Effect of Bias Gas Flow on Tracheal Cytokine Concentrations in Ventilated Extremely Preterm Infants: A Randomized Controlled Trial.

BACKGROUND: The objective of this study was to determine whether ventilator bias gas flow affects tracheal aspirate (TA) cytokine concentrations in ventilated extremely preterm infants. METHODS: This is a randomized controlled trial in a tertiary neonatal unit in New Zealand. Preterm infants (<28 weeks' gestation/<1,000 g) requiring intubation in the first 7 days after birth were randomized to bias gas flows of 4 or 10 L/min. Cytokine concentrations in TA and plasma were measured at 24, 72, and 120 h after the onset of ventilation. The primary outcome measure was concentration of interleukin (IL)-8 in TA 24 h after the onset of mechanical ventilation. RESULTS: Baseline demographics were similar in babies randomized to 4 (n = 50) and 10 (n = 45) L/min bias gas flow. TA IL-8 concentrations were not different between groups. Plasma IL-8 concentrations decreased over time (p < 0.05). Respiratory support and incidence of bronchopulmonary dysplasia at 36 weeks' corrected gestational age were similar between groups. Fewer babies ventilated at 4 L/min developed necrotizing enterocolitis (NEC) ≥ stage 2 (n = 0 vs. n = 5; p = 0.02) and fewer died (n = 1 vs. n = 5, p = 0.06). CONCLUSIONS: Lower bias gas flow in ventilated extremely preterm infants did not alter TA cytokine concentrations but the lower incidence of NEC and mortality warrants further investigation.

introduce nationwide pulse oximetry screening for the detection of critical congenital heart disease and other hypoxaemic conditions in the newborn.

The mortality risk for infants with critical congenital heart disease (CCHD) unrecognised at the time of birth is high. Pulse oximetry has been utilised as a screening tool for the detection of these anomalies in the newborn as the majority will have a degree of hypoxaemia. This screening strategy has a moderate sensitivity and excellent specificity for the detection of CCHD, and a low false-positive rate. Respiratory and infective diseases are responsible for a large number of positive test results. The early recognition of these diseases can also improve health outcomes. Different approaches have been taken to introduce screening, ranging from hospital-led initiatives to mandatory state-wide policies. A study conducted in New Zealand demonstrated that sector-led screening initiatives are unlikely to result in equitable outcomes. In this midwifery-led maternity setting a nationwide pulse oximetry screening programme with adequate human and material resources should be introduced.

A Core Outcome Set for the prevention and treatment of fetal GROwth restriction: deVeloping Endpoints: the COSGROVE study.

BACKGROUND: Fetal growth restriction refers to a fetus that does not reach its genetically predetermined growth potential. It is well-recognized that growth-restricted fetuses are at increased risk of both short- and long-term adverse outcomes. Systematic evaluation of the evidence from clinical trials of fetal growth restriction is often difficult because of variation in the outcomes that are measured and reported. The development of core outcome sets for fetal growth restriction studies would enable future trials to measure similar meaningful outcomes. OBJECTIVE: The purpose of this study was to develop core outcome sets for trials of prevention or treatment of fetal growth restriction. STUDY DESIGN: This was a Delphi consensus study. A comprehensive literature review was conducted to identify outcomes that were reported in studies of prevention or treatment of fetal growth restriction. All outcomes were presented for prioritization to key stakeholders (135 healthcare providers, 68 researchers/academics, and 35 members of the public) in 3 rounds of online Delphi surveys. A priori consensus criteria were used to reach agreement on the final outcomes for inclusion in the core outcome set at a face-to-face meeting with 5 healthcare providers, 5 researchers/academics, and 6 maternity service users. RESULTS: In total, 22 outcomes were included in the final core outcome set. These outcomes were grouped under 4 domains: maternal (n=4), fetal (n=1), neonatal (n=12), and childhood (n=5). CONCLUSION: The Core Outcome Set for the prevention and treatment of fetal GROwth restriction: deVeloping Endpoints study identified a large number of potentially relevant outcomes and then reached consensus on those factors that, as a minimum, should be measured and reported in all future trials of prevention or treatment of fetal growth restriction. This will enable future trials to measure similar meaningful outcomes and to ensure that findings from different studies can be compared and combined.

Antenatal Detection of Treatable Critical Congenital Heart Disease Is Associated with Lower Morbidity and Mortality.

