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Biomedical subjects

W Szymonowicz

Publications and source records attributed to W Szymonowicz.

At least 19 recordsLinked to original sources
PubMed1990

Regional cerebral blood flow after hemorrhagic hypotension in the preterm, near-term, and newborn lamb.

Developmental changes in regional cerebral blood flow (CBF) responses to hemorrhagic hypotension during normoxia and normocapnia were determined using radioactively labeled microspheres to measure flow to the cortex, brainstem, cerebellum, white matter, caudate nucleus, and choroid plexus in three groups of chronically catheterized lambs: 90- to 100-d preterm fetal lambs (n = 9); 125- to 136-d near-term fetal lambs (n = 9); and newborn lambs 5- to 35-d-old (n = 8). Heart rate, central venous pressure, and arterial blood pressure were monitored continuously and arterial blood gas tensions, pH, Hb, and oxygen saturation together with regional CBF were measured periodically. Hemorrhagic hypotension produced a mean decrease in arterial blood pressure of 27 +/- 4, 23 +/- 2, and 41 +/- 4% in the three groups, respectively, whereas reinfusion of the lamb's blood resulted in a return to control blood pressure within 3% in all three groups. In the pre-term fetal lamb, CBF decreased significantly in all regions during hypotension. In the near-term fetal lamb, only blood flow to the cortex decreased significantly during hypotension. In the newborn lamb, only the choroid plexus demonstrated a significant decrease in blood flow during hypotension. The lower limit of regional CBF autoregulation was identical to the resting mean arterial pressure in fetal life but significantly lower in newborn lambs. These experiments demonstrate for the first time that vulnerability to hypotension decreases with increasing maturity and that the brainstem, the phylogenetically oldest region of the brain, is the least vulnerable to the effects of hypotension at any age in the lamb model.

Animals↗
PubMed1988

Thyroid function in very preterm infants.

Indices of thyroid function were measured in 108 infants born at 23-31 weeks gestation, after birth, at 24 and 72 h, and at 1, 3, 4, 5 and 6 weeks of age. This group was characterised by low serum thyroxine (T4), normal thyroid stimulating hormone (TSH), low-normal thyroid binding globulin (TBG), low free thyroxine index (FTI) and low triiodothyronine (T3). The incidence of hypothyroxinaemia defined as a serum T4 value of less than 65 nmol/l was 58% after birth, increasing to 84% at 1 week, after which there was progressive reduction to 36% by 6 weeks of age. Mean T4 values were inversely proportional to gestational age during this study period. Infants of 23-28 weeks gestation had significantly lower T4, TBG, FTI and T3 values compared to those of 29-31 weeks gestation. Infants who had hyaline membrane disease (HMD) had significantly lower T4 and FTI values compared to those without HMD for up to 3 weeks of age. Similar differences were found between deaths and survivors in the first week after birth. This study suggests that there is increasing delay in maturation of the hypothalamic-pituitary-thyroid axis control with increasing prematurity. In addition, the data suggest that infants who were extremely preterm or those with HMD had worse and more persistent abnormalities of thyroid function secondary to their illness and metabolic stress. The significance of our findings, in particular that of prolonged hypothyroxinaemia, is uncertain. The role of thyroid replacement therapy in these very preterm infants therefore need to be assessed with a randomised clinical trial.

Age Factors↗
PubMed1988

Systemic candidiasis and pneumonia in preterm infants.

Twenty-two preterm infants with systemic candidiasis are reported, of which seven cases were presumed to be antenatally acquired and 15 postnatally acquired. All except one were of very low birthweight. Fifteen infants had positive cultures of blood, cerebrospinal fluid or urine and seven had candida pneumonia only. Clinical features included general instability, respiratory deterioration and a necrotizing enterocolitis-like presentation. The incidence of leukocytosis, shift to the left, eosinophilia and thrombocytopenia were not different from those with bacterial infection. The diagnosis was made after death in two infants. In the remaining 20 infants, treatment was initiated between 5 and 97 days of age, with a median delay of 4 days after the first positive cultures were taken. Complications of amphotericin and 5-flucytosine therapy which developed in five infants resolved on cessation of treatment. The mortality rate was 18% and impairment rate among the 17 very low birthweight survivors was 18%. A high index of suspicion is required for systemic candidiasis, especially in infants of less than 1000 g birthweight. If recognized early, effective and safe antifungal therapy is possible with favourable short- and long-term outcome.

