Use of Ambulatory Blood Pressure Monitoring for the Screening of Obstructive Sleep Apnea

Classification of blood pressure during sleep impacts designation of nocturnal nondipping

The identification of nocturnal nondipping blood pressure (< 10% drop in mean systolic blood pressure from awake to sleep periods), as captured by ambulatory blood pressure monitoring, is a valuable element of risk prediction for cardiovascular disease, independent of daytime or clinic blood pressure measurements. However, capturing measurements, including determination of wake/sleep periods, is challenging. Accordingly, we sought to evaluate the impact of different definitions and algorithms for defining sleep onset on the classification of nocturnal nondipping. Using approaches based upon participant self-reports, applied definition of a common sleep period (12 am -6 am), manual actigraphy, and automated actigraphy we identified changes to the classification of nocturnal nondipping, and conducted a secondary analysis on the potential impact of an ambulatory blood pressure monitor on sleep. Among 61 participants in the Eastern Caribbean Health Outcomes Research Network hypertension study with complete ambulatory blood pressure monitor and sleep data, the concordance for nocturnal nondipping across methods was 0.54 by Fleiss' Kappa (depending on the method, 36 to 51 participants classified as having nocturnal nondipping). Sleep quality for participants with dipping versus nondipping was significantly different for total sleep length when wearing the ambulatory blood pressure monitor (shorter sleep duration) versus not (longer sleep duration), although there were no differences in sleep efficiency or disturbances. These findings indicate that consideration of sleep time measurements is critical for interpreting ambulatory blood pressure. As technology advances to detect blood pressure and sleep patterns, further investigation is needed to determine which method should be used for diagnosis, treatment, and future cardiovascular risk.

Effect of Maternal Obstructive Sleep Apnea-Hypopnea on 24-Hour Blood Pressure, Nocturnal Blood Pressure Dipping and Arterial Stiffness in Hypertensive Disorders of Pregnancy

Rationale: Maternal obstructive sleep apnea-hypopnea (OSAH) is associated with hypertensive disorders of pregnancy (HDP). Attenuation of the normal nocturnal blood pressure (BP) decline (non-dipping) is associated with adverse pregnancy outcomes. OSAH is associated with nocturnal non-dipping in the general population, but this has not been studied in pregnancy. We therefore analyzed baseline data from an ongoing RCT (NCT03309826) assessing the impact of OSAH treatment on HDP outcomes, to evaluate the relationship of OSAH to 24-h BP profile, in particular nocturnal BP dipping, and measures of arterial stiffness.

Methods: Women with a singleton pregnancy and HDP underwent level II polysomnography. Patients with OSAH (apnea-hypopnea index (AHI) ≥ 5 events/h) then underwent 24-h ambulatory BP monitoring and arterial stiffness measurements (applanation tonometry, SphygmoCor). Positive dipping was defined as nocturnal systolic blood pressure (SBP) dip ≥ 10%. The relationships between measures of OSAH severity, measures of BP and arterial stiffness were evaluated using linear regression analyses.

Results: We studied 51 HDP participants (36.5 ± 4.9 years, BMI 36.9 ± 8.6 kg/m²) with OSAH with mean AHI 27.7 ± 26.4 events/h at 25.0 ± 4.9 weeks’ gestation. We found no significant relationships between AHI or other OSA severity measures and mean 24-h BP values, although BP was generally well-controlled. Most women were SBP non-dippers (78.4%). AHI showed a significant inverse correlation with % SBP dipping following adjustment for age, BMI, parity, gestational age, and BP medications (β = −0.11, p = 0.02). Significant inverse correlations were also observed between AHI and DBP (β = −0.16, p = 0.01) and MAP (β = −0.13, p = 0.02) % dipping. Oxygen desaturation index and sleep time below SaO₂ 90% were also inversely correlated with % dipping. Moreover, a significant positive correlation was observed between carotid-femoral pulse wave velocity (cfPWV) and REM AHI (β = 0.02, p = 0.04) in unadjusted but not adjusted analysis.

