Stephen T. Kempley

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.

Early or Delayed Enteral Feeding for Preterm Growth-Restricted Infants: A Randomized Trial

BACKGROUND: Growth-restricted preterm infants are at increased risk of developing necrotizing enterocolitis (NEC) and initiation of enteral feeding is frequently delayed. There is no evidence that this delay is beneficial and it might further compromise nutrition and growth. METHODS: Infants with gestation below 35 weeks, birth weight below the 10th centile, and abnormal antenatal umbilical artery Doppler waveforms were randomly allocated to commence enteral feeds “early,” on day 2 after birth, or “late,” on day 6. Gradual increase in feeds was guided by a “feeding prescription” with rate of increase the same for both groups. Primary outcomes were time to achieve full enteral feeding sustained for 72 hours and NEC. RESULTS: Four hundred four infants were randomly assigned from 54 hospitals in the United Kingdom and Ireland (202 to each group). Median gestation was 31 weeks. Full, sustained, enteral feeding was achieved at an earlier age in the early group: median age was 18 days compared with 21 days (hazard ratio: 1.36 [95% confidence interval: 1.11–1.67]). There was no evidence of a difference in the incidence of NEC: 18% in the early group and 15% in the late group (relative risk: 1.2 [95% confidence interval: 0.77–1.87]). Early feeding resulted in shorter duration of parenteral nutrition and high-dependency care, lower incidence of cholestatic jaundice, and improved SD score for weight at discharge. CONCLUSIONS: Early introduction of enteral feeds in growth-restricted preterm infants results in earlier achievement of full enteral feeding and does not appear to increase the risk of NEC.

Doppler Flow Velocimetry in the Superior Mesenteric Artery on the First Day of Life in Preterm Infants and the Risk of Neonatal Necrotizing Enterocolitis

OBJECTIVE. The purpose of this work was to relate Doppler indices of splanchnic perfusion and vascular resistance to the risk of developing necrotizing enterocolitis. METHODS. We conducted a prospective cohort study with analysis of Doppler flow velocity waveforms of splanchnic vessels on the first day of life. Clinical management and diagnosis of necrotizing enterocolitis were performed blind to the Doppler results in a tertiary NICU on 64 eligible preterm neonates admitted for intensive care. We measured necrotizing enterocolitis using an objective diagnostic classification. RESULTS. When adjusted for gestational age at birth, the following indices of the Doppler flow velocity wave form in the superior mesenteric artery were significantly predictive of the risk of necrotizing enterocolitis: end-diastolic velocity, mean velocity, and pulsatility index. The association between necrotizing enterocolitis and Doppler velocimetry indicative of high vascular resistance was independent of a range of other factors and comorbidities (race, mode of delivery, umbilical arterial catheter, growth restriction, patent ductus arteriosus, jaundice, respiratory distress syndrome, mechanical ventilation, and hypotension). CONCLUSIONS. We concluded that neonates with high resistance patterns of blood flow velocity in the superior mesenteric artery on the first day of life are at increased risk of developing necrotizing enterocolitis.

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.

Endotracheal tube length for neonatal intubation.

OBJECTIVE In the newborn infant, accurate endotracheal tube (ETT) placement is essential for adequate ventilation and surfactant delivery. This study aimed to determine the relationship between gestation, weight and endotracheal tube length, and to evaluate the promotion of gestation-based guidelines for ETT length. DESIGN A prospective audit of endotracheal tube placement, followed by an education drive to 24 hospitals, and a subsequent repeat audit. SETTING Neonatal intensive care transfer service. PATIENTS Infants referred for inter-hospital transfer between 33 neonatal units. INTERVENTIONS Education drive to local hospitals to encourage use of standardised guidelines for ETT length based on gestation. MEASUREMENTS AND MAIN RESULTS Endotracheal tube length, radiological position with respect to thoracic vertebral bodies and radiological complications were assessed by neonatal transport team staff. The association between satisfactory ETT length and gestation was linear, whereas the relationship with weight was non-linear. In participating centres, use of gestation-based guidelines were associated with a reduction in tubes needing repositioning (8% vs. 53%, p<0.01) and in the incidence of uneven lung expansion (3% vs.17%, p<0.05). As use of gestation guidelines increased from 18% to only 32% overall, the intervention did not produce statistically significant changes in the entire patient population. CONCLUSION Use of gestation-based guidelines on ETT length for neonatal intubation was associated with a reduction in tube malposition and uneven lung expansion. A table of ETT length against gestation and weight is provided to assist those carrying out this procedure, which could be incorporated into neonatal resuscitation training.

