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Biomedical subjects

L W Doyle

Publications and source records attributed to L W Doyle.

At least 55 records · Page 3Linked to original sources
PubMed1999

Is sudden infant death syndrome still more common in very low birthweight infants in the 1990s?

OBJECTIVE: To determine the rate of sudden infant death syndrome (SIDS) in very low birthweight children (VLBW) relative to children with low (LBW) and normal birthweights. DESIGN, SETTING AND SUBJECTS: Cohort study of consecutive live births in Victoria, 1993-1997 inclusive. MAIN OUTCOME MEASURES: All sudden unexpected deaths in early childhood over this five-year period; all deaths from SIDS (defined as a sudden unexpected death without a definite pathological explanation); and the proportion of SIDS in live births in three birthweight subgroups (VLBW, 500-1499 g; LBW, 1500-2499 g; and normal birthweight, > 2499 g). RESULTS: There were 316,028 live births (with known birthweight) in Victoria over the five-year period; 224 (0.71 per 1000 live births) died unexpectedly. In 10 of these deaths there was a definite pathological explanation, giving a rate of SIDS of 0.68 per 1000 live births. The rate of SIDS in VLBW children was 2.52 per 1000 live births, lower than the rate reported before the 1990s. The rate of SIDS in VLBW children was not significantly different from the rate in LBW children of 1.98 per 1000 live births (difference per 1000 live births, 0.53; 95% CI, -1.45 to 2.52), but was significantly higher than the rate in normal birthweight children of 0.59 per 1000 live births (difference per 1000 live births, 1.93; 95% CI, 0.06-3.79). CONCLUSIONS: The rate of SIDS in VLBW children has fallen in the 1990s, along with the overall fall in the rate of SIDS, but remains higher than that in normal birthweight children.

Humans↗
PubMed1999

Why do preterm infants die in the 1990s?

OBJECTIVES: To describe the mortality rate for preterm infants (born 23-36 completed weeks' gestational age) and to determine the causes of death, focusing on avoidable causes. DESIGN AND SETTING: Prospective cohort study of preterm infants born at Royal Women's Hospital, Melbourne (a tertiary referral hospital with a neonatal intensive care unit and a special care nursery) from January 1994 to December 1996. SUBJECTS: 2475 consecutive liveborn infants with gestational ages from 23 to 36 weeks. MAIN OUTCOME MEASURES: Mortality rate during the primary hospitalisation, and causes of death. RESULTS: The total mortality rate was 4.8% (118/2475). The mortality rate declined with increasing maturity. The decrease in mortality was rapid between 23 and 28 weeks' gestational age, from 64.5% at 23 weeks to 4.0% at 28 weeks, then slower, falling to 0.4% at 36 weeks. Fifty of the 118 infants who died had lethal congenital anomalies. Lethal anomalies accounted for three-quarters of deaths in infants aged 28-36 weeks. The mortality rate in infants free of lethal anomalies was 2.8% (68/2425) and only 0.2% (4/1759) for infants aged 32-36 weeks. In the 68 infants without lethal anomalies who died, few obvious preventable causes were identified. CONCLUSIONS: Mortality rates fell rapidly between 23 and 28 weeks' gestational age. Survival rates for preterm infants born after 31 weeks' gestational age approached the survival rates of term infants. Lethal congenital anomalies were the most common cause of death; preventable causes of death were rare.

Australia↗
PubMed1999

Changes in lung function between age 8 and 14 years in children with birth weight of less than 1,501 g.

