The disclosure relates to a blood treatment device for use in blood treatment therapies, comprising: an extracorporeal blood circuit, a dialyzer and a dialysis fluid circuit, wherein the extracorporeal blood circuit and the dialysis fluid circuit are separated from each other via a membrane provided in the dialyzer, via which blood can be filtered; at least one substitution solution pump, which is configured to supply a substitution solution to the extracorporeal blood circuit before and/or after the dialyzer; an effluent pressure sensor, which is configured to measure a pressure in the dialysis fluid circuit after the dialyzer, and a control unit, which is configured to automatically reduce a flow rate of the at least one substitution solution pump when an effluent pressure measured by the effluent pressure sensor drops during an ongoing blood treatment therapy.