OBJECTIVE: To establish the impact that timing of diagnosis and place of birth have on neonatal outcomes in those with readily treatable critical congenital heart disease. STUDY DESIGN: This was a population-based study with a complete national cohort of live-born infants with transposition of the great arteries and aortic arch obstruction in New Zealand between 2006 and 2014. Timing of diagnosis, place of birth, survival to surgery, in-hospital events, and neonatal mortality were reviewed. Live births with a gestation of ≥35 weeks and without associated major extracardiac anomalies were included for analysis. RESULTS: A total of 166 live-born infants with transposition of the great arteries and 87 with aortic arch obstruction were included. Antenatal detection increased from 32% in the first 3 years to 47% in the last 3 years (P = .05). During the same period, neonatal mortality decreased from 9% to 1% (P = .02). No deaths occurred after surgical intervention. An antenatal diagnosis was associated with decreased mortality (1/97 [1%] vs 11/156 [7%]; P = .03) and birth outside the surgical center was associated with increased risk of mortality (11/147 [7%] vs 1/106 [1%]; P = .02). Those with an antenatal diagnosis required fewer hours of mechanical ventilation (P = .02) and had shorter durations of hospital stay (P = .05) compared with those diagnosed >48 hours after birth. CONCLUSIONS: The mortality risk for transposition of the great arteries and critical aortic arch obstruction is greatest before cardiac surgery. Improved antenatal detection allowing delivery at a surgical center is associated with reduced mortality.

The DIAMOND trial - DIfferent Approaches to MOderate & late preterm Nutrition: Determinants of feed tolerance, body composition and development: protocol of a randomised trial.

BACKGROUND: Babies born at moderate-late preterm gestations account for > 80% of all preterm births. Although survival is excellent, these babies are at increased risk of adverse neurodevelopmental outcomes. They also are at increased risk of adverse long-term health outcomes, such as cardiovascular disease, obesity and diabetes. There is little evidence guiding optimal nutritional practices in these babies; practice, therefore, varies widely. This factorial design clinical trial will address the role of parenteral nutrition, milk supplementation and exposure of the preterm infant to taste and smell with each feed on time to tolerance of full feeds, adiposity, and neurodevelopment at 2 years. METHODS/DESIGN: The DIAMOND trial is a multi-centre, factorial, randomised, controlled clinical trial. A total of 528 babies born between 32+ 0 and 35+ 6 weeks' gestation receiving intravenous fluids and whose mothers intend to breastfeed will be randomised to one of eight treatment conditions that include a combination of each of the three interventions: (i) intravenous amino acid solution vs. intravenous dextrose solution until full milk feeds established; (ii) milk supplement vs. exclusive breastmilk, and (iii) taste/smell given or not given before gastric tube feeds. Babies will be excluded if a particular mode of nutrition is clinically indicated or there is a congenital abnormality. Primary study outcome: For parenteral nutrition and milk supplement interventions, body composition at 4 months' corrected age. For taste/smell intervention, time to full enteral feeds defined as 150 ml.kg- 1.day- 1 or exclusive breastfeeding. SECONDARY OUTCOMES: Days to full sucking feeds; days in hospital; body composition at discharge; growth to 2 years' corrected age; development at 2 years' corrected age; breastfeeding rates. DISCUSSION: This trial will provide the first direct evidence to inform feeding practices in moderate- to late-preterm infants that will optimise their growth, metabolic and developmental outcomes. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry - ACTRN12616001199404 . This trial is endorsed by the IMPACT clinical trials network ( https://impact.psanz.com.au ).

Presence and pattern of scarring in children born very preterm.

The long-term scarring burden of preterm infants undergoing modern neonatal intensive care is not known. This observational cohort study aimed to document the presence and pattern of scarring in children born <30 weeks' gestation or <1500 g birth weight and cared for at the National Women's Health neonatal intensive care unit, Auckland, New Zealand. Children were examined at 7 years' corrected age and the presence, size, number and distribution of scars documented. Scarring was seen in 90% of 129 children assessed, with 81% having multiple scars, 60% having large scars (85% of whom had no history of major neonatal surgery) and 75% having more than one body area scarred. Scarring was more common in boys and in children of non-European ethnicity. Despite modern neonatal intensive care practices, children born very preterm are frequently and extensively scarred at school age.

