Pump, Pipes, and Fluid

Years ago, I was taught about shock using the pump, pipes, and fluid analogy. The pump is the heart, the pipes are the vessels, and the fluid is the blood. There is a certain similarity between the plumbing in my house and the “plumbing” in my body.

The other thing I was told, and something I occasionally see online, is that “Air goes in and out, blood goes round and round, and anything that stops either of those will kill you.” People will then say, “This is all you need to know in EMS!”

These are wonderfully simple and represent complex physiological mechanisms when discussing shock. EMT classes in the days of old were taught with concepts like this. But if you are still teaching with just these concepts—and not the proper physiology—you aren’t teaching enough.

But Simple Is Good for Teaching EMS, Right?

Simple is good. It’s a start. It’s the beginning of a bridge. But it’s not enough for today’s EMT in three ways:

1. It doesn’t match the education standards in depth regarding pathophysiology.
2. It doesn’t match the terminology used in your text and on the NREMT exam.
3. It doesn’t prepare EMTs with the foundation needed for AEMT and paramedic classes.

Building the Bridge Between Simple Concepts and Clinical Competency

Below, you’ll find two charts that illustrate the gap between simple plumbing terms and the things EMT students really need to know.

Remember:
Cardiac Output = Heart Rate x Stroke Volume
Blood Pressure = Cardiac Output x Systemic Vascular Resistance

Circulatory System Scenarios for EMT Students

Now provide the following short scenarios for your students to relate to each part of the circulatory system. These short scenarios will create these bridges, help hone intuition, and be useful for NREMT prep. Be sure to relate the patient presentation to the mechanisms causing shock—and use the correct terms when doing so! (answers in parens)

Each of these patients has signs of shock.

• A 29-year-old feels dizzy and has a heart rate of 188.  (pump – cardiogenic – reduced cardiac output)
• A 67-year-old feels tired and has a heart rate of 48. (pump – cardiogenic – reduced cardiac output)
• A 74-year-old has crushing chest pain, and sounds like it bubbles when they breathe.  (pump – cardiogenic – MI – heart failure)
• A 12-year-old has hives around his neck and face and says his face is swelling.  (pipes – distributive – anaphylaxis)
• An 88-year-old with an altered mental status has had a cough and low-grade fever for two weeks.  (pipes – distributive – sepsis)
• A 6-month-old has had diarrhea and poor feeding for three days.  (fluid – hypovolemic – dehydration)
• A 40-year-old has been shot in the chest. They have flat neck veins.  (fluid – hypovolemic – hemorrhage)
• A 56-year-old diabetic patient with a BG reading of 342.  (fluid – hypovolemic – dehydration)

We hope you and your students enjoy these!