Target Oxygen Levels and Critical Care of the Newborn

Delivery room and early postnatal management of neonates with congenital heart disease

Advancements in prenatal detection have improved postnatal outcomes for patients with congenital heart disease (CHD). Detailed diagnosis during pregnancy allows for preparation for the delivery and immediate postnatal care for the newborns with CHD. Most CHDs do not result in hemodynamic instability at the time of birth and can be stabilized following the guidelines of the neonatal resuscitation program (NRP). Critical CHD that requires intervention immediately after birth is recommended to be delivered in facilities where immediate neonatal and cardiology care can be provided. Postnatal stabilization and resuscitation for these defects warrant deviation from the standardized NRP. For neonatal providers, knowing the diagnosis of fetal CHD allows for preparation for the anticipated instability in the delivery room. Prenatal detection fosters collaboration between fetal cardiology, cardiology specialists, obstetrics, and neonatology, improving outcomes for neonates with critical CHD.

Hypoxic gas therapy in neonatology, considerations in practice

BACKGROUND

Adequate oxygenation is essential in sick newborns. Each disease determines the target of oxygenation. Nevertheless, hyperoxia and hypoxia are related to adverse outcomes. Most studies about this had been made in preterm infants or term babies with pulmonary pathology.

INTRODUCTION

Congenital heart diseases may also require careful oxygenation control and management of oxygen supply.

PROBLEM

Presurgical stabilization of complex heart diseases (CHD) may be difficult, especially after the physiological decrease of pulmonary resistance, which generates pulmonary edema (due to over-circulation) and systemic hypoperfusion. Several strategies have been described to avoid this phenomenon, such as prostaglandin, vasodilators, inotropes, positive airway pressure, and even hypoxic mixture (Inspired fraction of oxygen (FiO2) below 21%).

DISCUSSION

The last therapy is mainly used in single ventricular physiology heart diseases, such as the hypoplasic left heart syndrome (HLHS) or systemic ductus dependent flow CHD (interruption of the aortic arch and coarctation of the aorta). Alveolar oxygen affects pulmonary vascular resistance modifying lung flow. This modification could help the stabilization during the presurgical period of complex CDH. Many centers use hypoxic therapy to avoid hypotension, metabolic acidosis, coronary-cerebral ischemia, and liver, renal and intestinal injury. Despite the theoretical benefits, there are doubts about how tissue oxygen supply would change during hypoxic gas ventilation. It is worrisome that FiO2 < 21% causes a decrease in brain oxygenation, adding neurological injury to the already established because of CHD and other not modifiable factors. Brain monitoring through near-infrared spectroscopy (NIRS) during hypoxic gas therapy is mandatory. Recent studies have shown that hypoxic gas ventilation therapy in patients with HLHS in the preoperative period decreases the ratio between systemic and pulmonary circulation (Qp/Qs) but does not improve regional oxygenation delivery. The use of hypoxic gas ventilation therapy continues to be controversial. It could be an option in some complex CHD, mainly HLHS.