There is a special reason I am super cautious about making recommendations concerning potassium channel problems at the moment. This probably does not apply to most of you, but there are some people out there with extreme problems that don't become apparent until they are given particular drugs.
Patients who have problems with general anesthesia are one kind, and you can check published statistics to see that a small percentage die for unexplained reasons. The people I'm talking about have problems with routine medical procedures like use of muscle relaxants during colonoscopies. Use the wrong type and the patient goes into
malignant hyperthermia. In one case where there was a known sensitivity to common anesthetics the surgeon ignored warnings and used a muscle relaxant so he could intubate the patient. The resulting malignant hyperthermia caused the patient to die hours later. Once the response had been triggered there was little medical personnel could do.
I've just had a report from another patient with a severe channelopathy about a colonoscopy which took unusually long -- without anesthesia. After this was over the doctor asked questions which revealed he had only read the instructions directly associated with what he was supposed to do normally during the procedure. He had ignored the pages about what to do, or not, if anything went wrong. The doctor was merely curious about what was going on in a strange case; the patient was alarmed at how close he had been to an agonizing death if the surgeon had done what was customary in a crisis.
I want to emphasize that such cases are extremely rare, just not nonexistent. The patient who survived calls himself "a zebra among zebras" (based on the medical advice to young doctors "when you hear hoofbeats think horses, not zebras.") Using arguments from "evidence-base medicine" to recommend treatments that work for the vast majority will tacitly condemn some number of exceptional patients to death. I'm still waiting for an answer from medical doctors to my question: "what number of excess deaths do you consider acceptable in medical practice?"