Euthanasia is not always clean, controlled...
Euthanasia by a doctor in the Netherlands is not idiot-proof.
Most cases of euthanasia are performed by a general practitioner. Usually, GPs have little experience with it.
There have been cases where the order of the medications was reversed, according to the Dutch Euthanasia Review Committee. The patient in question first received a paralyzing agent and only then a sedative (thiopental or propofol). As a result, the patient suffocated while fully conscious. A horrific death.
In the Netherlands, it is also possible to choose a drink (this is referred to as assisted suicide, not euthanasia). In this case, you drink the substance (pentobarbital) yourself and are not dependent on a doctor. That's why I recommend the drink for anyone eligible for euthanasia or assisted suicide. Or, make sure the doctor has experience with euthanasia before deciding.