Michigan Medicine, Department of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, MI 48109, USA.
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
Sensors (Basel). 2023 Sep 28;23(19):8128. doi: 10.3390/s23198128.
Heart rate variability (HRV) has been used to measure autonomic nervous system (ANS) activity noninvasively. The purpose of this study was to identify the most suitable HRV parameters for ANS activity in response to brief rectal distension (RD) in patients with Irritable Bowel Syndrome (IBS). IBS patients participated in a five-session study. During each visit, an ECG was recorded for 15 min for baseline values and during rectal distension. For rectal distension, a balloon was inflated in the rectum and the pressure was increased in steps of 5 mmHg for 30 s; each distension was followed by a 30 s rest period when the balloon was fully deflated (0 mmHg) until either the maximum tolerance of each patient was reached or up to 60 mmHg. The time-domain, frequency-domain and nonlinear HRV parameters were calculated to assess the ANS activity. The values of each HRV parameter were compared between baseline and RD for each of the five visits as well as for all five visits combined. The sensitivity and robustness/reproducibility of each HRV parameter were also assessed. The parameters included the Sympathetic Index (SI); Root Mean Square of Successive Differences (RMSSD); High-Frequency Power (HF); Low-Frequency Power (LF); Normalized HF Power (HFn); Normalized LF Power (LFn); LF/HF; Respiratory Sinus Arrhythmia (RSA); the Poincare Plot's SD1, SD2 and their ratio; and the pNN50, SDSD, SDNN and SDNN Index. Data from 17 patients were analyzed and compared between baseline and FD and among five sessions. The SI was found to be the most sensitive and robust HRV parameter in detecting the ANS response to RD. Out of nine parasympathetic parameters, only the SDNN and SDNN Index were sensitive enough to detect the parasympathetic modulation to RD during the first visit. The frequency-domain parameters did not show any change in response to RD. It was also observed that the repetitive RD in IBS patients resulted in a decreased autonomic response due to habituation because the amount of change in the HRV parameters was the highest during the first visit but diminished during subsequent visits. In conclusion, the SI and SDNN/SDNN Index are most sensitive at assessing the autonomic response to rectal distention. The autonomic response to rectal distention diminishes in repetitive sessions, demonstrating the necessity of randomization for repetitive tests.
心率变异性（HRV）已被用于无创测量自主神经系统（ANS）活动。本研究的目的是确定在肠易激综合征（IBS）患者对短暂直肠扩张（RD）的反应中，最适合用于测量 ANS 活动的 HRV 参数。IBS 患者参加了一项五期研究。在每次就诊时，记录 15 分钟的心电图以获取基线值，并在直肠扩张时记录。对于直肠扩张，将气球充气到直肠中，并以 5mmHg 的步长增加压力 30 秒；每次扩张后，气球完全放气（0mmHg）30 秒，直到患者达到最大耐受程度或达到 60mmHg。计算时域、频域和非线性 HRV 参数以评估 ANS 活动。将五次就诊中的每次就诊的基线值和 RD 之间以及五次就诊的所有值进行比较，比较每个 HRV 参数的值。还评估了每个 HRV 参数的敏感性和稳健性/可重复性。参数包括交感神经指数（SI）；连续差异的均方根（RMSSD）；高频功率（HF）；低频功率（LF）；归一化高频功率（HFn）；归一化低频功率（LFn）；LF/HF；呼吸窦性心律失常（RSA）；Poincare 图的 SD1、SD2 及其比值；以及 pNN50、SDSD、SDNN 和 SDNN 指数。分析了 17 名患者的数据，并与 FD 进行了比较，并对五次就诊进行了比较。结果发现，SI 是检测 RD 对 ANS 反应最敏感和最稳健的 HRV 参数。在九个副交感神经参数中，只有 SDNN 和 SDNN 指数在第一次就诊时足以检测到对 RD 的副交感神经调节。频域参数对 RD 没有任何反应。还观察到，由于习惯化，IBS 患者反复 RD 导致自主反应减弱，因为 HRV 参数的变化量在第一次就诊时最高，但在随后的就诊中减少。总之，SI 和 SDNN/SDNN 指数在评估直肠扩张的自主反应方面最敏感。在重复的会话中，对直肠扩张的自主反应会减弱，这表明需要对重复测试进行随机化。
