Effects of olmesartan on blood pressure and insulin resistance in hypertensive patients with sleep-disordered breathing

Severity of obstructive sleep apnea is associated with the nocturnal fluctuation of pulse rate, but not with that of blood pressure, in older hypertensive patients receiving calcium channel blockers

AIM

Obstructive sleep apnea (OSA) is associated with increased variability in nocturnal blood pressure (BP). Calcium channel blockers (CCB) are superior to other classes of antihypertensives in decreasing BP variability. We investigated whether OSA severity is associated with nocturnal BP variability in older hypertensive patients treated with CCB.

METHODS

We measured home systolic and diastolic BP and pulse rate (PR) automatically during sleep at an interval of an hour once a week using an electronic sphygmomanometer in 29 hypertensive patients (aged ≥65 years) receiving CCB. We calculated the coefficient of variation (CV) from four consecutive measurements. All patients underwent a home-based portable sleep study.

RESULTS

We found no difference in PR, BP or CV of BP between the patients with no-to-mild OSA and with moderate-to-severe OSA, categorized by the respiratory disturbance index (RDI) and 3% oxygen desaturation index (ODI). The CV of PR in patients with moderate-to-severe OSA was higher than the patients with no-to-mild OSA categorized by 3% ODI (P = 0.01). Body mass index was correlated with RDI and 3% ODI (r = 0.56 and 0.43, respectively). The CV of BP did not correlate to RDI or 3% ODI. The CV of PR was positively correlated both with RDI and with 3% ODI (r = 0.41 and 0.42, respectively).

CONCLUSIONS

The severity of OSA was associated with PR variability, but not with BP variability, in older patients receiving CCB. Our results suggest the need for future studies to determine whether CCB can suppress the influence of OSA on BP fluctuation during sleep. Geriatr Gerontol Int 2019; 19: 604-610.

Prevalence of Sleep Disordered Breathing among Patients with Nocturia at a Urology Clinic

OBJECTIVE

We assessed the prevalence of sleep disordered breathing (SDB) and characteristics among patients who visited a urology clinic complaining of nocturia (URO group) and those who visited a sleep apnea (SA) clinic complaining of excessive daytime sleepiness (EDS) (SA group). Additionally, we evaluated the effects of continuous positive airway pressure (CPAP) therapy in the URO group patients with nocturia and SDB resistant to conventional therapy for nocturia.

METHODS

Questionnaires were used to assess EDS, nocturia and lower urinary tract symptoms in 34 URO group patients and 49 age-matched SA group patients. We also compared these factors in the male patients in both groups and the male and female patients in the SA group. Significant SDB was diagnosed as a 3% oxygen desaturation index (3%ODI) on pulse oximeter of >5/h. The treatment response was analyzed in six URO group patients treated with CPAP after not responding to the conventional medical treatment.

RESULTS

SDB was found in 91.8% of the SA group patients and 70.6% of the URO group patients. The level of EDS and lower urinary tract symptoms were similar in both groups. The SA group showed higher 3%ODI values, while the frequency of urination during bedtime was higher in the URO group. The frequency of nocturnal urination was reduced after CPAP in the subjects resistant to conventional therapy.

CONCLUSION

SDB is as prevalent in patients who visit a urology clinic complaining of nocturia as in those who visit a sleep apnea clinic. Patients who complains of nocturia must be assessed for SDB before starting therapy for nocturia.