We set out to determine whether lung function of children with a birth weight of <1,501 g changed relative to expectations between the ages of 8 and 14 years. We hypothesized that changes in lung function may differ between those of birth weight above and below 1,000 g. The subjects of this study were born in the Royal Women's Hospital, Melbourne. There were 86 consecutive survivors with birth weights <1,000 g born between January 1, 1977 and March 31, 1982, and 124 consecutive survivors with birth weights 1,000-1,500 g born between October 1, 1980 and March 31, 1982. Lung function was measured at both age 8 and 14 years, corrected for prematurity in 78% (67/86) of those with birth weight <1,000 g, and in 69% (86/124) of those with birth weight 1,000-1,500 g. Overall, lung function was similar to predicted values at both 8 and 14 years of age [e.g., (forced expired volume in 1 s, FEV1% predicted) at age 8 years mean 88.5% (SD 14.7) and at age 14 years, mean 94.9% (SD 13.8)]. There were significant changes, mostly improvements, in lung function between age 8-14 years relative to predicted values: FEV1 (% predicted) increased between 8-14 years of age by a mean of 6.4 (95% confidence interval, 4.4-8.3). The improvements in some lung function variables were significantly greater in those of birth weight <1,000 g compared with those of birth weight 1,000-1,500 g: improvement in FEV1 (% predicted) between age 8-14 years in infants with birth weight <1,000 g had a mean of 10.3 (SD 13.1), and in those with birthweight 1,000-1,500 g a mean of 3.3 (SD 10.1). We conclude that lung function improved significantly relative to predicted values in children of birth weight <1,501 g between age 8-14 years. The improvements were greatest in those of birth weight <1,000 g.

Adolescent↗
PubMed1999

Changing mortality and causes of death in infants 23-27 weeks' gestational age.

OBJECTIVE: To contrast the mortality rates and changes in the causes of death of very preterm infants (23-27 weeks), before and after the introduction of exogenous surfactant in 1991, and to identify any preventable causes of death remaining in the 1990s. METHODOLOGY: This was a cohort study on consecutive preterm infants of 23-27 weeks' gestational age born in the Royal Women's Hospital, Melbourne, a level III perinatal centre. The infants were livebirths free of lethal anomalies from two distinct eras, 1983-90, and 1992-96, inclusive. The main outcome measures were mortality during the primary hospitalization and the causes of death before and after the introduction of exogenous surfactant in 1991. RESULTS: In 1983-90, 261 of 508 livebirths (51.4%) of 23-27 weeks' gestational age died, a significantly higher proportion than the 109 of 384 (28.4%) livebirths who died in the period 1992-96. The mortality rate fell significantly with increasing gestational age and was lower at each week of gestational age in 1992-96. More infants who died in 1992-96 were treated intensively in the neonatal intensive care unit (NICU). Of the group of infants who died or who were treated intensively in NICU, respiratory causes of death predominated. However, the causes of death changed over time. In 1992-96 proportionally fewer infants died from respiratory causes (1983-90, 82.5%; 1992-96, 60.0%; odds ratio (OR) 0.31, 95%; confidence interval (CI) 0.16-0.57), but more from septic causes (1983-90, 14.3%; 1992-96, 43.8%; OR 4.9, 95%; CI 2.6-9.2). CONCLUSIONS: As the mortality rate has fallen over time, respiratory causes of death have diminished, but septic causes of death have increased. Further advances in the use of exogenous surfactant and respiratory support may reduce respiratory deaths. Effective strategies to reduce nosocomial infections are urgently required.

Cause of Death↗
PubMed1998

Establishment of a normal range of penile length in preterm infants.

RATIONALE: Recognition of micropenis is important because it may be the only obvious manifestation of pituitary or hypothalamic hormone deficiencies. Alternatively it may indicate the presence of dysgenetic testicular tissue with malignant potential. Previously published normal ranges for premature males are based on small sample sizes, with few infants <30 weeks and none <28 weeks. SETTING: Intensive and Special Care Nurseries, Royal Women's Hospital, Melbourne, Victoria. SUBJECTS: 188 consecutive male infants, inborn and outborn, with gestational age <37 completed weeks were examined in the first week of life. They included multiple births (n=51) and small for gestational age infants (n=16). Infants with hypospadias (n=3) or an endocrine disorder (n=1) were excluded from the study. MANOEUVRE: Stretched penile length was determined by a single examiner (RT) using a standardized measure. RESULTS: A mean penile length with associated 95% confidence intervals is described for infants between 24 and 36 weeks inclusive. The relationship between penile length (PL, cm) and gestational age (GA, weeks) was: PL=2.27+0.16 GA. CONCLUSION: This study confirms the normal range for penile length of premature male infants 30-36 weeks and defines the normal range <30 weeks. This should prove useful to paediatricians, paediatric surgeons and endocrinologists dealing with the increasing number of surviving male infants <30 weeks in whom penile size is questioned.

Anthropometry↗
PubMed1998

Disproportionate consumption of ventilator resources by very preterm survivors persists in the 1990s.

