Shock States and Hemodynamic Management
4
Shock Categories
Hypovolemic cardiogenic distributive obstructive
≥65 mmHg
MAP Target
Minimum perfusion pressure
1st Line
Norepinephrine
For septic shock
Four Categories of Shock
each type has its own hemodynamic fingerprintHypovolemic
Hemorrhage, dehydration, burns, third-spacing
Low CVP, Low PAOP, Low CO, High SVR
Treatment Volume resuscitation (crystalloids, blood products)
Cardiogenic
MI, cardiomyopathy, valvular emergency, dysrhythmia
High CVP, High PAOP, Low CO, High SVR
Treatment Inotropes (dobutamine), mechanical support (IABP)
Distributive
Sepsis, anaphylaxis, neurogenic, adrenal crisis
Low CVP, Low PAOP, High CO (early), Low SVR
Treatment Norepinephrine first-line, source control in sepsis
Obstructive
Tamponade, tension pneumo, massive PE
High CVP, Variable PAOP, Low CO, High SVR
Treatment Treat the obstruction (pericardiocentesis, chest tube, thrombolytics)
Vasopressors vs Inotropes
Vasopressors (Raise BP)
- Norepinephrine Alpha + Beta-1, first-line sepsis
- Vasopressin V1 receptor, second-line sepsis
- Phenylephrine Pure alpha, use in SVT with hypotension
Inotropes (Increase Contractility)
- Dobutamine Beta-1, increases CO, may drop BP
- Milrinone PDE3 inhibitor, inotrope + vasodilator
Dobutamine is an inotrope, NOT a vasopressor. It can actually drop blood pressure through its beta-2 vasodilatory effects.
Key Values to Memorize
MAP ≥65 mmHg target
Norepi = 1st line sepsis
Lactate >2 = tissue hypoperfusion
SvO2 <60% = increased extraction
30 mL/kg crystalloid bolus
Vasopressin = 2nd line
you know the pathophysiology, now prove it under pressure
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Practice CCRN QuestionsExam Traps
Norepinephrine is first-line for septic shock, not dopamine
Dopamine was previously used but causes more tachycardia and arrhythmias. Current guidelines recommend norepinephrine as the first-line vasopressor for septic shock. Vasopressin is added as second-line.
Dobutamine is NOT a vasopressor
Dobutamine is a pure inotrope that increases contractility via beta-1 stimulation. It can actually decrease blood pressure through beta-2 vasodilation. Never use it as a stand-alone pressor.
Cardiogenic shock needs improved contractility
The problem is a failing pump. Vasopressors increase afterload and make the pump work harder. The priority is inotropic support (dobutamine, milrinone) to help the pump, then mechanical support if needed.
Obstructive shock requires treating the CAUSE
Tamponade needs pericardiocentesis. Tension pneumothorax needs needle decompression. Massive PE needs anticoagulation or thrombolytics. Vasopressors are a bridge, not the fix.
Dopamine is Outdated
Dopamine is NOT first-line for septic shock anymore. Norepinephrine has fewer adverse effects and better outcomes.
Obstructive = Fix the Cause
Obstructive shock (tamponade, tension pneumo, massive PE) = treat the CAUSE. Vasopressors alone will not fix it.
The car is running but the gas tank is nearly empty. The engine sputters because there is not enough fuel. Treatment is simple: refill the tank with fluids or blood products.
The tank is full but the engine itself is failing. It cannot generate enough power to move the car. You need a mechanic (inotropes, mechanical support) to fix the engine, not more gas.
The fuel lines are leaking everywhere. Even though the tank has fuel and the engine works, fuel is escaping through dilated, leaky pipes. Vasopressors tighten the pipes back up.
Something is physically blocking the system. Maybe the exhaust pipe is crimped (tamponade) or the air intake is blocked (tension pneumo). No amount of fuel or engine repair helps until you remove the blockage.
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