Amphotericin B↗
PubMed1988

Significance of seizures in very low-birthweight infants.

Of 506 very low-birthweight (VLBW) infants, the authors review data on 67 identified as having seizures. 29 survivors with seizures and 305 without were followed up at the ages of one, two and five years: statistical significance of psychological and mental impairment was evaluated. Impairment was higher in the seizure group at 66 per cent (15 per cent in non-seizure group) and 43 per cent of these were considered to be severely impaired. Infants with seizures occurring for more than seven days and lasting for more than five minutes had the poorest outcome, and infants with late onset had the best outcome. Analysis showed that 40 per cent of seizures were caused by birth asphyxia, and these were strongly prognostic, correlating with mortality and impairment rates. 60 per cent of the infants who died had the same cause for both their seizures and death, and for 57 per cent of these the cause was perinatal asphyxia. The poor outlook for the VLBW infants suggests that the seizures themselves are a serious neurological insult.

Female↗
PubMed1988

Developmental changes in regional cerebral blood flow in fetal and newborn lambs.

Developmental changes in regional cerebral blood flow (CBF) were determined using radioactively labeled microspheres to measure flow to the cortex, brain stem, cerebellum, white matter, caudate nucleus, and choroid plexus in three groups of chronically catheterized lambs under physiological conditions: 90- to 100-day preterm fetal lambs (n = 14), 125- to 136-day near-term fetal lambs (n = 11), and newborn lambs 5-44 days old (n = 10). We continually monitored heart rate, central venous pressure, and mean arterial blood pressure (MAP) and periodically measured arterial blood O2 and CO2 tensions (PaO2, PaCO2, respectively), pH, hemoglobin, and oxygen saturation (SaO2). The regional CBF measurements (ml.100 g-1.min-1) revealed that in all three age groups the high flow areas are the choroid plexus and caudate nucleus, whereas the lowest flow area is the white matter. There is, however, a different hierarchy of regional CBF in utero (cortex less than cerebellum and brain stem) compared with extrauterine life in the newborn lamb (cortex and cerebellum greater than brain stem). Analysis of regional cerebral oxygen delivery [CBF times arterial oxygen content (CaO2)] demonstrated a progressively increasing oxygen transport to the cortex with increasing gestational maturity and after birth. Oxygen transport to the brain stem, cerebellum, and white matter increased with gestational age, but did not increase after birth. Relationships between regional CBF and natural physiological variations of cardiorespiratory parameters (PaO2, SaO2, CaO2, pH, PaCO2, and MAP) were assessed using regression analysis. Correlations of regional CBF with PaO2 and SaO2 suggest that cerebral perfusion is not primarily determined by CaO2 when variations occur within the physiological range.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Periventricular haemorrhage: association with patent ductus arteriosus and its treatment with indomethacin or surgery.

A prospective study on 150 infants with a birthweight of 1250 g or less was carried out to investigate the effects of patent ductus arteriosus (PDA), haemorrhagic pulmonary oedema (HPO), Indomethacin therapy and surgical ligation on the development of periventricular haemorrhage (PVH) or the extension of pre-existing PVH. The incidence of PVH, diagnosed by serial cerebral ultrasonography was 44% and the incidence of PDA, diagnosed by serial M-mode and contrast echocardiography, was 45%. During the first 8 days after birth when the infants were vulnerable to PVH, the development of PDA did not lead to the development or extension of PVH in 85% of infants. Haemorrhagic pulmonary oedema also had no effect on PVH in 71% of infants. Compared with infants whose PDA or HPO had no effect on PVH, those who had development or extension of haemorrhage had significantly more severe hypercapnia, blood gas instability and hypotension associated with the occurrence of PDA or HPO. Early Indomethacin therapy was not associated with the development or extension of PVH in 93% of infants. Although an elevation of arterial blood pressure was demonstrated after ductal ligation, surgery was performed after 1 week of age in all infants and in no instance was there an effect on PVH. This study suggests that PDA leads to PVH only if it causes significant blood gas and blood pressure disturbances which are known to affect cerebral blood flow adversely.

