight. Population growth curves of fetal weight, fetal femur length, abdominal circumference and biparietal diameter were constructed by weighted polynomial regression. After 27 weeks of gestational age the weight growth curve showed only insignificant non-linearity. Compared to a Danish growth curve based on birth weights, significant higher mean weight was found, especially before 31 weeks of gestational age. The 10th and 90th percentiles for the individual percentage deviation change was +/- 4.4% per 28 days.

Body Weight↗

PubMed1990

Vasoparalysis associated with brain damage in asphyxiated term infants.

The relationship of cerebral blood flow to acute changes in arterial carbon dioxide and mean arterial blood pressure (MABP) was determined during the first day of life in 19 severely asphyxiated term infants supported by mechanical ventilation. For comparison, 12 infants without perinatal asphyxia were also investigated. Global cerebral blood flow (CBF infinity) was determined by xenon 133 clearance two or three times within approximately 2 hours. During the cerebral blood flow measurement, the amplitude-integrated electroencephalogram and visual-evoked potential were recorded. Changes in arterial carbon dioxide pressure followed adjustments of the ventilator settings, whereas MABP fluctuated spontaneously. Arterial oxygen pressure and blood glucose concentration were in the normal range. Five of the asphyxiated infants had isoelectric electroencephalograms and died subsequently with severe brain damage. They had a high CBF infinity (mean 30.6 ml/100 gm/min) and abolished carbon dioxide and MABP reactivity. Lower CBF infinity (mean 14.7 ml/100 gm/min) and abolished MABP reactivity were found in another five asphyxiated infants with burst-suppression electroencephalograms in whom computed tomographic or clinical signs of brain lesions developed. The carbon dioxide reactivity was preserved in these infants. In the remaining nine asphyxiated infants without signs of central nervous system abnormality, carbon dioxide and MABP reactivity were preserved, as was also the case in the control group. We conclude that abolished autoregulation is associated with cerebral damage in asphyxiated infants and that the combination of isoelectric electroencephalograms and cerebral hyperperfusion is an early indicator of very severe brain damage.

Asphyxia Neonatorum↗

PubMed1990

Redistribution of cerebral activity during childhood.

Data on the functional development of brain structures in early childhood are scarce. Cognition changes markedly from pre-school age to school age, and we thought it of interest to examine the level of functional activity of selected brain regions. Nine preschool children were studied and compared with eight school children and eighteen adults. Xe133 emission tomography was used for determination of regional cerebral blood flow (rCBF). It was demonstrated that activity in the striatal regions is low in early childhood. In school age the proportion of flow to these regions is increased by about 11-14 per cent (difference between medians). Perfusion of the occipital lobes decreased with age when studied with open eyes and closed eyes, possibly reflecting loss of synapses and decreased plasticity.

Adolescent↗

PubMed1990

Carbon dioxide-related changes in cerebral blood volume and cerebral blood flow in mechanically ventilated preterm neonates: comparison of near infrared spectrophotometry and 133Xenon clearance.

Carbon dioxide-induced changes in near infrared spectrophotometry recordings were compared with changes in cerebral blood flow estimated by 133Xenon clearance (global cerebral blood flow (infinity)) at serial measurements in 24 mechanically ventilated preterm infants (mean gestational age 30.2 wk). In all infants, three measurements were taken at different arterial carbon dioxide tension levels (mean 4.4 kPa, range 2.1-7.8) obtained by adjustment of the ventilator settings. Mean arterial blood pressure changed spontaneously, whereas arterial oxygen tension was kept within normal range. At all wavelengths (904, 845, 805, and 775 nm), the OD increased at higher arterial carbon dioxide tension levels, indicating cerebral vasodilation. This conclusion was supported by conversion of the data to changes in oxygenated and deoxygenated Hb concentration. A parallel increase in cerebral blood volume index and global cerebral blood flow (infinity) was found (p less than 0.0001). The oxygenation level of cytochrome aa3 increased with increases in oxygen delivery (p less than 0.0001). This observation, however, may have been artifactual due to cross-talk between the oxidized cytochrome aa3 and the oxygenated Hb signals, as these signals were closely interrelated in the present experimental design. We suggest that near infrared spectrophotometry may be used for estimation of the cerebral blood volume index/cerebral blood flow-CO2 reactivity within a wide range of arterial carbon dioxide tension. Knowledge of the light path length would put this estimation on a quantitative basis.

Birth Weight↗

PubMed1990

Status at four years of age in 280 children weighing 2,300 g or less at birth.

To assess the functional ability in low birth weight children at age 4-5, 114 survivors with very low birth weight (VLBW) less than or equal to 1,500 g, 166 survivors with birth weight 1,501-2,300g (LBW), and 115 comparison children with normal birth weight (NBW) were enrolled in a follow-up study. Twenty-four (21%) VLBW and 11 (6.6%) LBW-children had major clinical abnormalities compared to 1 (0.9%) of the NBW children. Twenty-two percent of the VLBW-children were below the 3rd-centile for height and weight. Fewer VLBW than LBW-children were neurologically and ophthalmologically normal. Even after exclusion of the handicapped children, the LBW as well as the VLBW children scored significantly lower than the NBW children in the McCarthy Scales of Children's Abilities, most markedly in the motor and perceptual performance scales. A simple test using grooved pegs clearly demonstrated the poor visual-motor integration in VLBW and LBW children. A marked difference between the NBW and the two LBW groups was seen in a qualitative evaluation of motor performance. Only 5% of VLBW children scored at or above the median for the NBW in all of three fields: general cognitive, motor performance, and pegboard, as opposed to 11% of LBW and 18% of NBW children. Neither sex, age corrected for prematurity, nor psycho-social background factors explained the differences between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