A supportive physiologic environment for the extreme premature infant: Improving life outside the womb

Extreme prematurity remains an unsolved problem and is the leading cause of pediatric mortality and morbidity in developed countries. The extreme premature infant is physiologically a fetus, and current supportive measures in our NICUs are for the most part non-physiologic. In order to improve morbidity and mortality in this population, we have developed the Extra-uterine environment for newborn development (EXTEND) system which seeks to mimic as closely as possible the environment of the womb. The primary components of EXTEND include a sterile fluid environment, a pumpless arteriovenous extracorporeal oxygenator circuit, and vascular access via umbilical arterial and venous vessels. While supported on the EXTEND system, premature fetal lambs grow and develop normally for up to 4 weeks. Fetal physiology is maintained, and detailed organ system analysis supports normal development. This article summarizes current progress in the development of EXTEND, the pathway for human translation, ethical considerations related to EXTEND, and anticipated clinical applications of this potentially paradigm changing technology. LEVEL OF EVIDENCE: IV.