The aim of this study of consecutive livebirths between 23 and 30 weeks of gestational age was to determine the changes over time in the relationship between gestational age and the consumption of nursery resources by surviving preterm infants. Three discrete eras, comprising the years 1977-1985, 1986-1990, and 1991-1995, were identified, based on availability of ventilators and changes in perinatal care. The survival rate rose dramatically with each week's increase in gestational age, and increased significantly between successive eras. Overall, consumption of resources for assisted ventilation by survivors increased over time. In infants born before 28 weeks, for each week of decrease in gestational age, survivors averaged an extra 12.9 days of assisted ventilation in 1977-1985, 13.4 days in 1986-1990, and 13.5 days in 1991-1995, while infants born between 28-30 weeks of gestational age needed only an extra 2.3 days, 3.3 days, and 4.6 days of assisted ventilation for each week of decrease in gestational age in successive eras, respectively. There was no indication that improvements in perinatal care over time shortened the duration of assisted ventilation for surviving preterm infants.

Gestational Age↗
PubMed1998

Preterm infants 30-36 weeks' gestation in Victoria--where should they be delivered?

There is little doubt that very preterm infants <30 weeks' gestation should be born in level-3 perinatal centres. For preterm infants 30-36 weeks' gestation, however, the optimum place of birth is not so clear-cut. The aims of this study of livebirths 30-36 weeks' gestational age born in Victoria were to determine: 1) the proportions delivered outside level-3 centres, and 2) for infants born outside level-3 centres, the proportions transferred after birth to a level-3 nursery in the first days after birth. Data on the number of livebirths 30-36 weeks' gestational age in Victoria in the 3 years 1994-1996, inclusive, were supplied by the Victorian Perinatal Data Collection Unit. Data were obtained from the Newborn Emergency Transport Service (NETS) on all transfers within the first 3 days after birth to a level-3 centre for infants born outside level-3 centres. For the 3 years 1994-1996 there were 11,375 livebirths 30-36 weeks' gestational age in Victoria. The proportion born outside a level-3 perinatal unit was 57.9% overall, and rose with increasing gestational age, from 10.9% at 30 weeks to 69.0% at 36 weeks. Of the 6,587 livebirths outside a level-3 centre, 808 (12.3%) were transferred within the first 3 days after birth by NETS to a level-3 centre, the proportions falling with increasing maturity, being 73.7%, 48.5%, 28.4%, 26.9%, 18.8%, 11.8%, and 7.0% at 30, 31, 32, 33, 34, 35, and 36 weeks, respectively. These data may help medical practitioners when determining the place of delivery for infants 30-36 weeks' gestation.

Delivery Rooms↗
PubMed1997

Changes over time in attitudes to treatment and survival rates for extremely preterm infants (23-27 weeks' gestational age).

We determined the changes over time in attitude to treatment of very preterm infants (23-27 weeks of gestational age) born at the Royal Women's Hospital, Melbourne, and their survival rate. The subjects were consecutive livebirths at 23-27 weeks' gestational age born from 1983-1994, inclusive. The main outcomes measured were the proportions of livebirths treated intensively and survival rates to hospital discharge, both excluding lethal abnormalities. Over the 12 years of the study there were 788 livebirths free of lethal abnormalities born at 23-27 week's gestational age. Overall 669 (85%) were treated intensively; the proportions treated intensively rose significantly over time from 74% in 1983-1985 to 91% in 1992-1994, and with increasing gestational age, from 19% at 23 weeks to 100% at 27 weeks. Overall 439 (56%) survived their primary hospitalization; the survival rate rose significantly over time, from 43% in 1983-1985 to 70% in 1992-1994, and with increasing gestational age, from 3% at 23 weeks to 78% at 27 weeks. In 1992-1994, the survival rates were 11% at 23 weeks, 53% at 24 weeks, 70% at 25 weeks, 81% at 26 weeks, and 87% at 27 weeks. For infants treated intensively, the survival rate rose significantly from 53% in 1983-1985 to 76% in 1992-1994. The largest increases in survival have occurred in the 1990s, and at 24 and 25 weeks' gestational age. The proportions of very preterm infants treated intensively and their survival rates have increased over time, and have always been higher with increasing gestational age.

