Despite our growing experience in the medical care of extremely preterm infants and
critically ill neonates, there are serious gaps in the understanding and clinical application of the
adaptive physiology of the newborn. Neonatal physiology is often misinterpreted and considered
similar to that of adult physiology. The human psyche has been seriously influenced, both from an
evolutionary and survival point of view, by the cause and effect of hypoxemia which is considered
as a warning sign of impending death. Within this context, it is unimaginable for even the highly
trained professionals to consider saturation as low as 65% as acceptable. However, all available
data suggests that newborns can thrive in a hypoxemic environment as they are conditioned to
withstand extreme low saturations in the fetal environment. An approach utilizing the benefits of
the hypoxic conditioning would prompt the practice of optimal targeted oxygen saturation range in
the clinical management of the newborn. Our current understanding of cyanotic congenital heart
disease and the physiology of single ventricle circulation, where oxygen saturation in mid 70s is
acceptable, is supported by clinical and animal studies. This article argues the need to challenge our
current acceptable target oxygen saturation in the newborn and provides the reasoning behind accepting
lower target oxygen levels in the critically ill newborn. Challenging the current practice is
expected to open a debate paving the way to understand the risks of high target oxygen levels in the
newborn compared with the benefits of permissive hypoxia in avoiding the associated morbidity
and mortality of oxygen radical injury.
Keywords: Cyanotic congenital heart disease, hypoxic preconditioning, hypoxemic hypoxic preconditioning, ischemic preconditioning,
primary hypoxic preconditioning, critical care.
open access plus
Lemus-Varela ML, Flores-Soto ME, Cervantes-Munguía R, et al. Expression of HIF-1 alpha, VEGF and EPO in peripheral blood from patients with two cardiac abnormalities associated with hypoxia. Clin Biochem 2010; 43(3): 234-9.
Rights & PermissionsPrintExport