禪坐者之心肺相位同步分析

Abstract

本研究主要是想探討禪坐練習者在不同的呼吸速率下，心肺交互作用的情形，我們用心率時間序列和呼吸訊號的瞬時相位去觀察此一現象，由於心率的變化是由很多不同的生理機制所影響，故使用傳統的線性方法很難準確的估算心率時間序列的瞬時相位，故本研究使用希爾伯特-黃轉換去分析心率時間序列，它是近來被用來處理非線性訊號的方法，我們希望藉由希爾伯特-黃轉換去獲得更為準確的瞬時相位。本研究共收集了12年齡相似的受測者的心電圖和呼吸訊號，其中實驗組為6具有禪坐經驗者，而控制組6受測者則無此經驗。由結果發現，控制組在控制呼吸為每分鐘10次的實驗階段有顯著性(p<0.02)心肺相位同步現象發生，而實驗組所呈現的結果相較於控制組是較分歧的。我們假設主要的原因為實驗組在禪定過程中的呼吸率是不一致的，禪定者的呼吸率會隨著時間而一直變化著。根據此結果，我們推論在比較慢並且變化比較平穩的呼吸速率下，可能會增加心肺系統之間的同步現象。

This research is aimed at the investigation of the effect of respiratory rate on cardiorespiratory phase synchronization (CRPS) for the Chan-meditation practitioners (experimental group) and normal, healthy people (control group). Cardiorespiratory phase synchronization was evaluated by the instantaneous phase of the heart-rate (HR) sequence and respiratory signal. Conventional linear method cannot provide a reliable estimate of instantaneous phase of HR sequence due to the possible interference of other biological artifacts to the HR activities. To deal with the issue, Hilbert-Huang transform (HHT) was adopted to decompose HR sequence. HHT has been applied to nonlinear signal processing recently. We aimed to attain a more precise estimate of instantaneous phase by HHT scheme. In this study, ECG (electrocardiograph) signals and respiratory signals of twelve subjects were recorded. Among them, six subjects were Chan-meditation practitioners and the other six subjects are normal people in the same age range, yet, without any meditation experience. The control group was requested to follow intentionally designed protocol in the recording, while the experimental subjects only practiced Chan meditation. In our preliminary results, control subjects exhibited significant better degree of CRPS in the session of breathing control at the rate of 10 breaths/min. One the other hand, experimental group did not exhibit significant correlation between CRPS and respiratory rate. According to the time-dependent respiratory signal, meditation practitioners breathed in a free style during Chan meditation and thus could not keep a constant respiratory rate for a moderate duration. The experimental group thus did not achieve the state of CRPS as good as the control group even at the same respiratory rate of 10 breaths/min. We thus make an assumption that a consistently slow respiration can induce an efficient CRPS.