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Shock之分類
=Hypovolemic shock
-Loss of circulating blood volume (usually at least 20%)
=Distributive shock
-Septic shock, anaphylatic shock, adrenal insufficiency, liver failure, SIRS
=Cardiogenic shock
-AMI, valvular diseases (stenosis, regurgitation, rupture), arrhythmia, cardiomyopathy
=Neurogenic shock
=Obstructive shock
-Pulmonary embolism, tension pneumothorax, cardiac tamponade

各種休克之臨床表現

肺微血管嵌塞壓(PCWP, pulmonary capillary wedge pressure)

系統血管阻力(SVR, systemic vascular resistance)

靜脈血氧含量(VOC, venous oxygen content)

Shock依表現之分級
=第一級：
-代償性休克
-身體靠心跳血管收縮及交感神經興奮代償
=第二級：
-失償性休克
-身體代償失調，開始出現血壓降低四肢冰冷寡尿
=第三級：
-不可逆性休克
-長時間灌流不足導致細胞受損

評估溶液流失以及出血的狀況可分四級(以50Kg的成人為例)

※失血超過50%，直接失去意識、心跳、血壓

※3:1規則 = 每失血1cc，要補充3cc的晶體溶液

※壓碎性傷害需要較多的晶體溶液

※正在出血中，則需要較多的輸血

※脈搏壓=SBP-DBP

升壓藥物

※Dobutamine高劑量會有降血壓效果，所以不超過20µg/kg/min

Inotropes: Dopamine, Dobutamine, Milrinone
Vasopressors: Dopamine, Phenylephrine, Norepinephrine,
Epinephrine, Vasopressin

Inotropes:
-- Chronotropic effect: heart rate
-- Inotropic effect: myocardial contractility
Vasopressors:
-- Vasoconstrictive effect: arterial pressure, increase afterload
-- Vasodilator effect: reduce afterload

One drug, many receptors:
-- Dobutamine:
......a. beta-1 receptor: increase cardiac output
......b. beta-2 receptor: induces vasodilation and can cause
hypotension
Dose response curve:
-- Dopamine:
......a. beta-1 receptor: 2~10 mcg/kg/min
......b. alpha receptor: > 10 mcg/kg/min
Direct versus reflex actions:
-- Norepinephrine:
......a. beta-1 stimulation: tachycardia
......b. alpha receptor-induced vasoconstriction: reflex decrease in
heart rate
......c. net result: stable or slightly reduced heart rate

Norepinephrine 4mg/4mL/amp
Epinephrine 1mg/mL/amp
Ephedrine 40mg/mL/amp
Dopamine 40mg/mL, 5mL/amp
Dobutamine 250mg/20mL/vial
Isoproterenol 0.2mg/mL/amp

Drug of choice:
Septic shock:
-- 1st Norepinephrine
-- 2nd Vasopressin or epinephrine
Neurogenic shock:
-- 1st Norepinephrine
-- 2nd Epinephrine or phenylepinephrine
Cardiogenic shock:
-- 1st Norepinephrine
-- Dobutamine in case of cardiac failure without significant
hypotension
-- Dopamine: beneficial in preserving renal function
Anaphylactic shock:
-- 1st Epinephrine

VanValkinburgh D, Hashmi MF. Inotropes And Vasopressors.
[Updated 2019 Oct 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.
Available from: https://www.ncbi.nlm.nih.gov/books/NBK482411
 

在使用升壓藥物時，有時會因為vasospasm or extravasation造成局部組織的缺血和壞死，此時可以使用Phentolamine (5~10mg in 10mL normal saline)皮下注射，以減緩局部的血管收縮(vasoconstriction)

如果多巴胺或任何其他血管升壓藥物，滲漏到周邊組織時，可以經由注射phentolamin (alpha-receptor antagonist)到受影響的區域，以減少缺血性組織壞死的程度，建議注射的劑量為5~10mg phentolamine in 15mL NS。