Obstructive sleep apnea syndrome in male hypertensives, refractory to drug therapy. Nocturnal automatic blood pressure measurements--an aid to diagnosis?

Sixteen therapy resistant hypertensive males and 16 responders to antihypertensive drug treatment, matched for age, gender and body mass index, were examined by means of Static Charge Sensitive Bed (SCSB) and oximetry for the presence of obstructive sleep apnea syndrome (OSAS). In borderline cases, polysomnography was performed. The prevalence of OSAS among therapy resistant patients was 56%, as compared to 19% in the control group (p less than 0.05). This higher prevalence of OSAS in a weight-matched group of subjects with severe hypertension supports the notion of a causal connexion between hypertension and OSAS. In 10 OSAS patients and 10 hypertensives with normal respiration during sleep, ambulatory noninvasive monitoring (ABPM) of arterial pressure (AP) and heart rate (HR) was also performed. The OSAS patients had a higher nocturnal variability of HR, systolic blood pressure (both p less than 0.05), and diastolic blood pressure (p less than 0.01) in 8 half-hourly single ABPM measurements. Contrary to the non-OSAS subjects they also had a higher HR variability during sleep than they had in the waking state (p less than 0.05). For subjects less than 60 yrs a range/median value of greater than 0.32 for nocturnal diastolic pressure was found to predict OSAS with a sensitivity of 87.5% and a specificity of 100%. It is concluded that therapy-resistant male hypertensives have a high prevalence of OSAS. As this may be a deleterious combination, screening for OSAS is highly indicated in such patients. A high variability of HR and AP in nocturnal ABPM suggests OSAS.