Neonatal Blood Gases

Neonatal blood gases refer to blood tests that evaluate the levels of oxygen, carbon dioxide, and acid in a baby’s blood.  When a baby breathes, the infant is drawing oxygen into his or her lungs.  The oxygen is then absorbed into the bloodstream.  Carbon dioxide is what is considered a waste product of cells during energy production, and is removed from the body, via the lungs, by exhaling¹.

Infants with respiratory conditions, as well as premature babies, may have difficulty managing their own respiratory systems.  Often, they will be placed in the neonatal intensive care unit, also called the NICU, for respiratory management.  In the NICU, blood gas levels can help a doctor or practitioner adjust oxygen management machines, such as oscillators, ventilators, and CPAP.

There are three types of neonatal blood gases that can be drawn:

  • Arterial blood gas (ABG) – Arterial blood gases are drawn from a baby’s artery to determine oxygen, carbon dioxide, and acid levels in the infant’s blood.  This blood gas source usually delivers the most accurate results in regards to determine how well the baby is managing their breathing.
  • Capillary blood gas (CBG) – Capillary blood gases are drawn from a capillary to determine oxygen, carbon dioxide, and acid levels in the infant’s blood.  This can often be seen being done as a ‘heel stick’.  In adults, it would be similar to pricking your finger for blood.
  • Venous blood gas (VBG) – Venous blood gases are drawn from a baby’s veins to determine oxygen, carbon dioxide, and acid levels in the infant’s blood.

If a parent with a baby in the NICU hears about a blood gas level, it is important for them to know the reasoning behind the lab test.  The neonatal blood gas is being drawn so as to determine how the infant is managing his or her own respiratory system.  This can include the ability to keep their lungs inflated, as well as the ability to control the rate at which they breathe.

Always check with you neonatologist or neonatal practitioner in regards to any medical advice about neonatal blood gases.  Online resources, such as this one, should be treated as informational and educational, but never as medical advice.  Take the knowledge you learn online and use that as a tool to help ask your pediatrician educated questions in regards to neonatal blood gases.


1. Zaichkin, Jeanette RN, MN, NNP-BC. Newborn Intensive Care What Every Parent Needs to Know. 3rd Edition. Ann Arbor, MI.Sheridan Books; 2009