Figure 4.

Fragment of a polygraph recording in a representative sleepy patient with severe obstructive sleep apnea.

Notes: Patient undergoing simultaneous continuous finger blood pressure monitoring and ambulatory blood pressure monitoring (ABPM). Top to bottom: pressure detected by an open hose placed under the cuff for ABPM measurements; beat-by-beat blood pressure (BP); nasal airflow; oxyhemoglobin saturation (SaO₂). A flat airflow signal identifies apnea time. In this patient, apnea duration was similar before and during ABPM measurement, which indicates that the cuff inflation did not cause any arousal shortening habitual apnea duration. ABPM measurement required a time exceeding the duration of an apnea cycle, ie, of an apnea and following ventilation. During that period, BP values largely varied, but only one systolic and one diastolic value were obtained by ABPM.