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Biomedical subjects

O Pryds

Publications and source records attributed to O Pryds.

50 records · Page 3Linked to original sources
PubMed1988

Poor reversibility of EEG abnormality in hypotensive, preterm neonates.

Twenty-four infants, 32 weeks of gestation or less, were studied with continuous recording of amplitude integrated electroencephalogram (aEEG) and repeated Doppler ultrasound determination of the mean blood flow velocity in the internal carotid artery (cMFV). The recording was started after the initiation of mechanical ventilation for respiratory distress. Of twelve infants receiving blood or albumin transfusion to expand the intravascular volume and in whom adequate data were available, both mean arterial blood pressure and cMFV increased in eight, and cMFV but not blood pressure in further two. In the present circumstances we consider the cMFV increases to represent true increases in cerebral blood flow. aEEG burst rate increased distinctly in five of the twelve infants during or immediately following transfusion, but did only approach the level of the four non-transfused infants after several hours, indicating a dysfunction of neural tissue not readily reversible by improved blood flow.

Blood Flow Velocity↗
PubMed1988

Comparison of electrical impedance and 133xenon clearance for the assessment of cerebral blood flow in the newborn infant.

The peak amplitude of pulsatile cerebral electrical impedance (delta Zp) was compared with simultaneous 133xenon clearance estimations of cerebral blood flow (CBF infinity) on 28 occasions in nine infants receiving assisted ventilation who had changes in PaCO2 and thereby presumably in cerebral blood flow. Percentage changes from one measurement to the next in each infant were compared. Using linear regression the relationship was delta Zp = 0.5 CBF infinity-1.5 with r = 0.67. The 95% confidence interval for the regression coefficient was 0.2-0.8 and the mean residual was 28%. Changes in cerebral blood flow in these clinical conditions were similarly detected by the two methods but delta Zp underestimated the magnitude of the change in comparison with CBF infinity and its accuracy was insufficient to allow conclusions about the magnitude of small changes in cerebral blood flow in individual infants.

Blood Flow Velocity↗
PubMed1988

Age-related reference values for ionized calcium in the first week of life in premature and full-term neonates.

Reference values for ionized calcium were measured in anaerobic samples of capillary blood from 22 healthy premature neonates, gestational age 33-36 weeks, birth weight 1660-2480 g. Reference values (mean +/- 2SE) for premature neonates aged 5-12, 13-19, 25-48, 51-72, 77-99, 108-140, 150-185 h were: 1.21 +/- 0.16, 1.17 +/- 0.12, 1.21 +/- 0.16, 1.28 +/- 0.18, 1.34 +/- 0.14, 1.38 +/- 0.13, 1.40 +/- 0.16 mmol/l, respectively. Ionized calcium in 59 full-term neonates with mild pathological hyperbilirubinaemia (no phototherapy needed) and 28 neonates born by section (no neonatal complications) showed no statistical difference (unpaired t-test) in age-related values compared with matching healthy neonates with no clinical remarks. Data for full-term neonates were pooled and age-related reference values (mean +/- 2SE) for ionized calcium in capillary whole blood for 168 full-term neonates, gestational age 38-41 weeks, birth weight 2550-4700 g, aged 1-12, 13-24, 25-48, 49-72, 73-99, 99-120, 121-144, 146-168, 178-264 h were: 1.24 +/- 0.11, 1.19 +/- 0.12, 1.21 +/- 0.13, 1.22 +/- 0.14, 1.29 +/- 0.17, 1.35 +/- 0.12, 1.37 +/- 0.12, 1.38 +/- 0.16, 1.40 +/- 0.10 mmol/l, respectively.

Age Factors↗
PubMed1988

Group G streptococcal neonatal septicaemia: two case reports and a brief review of literature.

We present 2 cases of early onset group G streptococcal septicaemia in full term neonates, together with a review of 15 previously reported cases, including 3 late onset cases. Most likely the neonates were infected during passage through the birth canal or had been exposed in utero. In one neonate, meconium aspiration occurred, while in the other prolonged rupture of maternal membranes was a risk factor. Both responded well to treatment with benzylpenicillin and gentamicin. Among the 12 previously reported early onset cases, 5 (43%) had a fulminant course with complications such as progressive respiratory distress, shock, and disseminated intravascular coagulation.

