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Biomedical subjects

M L Chiswick

Publications and source records attributed to M L Chiswick.

At least 19 recordsLinked to original sources
PubMed1998

Increased survival and deteriorating developmental outcome in 23 to 25 week old gestation infants, 1990-4 compared with 1984-9.

AIMS: To assess whether changes in survival over time in infants of 23 to 25 weeks of gestational age were accompanied by changes in the incidence of disability in childhood during an 11 year period. METHODS: Obstetric and neonatal variables having the strongest association with both survival to discharge from a regional neonatal medical unit and neurodevelopmental disability in 192 infants of 23 to 25 weeks of gestation, born in 1984 to 1994, were studied as a group and in two cohorts (1984 to 1989 n = 96 and 1990 to 1994 n = 96). The data collected included CRIB (clinical risk index for babies) scores and cranial ultrasound scan findings. The children were followed up at outpatient clinics. RESULTS: Between 1984 and 1989 (cohort 1) and 1990 and 1994 (cohort 2) the rate of survival to discharge increased significantly from 27% to 42% and the rate of disability in survivors increased from 38% to 68%; most of this increase was in mild disability. The proportions of survivors with cerebral palsy did not alter significantly (21% vs 18%), but more survivors with blindness due to retinopathy of prematurity (4% vs 18%), myopia (4% vs 15%) and squints (8% vs 13%) contributed to the increased rate of disability. Clinically significant cranial ultrasound findings and a high CRIB score were strongly associated with death. A high CRIB score was most strongly associated with disability. CONCLUSIONS: The rise in disability with improved survival was not due to cerebral palsy; rather the main contributors were blindness due to retinopathy, myopia, and squint. The causes of these disabilities seem to be linked to high CRIB scores. A system of regular and skilled retinal examination and access to facilities for retinal ablation should be in place in all neonatal units which undertake the care of such extremely preterm infants.

Birth Weight↗
PubMed1997

Retinopathy of prematurity: systemic complications associated with different anaesthetic techniques at treatment.

BACKGROUND: Treatment of retinopathy of prematurity (ROP) in the UK is subject to considerable regional variation in terms of anaesthetic support. Change in practice at St Mary's neonatal medical unit from topical to general anaesthesia and, subsequently, to sedation/analgesia allowed comparison of the impact of these three modalities on infants' early postoperative course in a consecutive, non-randomised, observational study. METHODS: The study population consisted of 30 babies undergoing treatment of threshold ROP. Twelve were treated using topical anaesthesia alone (group A), six using general anaesthesia (group B), and 12 using sedation/analgesia combined with elective intubation and artificial ventilation (group C). Daily measurements of infant health were recorded starting 4 days preoperatively and continuing for 7 days postoperatively to facilitate the formulation of a cardiorespiratory stability index as follows: (0) improvement from baseline, (1) no change from baseline, (2) mild instability, (3) marked instability, and (4) life threatening event. RESULTS: Within the first 48 hours postoperatively in group A 5/12 showed mild instability and 4/12 showed marked instability (including three babies suffering life threatening events requiring emergency resuscitation). In group B within the first 48 hours postoperatively 1/6 showed mild and 1/6 showed marked instability, and in group C 5/12 babies showed mild instability alone. There was a significant difference for cardiorespiratory stability scores between the three groups overall for the 7 days postoperatively (repeated measures ANOVA, p = 0.018). CONCLUSIONS: Premature infants undergoing cryotherapy for ROP who were treated using topical anaesthesia alone had more severe and protracted cardiorespiratory complications.

Anesthetics↗
PubMed1995

Blood pressure, heart rate, and skin temperature in preterm infants: associations with periventricular haemorrhage.

The mean arterial blood pressure (MABP), heart rate, and skin temperature were monitored every 15 minutes in the first 10 days after birth in 34 preterm infants, gestational age 24 to 33 weeks. Ultrasound brain scans carried out daily showed that a periventricular haemorrhage (PVH) occurred in a subgroup of infants (n = 15) of lower birthweight and gestational age. In infants without PVH the daily median of MABP increased with birthweight and postnatal age; that of heart rate was not affected by postnatal age, body weight, or gestational age; and that of skin temperature showed a slight fall with postnatal age. In infants with PVH, on or before the day of PVH, daily medians of MABP and skin temperature were not significantly different from those of infants without PVH, but the daily median of heart rate tended to be slightly higher. The percentage of positive correlations between the 96 15 minute values per day for heart rate and MABP increased with postnatal age and with birthweight, but did not differ in infants who developed a PVH. The coefficient of variation (CV) of the 96 15 minute values for MABP tended to be higher in infants on the day of PVH, and a similar trend was apparent on the day before. The processes of development of blood pressure, heart rate, and skin temperature are similar in infants with or without PVH but at lower gestational ages altered blood pressure control may cause brain haemorrhage.

Birth Weight↗
PubMed1993

Measurement of ionised calcium concentration in neonates.

Whole blood ionised calcium concentration was measured simultaneously in capillary and arterial blood from neonates being nursed on an intensive care unit using an ion selective electrode. The mean arterio-capillary difference was -0.027 mmol/l (95% confidence intervals -0.041 to -0.012 mmol/l) and the limits of agreement between the two measurements were 0.034 and -0.088 mmol/l. Measurement of ionised calcium in capillary blood is acceptable for clinical purposes.