Conclusion: Blood pressure non-dipping was observed in a majority of women with HDP and OSAH. There were significant inverse relationships between OSAH severity measures and nocturnal % dipping. Increased arterial stiffness was associated with increasing severity of OSAH during REM sleep in unadjusted although not adjusted analysis. These findings suggest that OSAH may represent a therapeutic target to improve BP profile and vascular risk in HDP.

Obstructive sleep apnea and ambulatory blood pressure monitoring: current evidence and research gaps

Obstructive Sleep Apnea (OSA) is a common condition characterized by intermittent collapse of the upper airway during sleep, resulting in partial (hypopnoeas) and total obstructions (apneas). These respiratory events observed in OSA may trigger multiple pathways involved in the blood pressure (BP) instability during the night and potentially influencing daytime BP as well (carry-over effects). This review provides an update about the impact of OSA and its treatments on 24-h BP control. Overall, there is growing evidence suggest that OSA is associated with higher frequency of nondipping BP pattern and nocturnal hypertension in a dose-dependent manner. The presence of nondiping BP (especially the reverse pattern) is independently associated with OSA regardless of sleep-related symptoms suggesting a potential tool for screening OSA in patients with clinical indication for performing ABPM. Beyond dipping BP, preliminary evidence associated OSA with white-coat effect and higher frequency of masked hypertension and BP variability than the control group (no OSA). Unfortunately, most of the evidence on the evidence addressing the impact of OSA treatment on BP was limited to office measurements. In the last years, data from observational and randomized studies pointed that CPAP is able to promote 24-h BP decrease especially in patients with resistant and refractory hypertension. A randomized trial suggests that CPAP is able to decrease the rate of masked hypertension as compared to no treatment in patients with severe OSA. Interestingly, nondipping BP is a good predictor of BP response to CPAP making ABPM an interesting tool for better OSA management.

Demographic, clinical, and biomarker predictors of apnea-hypopnea index from polysomnography in Midwestern sleep clinic patients

BACKGROUND

To examine if selected demographic (age, gender), clinical (diabetes, coronary artery disease, hyperlipidemia, myocardial infarction, stroke, lung disease, smoking history, alcohol intake), and biomarker [blood pressure (BP), heart rate, body mass index (BMI), neck circumference, Mallampati score] variables are predictors of apnea-hypopnea index (AHI) from polysomnography (PSG).

METHODS

This cross-sectional study recruited a sample of adults (N = 170) who were being evaluated for OSA. Participants completed self-reported demographic and clinical questionnaires, and then completed PSG (n = 142). Multi-collinearity was assessed. Confounding factors, correlations, and potential interactions were explored.

RESULTS

The final regression model was performed on 130 participants; 61 (46.9%) had an AHI ≥ 15. Systolic and diastolic BPs were highly correlated. Interactions were tested between gender and other variables (high cholesterol, BMI, neck circumference, systolic BP) and between systolic BP and other variables (high cholesterol, BMI, neck circumference, and lung disease). No interactions occurred between gender or systolic BP and other variables, meaning that the effects of the variables on AHI levels from PSG did not vary depending on gender or systolic BP. BMI, systolic BP, and absence of lung disease were predictors for AHI levels ≥ 15 from PSG.

CONCLUSIONS

BMI and systolic BP were significant predictors of OSA in this study. The absence of lung disease as a significant predictor was unique and may be due to the small number of participants who self-reported lung disease. To our knowledge, this is the first study to report this combination of variables to predict AHI levels ≥ 15 from PSG.

Normotensive patients with obstructive sleep apnoea: changes in 24-h ambulatory blood pressure monitoring with continuous positive airway pressure treatment

BACKGROUND

Continuous positive airway pressure (CPAP) treatment reduces blood pressure (BP) in obstructive sleep apnoea (OSA) and hypertensive patients, but there is a lack of data about the effects of CPAP on the BP in normotensive patients.

OBJECTIVE

The aim of the study was to evaluate BP changes in normotensive OSA individuals receiving CPAP treatment.

