Shock (江建昌)

Shock

Blood pressure is not perfusion, falling BP is a late sign.
Anticipate shock in all critically ill patient.

當血量減少15~25%，或成人正常循環量減少500~1500cc時，低血容積性休克的症狀及徵候即開始出

休克的分期不以血紅素分期，而是以 vital sign:
第一期只是有些不安
第二期脈博開始變快，血壓還是正常
第三期出血 30~40% 時血壓才開始掉

Pulse pressure = Systolic pressure – diastolic pressure ≈ Stroke volume

Hypovolemic shock 時一開始 central venous pressure 下降，但 heart rate 上升， venomotor tone 上升，讓 BP 還不會馬上掉

常見休克的原因:
– 低血容性休克 (hypovolemic shock)
– 心因性休克 (cardiogenic shock)
– 阻塞性休克 (obstructive shock)
– 分佈性休克 (distributive shock)

Sepsis: defined as life-threatening organ dysfunction caused by a dysregulated host response to infection.( JAMA. 2016;315(8):801)

Septic shock is a subset of sepsis in which underlying circulatory and cellular/metabolic abnormalities are profound enough to substantially increase mortality.
Circulatory abnormality: 血壓掉
Cellular/metabolic abnormality: Lactate 上升

敗血性休克有兩階段:
“Warm” shock -早期，血管擴張，心跳上升，病人摸起來是溫的
“Cold” shock–晚期，周邊阻力增加、心收縮力降低、心輸出量降低，病人摸起來是冷的

低血壓不等於休克，休克不等於低血壓
在醫院 shock 原因第一名是 septic shock

上課一定要問問題兼點名

指甲下微血管回血大於 2 秒的快去 ICU 報到

太相信血壓，遲早會倒大楣

測量 cardiac output 的方法:
– Cardiac ultrasound
– Thermodilution : PAC
– Pulse contour
– Bioimpedance

Swan-Ganz Catheterization

PiCCO (Pulse index Continuous Cardiac Output)

Cardiac ultrasound

Lactate 產生是 perfusion 不好的間接指標
Lactate 大於 4 時要小心

Mixed venous oxygen saturation = (3/4 SVC+ 1/4 IVC ) Oxygen saturation = 氧氣供應全身組織之後的結餘
CO is the cardiac output and CaO2 is arterial O2 content.
正常情況下, 組織的氧萃取率為 25%, 故 SvO2 為 75%