Arteries↗
PubMed1992

Skin temperature and heart rate rhythms in infants of extreme prematurity.

Nine preterm infants of 26 to 29 weeks' gestational age and 792 to 1200 g birth weight spent six to 17 weeks in our neonatal medical unit. Hourly recordings of skin temperature and heart rate were carried out. The first five to 15 weeks were spent in the intensive care ward, in continuous light, due to various medical conditions. After recovery they were moved to a nursery for one to nine weeks, with 12 hourly periods of light and darkness. Four infants developed circadian rhythms in temperature and three in heart rate in light-dark periods, the remainder failing to do so. Some infants take longer than others to develop circadian rhythms but the reasons for this are not clear. It is suggested that earlier exposure to a light-dark environment may synchronize the 'body clock' to a 24 hour period in more preterm infants.

Circadian Rhythm↗
PubMed1991

Gastrointestinal blood flow velocity after the first feed.

Twenty preterm infants (gestational age range 27-36 weeks) who had never been fed enterally were studied. Doppler indices of flow velocity from the superior mesenteric and coeliac arteries were measured immediately before, and at postprandial time intervals up to 60 minutes after, a first feed of 1 ml of milk given through a nasogastric tube. There were no significant differences between the preprandial and postprandial values of blood pressure, heart rate, oxygen and carbon dioxide tensions, and pH. The median peak systolic velocity (PSV) (55.9 cm/sec) and time average mean velocity (TAV) (10.6 cm/sec) before the feed at the superior mesenteric artery rose progressively and significantly to postprandial peaks of 88.5 cm/sec and 20.5 cm/sec at 45 minutes, respectively. Significant postprandial rises in the median PSV and TAV values at the coeliac artery were also observed, with a peak at 45 minutes. There were no significant correlations between blood flow velocity indices (preprandial or postprandial) and gestational age, postnatal age, conceptional age, or birth weight. We conclude that the first exposure of preterm babies to a small volume of milk feed is associated with postprandial changes in blood flow velocity consistent with an increase in blood flow in the superior mesenteric and coeliac arteries, although the mechanism of this response is uncertain.

Blood Flow Velocity↗
PubMed1990

Developmental delay in congenital myotonic dystrophy after neonatal intensive care.

Six infants with congenital myotonic dystrophy survived after neonatal intensive care. In later childhood they were assessed by the Griffiths Mental Development Scales: five children were functioning in the mildly handicapped to borderline range of development (DQ 64.0 to 79.0) and the remaining child was severely delayed in development (DQ 33.0). The five children with higher DQ values had a history of ventilatory support of 30 days or less after birth. By contrast, the remaining child with the lowest DQ value had been ventilated for 43 days. This study provides further evidence that prolonged ventilation after birth has prognostic significance in identifying severely affected cases with congenital myotonic dystrophy.

Child, Preschool↗
PubMed1990

Ischaemic brain lesions diagnosed at birth in preterm infants: clinical events and developmental outcome.

In 232 newborn babies of less than 32 weeks' gestational age ultrasound brain scans were carried out shortly after birth, daily for the first week of life, and at least twice weekly thereafter. Periventricular echogenicity associated with or progressing to periventricular leukomalacia (ischaemic brain lesions) was present in nine babies within two hours of birth (early onset); 30 other babies subsequently developed similar lesions (late onset). Babies with early onset lesions were more likely to have a history of intrauterine growth retardation and to have recurrent apnoea in the first few hours after birth. By contrast, late onset lesions were associated with hyaline membrane disease. In later childhood four of six survivors with early onset periventricular leukomalacia, and seven of 14 survivors with late onset periventricular leukomalacia, had various disabilities including spastic diplegia, impaired vision, squints, sensorineural hearing loss, and developmental delay. In a third of the children with disabilities ischaemic brain lesions were noted within two hours of birth, raising the possibility that some of this damage had taken place before or during birth.

Brain↗
PubMed1990

Skin conductance and arousal in the newborn.

We measured skin conductance continuously from the sole of a foot in babies of different conceptional ages before, during, and for 10 minutes after a 'heel prick' carried out for routine blood sampling. We studied 82 healthy babies whose gestational and postnatal ages ranged from 25-42 weeks, and 1-73 days. The median skin conductance level (preheel prick) in babies of 40-43 weeks' conceptional age was 0.6 microS (microsiemens) and differed significantly between awake babies (1.2 microS) and those who were asleep (0.5 microS). In contrast babies less than 40 weeks had a significantly lower median skin conductive level (0.3 microS) which was identical in awake and asleep babies. In response to the heel prick all babies became aroused and skin conductance rose sharply and immediately in 21 out of 22 (95%) babies 40-43 weeks' conceptional age, and in seven out of 23 (30%) babies 36-39 weeks. The median rise at one minute in babies of 40-43 weeks was significantly higher than those 36-39 weeks (2.7 microS compared with 0.5 microS). No babies less than 36 weeks had a change in their skin conductance after the heel prick. These results are consistent with the notion that 'emotional sweating' is a function of maturity and does not develop until 36 weeks' conceptional age.

Arousal↗