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.

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.

Risk-adjusted comparisons of bloodstream infection rates in neonatal intensive-care units.

Comparisons of bloodstream infection (BSI) rates between neonatal intensive-care units (NICUs) should take into account differences in babies' vulnerability and invasive procedures that can introduce infection. Our aim was to investigate which risk factors recorded in routine records should be adjusted for when NICUs are compared. This was a retrospective cohort study using routine records for two London NICUs. We analysed rates of BSI with Poisson regression models. The level of neonatal care used by the National Health Service was the strongest predictor of BSI incidence. The rate ratios for BSI, adjusted for birthweight, inborn/outborn status, and postnatal age, were 3.15 (95% CI 2.01-4.94) for intensive care and 6.58 (95% CI 4.18-10.36) for high-dependency care, relative to special care. Total parenteral nutrition was significantly associated with BSI incidence, but explained less of the variance among babies than level of care. A case-control study with the same dataset gave similar results. Further multicentre studies are required to confirm our predictive model. Until then, we recommend that comparisons of BSI rates between NICUs should include adjustments for level of care, birthweight, inborn/outborn status, and postnatal age, with the use of routinely recorded standardized measures in hospital administrative data.

Levels of periodontal pathogens in neonatal gastric aspirates and possible maternal sites of origin.

Maternal periodontal infection has been recognized as a risk factor for preterm and low birthweight infants. It is suspected that pathogens causing periodontal disease may translocate to the amniotic cavity and so contribute to triggering an adverse pregnancy outcome. This study aimed to determine levels and proportions of periodontal bacteria in neonatal gastric aspirates obtained from complicated pregnancies and the respective maternal oral and vaginal samples using a quantitative polymerase chain reaction approach, and also to determine the origin of the neonate's bacteria by sequence comparisons between the three sites. Aggregatibacter actinomycetemcomitans and Tannerella forsythia were not observed in the neonates or in the women's vaginas. Interestingly, Porphyromonas gingivalis was identified in the neonates in two samples (2.98E+02 and 1.75E+02 cells ml(-1)) and in association with Fusobacterium nucleatum, which was observed at high prevalence (10%) and at high levels reaching up to 2.32E+03 cells ml(-1). Although F. nucleatum was also present in the vaginal samples, the results demonstrated that the neonatal strains were more likely to originate from the mother's oral cavity than to be vaginal strains.

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.

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.

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.

Endotracheal tube position in neonates requiring emergency interhospital transfer.

A malpositioned endotracheal tube (ETT) is common following initial intubation. This study assessed ETT position in 53 orotracheally intubated neonates referred for interhospital transfer during a 3-month period. Position of the ETT on first chest radiograph (CXR) after intubation was assessed and related to radiographic lung expansion, with documentation that the final ETT length had achieved a satisfactory position. At the time of first CXR, median ETT length at the lips was 7.0 cm (range, 5 to 12 cm) with median tip position at T3.0 (range, C7 to T6). The ETT required repositioning in 58% of patients. Most malpositioned tubes were too low (26 were withdrawn and only four were advanced; p < 0.001), with lung expansion more closely related to vertebral than clavicular position of the ETT. Final ETT length correlated well with corrected gestation ( r = 0.83; p < 0.01) and marginally less well with weight ( r = 0.79; p < 0.01). From the regression analysis, we provide a table of recommended tube lengths by gestation.

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.

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.

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.

Acute neonatal collapse resulting from pericardial effusion.

UNLABELLED: Two patients are described with acute collapse caused by pericardial effusion following central venous catheterisation. Echocardiography during resuscitation allowed prompt identification and management. CONCLUSION: Pericardial effusion should be considered in any baby experiencing acute deterioration with a central venous catheter in place.

The effects of synthetic and natural surfactant on fluid balance in acute respiratory distress syndrome.

UNLABELLED: To evaluate the effect of different surfactants on fluid balance in respiratory distress syndrome, we studied 24 premature infants who were randomised to receive either natural or synthetic surfactant. Data were collected on ventilatory parameters, daily urine output, daily weight, fluid intake and serum electrolytes. Ventilatory requirements decreased more rapidly in babies receiving natural surfactant, with significantly greater reductions in mean airway pressure from 1 to 48 h and oxygenation index from 1-18 h (P < 0.05). There were no differences in fluid intake and serum electrolytes. Mean daily urine output was higher in the group receiving natural surfactant (87 ml versus 61 ml, P < 0.05). This group also had a greater weight loss from birth weight (-146 g versus -65 g, P < 0.05). CONCLUSION: Natural surfactant produces an earlier reduction in ventilatory requirements with an earlier diuresis. This should influence fluid management in respiratory distress syndrome.