Resistant Hypertension in Chronic Kidney Disease

209

Additionally, recent meta-analyses have provided further support for the therapeutic
benefit of CPAP therapy specifically on resistant hypertension [ 66 ]. Table 13.3
shows the magnitude of blood pressure reduction across the six studies included in
this meta-analysis. CPAP was found to have a greater effect on blood pressure
reduction in patients with resistant hypertension than those without resistant hyper-
tension, with average reductions of 6–7 and 5–6 mmHg in ambulatory systolic and
diastolic blood pressures.
Taken together, these studies suggest that CPAP can be expected to result in a
modest, favorable effect on blood pressure reduction, on the order of 2–3 mmHg for
the population at large. However, this degree of reduction should be considered
significant, as it has been shown to reduce cardiovascular mortality by 4–8%. In
patients with severe and resistant hypertension, the magnitude of BP reduction
attributable to CPAP appears to be even more significant.

CPAP vs. Antihypertensives for Blood Pressure Control

The effect of CPAP on blood pressure does not appear to be as potent as that of
antihypertensives, albeit from the limited direct comparisons that exist. An impor-
tant clinical question, and one likely of interest to patients, is how CPAP impacts
blood pressure relative to that obtained with standard antihypertensive medications.
The first such trial randomized patients to receive either CPAP or an antihyperten-
sive regimen with valsartan using a crossover design [ 67 ]. Valsartan was found to be
superior to CPAP, with patients on valsartan experiencing a fourfold greater reduc-
tion in 24-h mean blood pressure than those on CPAP alone (11 mmHg vs. 3 mmHg)
over an 8-week time period. Another study sought to evaluate the blood pressure
response to CPAP as “add-on” therapy in patients already taking losartan [ 68 ]. They
found that losartan resulted in blood pressure reductions but to a lesser degree in
patients with OSA than those without OSA.

Table 13.3 Nocturnal blood pressure reduction with CPAP use in patients with resistant
hypertension

No. of

studies

Mean change

(mmHg) 95% CI, P value

Mean difference in SBP after CPAP 5 −6.79 −13.86 to 0.26,

P = 0.05

Mean difference in DBP after CPAP 5 −3.67 −8.05 to 0.71,

P = 0.10

Mean net change in SBP between

CPAP and control

3 −2.08 −4.33 to 0.16,

P = 0.06

Mean net change in DBP between

CPAP and control

3 −1.47 −3.22 to 0.28,

P = 0.10

From reference Iftikhar et al. [ 66 ]; with permission

13 Obstructive Sleep Apnea and Resistant Hypertension