Chaos theory. Doctors call medicine a “science” but there is still so much that can happen within the human body that, when multiple issues arise at once, can throw even the best doctor off.
Eat too much, get gas, but it presents as a cardiac issue. And then there’s the fact that everyone is different. Take me. Just about every textbook will tell you I have to be diabetic with high blood pressure and a cardiac issue as I have quite a few candles on my cake, enjoy Tim Horton’s and don’t belong to a gym. However, my BP is typically 110-120 systolic (114 at my last FF physical), my body processes sugars like nuts and my EKG at my last physical is normal sinus (by machine AND cardiologist interpretation). My PCPs constantly tell me my numbers can’t be right even though they took my BP, EKG, etc., but they are.
Algorithms cannot be programmed for the infinite number of variables, but they can guide us. It’s up to the medic to put the puzzle pieces together. And any EMS instructor worth their salt will teach to “treat the patient, not the numbers.”