Definition - What does flow limitation index mean?
A flow limitation index is a metric used to measure the average number of flow limitation events that occur when someone is sleeping. A flow limitation index may be derived from a specific sleep study or from information gathered by an automatic positive airway pressure (APAP) device used for the treatment of sleep apnea.
A flow limitation event is recorded when an airway pressure measurement device detects what is known as a flow limitation. A flow limitation occurs when the sleeper's airway becomes partially obstructed, altering the airflow pressure.
The flow limitation index is calculated by dividing the total number of flow limitation events which occur by the number of hours over which events were recorded. This information may then be used to diagnose disorders including obstructive sleep apnea or to assess the effectiveness of an individual's treatment for an obstructive airway disorder.
SureHire explains flow limitation index
During sleep, a person's airway may become partially or fully obstructed, limiting the body's supply of oxygen. Often this situation is caused by a condition known as obstructive sleep apnea (OPA). A constant positive airway pressure (CPAP) or automatic positive airway pressure (APAP) device is used to treat obstructive sleep apnea. These devices deliver a flow of air through the user's air passage which supports weakened muscles and keeps his or her airway open during sleep.
To determine whether a person has obstructive sleep apnea or related disorders such as Upper Airway Resistance Syndrome (UARS), a flow limitation study may be ordered. By calculating the number of times during the night that a person experiences a reduction in airflow — a flow limitation —medical professions can better gauge the severity of his or her condition and begin to investigate potential causes.