A gestation- and postnatal age-based reference chart for assessing renal function in extremely premature infants.

OBJECTIVE: A single value of plasma creatinine cannot be used to define renal dysfunction in premature babies, as levels are influenced by gestation and postnatal age. The aim of this study was to create reference ranges for plasma creatinine in cohort of extremely premature infants. STUDY DESIGN: Retrospective analysis of plasma creatinine levels in the first 8 weeks of life from 161 consecutively admitted premature infants 28 weeks gestation. RESULT: Babies were divided into three groups according to gestation. Peak (10th, 90th percentiles) creatinine levels were 132 (106,162) in 22 to 24 weeks gestational infants, 127 (89,151) in those from 25 to 26 weeks and 110 (87,134) in those from 27 to 28 weeks (P<0.001). Creatinine at birth was similar across the groups with levels increasing during the first few days. It decreases thereafter before reaching stable levels by 5 weeks of age. CONCLUSION: Gestation- and age-based reference charts should be used for interpretation of creatinine values in extremely premature babies.

Critical dependence of acetate thermal mattress on gel activation temperature.

BACKGROUND: Sodium acetate gel mattresses provide an active method of warming patients through release of latent heat of crystallisation. They can be used as an adjunct to incubator care or as an exclusive heat source. OBJECTIVE: To determine activation temperatures of the Transwarmer mattress needed to achieve plateau temperatures of 38-42 degrees C. DESIGN AND SETTING: In vitro testing of mattress temperature. METHODS AND OUTCOME MEASURES: Transwarmer mattresses were activated at initial temperatures ranging from 5 to 40 degrees C. Mattress temperature was recorded up to 4 h to determine peak and plateau temperatures. Peak and plateau temperatures achieved by the mattress were related to the initial starting temperature. RESULTS: The starting temperature of the mattress was strongly correlated with peak and plateau temperature (r = 0.99, p<0.001). To achieve the target temperature of 38-42 degrees C, the Transwarmer mattress requires activation between 19.2 degrees C and 28.3 degrees C. A temperature of 37 degrees C could be generated by activation at 17 degrees C. CONCLUSIONS: Safe use of this device is critically dependent on gel temperature at the point of activation. To ensure warming of a hypothermic neonatal patient without running any risk of burns, the mattress should be activated with a gel temperature between 19 degrees C and 28 degrees C.

Effect of a centralised transfer service on characteristics of inter-hospital neonatal transfers.

OBJECTIVE: To determine the effect of a centralised neonatal transfer service on numbers of neonatal transfers and the time taken for teams to reach the baby. DESIGN: Prospective census of neonatal inter-hospital transfers between May and July 2004. Comparison with a previous census undertaken before introduction of the service. Analysis of requests for antenatal in-utero transfer to the regional emergency bed service. SETTING: Geographically defined area in London and southeast England. PATIENTS: Babies transferred to or from a neonatal unit. INTERVENTIONS: Introduction of a centralised neonatal transfer service. MAIN OUTCOME MEASURES: Numbers of transfers, time taken for teams to arrive to the baby (response time). RESULTS: During the census there were 835 transfers with an increase of 34% from the previous census (n = 619). Most of the increase was in urgent transfers for neonatal intensive care. There was a mean of 4.4 urgent transfers a day, with 3.9 elective and 0.8 short-term transfers. Over the same period in-utero transfers decreased. Response times improved from a median of 2 h in 2001 to 1.45 h in 2004 (p<0.05). The 90th centile fell from 6 h to 4.9 h. CONCLUSION: Following the introduction of a centralised neonatal transfer service, response times improved significantly. An increase in the numbers of transfers for medical intensive care was associated with a reduced number of in-utero transfers. To balance the improved safety and accessibility of neonatal transfer, similar developments may be needed to facilitate in-utero transfer.

Impact of volume guarantee ventilation on arterial carbon dioxide tension in newborn infants: a randomised controlled trial.

