Apnea is suspension of breathing. During apnea, there is no movement of the muscles of inhalation, and the volume of the lungs initially remains unchanged. Depending on how blocked the airways are (patency), there may or may not be a flow of gas between the lungs and the environment; gas exchange within the lungs and cellular respiration is not affected.

Apnea of prematurity is defined as cessation of breathing by a premature infant that lasts for more than 20 seconds and/or is accompanied by hypoxia or bradycardia.

Apnea is traditionally classified as either obstructive, central, or mixed. Obstructive apnea may occur when the infant’s neck is hyperflexed or conversely, hyperextended. It may also occur due to low pharyngeal muscle tone or to inflammation of the soft tissues, which can block the flow of air though the pharynx and vocal cords. Central apnea occurs when there is a lack of respiratory effort. This may result from central nervous system immaturity, or from the effects of medications or illness. Many episodes of apnea of prematurity may start as either obstructive or central, but then involve elements of both, becoming mixed in nature.

Apnea. (2016, September 21). In Wikipedia, The Free Encyclopedia. Retrieved 02:53, September 21, 2016, from https://en.wikipedia.org/w/index.php?title=Apnea&oldid=740441341

Apnea of prematurity. (2016, October 6). In Wikipedia, The Free Encyclopedia. Retrieved 16:44, October 6, 2016, from https://en.wikipedia.org/w/index.php?title=Apnea_of_prematurity&oldid=742916823