脈之根柢探源－－由中醫典籍及現代生理切入探討

AN EXPLORATION ON THE ROOT OF PULSE: FROM THE VIEWPOINTS OF CHINESE MEDICAL CLASSICS AND CARDIOVASCULAR PHYSIOLOGY

脈之根柢最早在《難經》時即被提出，一般典籍陳述為「根」或「脈之根」，或言脈之「有根」、「無根」等，能反映出腎氣、元氣充足與否，並作為疾病嚴重度的參考依據。其操作方法後世普遍理解為「尺脈沉取應指有力」，然驗之於臨床有應有不應。本文透過「以經解經」的檢索及評讀方法，追尋《內》《難》等經典，同時參考後代醫家觀點，企圖還原脈之根柢的操作方式，並釐清其內涵，進而旁證於現代生理、醫學期刊文獻的相關論述。脈之根柢的臨床操作為：尺脈沉取到底後，於同一部內稍微上舉；有根的依據在於脈來有飽滿之形，並且是快速有力地動態呈現。脈之根柢在現代生理上代表的意義，是心血管系統中血液動力學於手指上提之臨界點前後狀態的變化，可能投射的生理指標如舒張壓、或心輸出量，惟實際上兩者的關連度仍須透過進一步的實驗設計及統計驗證才能得知。The root of pulse, first proposed in the Classic of Difficult Issues (Nan Jing), appears in traditional literature and is reflected in descriptions of the pulse as “having a root” or “having no root.” It can reflect not only whether kidney qi and original qi are sufficient or not, but also the severity of disease. The root of pulse has been traditionally defined as “forceful rebounding when felt the deep level of cubit pulse,” but this is sometimes found to be ineffective in clinical experience. In this paper, we identify descriptions of the root of the pulse from the Inner Classic (Nei Jing) and the Classic of Difficult Issues (Nan Jing), and then apply the principle of “exegesis through the Classic itself” and referring to opinions of later medical scholars, in order to recover the clinical criteria for determining the root of pulse, and clarify its meaning. Furthermore, we explain the possible mechanism of the root of pulse according to cardiovascular physiology, and verify its significance through research in journal literature. The clinical method of determining the root of pulse is to “gently lift fingertip, in the same position, after pressing fully to the deep level at the cubit pulse,” and the definition of pulse with root is “rapidly forceful rebounding with full shape” when slightly lifting fingertip. Physiologically, the root of pulse means the changes before and after the critical point in hemodynamics, which is created by lifting fingertip slightly. The possible projective physiological signal is diastolic blood pressure or cardiac output. However, further study design and statistical validation are necessary to understand the correlation between the root of pulse and physiological signal.