OBJECTIVE: To compare the effects of the two modes of ventilation, synchronous intermittent positive pressure ventilation (SIPPV) and SIPPV with Volume Guarantee (VG), on arterial carbon dioxide tension (PaCO(2)) immediately after neonatal unit admission. STUDY DESIGN: Randomised study of ventilation mode for premature inborn infants admitted to two tertiary neonatal units. After admission, infants were randomised to receive either SIPPV or VG using a Dräger Babylog 8000 plus ventilator. In the SIPPV group, peak airway pressure was set clinically. In the VG group, desired tidal volume was set at 4 ml/kg, with the ventilator adjusting peak inspiratory pressure to deliver this volume. The study was completed once the first arterial PaCO(2) was available, with the desirable range defined as 5-7 kPa. RESULTS: PaCO(2) was significantly higher in the VG group (VG: 5.7 kPa, SIPPV: 4.9 kPa; p=0.03). The VG group had fewer out-of-range PaCO(2) values (VG: 42%, SIPPV: 57%) and fewer instances of hypocarbia <5 kPa (VG: 32%, SIPPV: 57%) but neither difference achieved statistical significance. Regression analysis showed PaCO(2) was negatively correlated with gestation (r=-0.41, p=0.01) and also with the mode of ventilation (r=0.32, p<0.05). In the VG group, all infants 23-25 weeks' gestation had out-of-range PaCO(2) values. VG significantly reduced the incidence of out-of-range PaCO(2) and hypocarbia in infants over 25 weeks' gestation (VG: 27%, SIPPV: 61%; p<0.05). CONCLUSION: Using this strategy, VG appears feasible in the initial stabilisation of infants over 25 weeks' gestation, with a halving of the incidence of hypocarbia. In the small number of babies studied below this gestation, VG was not found to be effective.

Blood flow in the common carotid artery in term and preterm infants: reproducibility and relation to cardiac output.

AIM: To assess the reproducibility of, and determine normative data for, flow volume measurements from the right common carotid artery (CCA) and its relation to left ventricular output (LVO) in stable term and preterm babies using Doppler ultrasound. METHODS: Right CCA flow volume was measured using a near focus, high frequency transducer by obtaining intensity weighted mean velocity and right CCA diameter. LVO was determined using standard Doppler techniques. Reproducibility studies were performed on 30 newborn infants by two observers. Normative data were obtained from 40 spontaneously breathing preterm babies and 21 term babies. RESULTS: The intraobserver coefficient of variation for CCA flow measurements was 10.5% for observer 1 and 15.4% for observer 2, whereas the interobserver coefficient of variation was 16.4%. In term and preterm infants, right CCA flow was about 20 ml/kg/min, accounting for 11% of cardiac output. Among the preterm infants, there was a positive correlation of right CCA flow with gestation (r = 0.61, p<0.001), weight (r = 0.64, p<0.001), and LVO (r = 0.59, p<0.001). Right CCA diameter also increased with weight (r = 0.63, p<0.001) and gestation (r = 0.58, p<0.001). The proportion of LVO distributed to the right CCA did not increase with gestation, nor did the right CCA flow per kg body weight. CONCLUSIONS: It is possible to perform reproducible measurements of flow volume in the CCA of newborn infants. In stable, spontaneously breathing babies, both cardiac output and carotid flow increased with gestation and body weight. The proportion of cardiac output distributed to the right CCA remained relatively constant across gestation.

Feeding growth restricted preterm infants with abnormal antenatal Doppler results.

Absence or reversal of end diastolic flow (AREDF) in the umbilical artery is associated with poor outcome, and elective premature delivery is common. Feeding these infants is a challenge. They often have poor tolerance of enteral feeding, and necrotising enterocolitis may develop. This review explores current practice to see if there is evidence on which to base guidelines. The incidence of necrotising enterocolitis is increased in infants with fetal AREDF, especially when complicated by fetal growth restriction. Abnormalities of splanchnic blood flow persist postnatally, with some recovery during the first week of life, providing justification for a delayed and careful introduction of enteral feeding. Such a policy exposes babies to the risks of parenteral nutrition, with no trials to date showing any benefit of delayed enteral nutrition. Trials are required to determine the optimum timing for introduction of enteral feeds in growth restricted infants with fetal AREDF.

