The invention relates to a device for treating an individual suffering from cardiac or circulatory arrest or from a stroke, comprising a blood withdrawal device (BE) that is applied to the individual (P), an analysis unit (BA) which is directly or indirectly connected to the blood withdrawal device for detecting a blood analysis result (BAE) providing at least one characteristic of the blood, directly or indirectly connected to a blood return device (BR) that is applied to the individual (P) and is designed to deliver a substance to the individual via the return device (BR).