Twin Conception in Sheep Leads to Impaired Insulin Sensitivity and Sexually Dimorphic Adipose Tissue and Skeletal Muscle Phenotypes in Adulthood.

Twins are often born small and early and have increased risk of obesity and diabetes later in life. Twin conception in sheep, regardless of whether the pregnancy continues as twins or is reduced to singleton in early gestation, alters offspring growth trajectory and body composition in young adulthood. We hypothesized that twin conception would result in insulin resistance in adulthood, with insulin-resistant adipose tissue and skeletal muscle phenotypes. At 3 years of age, body weight was not different among singletons, twins, and reductions; females weighed less than males. Singletons were leaner than reductions, with twins intermediate. Twins and reductions had decreased insulin sensitivity compared with singletons (singletons: mean [standard error of the mean]: 4.75 [0.4], twins: 3.34 [0.3], reductions: 3.67 [0.2] mg·I µU-1·kg-1·min-1, P < .01). There were no group differences in adipocyte size, adipose tissue, or circulating tumor necrosis factor α, monocyte chemoattractant protein 1, or interleukin 6 concentrations. In males, omental and subcutaneous adipose SLC2A4 was 1.5- to 2.0-fold greater in twins and reductions than in singletons ( P < .01) and SLC2A1 was greater in reductions than in singletons. Skeletal muscle IRS-1 was decreased in male twins but increased in female twins, compared to singletons ( P ≤ .01), with no effect on reductions in either sex. Skeletal muscle SLC2A4 was decreased in female twins and reductions but elevated in male twins and reductions compared to singletons ( P ≤ .01). We conclude that adult twin insulin resistance is not due to adipose tissue phenotype, but potentially phenotypic effects in skeletal muscle, and obesity is a result of twin conception per se with its origins in early gestation.

High bias gas flows increase lung injury in the ventilated preterm lamb.

BACKGROUND: Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI), leading to the development of bronchopulmonary dysplasia (BPD). It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI. METHODS: Preterm lambs of 131 days' gestation (term = 147 d) were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13), 18 L/min (n = 12) or 28 L/min (n = 14). Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate. RESULTS: High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung. CONCLUSIONS: High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD.

Ventilator gas flow rates affect inspiratory time and ventilator efficiency index in term lambs.

BACKGROUND: Despite increasing survival in the smallest preterm infants, the incidence of chronic lung disease has not decreased. Research into ventilatory strategies has concentrated on minimising barotrauma, volutrauma and atelectotrauma, but little attention has been paid to the role of bias gas flow rates and the potential for rheotrauma or shear stress injury. Ventilated preterm infants frequently receive relatively high gas flow rates. OBJECTIVES: We hypothesised that altering bias gas flow rates would change the efficiency of ventilation and thereby affect ventilatory parameters. METHODS: We tested this hypothesis using an artificial lung followed by ventilation of 8 term lambs. RESULTS: Between flows of 2 and 15 l/min, inflation time (Ti) in the artificial lung was inversely related to the bias gas flow rate. In the ventilated lambs, Ti was inversely related to flow rates up to 10 l/min, with no statistically significant effect at flow rates >10 l/min. There were no adverse effects on gas exchange or cardiovascular parameters until a flow rate of 3 l/min was used, when inadequate gas exchange occurred. CONCLUSIONS: Ti is inversely associated with the bias gas flow rate. Flow rates much lower than those used in many neonatal units seem to provide adequate ventilation. We suggest that the role of ventilator gas flow rates, which may potentially influence shear stress in ventilator-induced lung injury, merits further investigation.

Effects of periconceptional undernutrition on the initiation of parturition in sheep.

