@Viro_Major I believe compiled stats published in journals dealing with the assisted suicide organizations. Of the hundred or two hundred cases, there may have been one or two protracted cases in which the individual was hospitalized. I don't recall if any survived.
Threads like this will ALWAYS find an exception, almost always to user error. there is no 100% reliable method when human error is factored in. That said, you would be hard pressed to find a more tried and reliable method. Very few have access to N anyway, so these threads are almost always hand wringing and pointless, not to mentioned asked dozens of times previously.