Predictors of Blood Pressure Reduction With Nocturnal Continuous Positive Airway Pressure Therapy in Patients With Obstructive Sleep Apnea and Prehypertension

Circadian blood pressure profile and blood pressure changes following oral appliance therapy for obstructive sleep apnoea

OBJECTIVES

Oral appliance therapy for obstructive sleep apnoea (OSA) reduces blood pressure (BP) but there is little information on relationship to circadian BP pattern (nocturnal BP dipping or non-dipping). The aims of this study were to determine whether nocturnal dipping pattern influences BP changes following oral appliance therapy, and to determine the effect of oral appliance therapy on circadian BP pattern.

METHODS

Participants in two randomized trials of oral appliance therapy (1-2 months) with 24-h ambulatory BP monitoring (ABPM) data were included (N = 152). Nocturnal BP Dippers (nocturnal/diurnal SBP ratio <0.9) and non-dippers were compared for BP changes following oral appliance therapy and the effect of oral appliance therapy on nocturnal BP dipping was assessed.

RESULTS

Of 152 participants, 64.5% were dippers. Dippers were on average younger and less likely to be hypertensive (42 vs. 82.7%, P < 0.001). Nondippers showed greater reduction in nocturnal BP measures, related to higher BP measures at baseline. There was no difference in the relationship between treatment effectiveness and BP changes between groups. Oral appliance therapy converted only 23% of baseline non-dippers to a nocturnal dipping profile.

CONCLUSION

Baseline circadian BP profile influenced the BP response to oral appliance therapy, largely because of higher baseline BP in the non-dipper subgroup. Oral appliance therapy did not convert OSA patients to a more favourable circadian BP profile. Further work is required to understand the effect of oral appliance therapy on circadian BP profile and of the individuals who will receive cardiovascular benefit from oral appliance therapy.

Non-dipping nocturnal blood pressure correlates with obstructive sleep apnoea severity in normotensive subjects and may reverse with therapy

Background

Obstructive sleep apnoea (OSA) is strongly associated with systemic hypertension, but there are limited data on the relationship with blood pressure (BP) in normotensive subjects. Here, we examined the relationship of OSA with nocturnal BP in a documented diurnal normotensive cohort, explored potential intermediate pathways and assessed the effects on BP of continuous positive airways pressure (CPAP) therapy.

Methods

65 males referred for assessment of possible OSA and normotensive on 24-hour BP monitoring underwent overnight inpatient polysomnography (age 41±7 years, body mass index (BMI) 34±6 kg·m⁻², apnoea–hypopnoea index (AHI) 14 (interquartile range 5–26)). Urine and serum were assessed for markers of sympathetic activation, renin–angiotensin–aldosterone system activity, oxidative stress, endothelial function and systemic inflammation. In a subset of patients, 24-hour BP monitoring was repeated after CPAP therapy.

Results

Within this normotensive cohort, night-time systolic and diastolic BP and nocturnal BP dip were highest in the fourth OSA severity quartile (p<0.05). Nocturnal BP dip correlated with AHI (r=−0.327, p<0.05) and oxygen desaturation index (ODI) (r=−0.371, p<0.05), but only ODI was an independent predictor of BP dip (B=–0.351, p<0.01) and non-dipping status (B=0.046, p<0.05). Overnight urinary norepinephrine correlated with nocturnal systolic BP (r=0.387, p<0.01) with a trend towards correlation with systolic dipping (p=0.087). In 20 CPAP-treated patients, night-time systolic BP decreased (p<0.05) and mean nocturnal BP dip increased (p≤0.05).

Conclusion

In this normotensive cohort, OSA severity was associated with higher nocturnal BP, which improved following CPAP therapy, and intermittent hypoxia was the most important OSA-related variable in this relationship.

There is a strong association in a normotensive cohort between OSA and nocturnal blood pressure, with intermittent hypoxia as an important mechanistic pathwayhttps://bit.ly/2SFvWiB

Association of continuous positive airway pressure adherence with complications in patients with type 2 diabetes and obstructive sleep apnea

STUDY OBJECTIVES

To explore the association of continuous positive airway pressure (CPAP) adherence with clinical outcomes in patients with type 2 diabetes and obstructive sleep apnea in a real-world setting.

