Title:Hypoxic Gas Therapy in Neonatology: Considerations in Practice
Volume: 19
Issue: 5
Author(s): Jorge Luis Alvarado Socarras*, Delia Edith Theurel Martin and Edgar Fabian Manrique Hernández
Affiliation:
- Pediatrics Department, Fundación Cardiovascular de Colombia, Neonatal Intensive Care Unit, Bucaramanga, Colombia
Keywords:
Congenital heart disease, neonate, hypoplastic left heart syndrome, hypoxic gas, nitrogen, fraction of inspired oxygen.
Abstract:
Background: Adequate oxygenation is essential for sick newborns. Each disease determines
the target of oxygenation. Nevertheless, hyperoxia and hypoxia are related to adverse outcomes.
Most studies related to this aspect have been conducted in preterm infants or term babies with pulmonary
pathology.
Introduction: Congenital heart diseases may also require careful oxygenation control and management
of oxygen supply.
Methods: Presurgical stabilization of complex heart diseases (CHD) may be difficult, especially after
the physiological decrease of pulmonary resistance, which generates pulmonary edema (due to overcirculation)
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 latter 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, coronarycerebral
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 as a complication
to the already established disease 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.