In sheep, parturition is initiated by increased fetal hypothalamic-pituitary-adrenal axis (HPAA) activity leading to PGE(2) and PGF(2alpha) production and a rise in the 17beta-estradiol-progesterone (E(2)/P(4)) ratio. Uteroplacental PG production can also increase fetal HPAA activity. Periconceptional maternal undernutrition accelerates fetal HPAA maturation resulting in preterm labor. We determined whether preterm labor was preceded by an increase in PG concentrations and E(2)/P(4) ratio and whether these increases preceded or followed the corresponding rise in cortisol concentrations. Singleton-bearing ewes were nourished ad libitum (N, n = 9) or undernourished (UN, n = 10) to reduce maternal weight by 15% from -61 days (d) to +30 d after mating with ad libitum intake thereafter. Paired maternal and fetal blood samples were collected from 126 d until delivery. Half the UN group delivered prematurely (>2 SD below mean gestation for the flock). PG and cortisol concentrations and E(2)/P(4) ratio increased before delivery in the same way in both groups. However, the increases occurred 7-10 d earlier in UN than in N animals. In both UN and N fetuses cortisol concentrations rose before fetal and maternal PG concentrations and maternal E(2)/P(4) ratio. Periconceptional maternal undernutrition induces preterm delivery in sheep by advancing the expected prepartum rise in cortisol and PG concentrations and E(2)/P(4) ratio. The rise in fetal cortisol concentration precedes the rise in fetal and maternal PG concentrations and maternal E(2)/P(4) ratio, suggesting that the underlying mechanism is likely to be acceleration of fetal HPAA maturation, resulting in initiation of the normal process of parturition.

Periconceptional undernutrition in sheep accelerates maturation of the fetal hypothalamic-pituitary-adrenal axis in late gestation.

We investigated the effects of moderate maternal periconceptional undernutrition from 60 d before to 30 d after mating on fetal hypothalamic-pituitary-adrenal axis function in late gestation. Ewes were sampled regularly during the period of undernutrition for circulating hormone levels. Vascular catheters were inserted into ewes and their singleton fetuses at 112 d gestation (term, 145 d), and fetal ACTH(1-24) and metyrapone challenge tests were performed at 127 and 128 d. Postmortems were performed at 132 d. Fetuses of undernourished ewes (UN, n = 12) had elevated baseline cortisol concentrations (P < 0.05), compared with fetuses of ad libitum-fed ewes (n = 10). There were no differences between groups in fetal responses to ACTH challenge, but only UN fetuses demonstrated ACTH and 11-deoxycortisol responses to metyrapone (P < 0.05). UN fetuses had increased mRNA levels for proopiomelanocortin and prohormone convertase-1, but not -2, in the pars intermedia of the pituitary gland (P < 0.05). Glucocorticoid receptor mRNA levels were not different between groups in pituitary or hypothalamus. Maternal cortisol and ACTH levels during undernutrition were profoundly suppressed (P < 0.001), rather than elevated, in UN ewes. Furthermore, the normal pregnancy rise in maternal serum progesterone concentrations was delayed in undernourished mothers. These data demonstrate that events around the time of conception have profound effects on fetal hypothalamic-pituitary-adrenal development in late gestation and that factors other than fetal exposure to excess glucocorticoids may be important.

Brief undernutrition in late-gestation sheep programs the hypothalamic-pituitary-adrenal axis in adult offspring.

Reduced size at birth in humans has been associated with altered function of the hypothalamic-pituitary-adrenal (HPA) axis in childhood and adult life. Experimentally, maternal undernutrition has also been associated with altered fetal HPA function. However, the relationship between birth size, fetal nutrition, and adult pathophysiology is not clear. We recently have reported that glucose tolerance, blood pressure, and IGF-I levels in adult sheep were more closely associated with birth weight than with nutritional insult in late gestation or with current weight. Here, we report adult HPA function in the same group of animals. Pregnant ewes were severely undernourished for 10 d (UN10) or 20 d (UN20) from 105 d gestation (term, 146 d), or were ad libitum-fed controls. At 30 months, female offspring were subjected to an insulin tolerance test and a CRH plus arginine vasopressin (AVP) challenge. UN20 lambs were lighter at birth, but there were no significant differences in weight at 30 months. Adult UN10 ewes had an increased ACTH response to both CRH+AVP challenge and insulin tolerance test, but no differences in cortisol response. UN10 ewes also demonstrated elevated 11-deoxycortisol concentrations, but lower progesterone concentrations, in response to CRH+AVP challenge. In contrast, the responses of UN20 ewes to these challenges were not different from ad libitum controls. Protein levels of P450(c17) and P450(11beta1) were not significantly different among groups. We conclude that brief maternal undernutrition for 10 d, but not 20 d, in late gestation alters HPA function in adult offspring. In contrast to our previous findings, these HPA effects are independent of birth weight and current weight, suggesting that different mechanisms may be involved in programming different physiological axes.