Adult↗
PubMed1988

Cerebral electrical impedance: do indices derived from it provide information on cerebral blood flow in the neonate?

Cerebral electrical impedance was compared with simultaneous estimations of cerebral blood flow (CBF infinity) using the 133Xe clearance technique on 28 occasions in 9 neonates who had changes in PaCO2 and hence presumably cerebral blood flow between measurements. Various indices derived from the impedance waveform which have been reported in the adult to correlate with blood flow were analysed for their relationship with CBF infinity. Percentage change of the two variables was calculated and three indices showed a significant correlation using linear regression. They were peak amplitude (delta Zp), delta Zp times heart rate (delta Zp x HR), and backslope projection. The regression equation for the index with the closest correlation was delta Zp x HR = 0.57CBF infinity + 3.4 with r = 0.68 (p = 0.003) and standard error of the estimate = 29%. Some cerebral electrical impedance indices did correlate with cerebral blood flow changes under the conditions of this study and provide accurate information on the direction of changes but because of the wide confidence limits cannot be used for quantification of cerebral blood flow changes.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Thyroid dysfunction after delivery: incidence and clinical course.

In a prospectively planned study of 591 Danish women thyroid dysfunction after delivery was found in 23 (3.9%). Seven women were hypothyroid and 16 were thyrotoxic. In seven of the thyrotoxic subjects a hypothyroid phase followed. Thyroid dysfunction was mostly transient with complete resolution within a year but persisted in three women (13%). Three months after delivery a positive titre of thyroid microsomal antibodies (TMAb) was found in 38 women (6.4%). Positive titres of TMAb were more often found in women with thyroid dysfunction than in those without (20/38 vs. 3/553). Maximal TMAb titres were seen 5-6 months after delivery and were associated with the occurrence of hypothyroidism. Postpartum thyroid dysfunction was found more often in women with a personal or family history of autoimmune thyroid disorder.

Antibodies↗
PubMed1987

HLA-DR factors associated with postpartum hypothyroidism: an early manifestation of Hashimoto's thyroiditis?

Thirty-three Danish women selected from a prospective study of postpartum thyroiditis were HLA-DR typed. All women had positive titers of antimicrosomal antibodies, and 20 women developed thyroid dysfunction after delivery. DR5 and the phenotype 4.5 were significantly increased in the whole group (p less than 0.001) and strongly associated to hypothyroidism (p less than 0.01), whereas DR3 was insignificantly increased in thyrotoxic women. It is concluded that postpartum hypothyroidism is an autoimmune disorder and may be an early manifestation of Hashimoto's thyroiditis.

Female↗
PubMed1987

Circulating autoantibodies to thyroid hormones: a diagnostic pitfall.

Circulating autoantibodies to thyroid hormones are occasionally detected and may cause confusion, because symptoms and signs are inconsistent with the measured thyroid hormone values. We present a 5 1/2 year old girl with Hashimoto's thyroiditis and false high concentrations of free thyroxine and total triiodothyronine.

Autoantibodies↗
PubMedDate not supplied

T1, T2, and concentrations of brain metabolites in neonates and adolescents estimated with H-1 MR spectroscopy.

The protein and lipid content of the human brain increases dramatically from infancy to adolescence. The authors investigated whether this change influences the relaxation behavior of metabolites measurable with hydrogen-1 magnetic resonance (MR) spectroscopy. H-1 MR spectroscopy was performed in eight neonates and eight adolescents at 1.5 T with STEAM (stimulated-echo acquisition mode) sequences. Five spectra were obtained in each volume of interest with different TE and TR values. T1 and T2 were subsequently calculated. T1 and T2 for inositols, choline-containing compounds (Cho), phosphocreatine plus creatine (PCr + Cr), and N-acetylaspartate (NAA) did not differ significantly between the two subject groups. Metabolite concentrations were estimated by using the fully relaxed water signal as an internal standard. Mean estimated concentrations of NAA and PCr + Cr were higher in the adolescent group, whereas the concentration of Cho was lower. The concentration of inositols was similar in the two groups.

