PPI 是搏动血流（小动脉）与非搏动组织（静脉血、肌肉、骨骼等）吸收红

PPI 是搏动血流（小动脉）与非搏动组织（静脉血、肌肉、骨骼等）吸收红外光量的比值，其反映外周组织中小动脉血流量、每搏量灌注于局部量，是评价循环功能实时无创简便方法。局部灌注改变、心血管功能障碍、神经调节和精神状态等都会使PPI值发生改变 [1]。本研究通过安静恒温充分休息等措施初步除外神经精神影响，观察到了SHF患者基础PPI较健康对照者明显下降。SHF每搏量下降、外周灌注减少；为维持血压及组织灌注，机体代偿性活化神经体液内分泌激素，收缩血管、减少血流量、降低灌注，致PPI降低；SHF心脏搏动无力弱化了传导至外周小动脉强度、利尿还减少血量流向外周，均拉低了PPI。

PPI is the ratio of pulsatile blood flow (arterioles) to the amount of infrared light absorbed by non pulsatile tissues (venous blood, muscle, bone, etc.), which reflects the blood flow of small and medium arteries in peripheral tissues and the local volume of stroke perfusion. It is a real-time and noninvasive method to evaluate circulatory function. Local perfusion changes, cardiovascular dysfunction, neuromodulation and mental state will change the PPI value [1]. In this study, the neuropsychiatric effects were preliminarily excluded through measures such as quiet, constant temperature and full rest. It was observed that the basic PPI of SHF patients was significantly lower than that of healthy controls. The stroke volume of SHF decreased and the peripheral perfusion decreased; In order to maintain blood pressure and tissue perfusion, the body compensatively activates neurohumoral endocrine hormones, constricts blood vessels, reduces blood flow and perfusion, resulting in the decrease of PPI; The weak heart beat in SHF weakens the intensity of conduction to peripheral arterioles, diuresis, and reduces the blood flow to the periphery, all pulling down the PPI.

PPI is the ratio of pulsatile blood flow (arteriole) to infrared light absorbed by non-pulsatile tissues (venous blood, muscle, bone, etc.), which reflects the blood flow of arterioles in peripheral tissues and the local amount of perfusion per stroke, and is a real-time noninvasive and simple method for evaluating circulatory function. Local perfusion changes, cardiovascular dysfunction, neuromodulation and mental state will all change PPI value [1]. In this study, we preliminarily excluded the neuropsychiatric effects by taking measures such as quiet, constant temperature and adequate rest, and observed that the basic PPI of SHF patients was significantly lower than that of healthy controls. The stroke volume of SHF decreased and the peripheral perfusion decreased. In order to maintain blood pressure and tissue perfusion, the body compensatively activates neurohumoral endocrine hormones, constricts blood vessels, reduces blood flow and perfusion, resulting in a decrease in PPI; SHF's inability to beat the heart weakens the intensity of small arteries to the periphery, diuresis also reduces the flow of blood to the periphery, all of which lower PPI.