Blood pressure response to CPAP treatment in subjects with obstructive sleep apnoea: the predictive value of 24-h ambulatory blood pressure monitoring

Abstract

The reduction in blood pressure (BP) with continuous positive airway pressure (CPAP) is modest and highly variable. In this study, we identified the variables that predict BP response to CPAP.24-h ambulatory BP monitoring (ABPM), C-reactive protein (CRP), leptin, adiponectin and 24-h urinary catecholamine were measured before and after 6 months of CPAP in obstructive sleep apnoea (OSA) patients.Overall, 88 middle-aged, obese male patients with severe OSA (median apnoea-hypopnoea index 42 events·h) were included; 28.4% had hypertension. 62 patients finished the study, and 60 were analysed. The daytime diastolic BP (-2 mmHg) and norepinephrine (-109.5 nmol·day) were reduced after CPAP, but no changes in the 24-h BP, night-time BP, dopamine, epinephrine, CRP, leptin or adiponectin were detected. The nocturnal normotension was associated with an increased night-time-BP (+4 mmHg) after CPAP, whereas nocturnal hypertension was associated with a reduction of 24-h BP (-3 mmHg). A multivariate linear regression model showed differential night-time BP changes after CPAP. Specifically, low night-time heart rate (<68 bpm) and BP dipper profile were associated with increased night-time BP and new diagnosis of nocturnal hypertension.Our results suggest that nocturnal hypertension, circadian BP pattern and night-time heart rate could be clinical predictors of BP response to CPAP and support the usefulness of 24-h ABPM for OSA patients before treatment initiation. These results need to be confirmed in further studies.

Blood pressure response to treatment of obese vs non‐obese adults with sleep apnea

“…However, an increase in sympathetic activity in individuals with OSA is supported by our finding of a 14% reduction in mean 24‐hour urinary norepinephrine at follow‐up among all PAP‐adherent OSA participants. Previous studies report decreases in urinary norepinephrine excretion of similar magnitude . Extending those findings, our results, controlling for baseline AHI, indicate that OSA participants who are obese have the greatest reduction in urinary norepinephrine excretion following PAP treatment.…”

Decrease in blood pressure during continuous positive airway pressure treatment for obstructive sleep apnoea: still searching for predictive factors

“…Factors like normal baseline BP [6], mild respiratory disorders [4], low cardiovascular responsiveness to autonomic activation [7] or lack of sleepiness [8], may attenuate the effect of apnoea abolition or give rise to unexpected findings. For example, some authors have described a small increase in nocturnal BP in some OSA patients [9,10], and hypothesised the existence of some "OSA phenotypes" with specific BP responses to CPAP [9]. Identification of such phenotypes would be helpful for better and individualised patient management.…”

Rebuttal From Drs Cardoso and Salles

“…First, an abnormal BP dipping pattern is a predictor of cardiovascular events, and a previous study showed that this BP pattern's manifestation during ambulatory BP monitoring is a good predictor of BP response to CPAP. 9 Second, participants recruited in the SAVE trial comprised patients with previous coronary or cerebrovascular disease. Not all patients had hypertension (and most of them had BP controlled at baseline, as suggested by the baseline characteristics).…”