The fundamentals of... apnea monitors.

Apnea is a Greek word meaning “without wind.” Apnea, in the modern lexicon, refers to the cessation of breathing and is a reversible condition if caught early enough. Apneic events fall under one of three classifications—central, obstructive, or mixed. The event is classified as “central apnea” if the brain stops sending the signals to the chest muscles to expand, causing inhalation. This can occur even when the patient has normal muscle function in the chest. An upper airway obstruction of the airflow is termed “obstructive apnea.” When elements of both are present, it is termed “mixed apnea.” Prolonged apnea reduces blood and tissue oxygen levels, leading to permanent brain damage and, if not remediated, death. Apnea occurring during otherwise normal sleep is called “sleep apnea” and is suspected to be a factor in Sudden Infant Death Syndrome (SIDS). Because the overall risk factors for apnea are reasonably well defined but the actual onset is unpredictable, apnea monitors provide constant monitoring of those at risk and set off an alarm when apnea is identified.