Cerebral Hemorrhage↗
PubMed1987

Outcome of singleton infants delivered vaginally or by caesarean section at 23 to 28 weeks' gestation.

The survival and impairment rates of 276 inborn singleton infants of 23-28 weeks' gestation were reported according to route of delivery and mode of presentation. The Caesarean section rate was 29% overall, ranging from 13% at 25 weeks to 46% at 28 weeks. In the vertex group, no significant difference in survival or impairment rate was found between Caesarean and vaginal births. In the non-vertex group, Caesarean births had a similar survival rate but a significantly lower impairment rate compared to vaginal births. For Caesarean births, no significant difference in survival or impairment rate was found between vertex and non-vertex groups. In contrast, for vaginal births, the mode of presentation was important: the non-vertex group had a significantly lower survival rate and higher impairment rate compared to the vertex group. We found no evidence to support the use of Caesarean section in extremely preterm infants with vertex presentation, except for recognized maternal or fetal indications. The findings in the non-vertex group indicated that there is a definite need for a randomized clinical trial to investigate the possible benefits of Caesarean section in extremely preterm infants with non-vertex presentation.

Cesarean Section↗
PubMed1987

Severe pre-eclampsia and infants of very low birth weight.

The effect of severe pre-eclampsia on the outcome of infants of very low birth weight was studied in a prospective case control study of 35 pairs of infants of comparable gestation. Significantly more infants were delivered before the onset of labour and by caesarean section in the group with pre-eclampsia. These babies tended to be smaller and had a higher incidence of hyaline membrane disease, patent ductus arteriosus, pulmonary air leak, and hypotension. They also required more intensive treatment with oxygen and mechanical ventilation. The significant difference in birth weight was still apparent at 2 years of age. Although the mean psychomotor developmental index and the incidence of specific neurodevelopmental impairments were not significantly different between the two groups, survivors in the group born to pre-eclamptic mothers had a significantly lower mean mental developmental index, and significantly more of these children had one or more impairments compared with the control group at 2 years of age.

Birth Weight↗
PubMed1987

Symptomatic hypothyroxinemia with normal TSH levels in preterm infants.

The authors report eight preterm infants with hypothyroxinemia who developed clinical features similar to those described in congenital hypothyroidism: prolonged jaundice, hypoactivity, lethargy, constipation, edema, and hoarse cry. All had low serum thyroxine, normal thyroid stimulating hormone, and normal thyroid binding globulin levels. After exclusion of other causes for the symptoms, thyroid replacement therapy was started, resulting in rapid resolution of symptoms and return to euthyroid status. Follow-up of these infants after cessation of therapy revealed normal growth and development and normal thyroid function. The authors therefore recommend a prospective study to investigate the incidence of hypothyroxinemia, frequency of associated clinical features, and the benefits of thyroid replacement therapy based on a randomized controlled trial.

Humans↗
PubMed1986

Prognosis for infants born at 23 to 28 weeks' gestation.

The survival and neurodevelopmental outcome of 356 extremely preterm infants born at 23 to 28 weeks' gestation were reported by week of gestation. Their corrected 1 year survival improved from 7% at 23 weeks to 75% at 28 weeks. The overall incidence of impairment was 19% and of major disability 12%. Boys had a significantly lower normal survival than girls. Multiple births had a significantly lower survival and higher incidence of impairment than singleton births. Predictions of outcome were made before delivery, after resuscitation, and at 1 week to aid the development of guidelines on when perinatal intensive care is justified, whether obstetric intervention for fetal reasons is warranted, and what initial and ongoing prognoses to give to parents. Intensive care for progressively smaller and more immature infants, many of whom were previously considered non-viable, needs to be carefully monitored by every perinatal centre.

