Figure 1: Excerpt from a polysomnographic study showing three typical hypopnoeic events. | British Dental Journal

Figure 1: Excerpt from a polysomnographic study showing three typical hypopnoeic events.

From: Current principles in the management of obstructive sleep apnoea with mandibular advancement appliances

Figure 1

The five traces illustrated are, from above downwards: blood oxygen saturation, thoracic and abdominal respiratory movement, airflow and sound. As the oxygen saturation level falls, during hypopnoea, an increase in thoracic and abdominal respiratory activity takes place with a sudden resurgence of airflow. At the same time a loud snore occurs. The oxygen saturation then returns to normal levels until the next episode occurs

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