Postnatal dilatation of umbilical cord vessels and its impact on wall integrity: Prerequisite for the artificial placenta.

INTRODUCTION: A lung assist device, which acts as an artificial placenta, can provide additional gas exchange for preterm and term newborns with respiratory failure. The concept of the lung assist device requires a large bore access via umbilical vessels to allow pumpless extracorporeal blood flow rates up to 30 mL/kg/min. After birth, constricted umbilical vessels need to be reopened for vascular access. The objective is to study the impact of umbilical vessel expansion on vessel integrity for achieving large bore access. METHODS: Umbilical cords from healthy term deliveries were cannulated and dilatated with percutaneous transluminal angioplasty catheters in 1 mm increments from 4 to 8 mm for umbilical artery and from 4 to 15 mm for umbilical vein, n = 6 per expansion diameter. Paraffin-embedded transverse sections of dilated and control samples were HE & Van Gieson stained. Effects of dilatation, shown by splitting, were measured. RESULTS: Umbilical vessel expansion led to concentric splitting, shown by areas devoid of extracellular matrix and nuclei in the tunica intima and media. No radial splitting was observed. Results suggest an expansion threshold of umbilical artery at 6 mm and umbilical vein at 7 mm, while maximal splitting was observed above this threshold (3.6 ± 0.8%, p = 0.043 for umbilical artery 7 mm and 6.3 ± 1.8%, p = 0.048 for umbilical vein 8 mm). Endothelial cell sloughing was present in all dilated samples but not in the control samples. CONCLUSION: The suggested thresholds for safe expansions are similar to in utero umbilical vessel diameters and demonstrate a proof of concept for attaining large bore access for the lung assist device.

Rapid measurement of macronutrients in breast milk: How reliable are infrared milk analyzers?

BACKGROUND & AIMS: Significant biological variation in macronutrient content of breast milk is an important barrier that needs to be overcome to meet nutritional needs of preterm infants. To analyze macronutrient content, commercial infrared milk analyzers have been proposed as efficient and practical tools in terms of efficiency and practicality. Since milk analyzers were originally developed for the dairy industry, they must be validated using a significant number of human milk samples that represent the broad range of variation in macronutrient content in preterm and term milk. Aim of this study was to validate two milk analyzers for breast milk analysis with reference methods and to determine an effective sample pretreatment. Current evidence for the influence of (i) aliquoting, (ii) storage time and (iii) temperature, and (iv) vessel wall adsorption on stability and availability of macronutrients in frozen breast milk is reviewed. METHODS: Breast milk samples (n = 1188) were collected from 63 mothers of preterm and term infants. Milk analyzers: (A) Near-infrared milk analyzer (Unity SpectraStar, USA) and (B) Mid-infrared milk analyzer (Miris, Sweden) were compared to reference methods, e.g. ether extraction, elemental analysis, and UPLC-MS/MS for fat, protein, and lactose, respectively. RESULTS: For fat analysis, (A) measured precisely but not accurately (y = 0.55x + 1.25, r(2) = 0.85), whereas (B) measured precisely and accurately (y = 0.93x + 0.18, r(2) = 0.86). For protein analysis, (A) was precise but not accurate (y = 0.55x + 0.54, r(2) = 0.67) while (B) was both precise and accurate (y = 0.78x + 0.05, r(2) = 0.73). For lactose analysis, both devices (A) and (B) showed two distinct concentration levels and measured therefore neither accurately nor precisely (y = 0.02x + 5.69, r(2) = 0.01 and y = -0.09x + 6.62, r(2) = 0.02 respectively). Macronutrient levels were unchanged in two independent samples of stored breast milk (-20 °C measured with IR; -80 °C measured with wet chemistry) over a period of 14 months. CONCLUSIONS: Milk analyzers in the current configuration have the potential to be introduced in clinical routine to measure fat and protein content, but will need major adjustments.