Case
Step one · what is going on?
On the cart
The monitor is running and the patient is on the table. Learn what each instrument reports and how each one lies to you — then take eight cases and answer the only two questions that matter: what is going on, and what do you do about it?
It reports heart rate, saturation, carbon dioxide, pressure and temperature. Not one of those is anaesthetic depth. Depth lives in the eye, the jaw and the reflexes — in what your hands find — and the numbers only tell you what the patient's body is doing about it.
So the failure mode in a real theatre isn't that someone can't define a capnograph. It's that they read one sign in isolation, in a patient whose protocol changed what that sign means, and act on it. A central eyeball means opposite things at opposite ends of the range. A tachycardia is a question, not a diagnosis. And a brisk palpebral reflex under ketamine means nothing at all.
The ECG, plethysmograph and capnogram are synthesised per case from the patient's own rate and rhythm — so an AV block drops real beats, a rebreathing circuit lifts the capnogram off its baseline, and vasoconstriction degrades the pleth until the saturation drops out. The waveform is the diagnosis; the number is only its summary.
The physical findings stay hidden until you go and get them, and the call stays locked until you've made at least three checks. That constraint is the lesson: nobody gets to judge depth from across the room.
Every case asks what is happening and then, separately, what you do about it — because the expensive mistakes are the ones where the read is right and the action is wrong. Turning the dial up on a light patient is correct and far too slow. Warming a cold patient is correct and leaves it overdosed.
Each incorrect call returns the reasoning that makes it tempting and the specific finding that rules it out — because in practice you're separating states that look identical on the monitor and take opposite treatment.