Search PubMed⌕ Search

Biomedical subjects

V Y Yu

Publications and source records attributed to V Y Yu.

At least 37 records · Page 2Linked to original sources
PubMed1990

Immunoglobulin and anti-Escherichia coli antibody in lower respiratory tract secretions from infants weighing less than 1500 g at birth.

Concentrations of immunoglobulins and anti-Escherichia coli antibody were studied longitudinally in tracheobronchial aspirates from 33 premature intubated neonates, median gestational age 27 weeks. Aspirates collected at birth contained IgG, IgA, and IgM in 100%, 93%, and 79% of samples, respectively. The median IgA concentration at birth was 0.7 micrograms/mg total protein and increased to 5.8 micrograms/mg protein by the sixth week. IgG and IgM antibodies to E coli were present in 90% and 30%, respectively, of tracheobronchial aspirates collected at birth. Samples from three of 28 neonates (11%) contained IgA anti-E coli antibody at birth, and the proportion with IgA antibody rose to 50% during the sixth week. Secretory component associated IgA and IgM were detectable in samples tested at birth and at 4 weeks of age, and secretory component associated anti-E coli antibody was present in aspirates from three of nine neonates studied at 4 weeks of age, but had not been detectable at birth.

Antibodies, Bacterial↗
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↗
PubMed1990

Clinical experience with preterm formulas in very low birthweight infants.

Infants below 1500 g at birth were randomly assigned to receive one of two preterm infant formulars: S26 Low Birthweight (S26-LBW, 25 infants) or Enfalac Premature (EPF, 24 infants). They were either exclusively formula-fed (13 infants) or the formula was used to supplement their own mother's fresh breast milk (36 infants). The mean age when milk feeds were commenced was 7 days and the mean age when birthweight was regained was 12 days. The mean age when 2000 g was reached was 45 days at which time 10 (20%) infants were below the tenth centile on the intrauterine growth chart. None of the above variables were significantly different between the S26-LBW and EPF groups. However, the S26-LBW group established full enteral feeding significantly earlier compared to the EPF group (42 versus 64 d) and the number with adverse gastrointestinal effects was lower (4 versus 10 infants). Both preterm infant formulas supported a growth rate in excess of that in utero without stressing the infants' metabolic system. The growth rate of infants fed preterm breast milk supplemented with preterm infant formula was quantitatively similar to those exclusively fed preterm infant formula.

Bottle Feeding↗
PubMed1988

The survival of extremely-low-birthweight infants in Victoria: 1982-1985.

A population-based survey of mortality in extremely-low-birthweight (500- to 999-g) infants was carried out in Victoria for the years 1982 to 1985. No increase in the number of extremely-preterm births occurred during that time. The still-birth rate fell from 498 still births per 1000 births in 1982-1983 to 403 still births per 1000 births in 1984-1985. The neonatal mortality in 1982-1985 was 638 deaths per 1000 live births, with no significant decline from that of the 1978-1981 cohort. The small increase in neonatal survivors was not associated with any change in the postneonatal death rate. Delivery in a level-3 unit was associated with a significantly better outcome. Multiple births made a major contribution to the extremely-low-birthweight group of infants.

Birth Weight↗
PubMed1988

Continuing morbidity in extremely low birthweight infants.

The pattern of lesser but continuing morbidity in the first 2 years was reported in 36 survivors who weighed 500-799 g at birth and in 83 survivors who weighed 800-999 g at birth. Over this period, there was one post-discharge death. Sixty-one percent of children were rehospitalized, most commonly for respiratory tract disorders and surgical procedures such as aural ventilation tube insertion and inguinal herniorrhaphy. Their three most common medical disorders were otitis media (55%), wheezing episode (48%) and lower respiratory tract infection (29%). At 2 years of age, 44% remained below the tenth percentile for weight, 45% for height and 12% for head circumference. Other lesser morbidity included iatrogenic scarring, abnormal head shape and behavioural problems. Except for otitis media, survivors of 500-799 g birthweight did not have a significantly higher rate of neurodevelopmental impairment, health problems, rehospitalization, suboptimal growth or behavioural disorders, compared to those of 800-999 g birthweight. This study confirms the need for providing extremely low birthweight children and their families with a continuity of comprehensive medical care and social support after hospital discharge.

Female↗
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

Guidelines for the use of pulse oximetry in the non-invasive estimation of oxygen saturation in oxygen-dependent newborn infants.

An Ohmeda Biox 3700 oximeter was evaluated during treatment of 12 patients with respiratory distress. The infants were of 27-33 weeks' gestation and between 2 days and 5 months postnatal age. Blood gases were taken from indwelling arterial catheters and were measured on an ABL 30 blood gas analyser. The study tested the accuracy of the oximeter in detecting hypoxia (PaO2 less than 55 mmHg) and hyperoxia (PaO2 greater than 80 mmHg). Results are based on 175 paired observations. Guidelines are suggested for the use of the pulse oximeter under three conditions. In a newborn infant with acute respiratory distress without direct arterial access, the limits should be set at 85% (lower) and 90% (upper). In an older infant with chronic respiratory distress, the upper limit of use should be 95%. In order to avoid oxygen tensions less than 55 mmHg which would increase the risk of pulmonary vasoconstriction, however, the lower limit should be 87%. Infants with indwelling arterial lines during their first few weeks of treatment should have oxygen tension measurements and simultaneous oxygen saturation readings plotted on a graph at the bedside. The graph should be updated every 48 h to take into account changed levels of 2,3-diphosphoglycerate, haemoglobin F, and carboxyhaemoglobin and the recommended limits should be changed accordingly.

Carbon Dioxide↗
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

Attitudes of Australian neonatal paediatricians to the treatment of extremely preterm infants.

A questionnaire survey was carried out to identify areas of consensus or disagreement in the attitudes and practices of Australian neonatal paediatricians with regard to the treatment of extremely preterm infants. Considerable variation was found in the estimated chances of survival and disability among respondents. The majority of neonatal paediatricians advocated prompt resuscitation and initiation of neonatal intensive care at birth, although all believed life-support treatment should be withdrawn in those instances where medical complications develop resulting in near certainty of death or life with total incapacity. The predominant view was for parents to be involved in the decision-making process for withdrawal of life-support and for the neonatal intensive care policy to be made known to the parents. Information from this survey which raised concerns included the variability in the estimate of the potential for survival, the lack of relevance of the law to everyday practices in the neonatal intensive care units, the small minority of respondents who felt that life-and-death decisions should be made by medical staff alone, and the reluctance of some neonatal paediatricians to inform parents about the policies of their unit.

Adult↗
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

The extremely low birthweight infant: ethical issues in treatment.

Survival and disability rates of extremely low birthweight infants have significantly improved. Since it is impossible to give an accurate prognosis at the time of birth, all such live births should be resuscitated and curative treatment, including the use of life support measures when appropriate, promptly initiated. In the event that medical facts indicate curative efforts are futile or lack compensating benefit, they should be discontinued and palliative treatment, which provides symptomatic relief and comfort, should be introduced. The attending neonatologist has the primary role as advocate for the infant and medical advisor to the parents, while the parents act as surrogates for their infant. The shift in emphasis from curative to palliative treatment requires medical consensus among all those involved in the care of the infant and consent from the parents closely involved in this widely shared decision. The role of infant bioethics committees is one of advisor and consultant to this decision-making process. Legislation needs to uphold the primary prejudice in favour of life while conceding that discontinuation of curative treatment, which is no longer effective, and the provision of palliative treatment, are appropriate medical decisions in exceptional cases.

Ethics Committees, Clinical↗
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↗