207more obese and sleepier patients have more to gain as far as a BP reduction with
CPAP use. Another study of non-sleepy patients with OSA found that the prescription
of CPAP compared with usual care did not result in a significant reduction in the inci-
dence of hypertension or cardiovascular events, lending further support to the greater
effect of CPAP in sleepy patients, for reasons that are not fully understood [ 59 ].
In order to control for effects PAP might have on BP independent of its effect on
sleep-disordered breathing, another group evaluated the effect of CPAP on blood pres-
sure in hypertensive patients with and without OSA. They found that 3 weeks of CPAP
resulted in a significant reduction in nocturnal blood pressure only in patients with
underlying OSA (−10.3 mmHg systolic and −4.5 mmHg diastolic).
Fig. 13.4 Mean arterial pressures in patients with OSA before and after effective CPAP (a) and
subtherapeutic CPAP (b). Substantial blood pressure reductions were seen in the group whose
OSA was effectively treated with CPAP for 9 weeks. Mean arterial blood pressure decreased by
9.9 ± 11.4 mmHg with effective nCPAP treatment, whereas no relevant change occurred with
subtherapeutic nCPAP (P = 0.01) (From Ref. [ 57 ]; with permission)
13 Obstructive Sleep Apnea and Resistant Hypertension