Wu H H, Wang Z J, Cheng C H, Wang J, Wang Q J, Chen R
Department of Respiratory and Critical Care Medicine, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China.
Zhonghua Jie He He Hu Xi Za Zhi. 2021 Oct 12;44(10):873-879. doi: 10.3760/cma.j.cn112147-20210210-00105.
To investigate the effects of daytime hypercapnia on logical memory and working memory in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). This prospective study recruited patients complaining of snoring and diagnosed with OSAHS at the Sleep Center of the Second Affiliated Hospital of Soochow University from January to November 2020. Patients were assessed clinically and scored for their memory function. All patients underwent daytime transcutaneous carbon dioxide (PtcCO) test, and overnight polysomnography (PSG). Logical memory was scored using the Logical Memory Test (LMT), while working memory was evaluated by Digit Span Test (DST) and Cambridge Neuropsychological Test Automated Battery (CANTAB) which included Pattern Recognition Memory (PRM), Spatial Span (SSP), and Spatial Working Memory (SWM). Patients were divided into the normocapnic group and the hypercapnic group using the daytime PtcCO test. The clinical and PSG parameters and the memory test scores between the two groups were compared. Binary logistic stepwise regression was conducted to identify risk factors of memory impairment in OSAHS patients. Among the 123 enrolled OSAHS patients, 79 were normocapnic and 44 were hypercapnic. There was no significant difference in the general clinical parameters between the two groups. The snoring history in years in the hypercapnic group was longer than that in the normocapnic group (<0.05). Compared with the normocapnic group, the apnea-hyponea index (AHI), oxygen desaturation index (ODI) and percentage of total sleep time with oxygen saturation level<90% (TS90) of the hypercapnic group were higher (all <0.05), while other PSG parameters exhibited no statistically significant differences. There was no statistically significant difference in the immediate logical memory and PRM immediate accuracy rate between the two groups, while the delayed logical memory, verbal and spatial working memory, and executive function were worse in the hypercapnic group, as shown by lower total LMT scores, lower DST, lower SSP scores (all <0.05), and higher between errors and strategy scores (<0.01) of SWM in the hypercapnic group. Binary logistic stepwise regression showed that PtcCO ≥45 mmHg (1 mmHg=0.133 kPa, =3.055, 95% 1.359-6.868, =0.007) and higher body mass index (BMI) (=1.132, 95% 1.005-1.275, =0.041) were risk factors for poor performance in Digit Span Backwards Test. Therefore, PtcCO ≥45 mmHg was an independent risk factors for poor performance in delayed LMT, SSP, and between errors and strategy scores in SWM (=3.109, 3.941, 3.238 and 2.785, respectively, all <0.05). Hypercapnia had negative impacts on logical memory and working memory of OSAHS patients, especially on the delayed logical memory, verbal working memory and spatial working memory impairment.
探讨日间高碳酸血症对阻塞性睡眠呼吸暂停低通气综合征（OSAHS）患者逻辑记忆和工作记忆的影响。本前瞻性研究于2020年1月至11月在苏州大学附属第二医院睡眠中心招募主诉打鼾且诊断为OSAHS的患者。对患者进行临床评估并对其记忆功能进行评分。所有患者均接受日间经皮二氧化碳（PtcCO）检测及整夜多导睡眠图（PSG）检查。逻辑记忆采用逻辑记忆测试（LMT）评分，工作记忆通过数字广度测试（DST）和剑桥神经心理测试自动成套系统（CANTAB）进行评估，后者包括模式识别记忆（PRM）、空间广度（SSP）和空间工作记忆（SWM）。采用日间PtcCO检测将患者分为正常碳酸血症组和高碳酸血症组。比较两组的临床和PSG参数以及记忆测试得分。进行二元逻辑逐步回归分析以确定OSAHS患者记忆损害的危险因素。在纳入的123例OSAHS患者中，79例为正常碳酸血症患者，44例为高碳酸血症患者。两组的一般临床参数无显著差异。高碳酸血症组的打鼾年限长于正常碳酸血症组（<0.05）。与正常碳酸血症组相比，高碳酸血症组的呼吸暂停低通气指数（AHI）、氧饱和度下降指数（ODI）以及氧饱和度<90%的总睡眠时间百分比（TS90）更高（均<0.05），而其他PSG参数无统计学显著差异。两组间即时逻辑记忆和PRM即时准确率无统计学显著差异，而高碳酸血症组的延迟逻辑记忆、言语和空间工作记忆以及执行功能较差，表现为LMT总分更低、DST更低、SSP得分更低（均<0.05），且高碳酸血症组SWM的错误与策略得分更高（<0.01）。二元逻辑逐步回归分析显示，PtcCO≥45 mmHg（1 mmHg = 0.133 kPa，= 3.055，95% 置信区间为1.359 - 6.868，= 0.007）和更高的体重指数（BMI）（= 1.132，95% 置信区间为1.005 - 1.275，= 0.041）是数字倒背测试表现不佳的危险因素。因此，PtcCO≥45 mmHg是延迟LMT、SSP以及SWM错误与策略得分表现不佳的独立危险因素（分别为= 3.109、3.941、3.238和2.785，均<0.05）。高碳酸血症对OSAHS患者的逻辑记忆和工作记忆有负面影响，尤其是对延迟逻辑记忆、言语工作记忆和空间工作记忆损害。