Colonization and persistence of antibiotic-resistant Enterobacteriaceae strains in infants nursed in two neonatal intensive care units in East London, United Kingdom.

ABSTRACT Stool samples were collected from infants nursed in two neonatal intensive care units (NICUs) in East London, United Kingdom. The aim of the study was to determine the incidence of and risk factors for the carriage of multiresistant Enterobacteriaceae strains (MRE; resistant to three or more classes of antibiotic) and the extent of the persistence of resistant strains following discharge. Sixty-two (50%) of 124 infants had acquired MRE by 2 weeks of postnatal age, and 69 (56%) infants had acquired MRE by discharge. The proportions of infants at 2 weeks carrying strains that were resistant to antibiotics were the following: tetracycline, 79%; amoxicillin, 78%; cephalosporins, 31%; trimethoprim, 20%; piperacillin-tazobactam, 11%; chloramphenicol, 9%; and aminoglycoside, 4%. A gestational age of less than 26 weeks was a risk factor for colonization with MRE at discharge, but not at 2 weeks. Analysis within a NICU showed that exposure of an infant to a specific antibiotic in the NICU was not a risk factor for the carriage of a strain resistant to that antibiotic. Estimates of persistence from discharge to 6 months were the following: for tetracycline, 57% (95% confidence intervals [CI], 0.35 to 0.87); chloramphenicol, 49% (95% CI, 0.20 to 0.83); trimethoprim, 45% (95% CI, 0.22 to 0.74); piperacillin-tazobactam, 42% (95% CI, 0.20 to 0.71); and augmentin, 34% (95% CI, 0.11 to 0.66). Strains resistant to cephalosporins or aminoglycosides showed lower levels of persistence. Nine of 34 infants (26.5%) with Escherichia coli and 4 (7.1%) of 56 infants with Klebsiella spp. at discharge carried strains indistinguishable by randomly amplified polymorphic DNA and antibiotic susceptibility patterns at 6 months. MRE were found at high frequency in the infants during their stay in the NICU and persisted in a proportion of infants.

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.

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.

Early onset systemicCandida infection in extremely preterm neonates

Classically, systemicCandida infections in preterm neonates occur at a mean age of 1 month. Over an 18-month period in a Regional Neonatal Intensive Care Unit we encountered seven cases of severeCandida infection, all in babies below 26 weeks gestation and weighing less than 0.75 kg. The median age of onset was 7 days (range 0–17), with thrombocytopenia, coagulopathy, hypotension, oedema, and skin breakdown being prominent features.

Randomized trial examining cerebral haemodynamics following artificial or animal surfactant

To determine the effects of animal and artificial surfactants on cerebral haemodynamics, 20 premature babies receiving mechanical ventilation were randomized to receive Curosurf or Exosurf surfactant. Anterior cerebral artery blood flow velocity (CABFV) was measured using Doppler ultrasound before and up to 2 h after treatment. Following animal surfactant there was a rapid reduction in CABFV (median ‐36%, range ‐43% to +8%,p < 0:01), whereas artificial surfactant resulted in a slower rise which was less marked (median +20%, range ‐7% to +62%, p < 0:05). There were no significant changes in blood pressure. Two hours after administration, the oxygenation index (OI) improved significantly only in babies receiving animal surfactant. In this group there was a significant association between the change in CABFV at 1 min and the change in OI at 2 h (r = 0:66, p < 0:05). Animal surfactant produces rapid improvements in ventilation which are associated with marked alterations in cerebral haemodynamics.