RESUMEN
Impaired cerebral vascular reactivity (CVR) increases long-term stroke risk. Obstructive sleep apnoea (OSA) is associated with peripheral vascular dysfunction and vascular events. The aim of this trial was to evaluate the effect of continuous positive airway pressure (CPAP) withdrawal on CVR.41 OSA patients (88% male, mean age 57±10â years) were randomised to either subtherapeutic or continuation of therapeutic CPAP. At baseline and after 2â weeks, patients underwent a sleep study and magnetic resonance imaging (MRI). CVR was estimated by quantifying the blood oxygen level-dependent (BOLD) MRI response to breathing stimuli.OSA did recur in the subtherapeutic CPAP group (mean treatment effect apnoea-hypopnoea index +38.0â events·h-1, 95% CI 24.2-52.0; p<0.001) but remained controlled in the therapeutic group. Although there was a significant increase in blood pressure upon CPAP withdrawal (mean treatment effect +9.37â mmHg, 95% CI 1.36-17.39; p=0.023), there was no significant effect of CPAP withdrawal on CVR assessed via BOLD MRI under either hyperoxic or hypercapnic conditions.Short-term CPAP withdrawal did not result in statistically significant changes in CVR as assessed by functional MRI, despite the recurrence of OSA. We thus conclude that, unlike peripheral endothelial function, CVR is not affected by short-term CPAP withdrawal.
Asunto(s)
Presión de las Vías Aéreas Positiva Contínua , Oxígeno/sangre , Polisomnografía , Apnea Obstructiva del Sueño/terapia , Adulto , Anciano , Presión Sanguínea , Encéfalo/diagnóstico por imagen , Circulación Cerebrovascular , Método Doble Ciego , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Perfusión , Recurrencia , Accidente Cerebrovascular/prevención & control , Resultado del Tratamiento , Adulto JovenRESUMEN
PURPOSE: Obstructive sleep apnoea (OSA) is a highly prevalent sleep-related breathing disorder associated with hypertension, impaired peripheral vascular function and an increased risk of stroke. Evidence suggests that abnormalities of the cerebral microcirculation, such as capillary rarefication, may be present in these patients. We evaluated whether the presence of hypertension may affect the cerebral capillary architecture and function assessed by Intravoxel Incoherent Motion (IVIM) magnetic resonance imaging (MRI) in patients with continuous positive airway pressure (CPAP)-treated OSA. METHODS: Forty-one patients (88% male, mean age 57 ± 10 years) with moderate-to-severe OSA were selected and divided into two groups (normotensive vs. hypertensive). All hypertensive OSA patients were adherent with their antihypertensive medication. Cerebral microvascular structure was assessed in grey (GM) and white matter (WM) using an echo-planar diffusion imaging sequence with 14 different b values. A step-wise IVIM analysis algorithm was applied to compute true diffusion (D), perfusion fraction (f) and pseudo-diffusion (D*) values. Group comparisons were performed with the Wilcoxon-Mann-Whitney-Test. Regression analysis was adjusted for age. RESULTS: Diffusion- and perfusion-related indexes in middle-aged OSA normotensive patients were quantified in both tissue types (D [10-3 mm2/s]: GM = 0.83 ± 0.03; WM = 0.72 ± 0.03; f (%) GM = 0.09 ± 0.01; WM = 0.06 ± 0.01; D* [10-3 mm2/s]: GM = 7.72 ± 0.89; WM = 7.38 ± 0.98). In the examined tissue types, hypertension did not result in changes on the estimated MRI IVIM index values. CONCLUSION: Based on IVIM analysis, cerebral microvascular structure and function showed no difference between hypertensive and normotensive patients with moderate-to-severe OSA treated with CPAP. Treatment adherence with antihypertensive drug regime and, in turn, controlled hypertension seems not to affect microvascular structure and perfusion of the brain. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02493673.
Asunto(s)
Circulación Cerebrovascular , Presión de las Vías Aéreas Positiva Contínua , Imagen de Difusión por Resonancia Magnética , Hipertensión/complicaciones , Microvasos/diagnóstico por imagen , Apnea Obstructiva del Sueño/terapia , Femenino , Humanos , Hipertensión/tratamiento farmacológico , Interpretación de Imagen Asistida por Computador , Masculino , Persona de Mediana Edad , Apnea Obstructiva del Sueño/complicacionesRESUMEN
BACKGROUND: Increased daytime blood pressure variability (BPV) is associated with cardiovascular risk. Preliminary data suggest that obstructive sleep apnoea (OSA) might contribute to increased daytime BPV. OBJECTIVE: The aim of this study was to evaluate the effect of continuous positive airway pressure (CPAP) therapy withdrawal on daytime BPV. METHODS: A total of 183 patients previously diagnosed with OSA and treated with CPAP were randomised to either continue or withdraw from CPAP within 4 trials. Office morning BP was measured in triplicate at baseline and at follow-up (day 14). In addition, the participants performed BP measurements at home on a daily basis (days 1-13). The main outcome of interest was the treatment effect on within-visit BPV expressed as the standard deviation (SD) of the triplicate measurements. Additional outcomes included morning home BPV and day-to-day home BPV. RESULTS: Within-visit variability in systolic BP significantly increased in response to recurrence of OSA in the CPAP withdrawal group (difference between groups in SD of systolic BPV, +1.14 mm Hg, 95% CI +0.20/+2.09, p = 0.02). There was no statistically significant effect on within-visit variability in diastolic BP (p = 0.38) or heart rate (p = 0.07). Neither morning home BP variability (systolic BPV, p = 0.81; diastolic BPV, p = 0.46) nor day-to-day variability in home BP measurements (systolic BPV, p = 0.61; diastolic BPV, p = 0.58) differed significantly between the groups. CONCLUSION: CPAP withdrawal results in a minor increase in within-visit variability in office systolic BP, but it has no effect on home BPV or day-to-day BPV. Although the treatment effect may be blunted by antihypertensives, it is unlikely that OSA contributes to cardiovascular risk via elevated daytime BPV.