Relationship between refractory hypertension and obstructive sleep apnea

Obstructive sleep apnea (OSA) is an independent cause of resistant hypertension (RH) but its association with refractory hypertension (RfH), a recently described form of severe hypertension, has not yet been investigated. This study seeks to analyze the association between the presence and severity of OSA/OSA syndrome with RfH and to compare it with a group of patients with OSA/OSA syndrome and RH. We conducted a multicenter, cross-sectional study of consecutive patients diagnosed with RH by means of 24-hour ambulatory blood pressure monitoring. Those patients with blood pressure levels ≥130/80 mm Hg, despite taking at least 5 antihypertensive drugs, were considered to have true RfH. All patients underwent a sleep study and completed a detailed clinical history related to OSA, current medication, and cardiovascular diseases. Overall, 229 patients were included (mean age, 58.3 years; 63% male), of whom 42 (18.3%) satisfied the criteria for RfH. Compared with those with RH, patients with RfH had a higher cardiovascular risk profile, higher blood pressure measurements, and a 2-fold greater risk of having both severe OSA (odds ratio, 2.1, with a prevalence of apnea-hypopnea index ≥15, 95.2% and apnea-hypopnea index ≥30, 64.3%) and OSA syndrome (apnea-hypopnea index ≥5+Epworth Sleepiness Scale >10; odds ratio, 1.9; 52.4% versus 37.3%; P=0.023), as well as higher OSA severity (apnea-hypopnea index, 41.8 versus 33.8 events/h; P=0.026). Patients with RfH had an even greater prevalence and severity of OSA and OSA syndrome than RH patients, highlighting the need to identify these patients to refer them to sleep units on a preferential basis.Peer reviewe

Good long‐term adherence to continuous positive airway pressure therapy in patients with resistant hypertension and sleep apnea

Although adequate adherence is paramount in achieving the beneficial effects of continuous positive airway pressure therapy in patients with obstructive sleep apnea, long‐term adherence and the variables involved in continuous positive airway pressure compliance in patients with resistant hypertension and obstructive sleep apnea are yet unknown. We conducted a prospective, multicentre, observational study in 177 patients recruited from hypertensive units with resistant hypertension confirmed by means of 24‐hr blood pressure monitoring (blood pressure ≥ 130 and/or ≥ 80 mmHg, despite taking at least three antihypertensive drugs or  3 drugs) and obstructive sleep apnea (apnea–hypopnea index ≥ 5 in a respiratory polygraph) who were prescribed continuous positive airway pressure treatment. Good adherence was defined as an average cumulative continuous positive airway pressure use of ≥ 4 hr per night at the end of the follow‐up. A multivariate Cox regression analysis was performed to identify independent predictors of continuous positive airway pressure adherence. Patients were followed for a median of 57.6 (42–72) months after initiating continuous positive airway pressure therapy. At the end of the follow‐up, the median continuous positive airway pressure use was 5.7 (inter‐quartile range 3.9–6.6) hr per night, and 132 patients (74.5%) showed good continuous positive airway pressure adherence. The only baseline variable associated with poor adherence was the presence of previous stroke (hazard ratio 4.00, 95% confidence interval 1.92–8.31). Adequate adherence at 1 month also predicted good adherence at the end of the follow‐up (hazard ratio 14.4, 95% confidence interval 4.94–56). Both variables also predicted adherence at a threshold of 6 hr per night. Our results show that good continuous positive airway pressure adherence is an achievable and feasible goal in patients with resistant hypertension and obstructive sleep apnea. Previous stroke and short‐term adherence predicted long‐term adherence.Peer reviewe

Intermittent Hypoxia Is Associated With High Hypoxia Inducible Factor-1α but Not High Vascular Endothelial Growth Factor Cell Expression in Tumors of Cutaneous Melanoma Patients

Epidemiological associations linking between obstructive sleep apnea and poorer solid malignant tumor outcomes have recently emerged. Putative pathways proposed to explain that these associations have included enhanced hypoxia inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) cell expression in the tumor and altered immune functions via intermittent hypoxia (IH). Here, we examined relationships between HIF-1α and VEGF expression and nocturnal IH in cutaneous melanoma (CM) tumor samples. Prospectively recruited patients with CM tumor samples were included and underwent overnight polygraphy. General clinical features, apnea–hypopnea index (AHI), desaturation index (DI4%), and CM characteristics were recorded. Histochemical assessments of VEGF and HIF-1α were performed, and the percentage of positive cells (0, <25, 25–50, 51–75, >75%) was blindly tabulated for VEGF expression, and as 0, 0–5.9, 6.0–10.0, >10.0% for HIF-1α expression, respectively. Cases with HIF-1α expression >6% (high expression) were compared with those <6%, and VEGF expression >75% of cells was compared with those with <75%. 376 patients were included. High expression of VEGF and HIF-1α were seen in 88.8 and 4.2% of samples, respectively. High expression of VEGF was only associated with increasing age. However, high expression of HIF-1α was significantly associated with age, Breslow index, AHI, and DI4%. Logistic regression showed that DI4% [OR 1.03 (95% CI: 1.01–1.06)] and Breslow index [OR 1.28 (95% CI: 1.18–1.46)], but not AHI, remained independently associated with the presence of high HIF-1α expression. Thus, IH emerges as an independent risk factor for higher HIF-1α expression in CM tumors and is inferentially linked to worse clinical CM prognostic indicators