Developmental Disabilities↗
PubMed1986

Neurodevelopmental outcome of periventricular haemorrhage and leukomalacia in infants 1250 g or less at birth.

The brains of 50 consecutively admitted infants weighing 1250 g or less at birth were serially examined beyond the neonatal period for periventricular haemorrhage and for periventricular leukomalacia with real-time ultrasound. There was significant correlation between the presence or absence and the severity of haemorrhage with survival. A prospective neurodevelopmental assessment was completed at 2 years of age, corrected for prematurity, on all survivors. None of the 20 survivors with normal scans or germinal layer haemorrhages had evidence of major disability and all four survivors with intracerebral haemorrhage or periventricular leukomalacia had major disability. The mental performance on the Bayley scales of infant development was also significantly worse in the latter group. Six of the eight survivors with intraventricular haemorrhage had no major disability, including three who had post-haemorrhagic hydrocephalus. Our results showed that cerebral ultrasound detection of brain pathology is a good predictor of neurodevelopmental outcome in such extremely low birthweight infants. However, as the maximum extent of periventricular haemorrhage may develop beyond one week of age and cystic periventricular leukomalacia commonly develops after the neonatal period, serial scanning is mandatory to ensure diagnostic accuracy for both periventricular haemorrhage and leukomalacia.

Blindness↗
PubMed1986

Pulmonary interstitial emphysema in infants less than 1000 g at birth.

Eighty (32%) of 249 infants weighing less than 1000 g at birth developed pulmonary interstitial emphysema (PIE); its incidence was 42% in infants at 500-799 g, 29% at 800-899 g and 20% at 900-999 g. Fifty-five per cent occurred in the first 24 h and 43% were associated with other forms of air leak. The incidence and mortality of PIE did not improve between 1977 and 1984. The mortality rates in infants with or without PIE were not significantly different in the first 4 years of the study period (53% vs 45%). As the mortality improved in infants without PIE during the second 4 years, the difference in mortality rates in infants with or without PIE became significant (68% vs 29%). PIE continues to be associated with serious mortality and morbidity in extremely low birthweight infants. Effective measures to prevent PIE are required before further improvement in their outcome can be achieved.

Female↗
PubMed1986

Periventricular haemorrhage and leukomalacia in extremely low birthweight infants.

Forty (49%) of 82 extremely low birthweight (ELBW, less than 1000 g) infants had periventricular haemorrhage (PVH). Ten (12%) had germinal layer haemorrhage (GLH) alone, 16 (20%) had intraventricular haemorrhage (IVH) and 14 (17%) had intracerebral haemorrhage (ICH). Almost all the cases of PVH had developed by 4 days of age. Small-for-gestational age infants (12% of study population) had a significantly lower incidence and severity of PVH than appropriate-for-gestational age infants. Of 94 infants born between 23 and 28 weeks gestation, 45 (48%) had PVH. The PVH incidence was 60% in those of 23-26 weeks and 38% in those of 27-28 weeks. The hospital survival rate of ELBW infants was 69% in those without PVH and 43% in those with PVH; 70% in GLH alone; 50% in IVH and 14% in ICH. Three survivors developed post-haemorrhage hydrocephalus of whom two required ventriculoperitoneal shunting. Five survivors developed periventricular leukomalacia (PVL) evidenced by cysts identified between 3 and 7 weeks of age. A significant decrease in the incidence of PVH occurred over the study period (67% in 1982, 38% in 1983 and 33% in 1984). This decrease was seen for all grades of PVH. The reasons for this decreased incidence are still to be ascertained but this trend suggests that improvements in neonatal intensive care have the potential to improve the neurological outcome of more recent ELBW survivors.

