central sleep apnea index
Also written as: CSAI — Central Sleep Apnea Index
A quantitative measure expressing the number of central apnea events per hour of sleep, used to assess the severity of central sleep apnea disorders.
Full Definition
The central sleep apnea index (CSAI) is a key polysomnographic parameter that quantifies the frequency of central apneic events during sleep study recordings. Unlike obstructive apneas where respiratory effort continues against airway obstruction, central apneas involve complete cessation of respiratory effort due to temporary failure of central nervous system respiratory drive. The CSAI is calculated by dividing the total number of central apnea events by the total sleep time in hours. Values above 5 events per hour are considered abnormal in most clinical contexts. This metric is essential for diagnosing central sleep apnea syndromes, monitoring treatment efficacy, and distinguishing central from mixed sleep-disordered breathing patterns.
Usage
Usage note: Can be abbreviated as CSAI in subsequent references after first defining the full term. Express as 'events per hour' rather than 'per hour' alone.
In Context
- "The central sleep apnea index was elevated at 15 events per hour, indicating significant central sleep-disordered breathing." — Sleep study interpretation
- "Following adaptive servo-ventilation therapy, the patient's central sleep apnea index decreased from 22 to 3 events per hour." — Follow-up sleep medicine note