Let's first agree on the basic definitions: AHI: Apnea hypopnea Index: Apneas: Complete cessations (>90%) of airflow lasting for at least 10 seconds. Hypopneas: Partial reductions (>30-50%) in airflow leading to a decrease in oxygen saturation (by at least 3% or 4%) or arousal from sleep....

We recently changed, per AASM guidelines, to reporting both AHI3a and AHI4. Since most sleep-disordered breathing events will qualify with the 3a decision, as it includes arousals, we have stopped reporting an RDI. If there are events that don't meet the 3a hypopnea definition, we might comment on i...