Antibiotic treatment duration and prevention of complications in neonatal Staphylococcus aureus bacteraemia.

BACKGROUND: In adults with Staphylococcus aureus bacteraemia, short duration of effective antibiotic treatment is associated with increased risk of complications and recurrence. The optimum duration of treatment for neonates is unknown and practice varies widely. AIM: To relate the duration of treatment of neonatal S. aureus bacteraemia to prevention of complications and recurrence. METHODS: Retrospective cohort study of confirmed S. aureus bacteraemia occurring over a 10 year period in two large tertiary neonatal units. Neonatal patients developing confirmed S. aureus bacteraemia between birth and discharge from the neonatal unit were identified from microbiology department records. Clinical details obtained from case notes included demographics, duration of antibiotics and clinical outcomes. Recurrence was determined from laboratory and clinical records. Adverse outcomes were related to duration of antibiotic therapy. FINDINGS: A total of 90 infants had S. aureus bacteraemia, of which six were meticillin-resistant S. aureus (7%). Median gestation was 27 weeks (range: 23-41), birth weight 846 g (434-3840) and postnatal age 16 days (0-116). Adverse outcomes were found in 44%, with death in 8%. Median duration of appropriate antibiotics was 19 days (range: 0-54). There were no cases of recurrent bacteraemia after finishing antibiotics. There was no relationship between antibiotic duration and complications. CONCLUSION: Neonatal S. aureus bacteraemia mainly affected preterm neonates and had a significant morbidity and mortality. Recurrent bacteraemia was rare, irrespective of treatment duration. For neonatal unit patients with S. aureus bacteraemia, antibiotic therapy for 14 days in uncomplicated cases may be sufficient to prevent recurrence, with longer treatment justified if there is inadequate source control.

Molecular epidemiology and significance of a cluster of cases of CMV infection occurring on a special care baby unit.

Sequencing of the amino-terminal region of the glycoprotein H gene was used to investigate the possibility of a common source for cytomegalovirus (CMV) infection occurring in five premature babies. All but two of the strains were different, indicating that this cluster of infection occurring on the special care baby unit was unlikely to be epidemiologically linked.

Birth weight and special educational needs: effects of an increase in the survival of very low birthweight infants in London.

OBJECTIVES: To assess the contribution of children with different birth weights to special educational needs within a single health district, and to determine whether this pattern changed over the time when the survival of very low birthweight (VLBW) infants was increasing. SETTING: An inner London health district. STUDY DESIGN: A cohort of children born to local parents between January 1974 and December 1980 was selected from birth notifications, including only those infants who survived for more than one month. Community child health records were then inspected to identify children from the cohort who had been formally assessed for special educational needs before their 8th birthday. The risk of special educational needs was compared for the years 1974-77 and 1977-80 (the first and second halves of the period studied). SUBJECTS: The infant cohort consisted of 31,846 children. Altogether 260 (0.8%) of these were later assessed formally. RESULTS: VLBW infants were 4.4 times more likely to be assessed than normal birthweight infants. Formal assessment within the district occurred in three of 68 VLBW infants from the first half of the period studied, and three of 120 from the second half. CONCLUSION: Although VLBW infants are at higher risk, an increase in their survival was not associated with any increase in their contribution to the group with special educational needs within our district. Their contribution, as a group, to the total number of children with special educational needs is very small.

Splanchnic haemodynamic disturbances in perinatal sepsis.

AIM: To determine the effect of perinatal bacterial infection on the neonatal splanchnic circulation. SUBJECTS/SETTING: 76 premature infants with appropriate birth weight for gestation admitted for neonatal intensive care. METHODS: Doppler ultrasound was used to measure blood flow velocity and pulsatility index in the superior mesenteric artery and coeliac axis during the first 24 hours of life. Babies were classified according to the results of blood and surface cultures, as well as the presence or absence of maternal prolonged membrane rupture. RESULTS: Infection status had a significant effect on pulsatility index in both arteries, with that in the coeliac axis being reduced from 1.27 to 0.80 in babies with infection (p < 0.0001). Coeliac axis blood flow velocity was significantly increased in those with infection (from 34.6 to 46.5 cm/s; p < 0.05). CONCLUSION: As early as the first day of postnatal life, infected neonates show a pattern of splanchnic hyperaemia similar to that found in adult systemic inflammatory response syndrome.

