Curds in the way: A milk curd obstruction review and normal sonographic bowel appearances using a novel scoring system in neonates on fortified breast milk feeds.

INTRODUCTION: Fortified expressed breast milk (FEBM) is a standard of care for premature and low birth weight neonates, but comes with an elevated risk of a rare but re-emergent pathology called milk curd obstruction (MCO). Little is known about normal sonographic appearances of bowel contents in this feeding setting, making the recognition of abnormalities difficult. Thus, we aimed to describe appearances that may be considered typical pre- and post-fortifier inclusion. METHODS: Ten neonates of <32 weeks' gestation or a birth weight of <1,800 g recruited from Auckland City Hospital Neonatal Intensive Care between 1/5/2019 and 10/9/2019 received bowel ultrasounds within 24 h before and 10-14 days after starting FEBM. Bowel contents in six abdominal regions were assigned scores of 1-6 based on increasing solidification. RESULTS: Lower gestational age was correlated with more solid contents on the pre-fortifier ultrasound (P = 0.02). Fortifier was significantly associated with increasing solidity, particularly in the left abdomen (P < 0.001). The left lower quadrant and rectum accounted for much of this change (P = 0.012 and P = 0.002). One subject who subsequently developed a clinical picture consistent with early MCO had uniquely demonstrated non-rectal solid contents (score 6). The interobserver kappa score for two assessors was 0.91 (95% CI 0.94-0.99) on still images. CONCLUSION: This small cohort demonstrated increasing bowel content solidification after breast milk fortification using a novel ultrasound scoring system with good interobserver agreement. Non-rectal solid contents (score 6) appeared atypical. Ultrasound shows promise for its non-irradiating diagnostic utility in the setting of early milk curd disease evaluation of the premature neonate.

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.

Comparison of positive pressure ventilation devices in a newborn manikin.

OBJECTIVE: To compare tidal volume (VT) delivery and ventilation rate between devices for positive pressure ventilation (PPV) during newborn resuscitation. METHODS: Neonatal resuscitation program providers (n = 25) delivered PPV to a newborn manikin in a randomized order with: a self-inflating bag (SIB), a disposable T-piece, a non-disposable T-piece, a stand-alone infant resuscitation system T-piece and the volume-controlled prototype Next StepTM device (KM Medical). All T-pieces used a peak inflation pressure of 20cmH2O and a 5cmH2O positive end-expiratory pressure (PEEP). The SIB neither had a PEEP valve nor manometer. The Next StepTM had a 5cmH2O PEEP valve. The participants aimed to deliver a 5 mL/kg VT (rate 40-60 min-1) for 1 min with each device and each of three compliances (0.5, 1.0 and 2.0 mL/cmH2O). VT and ventilation rate were compared between devices and compliance levels (ANOVA) Results: All devices, except the Next StepTM delivered a 4-5 mL/kg VT at the low compliance, but three- to four-fold that of the target at the higher compliance levels. The Next StepTM delivered a VT close to target at all compliance levels. The ventilation rate was within 40-60 min-1 with all devices and compliance levels. CONCLUSIONS: Routinely used ventilation devices for newborn resuscitation can triple intended VT and requires further investigation.

A Novel Prototype Neonatal Resuscitator That Controls Tidal Volume and Ventilation Rate: A Comparative Study of Mask Ventilation in a Newborn Manikin.

The objective of this randomized controlled manikin trial was to examine tidal volume (VT) delivery and ventilation rate during mask positive pressure ventilation (PPV) with five different devices, including a volume-controlled prototype Next Step™ device for neonatal resuscitation. We hypothesized that VT and rate would be closest to target with the Next Step™. Twenty-five Neonatal Resuscitation Program providers provided mask PPV to a newborn manikin (simulated weight 1 kg) in a randomized order with a self-inflating bag (SIB), a disposable T-piece, a non-disposable T-piece, a stand-alone resuscitation system T-piece, and the Next Step™. All T-pieces used a peak inflation pressure of 20 cmH2O and a positive end-expiratory pressure of 5 cmH2O. The participants were instructed to deliver a 5 mL/kg VT (rate 40-60/min) for 1 min with each device and each of three test lungs with increasing compliance of 0.5, 1.0, and 2.0 mL/cmH2O. VT and ventilation rate were compared between devices and compliance levels (linear mixed model). All devices, except the Next Step™ delivered a too high VT, up to sixfold the target at the 2.0-mL/cmH2O compliance. The Next Step™ VT was 26% lower than the target in the low compliance. The ventilation rate was within target with the Next Step™ and SIB, and slightly lower with the T-pieces. In conclusion, routinely used newborn resuscitators over delivered VT, whereas the Next Step™ under delivered in the low compliant test lung. The SIB had higher VT and rate than the T-pieces. More research is needed on volume-controlled delivery room ventilation.

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.