The role of local renin-angiotensin system in arterial chemoreceptors in sleep-breathing disorders

The renin-angiotensin system (RAS) plays pivotal roles in the regulation of cardiovascular and renal functions to maintain the fluid and electrolyte homeostasis. Experimental studies have demonstrated a locally expressed RAS in the carotid body, which is functional significant in the effect of angiotensin peptides on the regulation of the activity of peripheral chemoreceptors and the chemoreflex. The physiological and pathophysiological implications of the RAS in the carotid body have been proposed upon recent studies showing a significant upregulation of the RAS expression under hypoxic conditions relevant to altitude acclimation and sleep apnea and also in animal model of heart failure. Specifically, the increased expression of angiotensinogen, angiotensin-converting enzyme and angiotensin AT₁ receptors plays significant roles in the augmented carotid chemoreceptor activity and inflammation of the carotid body. This review aims to summarize these results with highlights on the pathophysiological function of the RAS under hypoxic conditions. It is concluded that the maladaptive changes of the RAS in the carotid body plays a pathogenic role in sleep apnea and heart failure, which could potentially be a therapeutic target for the treatment of the pathophysiological consequence of sleep apnea.

Relationship between atrial conduction delay and obstructive sleep apnea

Prolonged P-wave duration, indicating atrial conduction delay, is a marker of left atrial abnormality and is reported as a potent precursor of atrial fibrillation (AF). Several studies have shown that obstructive sleep apnea (OSA) is associated with AF. We evaluated the relationship between OSA and prolonged P-wave duration. Consecutive subjects who underwent overnight polysomnography and showed a normal sinus rhythm, had no history of AF or ischemic heart disease, and showed no evidence of heart failure were enrolled. Apnea-hypopnea index (AHI) is defined as the number of apnea and hypopnea events per hour of sleep. P-wave duration was determined on the basis of the mean duration of three consecutive beats in lead II from a digitally stored electrocardiogram. A total of 250 subjects (middle-aged, predominantly male, mildly obese, with a mean P-wave duration of 106 ms) were enrolled. In addition to age, male gender, body mass index (BMI), hypertension, dyslipidemia, and uric acid and creatinine levels, AHI (r = 0.56; P < 0.001) had significant univariable relationship with P-wave duration. Multivariate regression analysis showed that age, BMI, male gender, and AHI (partial correlation coefficient, 0.47; P < 0.001) were significantly independently correlated to P-wave duration. Severity of OSA is significantly associated with delayed atrial conduction time. Obstructive sleep apnea may lead to progression of atrial remodeling as an AF substrate.

Olmesartan/amlodipine combination versus olmesartan or amlodipine monotherapies on blood pressure and insulin resistance in a sample of hypertensive patients

Despite the wide range of antihypertensive medications, about 45.5% of treated patients fail to achieve the desired blood pressure (BP) target. This study evaluated the effects of an olmesartan/amlodipine single pill combination compared to olmesartan or amlodipine monotherapies on BP, lipid profile, insulin resistance, and insulin sensitivity parameters. Two hundred and seventy-six patients were randomly assigned to olmesartan (20 mg), amlodipine (10 mg), or a single pill containing olmesartan/amlodipine (5/20 mg) for 12 months. We evaluated the following parameters at the baseline, and after 6 and 12 months: body weight, body mass index (BMI), systolic and diastolic blood pressure (SBP and DBP), fasting plasma glucose (FPG), fasting plasma insulin (FPI), and lipid profile. At the baseline, and after 6 and 12 months, patients underwent an euglycemic, hyperinsulinemic clamp to assess M value. Olmesartan/amlodipine gave a greater decrease in SBP and DPB compared to amlodipine and olmesartan at 6 (P < .05) and 12 months (P < .01). There was a decrease in FPG with olmesartan/amlodipine after 12 months compared to amlodipine (P < .05). Olmesartan/amlodipine decreased FPI and homeostasis model assessment index compared to both baseline (P < .05) and olmesartan and amlodipine (P < .05). Olmesartan/amlodipine gave an increase in M value, compared to baseline (P < .01) and to olmesartan monotherapy (P < .05) and amlodipine monotherapy (P < .01). In this randomized, double-blind clinical trial, olmesartan/amlodipine combination resulted more effective than olmesartan and amlodipine monotherapies in reducing BP, in improving insulin resistance, and insulin sensitivity parameters in patients with stage I essential hypertension. The combination also resulted in less peripheral edema.