Census of neonatal transfers in London and the South East of England.

OBJECTIVES: To determine the number and characteristics of inter-hospital transfers of newborn infants in London and the South East of England. DESIGN: Prospective census of neonatal transfers over a three month period. SETTING: Transfers between the 53 hospitals that provide care for newborn infants within the former Thames regions. DATA SOURCES: Census returns from participating neonatal units. MAIN OUTCOME MEASURES: Number, timing, and hours of staff time spent on transfers. Gestation, birth weight, and reason for transfer of the baby. Time elapsed between request and retrieving team departing and arriving with patient. RESULTS: A daily average of 2.7 urgent, 3.5 elective, and 0.7 short term transfers took place during the census period. The most common reason for urgent transfer was neonatal surgery. Neonatal unit staff spent an average of 21 hours a day off their units accompanying transfers each day. It took over four hours for 90% of ambulances to set off with the retrieving team and over six hours for 90% of teams to reach the baby. CONCLUSIONS: During the census period, services for the transport of neonates in London and the South East of England involved long delays and used appreciable amounts of staff time. It is likely that a small number of dedicated neonatal transfer teams could meet the needs identified in this census more effectively than the 53 hospitals currently involved.

Congenital primitive neuroectodermal tumour presenting as obstructed labour.

Brain tumours presenting at delivery are extremely rare. A case of primitive neuroectodermal tumour (PNET) that presented intrapartum with failure to progress due to hydrocephalus is reported. Diagnosis required imaging with magnetic resonance and computed tomography in addition to open biopsy.

Prediction of early tolerance to enteral feeding in preterm infants by measurement of superior mesenteric artery blood flow velocity.

AIMS: To evaluate whether serial Doppler measurements of superior mesenteric artery (SMA) blood flow velocity after the first enteral feed could predict early tolerance to enteral feeding in preterm infants. METHODS: When clinicians decided to start enteral feeds, Doppler ultrasound blood flow velocity in the SMA was determined before and after a test feed of 0.5 ml milk. The number of days taken for infants to tolerate full enteral feeding (150 ml/kg/day) was recorded. RESULTS: Fourteen infants (group 1) achieved full enteral feeding within seven days. Thirty infants (group 2) took 8-30 days. There was no difference in the preprandial time averaged mean velocity (TAMV) between the groups at a median age of 3 (2-30) days. In group 1, there was a significant increase in TAMV (p<0.01) above the preprandial level at 45 and 60 minutes, but this did not occur in group 2. An increase in TAMV by more than 17% at 60 minutes has a sensitivity of 100% and a specificity of 70% for the prediction of early tolerance to enteral feeds. CONCLUSIONS: There is a significant correlation between an increase in mean SMA blood flow velocity and early tolerance of enteral feeding. Doppler measurements of SMA blood flow velocity may be useful for deciding when to feed high risk preterm infants.

Arterial blood pressure and blood flow velocity in major cerebral and visceral arteries. I. Interindividual differences.

In order to determine the relationship between blood pressure and arterial blood flow velocity in various regional circulations, Doppler ultrasound measurements of blood flow velocity were recorded on the first day of postnatal life from the anterior cerebral (ACA), superior mesenteric, coeliac axis and left renal artery. In 34 ventilated very low birth weight (VLBW) infants, results were correlated with arterial blood pressure and blood gases in a multiple regression model. ACA velocity was correlated with blood pressure (r = 0.70) and PaCO2 (r = 0.64), but there was no relationship between blood pressure and velocity in the other arteries. Repeated measurements were performed at one week of age in 15 infants. Blood flow velocity in the cerebral and renal arteries was related to blood pressure; velocity in the cerebral arteries was inversely correlated with PaO2 and velocity in the coeliac and mesenteric arteries was positively correlated with PaO2. In VLBW infants on the first day of life, blood flow velocity is related to blood pressure in the cerebral circulation only.

