Abstract
Recent studies showed only a moderate to negligible reduction in the nocturnal blood pressure of 5 to 3 mmHg (systolic) and 4 to 2 mmHg (diastolic) after CPAP therapy in patients with obstructive sleep apnea (Schein et al. Thorax 69, 2014; Fava et al. Chest 145, 2014). Since the investigated studies are performed with the traditional cuff method we assume that the cuff inflation influences the blood pressure measurement by inducing arousals and nocturnal blood pressure fluctuation (NBPF).
Polysomnography (PSG, SOMNOscreen, SOMNOmedics GmbH) according to American Academy of Sleep Medicine (AASM) standards was performed in 27 OSA patients (AHI 38 ±19, age 63 ±12, BMI 31±4 kg/m2) before and during CPAP therapy. Systolic and diastolic blood pressure (SBP and DBP) was recorded continuously using a cuff less method of blood pressure determination based on pulse-transit-time.
During CPAP therapy the apnea–hypopnea index (AHI), snoring time in % TST and respiratory NBPFs were reduced from 38/h to 4/h, 16% to 1% and 9/h to 0/h, respectively. The index of spontaneous NBPFs increased from 5/h to 15/h. Mean nocturnal SBP decreased by 12 ± 15 mmHg (138 mmHg to 126 mmHg) and mean DBP decreased by 4 ± 10 mmHg (83 mmHg to 79 mmHg).
This study suggests that nocturnal SBP and DBP values, measured continuously and cuff less based on PTT, are considerably decreased during CPAP therapy. In contrast to traditional cuff method, we found a stronger reduction in mean SBP and DBP by applying a cuff less method. This indicates that cuff inflations cause blood pressure deviations which influence the recorded nocturnal blood pressure behaviour.
- Copyright ©the authors 2016