Attitude of Health Personnel↗
PubMed1997

Serum levels of müllerian inhibiting substance in preterm and term male neonates.

PURPOSE: Müllerian inhibiting substance, also called anti-müllerian hormone, is responsible in the embryo for the regression of the müllerian structures. During the second and third trimesters the physiological functions that müllerian inhibiting substance may have after the period of müllerian duct regression are poorly understood. We obtained information on müllerian inhibiting substance levels in the male newborn during this period of gestation. MATERIALS AND METHODS: Müllerian inhibiting substance was measured by an enzyme immunoassay in cord blood obtained at birth in 27 preterm (25 to 36 weeks of gestation) and 92 term (37 to 42 weeks) male neonates. RESULTS: Cord serum müllerian inhibiting substance concentrations were relatively high from 25 to 31 weeks (mean plus or minus standard deviation 86.4 +/- 36.1 ng./ml.) and then they decreased from 32 weeks to term (mean 24.2 +/- 14.0 ng./ml.). CONCLUSIONS: The decline early in the third trimester may be consistent with müllerian inhibiting substance having a function during the second but a diminished role in the third trimester.

Anti-Mullerian Hormone↗
PubMed1996

Passive smoking and respiratory function in very low birthweight children.

AIM: To determine if an adverse relationship exists between passive smoking and respiratory function in very low birthweight (VLBW) children at 11 years of age. SETTING: The Royal Women's Hospital, Melbourne. PATIENTS: 154 consecutive surviving children of less than 1501 g birthweight born during the 18 months from 1 October 1980. METHODS: Respiratory function of 120 of the 154 children (77.9%) at 11 years of age was measured. Exposure to passive smoking was established by history; no children were known to be actively smoking. The relationships between various respiratory function variables and the estimated number of cigarettes smoked by household members per day were analysed by linear regression. RESULTS: Most respiratory function variables reflecting airflow were significantly diminished with increasing exposure to passive smoking. In addition, variables indicative of air-trapping rose significantly with increasing exposure to passive smoking. CONCLUSION: Passive smoking is associated with adverse respiratory function in surviving VLBW children 11 years of age. Continued exposure to passive smoking, or active smoking, beyond 11 years may lead to further deterioration in respiratory function in these children.

Child↗
PubMed1996

Assisted ventilation and survival of extremely low birthweight infants.

OBJECTIVE: To determine the incremental consumption of ventilator resources associated with the improving survival rate of extremely low birthweight (ELBW birthweight 500-999g) infants, from the time assisted ventilation was introduced. METHODOLOGY: Cohort study of ELBW infants born in one tertiary perinatal centre (The Royal Women's Hospital, Melbourne). All ELBW infants born from 1971 to 1993 were included in the study. In hospital survival rates and patient-days of assisted ventilation were the main outcome measures. Discrete eras of relatively stable survival rate and consumption of ventilator resources were identified. These comprised the years 1971-74, 1977-83, 1985-90, and 1992-93. Cost-effectiveness ratios (the incremental consumption of ventilator resources per additional survivor) were calculated between adjacent eras by dividing the increment in the consumption of ventilator resources by the increment in the survival rate. RESULTS: The survival rates rose progressively between eras (6.2, 33.9, 49.1, 68.8%, respectively, as did the consumption of ventilator resources (0.1, 6.6, 16.2, 24.7 patient-days of assisted ventilation per livebirth, respectively). The cost-effectiveness ratio deteriorated initially, increasing from 23.2 to 63.5 additional patient-days of assisted ventilation per additional survivor, but then improved, falling to 43.1 additional patient-days of assisted ventilation per additional survivor in the last era. These changes were even more marked for those of birthweight 750-999g (20.0, 63.2 to 35.9 additional patient-days of assisted ventilation per additional survivor, respectively). In contrast, the cost-effectiveness ratio was initially worse for those of birthweight 500-749 g, being three-fold higher than for the larger infants, and only improved substantially in the last era (59.8, 58.3 to 44.1 additional patient-days of assisted ventilation per additional survivor, respectively). CONCLUSIONS: The initial deterioration in cost-effectiveness ratios between successive eras probably reflected the increased availability of resources for assisted ventilation, without any other major advances in perinatal care. The improvement in cost-effectiveness in the last era reflected, in part, the increased use of antenatal steroid therapy and the introduction of exogenous surfactant to neonatal intensive care.

