Fig. 1From: Hypopnea definitions, determinants and dilemmas: a focused reviewThis figure shows an obstructive apnea. An apnea is a respiratory event lasting ≥10 s, characterized by a decrement in airflow of ≥90% from the baseline in the oronasal thermocouple signal. Clear crescendo effort in the abdominal belt suggests obstruction. Elevated and progressively increasing values in the Δ Pes during the event confirm the obstructive etiologyBack to article page