METHODS

This was a retrospective study of patients with type 2 diabetes diagnosed with obstructive sleep apnea between 2010 and 2017. CPAP adherence (usage for ≥ 4 h/night for ≥ 70% of nights) was determined from the first CPAP report following the polysomnography. Data including estimated glomerular filtration rate, hemoglobin A1c, systolic and diastolic blood pressure, lipid panel, and incident cardiovascular/peripheral vascular/cerebrovascular events were extracted from medical records. Mixed-effects linear regression modeling of longitudinal repeated measures within patients was utilized for continuous outcomes, and logistic regression modeling was used for binary outcomes. Models were controlled for age, sex, body mass index, medications, and baseline levels of outcomes.

RESULTS

Of the 1,295 patients, 260 (20.7%) were CPAP adherent, 318 (24.5%) were CPAP nonadherent, and 717 (55.3%) had insufficient data. The follow-up period was, on average, 2.5 (1.7) years. Compared to those who were CPAP nonadherent, those who were adherent had a significantly lower systolic blood pressure (β = -1.95 mm Hg, P = .001) and diastolic blood pressure (β = -2.33 mm Hg, P < .0001). Among the patients who were CPAP adherent, a 17% greater CPAP adherence was associated with a 2 mm Hg lower systolic blood pressure. Lipids, hemoglobin A1c, estimated glomerular filtration rate, and incident cardiovascular/peripheral vascular/cerebrovascular events were not different between the 2 groups.

CONCLUSIONS

Achieving CPAP adherence in patients with type 2 diabetes and obstructive sleep apnea was associated with significantly lower blood pressure. Greater CPAP use within patients who were adherent was associated with lower systolic blood pressure.

CITATION

Sheth U, Monson RS, Prasad B, et al. Association of continuous positive airway pressure adherence with complications in patients with type 2 diabetes and obstructive sleep apnea. J Clin Sleep Med. 2021;17(8):1563-1569.

The treatment of mild OSA with CPAP or mandibular advancement device and the effect on blood pressure and endothelial function after one year of treatment

STUDY OBJECTIVES

To evaluate and compare the effects of continuous positive airway pressure (CPAP), use of a mandibular advancement device (MAD), and no treatment on 24-hour ambulatory blood pressure monitoring and peripheral arterial tonometry at 6 and 12 months follow-up in individuals with mild obstructive sleep apnea (OSA), and in a subgroup who had an apnea-hypopnea index of < 5 events/h and adherence of ≥ 4 hours per night (effective-treatment subgroups).

METHODS

The inclusion criteria were individuals with mild obstructive sleep apnea, any sex, age between 18 and 65 years, and a body mass index of ≤ 35 kg/m². Patients were randomized into CPAP, MAD, and no-treatment groups. The evaluations included physical examination, full polysomnography, 24-hour ambulatory blood pressure monitoring, and peripheral arterial tonometry at baseline and after 6 and 12 months. A generalized linear mixed model was used for comparisons.

RESULTS

The CPAP and MAD groups had lower apnea-hypopnea indexes than the control group at 6 and 12 months, and the CPAP group had higher blood oxygen levels (SpO₂) than the MAD group. The MAD group had more hours of treatment per night and better adaptation to treatment than the CPAP group (MAD: 5.7 ± 2.7 h/night; CPAP: 3.8 ± 3.4 h/night; MAD: 16% did not adapt; CPAP: 42% did not adapt). No differences were found in the total sample and effective treatment in relation to peripheral arterial tonometry or 24-hour ambulatory blood pressure monitoring outcomes.

CONCLUSIONS

Treatment of mild obstructive sleep apnea with CPAP or MAD did not improve blood pressure or endothelial function after 1 year, even in patients with effective treatment.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Continuous Positive Airway Pressure and Oral Appliances Treatments in Mild Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT01461486; Identifier: NCT01461486.

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.

Association between nondipping pattern and EndoPAT signal in patients with mild obstructive sleep apnea

OBJECTIVE

To compare vascular endothelial function between dipping (D) and nondipping (ND) patterns in patients with and without mild obstructive sleep apnea (OSA) using EndoPAT, a test of reactive hyperemia used to assess peripheral vascular endothelial function.

METHODS

The sample consisted of individuals of both genders between 18 and 65 years of age with a body mass index (BMI) of ≤35 kg/m² and apnea/hypopnea index (AHI) of ≤15. The nondipping pattern was considered present when the dip of nocturnal blood pressure (NBP) was <10%. All of the sample underwent clinical and physical evaluation, full polysomnography, 24-hour ambulatory blood pressure monitoring, and EndoPAT evaluation. A generalized linear model was used for statistical analysis.