Cohort Studies↗
PubMed1996

Late onset haemorrhagic disease in premature infants who received intravenous vitamin K1.

The clinical details are reported of two premature infants who developed late onset haemorrhagic disease after receiving their initial doses of vitamin K1 prophylaxis intravenously. Both reported infants had received two doses of intravenous vitamin K1, 0.1 mg, in the 1st week of life, and a further oral dose, 1.0 mg, at 4 weeks. Bleeding due to vitamin K deficiency occurred on days 74 and 84, respectively. Vitamin K deficiency bleeding is rare in low birthweight infants, probably because it has been routine practice to give such infants intramuscular vitamin K1. One of the reported infants had cytomegalovirus hepatitis, the other did not have liver disease. These findings could be explained if intramuscular vitamin K1 were to have a longer duration of effect than intravenous vitamin K1. This may be because intramuscular vitamin K1 acts as a depot preparation. The findings suggest that intravenous vitamin K1 is less effective than intramuscular for long-term prophylaxis against late onset haemorrhagic disease. Intravenous vitamin K1 should not be used for long-term prophylaxis in the prevention of late onset haemorrhagic disease.

Age of Onset↗
PubMed1996

Bronchopulmonary dysplasia and very low birthweight: lung function at 11 years of age.

OBJECTIVE: To determine the relationship between lung function at 11 years of age and bronchopulmonary dysplasia (BPD) in very low birthweight (VLBW) children. METHODOLOGY: This study comprised 154 consecutive surviving VLBW children, divided into three groups with respect to their neonatal respiratory morbidity: group I developed BPD; group II required assisted ventilation but did not develop BPD; and group III required no assisted ventilation. Lung function tests were measured on 120/154 (77.9%) children at 11 years of age. The relationship between various lung function variables and neonatal lung disease was analysed by multiple linear regression. RESULTS: Several lung function variables reflecting airflow were significantly diminished in the BPD group (n = 15), and residual volume was significantly higher. Despite poorer lung function overall, few children in the BPD group had lung function abnormalities in the clinically significant range (n = 2[13.3%] with a forced expired volume in 1 $ < 75% predicted; n = 2[13.3%] with a forced vital capacity < 75% predicted; n = 1 [6.7%] with a residual volume/total lung capacity > 35%). There were no significant differences in lung function variables between group II (n = 41) and group III (n = 64). Changes in lung function tests between 8 and 11 years did not very significantly between the three groups. CONCLUSIONS: VLBW children with BPD in the newborn period have period have poorer lung function at 11 years of age than other surviving VLBW children without BPD, although few have lung function abnormalities in the clinically significant range.

Bronchopulmonary Dysplasia↗
PubMed1995

Outcome to five years of age of children born at 24-26 weeks' gestational age in Victoria. The Victorian Infant Collaborative Study Group.

OBJECTIVE: To determine the outcome to five years of age of liveborn children born at 24-26 weeks' gestation. DESIGN: Regional cohort study of preterm children. SUBJECTS: Consecutive children liveborn at 24-26 weeks' gestation in Victoria from 1 January 1985 to 31 December 1987. MAIN OUTCOME MEASURES: Survival rates and rates of sensorineural impairment and disability at five years of age. RESULTS: 95 of 316 (30.1%) children survived to five years; survival rates increased with gestational age. 94 children (99%) were assessed at five or more years of age, corrected for prematurity. Twelve children had some form of cerebral palsy, causing a severe disability in only one. Two children required hearing aids for sensorineural deafness, five had bilateral blindness, and four were too disabled for intelligence quotient measurement. Overall, sensorineural disability was severe in seven (7.4%), moderate in seven (7.4%), mild in 23 (24.5%), and nil in 57 (60.6%) of children assessed. There was no trend to increasing disability with lower gestational age. CONCLUSIONS: The sensorineural outcome for this cohort is mostly favourable, and is better than that reported from some contemporaneous regional cohorts born in other parts of the world. The rates of sensorineural impairments, such as blindness and cerebral palsy, are higher than in non-preterm children but are not inordinately high, and most have no sensorineural impairment or disability.