Adolescent↗
PubMedDate not supplied

Metabolite concentrations in the developing brain estimated with proton MR spectroscopy.

The purpose of the present study was to estimate absolute concentrations and relaxation time constants of metabolites that were detectable with proton magnetic resonance (MR) spectroscopy in the healthy preterm, term, and infant brain. Five MR spectra were recorded for each infant by using STEAM (stimulated-echo acquisition mode) sequences with different TEs and TRs. Water was used as an internal standard. The T1 of choline-containing compounds (Cho) and the T1 of phosphocreatine plus creatine (PCr+Cr) decreased. The T2 of the N-acetyl-L-aspartate (NAA) resonance increased, probably because of a relatively larger signal overlap with glutamate in the most immature brains. The concentration of NAA almost doubled, whereas the Cho concentration showed only a nonsignificant tendency to decrease; therefore, the well-known increase in the ratio of NAA to Cho appears to be due mostly to an increase in NAA concentration. The concentration of PCr+Cr increased rapidly and reached adolescent values at approximately 4 months of age.

Aspartic Acid↗
PubMedDate not supplied

Visual evoked potentials in preterm infants during the first hours of life.

Flash evoked cortical potentials (VEPs) were studied in 33 preterm infants with gestational ages from 27 to 33 weeks. During the first 12 h after birth a visual response was evoked in all infants. Better estimates of the VEP latency and amplitude were obtained by using the values of 3 VEPs recorded at 30 sec intervals. The VEP latency decreased during the first hours of life, which was accounted for by an increase in core temperature; the latency decreased 6 msec/degrees C increase. Changes in amplitude were less influenced by changes in temperature. Both VEP latency and amplitude were inversely related to gestational age, but there was no association between head circumference and latency. The flash intensity could be reduced from 155 cd to 39 cd without any effect on VEP latency or amplitude. Similarly, a variation of background illumination below 200 lux did not cause VEP changes. The VEP was not affected by development of minor subependymal haemorrhages but it was severely attenuated during a short episode of hypoxia. It is suggested that when taking core temperature into account the VEP can be used to determine changes in the cerebral function in preterm infants.

Cerebral Hemorrhage↗
PubMedDate not supplied

Stimulus rate-induced VEP attenuation in preterm infants.

The effect of the stimulus rate on the single flash VEP amplitude and latency (N1) was studied in 26 mechanically ventilated, preterm infants during the first days of life. Significant decreases in VEP amplitude and increases in latency were observed within a series of 3 single flash VEPs recorded with stimulus rates of 1/4 Hz. After a recovery period of 30 sec between series, the amplitude had attained baseline level, whereas the latency delayed progressively. The underlying cause of this rate effect is speculative, as individual degrees of VEP attenuation were not statistically related to gestational age, clinical state or cerebral oxygen delivery.

Analysis of Variance↗
PubMedDate not supplied

Preservation of single-flash visual evoked potentials at very low cerebral oxygen delivery in preterm infants.

Single-flash visual evoked potentials (VEPs) were recorded in 32 preterm infants (mean gestational age: 29 weeks) during extreme physiologic conditions within the first day of life. The VEP configuration was normal in all patients at the onset of the investigation. Hypoxic episodes (PaO2 less than 3 kPa) caused rapid and consistent attenuation of the VEP mostly with an instantaneous recovery after normalization of PaO2. In contrast, VEP amplitude and latency were unaffected during episodes with low cerebral blood flow (4.5 ml/100 gm/min) and correspondingly low oxygen delivery to the brain (1 ml/100 gm/min), severe hypocapnia (PaCO2 1.6 kPa), and severe arterial hypotension (MABP 10 mm Hg), provided that the arterial oxygen tension was greater than 5 kPa. Absence of N1 was observed soon after the development of severe intracranial hemorrhage; however, this abnormality was short in duration. We conclude that the neurons generating VEPs are supported sufficiently during extreme physiologic episodes, except during severe hypoxia. The recovery time may be proportional to the cerebral insult.

Carbon Dioxide↗