Practice Essentials
Apnea is defined by the cessation of respiratory airflow. The length of time necessary to be qualified as a true apneic event has changed dramatically over the last several decades: 2 minutes in 1956,
1 minute in 1959,
30 seconds in 1970,
and then 20 seconds or shorter if associated with bradycardia or cyanosis in 1978.
The reduction of the duration in the definition of apnea reveals doctors’ desire to intervene early enough to avoid systemic consequences.
The 3 main categories of apnea are central, obstructive, and mixed. Central apnea is a result of inadequate medullary responsiveness and thus results in no or poor muscle coordination for breathing. Obstructive apnea is when there is an obstruction of the airway passages and therefore poor to no air exchange. Often times with obstructive apnea, there is a vigorous inspiratory effort but it is ineffective against the obstruction. Mixed apnea refers to an episode where combinations of both central and obstructive forces are involved.