Blindness↗
PubMed1995

Retinopathy of prematurity in infants weighing 1000-1499 g at birth.

OBJECTIVE: To review the incidence and severity of retinopathy of prematurity (ROP) in infants with birthweights 1000-1249 g and 1250-1499 g, to establish whether the upper weight limit for routine ophthalmological examination might safely be lowered. METHODOLOGY: Prospective cohort study of infants born between 1 January 1977 and 31 December 1992 cared for in the neonatal nurseries at the Royal Women's Hospital, Melbourne. Data were retrieved on 1373 infants who survived their initial hospitalization. They comprised 657 with birthweights 1000-1249 g (group 1) and 716 with birthweights 1250-1499 g (group 2). There were 76 outborn infants in group 1 and 97 in group 2; the remaining infants were all born at the Royal Women's Hospital. Ocular examinations commenced at 2 weeks of age, when possible, and at 2-weekly intervals after that. RESULTS: In group 1, ROP was detected in 14.6% (96/657) and severe ROP (bilateral stage 3-5) in 5.0% (33/657). Five (0.8%) children required surgical intervention (reaching threshold disease); following surgery, one was legally blind, one had severely impaired vision, and the other three had near-normal vision. Another child was blind; he was born at 28 weeks gestational age with a birthweight of 1170 g, and was transferred to a Level II hospital at 9 weeks chronological age with no detectable retinopathy. He returned 1 year later totally blind with detached retinae (grade 5 ROP). The prevalence of bilateral blindness in this group was 0.3% (2/657). In group 2, ROP was detected in 6.4% (46/716) and severe ROP in 0.8% (6/716). No children required surgery; three were found to be myopic at follow-up but the corrected visual acuity was normal. No children in group 2 were blind. No significant difference was found between the rates of ROP in inborn and outborn infants. CONCLUSION: In neonatal units with similar rates of ROP and visual outcome, routine ophthalmological examination in the neonatal nursery of infants weighing more than 1249 g at birth is probably unnecessary.

Birth Weight↗
PubMed1995

Retinopathy of prematurity in extremely low birth weight infants.

OBJECTIVE: To review the survival rate, the incidence and severity of retinopathy of prematurity (ROP), and the rate of blindness caused by ROP in extremely low birth weight (ELBW, birth weight 500 to 999 g) infants born between January 1, 1977, and December 31, 1992, and to determine whether increasing survival rates of ELBW infants are accompanied by an increase in the rates of severe ROP or blindness. DESIGN: Prospective cohort study of ELBW infants. Survival rates and visual outcomes were contrasted between children born in successive 8-year periods (1977 through 1984 and 1985 through 1992, inclusive). SETTING: The premature nurseries at the Royal Women's Hospital, Melbourne, a level-3 perinatal center. PATIENTS: Of 1001 inborn ELBW infants over the 16-year period, 457 (45.7%) survived their initial hospitalization: of the survivors, 434 (95.0%) were examined by the ophthalmologist, starting at 2 weeks of age if possible, then 2-weekly unit discharge. Children were reassessed after discharge at ages ranging from 1 to 10 years. RESULTS: Survival rates to hospital discharge rose significantly over time, from 34.5% (145/420) in 1977 through 1984, to 53.7% (312/581) in 1985 through 1992 (odds ratio [OR] 2.2, 95% confidence interval [CI] 1.7 to 2.8). Of the 434 surviving ELBW infants seen by the ophthalmologist, ROP was detected in 48.2% (68/141) in 1977 through 1984, which dropped significantly to 35.8% (105/293) in 1985 through 1992 (OR 0.6, 95% CI 0.4 to 0.9). Severe ROP (bilateral stages 3 to 5) was detected in 25.5% (36/141) in 1977 through 1984, and 17.7% (52/293) in 1985 through 1992, but the reduction was not quite statistically significant (OR 0.6, 95% CI 0.4 to 1.0). Bilateral blindness (visual acuity in each eye less than 6/60) caused by ROP occurred in only 4 (0.88%) survivors overall, 2 in each era. CONCLUSION: The increase in the survival rate of ELBW infants is not always accompanied by an increase in the rate of severe ROP or blindness, at least for ELBW infants born in some large level-3 centers.

Blindness↗