RESULTS

The sample comprised 120 individuals, 35 in the control group and 85 in the mild OSA group. Four groups were formed: Control-ND, Control-D, Mild OSA-ND, and Mild OSA-D according to nocturnal ABPM patterns. The frequency of nondipping was (34.1%) in the Mild OSA group and (17.1%) in the Control group (p = 0.07). The Mild OSA-ND group had a higher augmentation index (AIx) than the Mild OSA-D group. Regression analysis showed that male gender, higher age, and nondipping status were associated with these results, whereas oxygen desaturation index (ODI) and AHI did not. With respect to the reactive hyperemia index (RHI), the Mild OSA-D group had lower values compared to the Control-ND group, but an association with OSA was not confirmed in the regression model.

CONCLUSION

Nondipping status was associated with a worse augmentation index in both groups independently of AHI or oxygen desaturation index. Male gender, higher age, and nondipping status were associated with augmentation index. ClinicalTrials.gov Identifier: NCT01461486.

The role of compliance with PAP use on blood pressure in patients with obstructive sleep apnea: is longer use a key-factor?

Scientific data about the effects of positive airway pressure (PAP) treatment on blood pressure (BP) control are continuously increasing; however, they are controversial. We aimed to determine the long-term effects of compliance with PAP therapy on BP in both hypertensive and normotensive patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). One thousand one hundred sixty eight consecutive patients with newly diagnosed OSAHS, who had been recommended PAP therapy, were followed up for a minimum of 2 years. Patients with previous cardiovascular disease were excluded. BP was measured at baseline and after 2 years of PAP treatment. In addition, the correlation between the changes in BP with different levels of PAP compliance was assessed. At the end of the follow-up period, in the hypertensive group of patients (n=586), a significant decrease was shown in systolic (-11.2 mm Hg, P<0.001) and diastolic BP (-4.2 mm Hg, P<0.001). Furthermore, in the patients without hypertension (n=528), a significant decrease was noted both in systolic and diastolic BP (-3.6, P<0.001 and -2.4, P<0.001, respectively). A correlation between the magnitude of change in systolic and diastolic BP and hours of use of PAP (r=0.14, P=0.002 and r=0.1, P=0.025, respectively) was observed in all patients. Long-term use of PAP treatment, as well as increased hours of PAP in patients with OSAHS use showed significant reductions in BP not only in patients with hypertension, but also in normotensive patients. Therefore a significant potential reduction in cardiovascular mortality and morbidity should be expected in these patients.

Effectiveness of continuous positive airway pressure in lowering blood pressure in patients with obstructive sleep apnea: a critical review of the literature

Obstructive sleep apnea (OSA) is an extremely common comorbid condition in patients with hypertension, with a prevalence of ~50%. There is growing evidence suggesting that OSA is a secondary cause of hypertension, associated with both poor blood pressure (BP) control and target organ damage in patients with hypertension. The application of continuous positive airway pressure (CPAP) during sleep is the gold standard treatment of moderate- to-severe OSA and very effective in abolishing obstructive respiratory events. However, several meta-analyses showed that the overall impact of CPAP on BP is modest (~2 mmHg). There are several potential reasons for this disappointing finding, including the heterogeneity of patients studied (normotensive patients, controlled, and uncontrolled patients with hypertension), non-ideal CPAP compliance, clinical presentation (there is some evidence that the positive impact of CPAP on lowering BP is more evident in sleepy patients), and the multifactorial nature of hypertension. In this review, we performed a critical analysis of the literature evaluating the impact of CPAP on BP in several subgroups of patients. We finally discussed perspectives in this important research area, including the urgent need to identify predictors of BP response to CPAP and the importance of precision medicine in this scenario.

Sleep, death, and the heart

Obstructive and central sleep apnea have been associated with increased risk of adverse cardiovascular events and mortality. Sympathetic dysregulation occurring as a result of the respiratory disturbance is thought to play a role in this increased risk. Sleep apnea increases the risk of arrhythmias, myocardial ischemia/infarction, stroke, and heart failure, all of which may increase mortality risk. A higher incidence of nocturnal arrhythmias, cardiac ischemia, and sudden death has been noted in subjects with sleep-disordered breathing (SDB). In this review, the association between SDB and each of these conditions is discussed, as well as the potential mechanisms underlying these risks and the effects of treatment of SDB. Particular emphasis is placed on the relationship between SDB and nocturnal atrial and ventricular arrhythmias, myocardial ischemia/infarction and sudden death.

