In the developed world, extreme prematurity is the leading cause of neonatal mortality and morbidity due to a combination of organ immaturity and iatrogenic injury. Until now, efforts to extend gestation using extracorporeal systems have achieved limited success. Here we report the development of a system that incorporates a pumpless oxygenator circuit connected to the fetus of a lamb via an umbilical cord interface that is maintained within a closed ‘amniotic fluid' circuit that closely reproduces the environment of the womb. We show that fetal lambs that are developmentally equivalent to the extreme premature human infant can be physiologically supported in this extra-uterine device for up to 4 weeks. Lambs on support maintain stable haemodynamics, have normal blood gas and oxygenation parameters and maintain patency of the fetal circulation. With appropriate nutritional support, lambs on the system demonstrate normal somatic growth, lung maturation and brain growth and myelination.

In a series of 137 patients managed with ECMO in a pediatric cardiac intensive care unit, survival to hospital discharge was 39%. In postoperative patients only, mortality risk was increased in males, patients <1 month old, patients with a longer duration of mechanical ventilation before initiation of ECMO, and patients who developed renal or hepatic failure while on ECMO.

EXTEND (EXTra-uterine Environment for Neonatal Development) is a novel system that promotes physiological development by maintaining the premature lamb in a sterile fluid environment and providing gas exchange via a pumpless arteriovenous oxygenator circuit. During the development of EXTEND, different cannulation strategies evolved with the aim of improving circuit flow. The present study examines how different cannulation strategies affect EXTEND circuit haemodynamics in extreme premature lambs. Seventeen premature lambs were cannulated at gestational ages 105-117 days (term 145-150 days) and supported on EXTEND for up to 4 weeks. Experimental groups were distinguished by cannulation strategy: carotid artery outflow and jugular vein inflow (CA/JV; n = 4), carotid artery outflow and umbilical vein inflow (CA/UV; n = 5) and double umbilical artery outflow and umbilical vein inflow (UA/UV; n = 8). Circuit flows and pressures were measured continuously. As we transitioned from CA/JV to CA/UV to UA/UV cannulation, mean duration of circuit run and weight-adjusted circuit flows increased (P < 0.001) and the frequency of flow interruptions declined (P < 0.05). Umbilical vessels generally accommodated larger-bore cannulas, and cannula calibre was directly correlated with circuit pressures and indirectly correlated with flow:pressure ratio (a measure of post-membrane resistance). We conclude that UA/UV cannulation in fetal lambs on EXTEND optimizes circuit flow dynamics and flow stability and also supports circuit flows that closely approximate normal placental flow.

Studies have continued to evaluate risk factors associated with post-transplant non-adherence in pediatric patients. However, many of these studies fail to evaluate how risk factors can be utilized to predict MNA. The aims of this study were to (i) determine salient risk factors associated with MNA to develop an adequate predictive risk model and (ii) assess transplant outcomes based on the presence of MNA in a large, diverse cohort of pediatric KTX recipients. One hundred and seventy-five solitary pediatric KTX recipients transplanted from 1999 to 2013 were included. AA, males, older patients, those who lived in urban environments, had legal issues, and lived shorter distances from the transplant center were more likely to have MNA. Using logistic regression, a parsimonious model applying nine risk factors together was developed for predicting MNA, demonstrating a PPV of 69% and a NPV of 81%. Patients with MNA had more than twice the risk of biopsy proven acute rejection, 1.6 times the risk of hospitalization, and 1.8 times the risk of graft loss. Utilization of a predictive model to determine risk of MNA after pediatric KTX may offer clinicians the ability to efficiently and effectively monitor MNA following transplant.