A possible treatment method, especially for therapy-resistant diseases, is ketamine therapy (esketamine). The therapy is characterised by high tolerability with only minor side effects. After the infusion, the patients are not fit to drive and therefore escorts are mandatory. Ketamine is an anaesthetic originally used for short anaesthesia. It has been used successfully in pain therapy for many years. A special side effect of ketamine is a rapid onset antidepressant effect. This effect can be used especially in the treatment of severe depression or suicidal patients. Already after a single administration, the so-called hit-and-go effect can be observed. Even severe depression can be broken through quickly and effectively. This discovery is considered one of the groundbreaking findings in psychiatry over the last few years. Ketamine follows a different mechanism of action than all other antidepressants and painkillers. While most antidepressants act on the concentration of neurotransmitters, such as serotonin or dopamine, and a few interfere with the melatonin balance, ketamine blocks the so-called NMDA receptors.The treatment is administered via an infusion machine, which dispenses a precisely calculated amount of the active substance to achieve the desired effect. During the therapy, the patient is continuously monitored via measuring devices and the blood pressure is checked.