Ambulatory screening for obstructive sleep apnea in patients with resistant arterial hypertension

Objective

Obstructive sleep apnea (OSA) is one of the most common causes of secondary arterial hypertension. It is important to rule out OSA as a cause of resistant hypertension. The ApneaLink device is a simple and cost-efficient outpatient examination, but its usefulness in screening OSA in resistant hypertension has not yet been evaluated.

Methods

A total of 69 patients with resistant arterial hypertension were enrolled. Patients underwent a physical examination, including the use of ApneaLink, followed by respiratory polygraphy. The presence of OSA was assessed by the apnea-hypopnea index (AHI), oxygen desaturation index (ODI), mean nocturnal desaturation (SpO₂), and percentage of sleep time with SpO₂ less than 90%.

Results

There was no significant difference between the values of AHI found during the use of ApneaLink and respiratory polygraphy (mean 30.4 ± 21.7 vs. 37.2 ± 20.9, P = 0.07). ApneaLink had 77.3% sensitivity and 100% specificity to diagnose OSA with the area under the ROC curve 0.866 (P < 0.001). We also found no significant difference in mean SpO₂ (91.3 ± 2.5 vs. 90.9 ± 3.3%, P = 0.22). The ODI evaluated via ApneaLink was significantly lower than by the polygraphy (31.1 ± 18.3 vs. 43.9 ± 24.8, P < 0.001), while the measured percentage of sleep time with SpO₂ less than 90% was higher (31.8 ± 23.7 vs. 23.3 ± 24.4, P = 0.001). The severity of OSA was correctly determined by ApneaLink in 50.7% of patients, underestimated in 23.2% and overestimated in 26.1%.

Conclusions

The use of ApneaLink is a suitable method for screening the presence of OSA in patients with resistant hypertension, but to accurately assess the severity of OSA, respiratory polygraphy or polysomnography is required.