Cerebral Hemorrhage↗
PubMed1986

Pulmonary air leak in extremely low birthweight infants.

The incidence of pulmonary air leak in 230 infants with a birth weight of 500-999 g who were ventilated was 41%. Pulmonary interstitial emphysema occurred in 35%, pneumothorax in 20%, pneumomediastinum in 3%, and pneumopericardium in 2%. The survival rates in those with or without pulmonary air leak were not significantly different in the first four years of the study period (46% v 53%). As the survival improved in infants without air leak during the second four years the difference in survival rates in infants with or without air leak became significant (30% v 71%). Effective measures of preventing pulmonary air leak are required before further improvement in the outcome of these extremely low birthweight infants can be achieved.

Air↗
PubMed1986

The surviving monozygotic twin.

It has been suggested that because of vascular interchange between the monozygous twins vascular disruptions from a deceased cotwin with disseminated intravascular coagulation causes embolisation in the surviving twin. This study reports six cases in which all the surviving monozygous twins had central nervous system infarcts and three had multiple organ infarcts, including pulmonary and hepatic infarcts, which have not been reported previously. Fetal death in utero occurred 1-11 weeks before the live birth of the monozygous survivor. In three cases there was pathological confirmation of a continuing process with infarcts ranging in age from a few days to eight weeks. Four infants died in the early neonatal period, and the remaining two survived with considerable handicap. A review of the published reports confirmed the high risk of vascular disruption affecting many organ systems and the extremely poor prognosis for subsequent death or handicap. We recommend that after detection of fetal death in utero in a suspected monozygous twin pregnancy careful consideration should be given to prompt delivery of the survivor and investigations should be carried out to rule out infarction in the central nervous system and other organs that are at risk.

Adult↗
PubMed1986

Reduction in periventricular haemorrhage in preterm infants.

Our previous cerebral ultrasound study of antecedents of periventricular haemorrhage in infants weighing 1250 g or less at birth suggested that neonatal events that caused increased or fluctuating cerebral blood flow lead to periventricular haemorrhage. As the risk period for this type of haemorrhage was the first four days of life strict guidelines were introduced to avoid the previously identified neonatal risk factors. No attempt was made to modify obstetric practice. Over the next two years, although the obstetric risk profile, the frequency and severity of hyaline membrane disease, and the gestation, birth weight, and sex distributions of a similar cohort of infants did not change, the incidence of periventricular haemorrhage decreased significantly from 60% to 36%. Significant antecedents of haemorrhage similar to those found in the previous study included severe bruising, low arterial:fractional inspiratory oxygen ratio and low packed cell volume on admission, hyaline membrane disease, hypercarbia, and hypoxaemia. Assisted ventilation, pneumothorax, treatment with tubocurarine, and hypotension were no longer significant risk factors for periventricular haemorrhage. A multivariate discriminant analysis correctly predicted haemorrhage in 86% of the study group when bruising, hypercarbia, hypoxaemia, hyaline membrane disease, and low gestation were considered. These results suggest that changes in neonatal practices can reduce the incidence of periventricular haemorrhage and that drug studies indicating similar reduction in haemorrhage need to be evaluated carefully to ensure that placebo and treated groups are in fact comparable.

Birth Injuries↗
PubMed1985

Outcome of intrauterine periventricular haemorrhage and leukomalacia.

This case study reports five very low birthweight infants with ultrasound evidence of intrauterine insult to the brain. Intrauterine periventricular haemorrhage (PVH) accompanied by ventricular dilation occurred in two preterm infants both of whom survived and were severely handicapped at follow-up. Three preterm infants had intrauterine periventricular leukomalacia (PVL); one survived and is severely handicapped at one year of age. Our experience and rare case reports in the literature indicate that intrauterine PVH and PVL carry a high risk of death in neonatal period and severe neurological sequelae in survivors.

Brain Ischemia↗