Arterial blood pressure and blood flow velocity in major cerebral and visceral arteries. II. Effects of colloid infusion.

To compare the effects of acute changes in blood pressure on arterial blood flow velocity in various regional circulations, Doppler ultrasound measurements of blood flow velocity were recorded from the anterior cerebral artery (ACA), superior mesenteric artery, coeliac axis and left renal artery. Measurements were obtained from 10 ventilated very low birth weight infants before and after plasma infusions given to treat systemic hypotension on the first day of postnatal life. Blood pressure increased in 8/10 infants, and in this group there was a significant increase in ACA and coeliac axis blood flow velocity. For the ACA only, there was a significant association between the change in blood flow velocity and the magnitude of the change in blood pressure (r = 0.73, P < 0.02). Mesenteric and renal artery velocity did not increase after the infusion. For ventilated VLBW infants on the first day of life, arterial blood flow velocity was affected by acute changes in blood pressure in the cerebral circulation only.

Cerebral and renal artery blood flow velocity before and after birth.

OBJECTIVE: To document perinatal changes in cerebral and renal artery haemodynamics in premature growth-retarded and normal term infants. DESIGN: Longitudinal study of individual infants. Doppler ultrasound measurements of blood flow velocity (BFV) in the middle cerebral and renal arteries were obtained before delivery, soon after delivery and during the first week of postnatal life. SETTING: Teaching hospital obstetric and neonatal units. SUBJECTS: 13 severely growth retarded infants born at 28-36 weeks gestation, and eight normally grown infants born at term. RESULTS: In both groups, BFV in the cerebral artery was significantly lower in the first few hours after birth than in fetal life, but subsequently increased to reach pre-delivery values by the end of the first week. In contrast, BFV in the renal artery during the first postnatal day was not significantly different from fetal values, but it also increased during the subsequent week. In six of the preterm growth-retarded infants, fetal blood gases were measured in samples obtained by cordocentesis, and in these cases an increase in blood oxygen content at birth was documented. CONCLUSIONS: Cerebral artery BFV falls at birth and is relatively low during the time that premature infants are at the greatest risk of developing periventricular haemorrhage.

Relation of maternal ethnicity to infant birthweight in east London, England.

OBJECTIVE: We sought to determine whether black race is a risk factor for very low birthweight in a developed country other than the United States. DESIGN: A cross-sectional study was performed. SETTING: We analyzed a dataset of 1987-1990 birth records from three hospitals in East London, England. PARTICIPANTS: All live born African (N = 3,495), West Indian (N = 3,471), and European white (N = 20,313) singleton infants born to East London residents. MAIN OUTCOME MEASURES: For each ethnic group, we calculated the proportion of very low birthweight (< 1500g) and moderately low birthweight (1500-2499g) infants. RESULTS: The very low birthweight rate was 2.9% for infants of West Indian descent and 2.2% for infants of African descent vs. 1.3% for European whites; odds ratio (95% confidence interval) = 2.1(1.7-2.8) and 1.8(1.2-3.1), respectively. West Indian and white mothers were similar in terms of age, social support, and prenatal care. African mothers were older and had less social support. The West Indian:white and African:white differentials in very low birthweight rates persisted among low risk mothers; odds ratio (95% confidence interval) = 2.7(1.7-4.0) and 2.3(1.5-3.6), respectively. CONCLUSIONS: We conclude that black race is a risk factor for very low birthweight in the United Kingdom.

Are patients with antenatally diagnosed hydronephrosis being over-investigated and overtreated?

