A daytime normotensive patient with nocturnal hypoxia-induced hypertension and severe obstructive sleep apnea

This is the case of a 60-year-old male. He had no past medical history at a regular medical check-up. According to findings at the regular medical check-up, he was obese (body mass index, 32.8 kg/m²), and had short neck, small jaw, and low soft palate; therefore, it was suspected that he may have sleep-disordered breathing. Blood pressure (BP) at the medical check-up was 121/80 mmHg, and the results of electrocardiogram and chest radiography were normal. Blood test data at the medical check-up indicated abnormality of lipid metabolism and hyperuricemia. No other abnormalities were found. It became clear that he became sleepy during daytime at an additional medical interview. Accordingly, he was diagnosed as having severe obstructive sleep apnea (OSA) with apnea–hypopnea index 65.3/h and arousal index 64.4/h by polysomnography. The oxygen-triggered nocturnal BP monitoring that was conducted at home around the same time indicated remarkable hypoxia-induced hypertension (Day 1: hypoxia-peak nocturnal BP 181/117 mmHg, Day 2: hypoxia-peak nocturnal BP 204/137 mmHg). The patient recognized the risk of OSA by visualizing the hypoxia-induced hypertension; therefore, introduction of continuous positive airway pressure (CPAP) therapy for severe OSA was smooth. As the results of CPAP therapy, we could confirm disappearance of hypoxia-induced hypertension. <Learning objective: An office worker without cardiovascular disease was diagnosed as having severe obstructive sleep apnea. Remarkable hypoxia-induced nocturnal hypertension was identified by oxygen-triggered blood pressure (BP) monitoring. It was considered that nocturnal hypertension, which was not able to be recorded by previous ambulatory blood pressure monitoring, was recorded by the oxygen-triggered BP monitoring method.>