The Advanced Trauma Life Support course lists “classes of hemorrhage”, and various other sources list a similar classification for shock. I’ve not been able to pinpoint where these concepts came from, exactly. But I am sure of one thing: you will be tested on it at some point in your lifetime.
Here’s the table used by the ATLS course:
The question you will always be asked is:
What class of hemorrhage (or what % of blood volume loss) is the first to demonstrate systolic hypotension?
This is important because prehospital providers and those in the ED typically rely on systolic blood pressure to figure out if their patient is in trouble.
The answer is Class III, or 30-40%. But how do you remember the damn percentages?
It’s easy! The numbers are all tennis scores. Here’s how to remember them:
| Class I | up to 15% | Love – 15 |
| Class II | 15-30% | 15 – 30 |
| Class III | 30-40 | 30 – 40 |
| Class IV | >40% | Game (almost) over! |
Bottom line: Never miss that question again!