Remember that Oxygen Delivery is composed of two parts:
What is Shock?
[Oxygen Delivery] = [Oxygen Content] [Cardiac Output]
In the first video, let’s go over problems with that second part: cardiac output.
How can cardiac output go wrong? All of these can lead to decreased cardiac output.
- Cardiac: problems with the PUMP. The heart won’t push blood forward.
- Blood vessels: problems with the PIPES. The blood vessels are causing either obstruction to flow or are so massively dilated that blood just pools within or leaks out.
- Fluid volume: problems with the TANK. There’s not enough fluid to pump around.
The commonly taught categories of causes of cardiogenic, obstructive, distributive and hypovolemic fit into the above three physiologic groups.
How do you diagnose shock?
You can recognize shock by hypoperfusion of organ systems. So you’ll find measured blood pressure is low. Also, decreased blood flow to the
- kidneys leads to decreased urine output
- brain leads to altered mental status
- skin leads to cyanosis.
Remember that H&P are the best diagnostic tools we have. So search for potential signs and symptoms for diseases of the pump, pipes or tank. Ultrasound (the RUSH protocol) is very helpful as well. Treatment depends on identifying the cause.
How do you treat shock?
Treatment depends on the cause of hypoperfusion.
- PUMP problem? Maybe you need an inotrope or other cardiac support
- TANK problem? Then fill up the tank. Use whatever fluid you need, but remember crystalloid doesn’t carry oxygen.
- PIPE problem? Then, assuming you have a full tank, you need a pressor.