METHODS

We selected 131 normotensive outpatients with an apnoea/hypopnoea index (AHI) greater than 15 events/hour who required CPAP treatment. All patients underwent a sleep study and 24-h ambulatory BP monitoring (ABPM) at baseline and after 6 months. In addition, the patients were assessed for the presence of baseline masked hypertension, defined as office BP less than 140/90 mmHg and increased BP on 24-h ABPM (mean 24-h BP ≥130/80 mmHg).

RESULTS

After 6 months of CPAP treatment, a mild reduction in all 24-h ABPM variables was observed, but only the mean 24-h DBP [-1.39 mmHg, 95% confidence interval (95% CI), -2.50 to -0.27], mean daytime DBP (-1.39 mmHg, 95% CI -2.56 to -0.22) and the mean 24-h ambulatory BP (-1.80 mmHg, 95% CI, -3.16 to -0.44) reached statistical significance. The reduction was primarily due to BP changes in individuals with masked hypertension who displayed a mean BP reduction of -4.78 mmHg (-7.25 to -2.30 mmHg). Consistent with a circadian BP pattern, a reduction in mean nocturnal BP of -4.73 mmHg (-7.39 to -2.06 mmHg) was observed at 6 months in nondippers; in contrast, the mean nocturnal BP in dippers increased by 2.61 mmHg (0.60-4.62 mmHg).

CONCLUSION

Our findings suggest that the CPAP effects may be different in normotensive outpatients depending on the presence of undiagnosed masked hypertension and the dipping pattern. Therefore, it is important to consider measuring ABPM in this type of patient.

Ambulatory blood pressure monitoring in clinical practice

Being one of the most widely prevalent diseases throughout the world, hypertension has emerged as one of the leading causes of global premature morbidity and mortality. Hence, blood pressure (BP) measurements are essential for physicians in the diagnosis and management of hypertension. Current American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend initiating antihypertensive medications on the basis of office BP readings. However, office BP readings provide a snapshot evaluation of the patient's BP, which might not reflect patient's true BP, with the possibility of being falsely elevated or falsely low. Recently, there is ample evidence to show that ambulatory blood pressure monitoring (ABPM) is a better predictor of major cardiovascular events than BP measurements at clinic settings. ABPM helps in reducing the number of possible false readings, along with the added benefit of understanding the dynamic variability of BP. This article will focus on the significance of ambulatory BP, its advantages and limitations compared with the standard office BP measurement and a brief outlook on its use and interpretation to diagnose and treat hypertension.

Nondipping Blood Pressure Patterns Predict Obstructive Sleep Apnea in Patients Undergoing Ambulatory Blood Pressure Monitoring

A nondipping blood pressure (BP) pattern is common in patients with obstructive sleep apnea (OSA). However, it is unclear how useful a nondipping BP pattern is in screening for OSA. In this cross-sectional study, we recruited consecutive patients with clinical indications for performing ambulatory BP monitoring evaluating the following dipping patterns: (1) normal: ≥10% but <20%; (2) extreme: ≥20%; (3) reduced: ≥0% but <10%; and (4) reverse (riser): <0%. Sleep questionnaires and sleep studies were performed within 7 days after ambulatory BP monitoring. OSA was defined as an apnea-hypopnea index ≥15 events/h. We evaluated 153 patients (OSA frequency, 50.3%). Patients with OSA had higher BPs during sleep, were taking more antihypertensive drugs, and more frequently used hypertensive drugs during the night than patients without OSA. Considering systolic BP, the frequency of OSA in patients with reverse dippers (73.5%) was higher than normal (37.3%), extreme (46.2%), and reduced dippers (49.1%; P =0.012). For diastolic BP, OSA was more common in reduced (66.7%) and reverse dippers (69.6%) as compared to normal (41.4%) or extreme dippers (33.3%; P =0.007). In the regression analysis, reverse systolic dipper was independently associated with OSA (odds ratio, 3.92; 95% CI, 1.31–11.78). Both reduced and reverse diastolic dippers increased the likelihood of OSA for 2.7-fold and 3.5-fold, respectively. Snoring and positive sleep questionnaire findings were associated with a modest increase in the accuracy of reverse dipping pattern for predicting OSA. In conclusion, reverse systolic, as well as reduced and reverse diastolic dippers are independently associated with OSA.