Chemoreflexes, sleep apnea, and sympathetic dysregulation

Obstructive sleep apnea (OSA) and hypertension are closely linked conditions. Disordered breathing events in OSA are characterized by increasing efforts against an occluded airway while asleep, resulting in a marked sympathetic response. This is predominantly due to hypoxemia activating the chemoreflexes, resulting in reflex increases in sympathetic neural outflow. In addition, apnea - and the consequent lack of inhibition of the sympathetic system that occurs with lung inflation during normal breathing - potentiates central sympathetic outflow. Sympathetic activation persists into the daytime, and is thought to contribute to hypertension and other adverse cardiovascular outcomes. This review discusses chemoreflex physiology and sympathetic modulation during normal sleep, as well as the sympathetic dysregulation seen in OSA, its extension into wakefulness, and changes after treatment. Evidence supporting the role of the peripheral chemoreflex in the sympathetic dysregulation seen in OSA, including in the context of comorbid obesity, metabolic syndrome, and systemic hypertension, is reviewed. Finally, alterations in cardiovascular variability and other potential mechanisms that may play a role in the autonomic imbalance in OSA are also discussed.

The efficacy of antihypertensive drugs in chronic intermittent hypoxia conditions

Sleep apnea/hypopnea disorders include centrally originated diseases and obstructive sleep apnea (OSA). This last condition is renowned as a frequent secondary cause of hypertension (HT). The mechanisms involved in the pathogenesis of HT can be summarized in relation to two main pathways: sympathetic nervous system stimulation mediated mainly by activation of carotid body (CB) chemoreflexes and/or asphyxia, and, by no means the least important, the systemic effects of chronic intermittent hypoxia (CIH). The use of animal models has revealed that CIH is the critical stimulus underlying sympathetic activity and hypertension, and that this effect requires the presence of functional arterial chemoreceptors, which are hyperactive in CIH. These models of CIH mimic the HT observed in humans and allow the study of CIH independently without the mechanical obstruction component. The effect of continuous positive airway pressure (CPAP), the gold standard treatment for OSA patients, to reduce blood pressure seems to be modest and concomitant antihypertensive therapy is still required. We focus this review on the efficacy of pharmacological interventions to revert HT associated with CIH conditions in both animal models and humans. First, we explore the experimental animal models, developed to mimic HT related to CIH, which have been used to investigate the effect of antihypertensive drugs (AHDs). Second, we review what is known about drug efficacy to reverse HT induced by CIH in animals. Moreover, findings in humans with OSA are cited to demonstrate the lack of strong evidence for the establishment of a first-line antihypertensive regimen for these patients. Indeed, specific therapeutic guidelines for the pharmacological treatment of HT in these patients are still lacking. Finally, we discuss the future perspectives concerning the non-pharmacological and pharmacological management of this particular type of HT.

Prevalence of hypertension and circadian blood pressure variations in patients with obstructive sleep apnoea-hypopnoea syndrome

OBJECTIVE

To investigate the prevalence of hypertension and circadian blood pressure (BP) variations in patients with obstructive sleep apnoea-hypopnoea syndrome (OSAHS).

METHODS

Patients referred to a sleep clinic underwent polysomnography with measurement of BP at four time points. They were classified into four groups (control, and mild, moderate or severe sleep apnoea) using the apnoea-hypopnoea index (AHI). Circadian variation was assessed using night-time to daytime mean BP (R(N/D)) and morning to evening mean BP (R(M/E)) ratios.

RESULTS

Hypertension was significantly more common in patients with OSAHS (50.5%) than in controls (30.4%). AHI was positively correlated with hypertension after controlling for related confounders. Mean BP values at all four time points rose with increasing AHI. The increase in night-time and morning values was more pronounced than the increase in daytime and evening values in patients with OSAHS, resulting in loss of the normal BP diurnal rhythm. The R(N/D) and R(M/E) ratios increased with increasing AHI. Daytime BP was significantly correlated with AHI and the lowest oxygen saturation value.

CONCLUSION

OSAHS was shown to be an independent risk factor for hypertension. It was also associated with loss of the normal BP diurnal rhythm.