ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain.
Department of Respiratory Medicine, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
PLoS One. 2018 Mar 14;13(3):e0194204. doi: 10.1371/journal.pone.0194204. eCollection 2018.
Obstructive sleep apnea (OSA) can impair cerebral vasoreactivity and is associated with an increased risk of cerebrovascular disease. Unfortunately, an easy-to-use, non-invasive, portable monitor of cerebral vasoreactivity does not exist. Therefore, we have evaluated the use of near-infrared diffuse correlation spectroscopy to measure the microvascular cerebral blood flow (CBF) response to a mild head-of-bed position change as a biomarker for the evaluation of cerebral vasoreactivity alteration due to chronic OSA. Furthermore, we have monitored the effect of two years of continuous positive airway pressure (CPAP) treatment on the cerebral vasoreactivity.
CBF was measured at different head-of-bed position changes (supine to 30° to supine) in sixty-eight patients with OSA grouped according to severity (forty moderate to severe, twenty-eight mild) and in fourteen control subjects without OSA. A subgroup (n = 13) with severe OSA was measured again after two years of CPAP treatment.
All patients and controls showed a similar CBF response after changing position from supine to 30° (p = 0.819), with a median (confidence interval) change of -17.5 (-10.3, -22.9)%. However, when being tilted back to the supine position, while the control group (p = 0.091) and the mild patients with OSA (p = 0.227) recovered to the initial baseline, patients with moderate and severe OSA did not recover to the baseline (9.8 (0.8, 12.9)%, p < 0.001) suggesting altered cerebral vasoreactivity. This alteration was correlated with OSA severity defined by the apnea-hypopnea index, and with mean nocturnal arterial oxygen saturation. The CBF response was normalized after two years of CPAP treatment upon follow-up measurements.
In conclusion, microvascular CBF response to a head-of-bed challenge measured by diffuse correlation spectroscopy suggests that moderate and severe patients with OSA have altered cerebral vasoreactivity related to OSA severity. This may normalize after two years of CPAP treatment.
阻塞性睡眠呼吸暂停（OSA）可损害脑血管反应性，并增加脑血管疾病的风险。不幸的是，目前尚不存在易于使用、非侵入性且便携的脑血管反应性监测仪。因此，我们评估了使用近红外漫反射相关光谱法测量轻度床头抬高引起的微血管脑血流（CBF）反应，作为评估慢性 OSA 引起的脑血管反应性改变的生物标志物。此外，我们还监测了两年持续气道正压通气（CPAP）治疗对脑血管反应性的影响。
我们在 68 例 OSA 患者（根据严重程度分为 40 例中重度和 28 例轻度）和 14 例无 OSA 的对照受试者中测量了不同床头位置变化（仰卧位至 30°仰卧位）时的 CBF。对 13 例重度 OSA 患者进行了两年 CPAP 治疗后的再次测量。
所有患者和对照组在从仰卧位变为 30°时，CBF 反应相似（p = 0.819），中位（置信区间）变化为-17.5（-10.3，-22.9）%。然而，当恢复到仰卧位时，对照组（p = 0.091）和轻度 OSA 患者（p = 0.227）恢复到初始基线，而中重度 OSA 患者未恢复到基线（9.8（0.8，12.9）%，p < 0.001），提示脑血管反应性改变。这种改变与呼吸暂停低通气指数定义的 OSA 严重程度以及夜间平均动脉血氧饱和度相关。在随访测量中，经过两年 CPAP 治疗后，CBF 反应得到了正常化。
总之，漫反射相关光谱法测量的床头挑战引起的微血管 CBF 反应表明，中重度 OSA 患者的脑血管反应性发生改变，与 OSA 严重程度相关。这种改变可能在两年 CPAP 治疗后恢复正常。
