Xu Mai (Deficient Pulse)
Author: Li Shimao, Tian Shuxiao
(1) Pulse Characteristics The “Pulse Classic” states: “Xu mai is slow, large, and soft; pressing it reveals weakness, and the pulse feels empty.” This describes the four components of Xu mai: floating, slow, large, and empty. Later physicians often reference this description.
In ancient descriptions of Xu mai, only one characteristic was noted: weakness upon pressure, without the implications of floating, slow, or large; as stated in the “Suwen: On Calmness” chapter: “If the pulse is floating, large, and deficient, it indicates a deficiency of spleen qi.” In the “Suwen: On Malaria” chapter: “In malaria, the pulse is large and deficient.” In the “Suwen: On the Generation of the Five Organs” chapter: “The yellow pulse is large and deficient.” The “Neijing” considers floating, large, and slow as characteristics of Xu mai, indicating that Xu mai itself does not inherently possess the traits of floating, large, or slow. Furthermore, the “Jinkui: On Deficiency and Labor” states: “For a healthy man, a large pulse indicates labor; an extremely deficient pulse also indicates labor.” This juxtaposition of deficiency and largeness suggests that deficiency does not necessarily imply largeness. The “Jinkui: On Blood Obstruction” states: “The pulse is extremely deficient, floating, and slow.” The slow pulse is a characteristic of Xu mai, indicating that slowness is not an inherent feature of Xu mai. Therefore, the primary characteristic of Xu mai is weakness upon pressure; whether it is floating, slow, or large is not an inherent element of Xu mai itself.
(2) Similar Pulses The main characteristic of Xu mai is weakness upon pressure. Similar pulse types include floating, hollow, leather, scattered, fine, weak, and soft, which must be distinguished.
1.Xu vs. Floating:
Floating pulse is easily felt with light pressure, abundant when lifted, but weak when pressed. Its weakness is only in comparison to floating, not indicating weakness upon pressure. Xu mai is characterized by weakness upon pressure.
2.Xu vs. Hollow:
Hollow pulse is floating, large, and empty on both sides. The emptiness feels suddenly hollow and empty; while Xu mai is weak upon pressure, it does not feel empty.
3.Xu vs. Leather:
Leather pulse feels like pressing on a drum skin; when floating, it is large and strong, giving a sensation of the drum skin being taut, but feels empty when pressed, having an outflow without inflow. Xu mai has insufficient floating strength, unlike the strong floating of leather pulse; the pressure strength decreases further, but does not reach the emptiness of leather pulse.
4. Xu vs. Scattered:
Scattered pulse is extremely large and weak, diffuse and unconfined, with indistinct edges, like the light and scattered nature of willow fluff, unpredictable in its trace. Xu mai, while floating and weak, still has clear edges, and its degree of weakness is not as severe as that of scattered pulse. 5. Xu vs. Fine:
Fine pulse is floating, thin, and weak, with both thinness and weakness being more pronounced than in Xu mai. 6. Xu vs. Weak:
Weak pulse is deep, weak, and not found in the floating position; its thinness and weakness are also more pronounced than in Xu mai. 7. Xu vs. Soft:
Most pulse texts describe soft as floating and fine. The author believes that soft pulse is simply a weak pulse, not necessarily floating and fine. Its softness also indicates insufficient pulse strength, but not as severe as Xu mai’s weakness. If soft is floating and fine, then it is only slightly different in thinness and weakness from fine pulse, making it clinically difficult to distinguish, and can be regarded as a single pulse type.
(3) Pulse Theory and Main Diseases
Xu mai is a very important pulse, as the pulse is governed by deficiency and excess; a deficient pulse indicates a deficiency of Zheng Qi (Vital Energy).
Xu mai indicates deficiency of Zheng Qi. Any deficiency of yin, yang, qi, or blood can lead to Xu mai.
Yang deficiency results in weak blood pulsation, leading to a deficient pulse. Yin and blood deficiency cannot maintain the internal, causing yang qi to float; when yin and blood cannot fill the blood vessels, the pulse cannot withstand heavy pressure, resulting in Xu mai. Clinically, whenever Xu mai is observed, it undoubtedly indicates a deficiency of Zheng Qi; whether it is due to yang deficiency, qi deficiency, or yin deficiency, blood deficiency must be assessed in conjunction with other pulse characteristics and the patient’s spirit, complexion, tongue, and symptoms for a comprehensive judgment.
Summary
Xu mai is primarily characterized by weakness upon pressure, indicating deficiency of Zheng Qi, with deficiencies in qi, blood, yin, and yang all potentially leading to it.
The pulse is governed by deficiency and excess; a deficient pulse indicates a deficiency of Zheng Qi. Master Li also mentioned when discussing deep pulses that the pulse is based on depth and rooted in depth.
Note: This article is excerpted from “Insights into Pulse Diagnosis,” compiled by Master Li Shimao, published by the Ancient Chinese Medicine Publishing House in 1994. This public account is solely for the dissemination of TCM culture and learning exchange; if there is any infringement, please contact us for removal.
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