BACKGROUND: It is usually recommended that neonates with antenatally diagnosed hydronephrosis are put on prophylactic antibiotics and undergo the following investigations--ultrasound, MCU and a radio-isotope renogram. OBJECTIVE: To question the need for such an extensive protocol in antenatally diagnosed hydronephrosis on the basis of an improved understanding of this condition. METHODS: Over a 3-year-period, persistent postnatal hydronephrosis was seen in 42 neonates; in 12 it was bilateral. Antibiotic prophylaxis was stopped in the unilateral cases. An MCU was done mainly in the following circumstances: bilateral hydronephrosis, dilated ureter(s) or presence of UTI. A renogram was avoided if the AP diameter of the renal pelvis was below 15 mm and the calyces were not dilated. RESULTS: 1) The AP diameter of the pelvis was recorded in 40 renal units as follows--< 15 mm--22, 15-20 mm--10, 20-40 mm--6, > 40 mm--2. Both the patients in the latter group needed a pyeloplasty--their AP diameter exceeded 8 cms and an RNS showed depressed function. 2) In those patients who did not receive antibiotics or had a MCU, none has had a UTI. 3) Four unilateral hydronephrotic kidneys showed a paradoxical supranormal function, ranging from 54-60%. The contralateral kidney was completely normal on the RNS. CONCLUSION: 1) The vast majority of antenatally diagnosed hydronephrosis have a benign course, only 2/54 or 3.7% required a pyeloplasty. 2) Invasive investigations like an MCU are not necessary in most cases. 3) Routine antibiotic prophylaxis is not required in all unilateral cases and in bilateral ones after VUR has been excluded.

The effects of priming with regularly and irregularly related words in auditory word recognition.

The experiment examines the effects of relatively long-term (10-40 minutes) priming on the recognition of spoken words presented in noise. The focus of the experiment was the extent to which the priming was lexical (i.e. whole word), morphological or physical. First, no priming was found for physically related words. Thus 'deflecting' spoken clearly in the pre-training task had no effect on the identification of 'reflecting' in the test phase. Second, there was very strong facilitation from a word with a regular inflectional relationship to the test word. Thus the word 'reflected' facilitated recognition of 'reflecting' almost as much as prior experience of 'reflecting' itself and, when responses were scored in terms of the root morpheme, counting 'reflect', 'reflects' and 'reflected' etc. as being correct, the morphemic effect was the same in the two cases. That this was a structural and not a semantic effect was shown by the complete lack of facilitation between irregularly related words such as 'held/holding', 'man/men', 'lost/loses'. These data suggest that there is a morphological/structural level of analysis which is pre-semantic, at which these long-term facilitation effects take place. They also pose a challenge to the cohort theory of word recognition.

Development of maternal and neonatal composite outcomes for trials evaluating management of late-onset pre-eclampsia.

OBJECTIVE: Pre-eclampsia is associated with significant maternal and neonatal complications, and delivery is often expedited to minimise complications. For randomised trials evaluating interventions in women with late-onset (>34 weeks) mild to moderate pre-eclampsia, no single outcome has been identified to be the most clinically important. Existing composite outcomes with more than one clinically relevant endpoint to evaluate interventions in pre-eclampsia provide limited justification for selection of the components. Our objective was to develop robust, valid composite maternal and neonatal outcome measures for clinical trials evaluating interventions in women with late-onset mild and moderate pre-eclampsia. STUDY DESIGN: A two-generational Delphi method was used to identify these clinically important maternal and neonatal outcomes. Composite outcomes were developed based on biological plausibility, independence from each other, frequency of occurrence and level of importance. RESULTS: The final maternal composite outcome included maternal death, eclampsia, stroke or reversible ischaemic neurological deficit, pulmonary oedema, major obstetric haemorrhage, need for positive inotropic support, haemolysis, elevated liver enzymes and low platelets syndrome and placental abruption; and the neonatal composite outcome included neonatal death, respiratory distress syndrome needing ventilator support and neurological outcomes as cystic periventricular leukomalacia and grade III/IV intraventricular haemorrhage. CONCLUSION: The composite outcomes developed will enable clinical trials to provide robust estimates on the effectiveness of the interventions in women with mild to moderate late onset pre-eclampsia to inform clinical practice. Caution is needed in the interpretation of composite outcomes due to variation in the importance of individual components.