A dialysis system includes: a blood filter (26)； a dialysate pump (50a, 50b) connected to a dialysate portion of the blood filter (26)； a blood pump (22a, 22b) connected to a blood portion of the blood filter (26), the blood pump (22a, 22b) including a diaphragm (28) that is moved in cycles to pump the blood, the cycles having a flow period and a no-flow period； a patient access device (20) in fluid communication with the blood portion of the blood filter (26), the no-flow period having a first characteristic of a property when the patient access device (20) is lodged in a patient (12) and a second characteristic of the. property when the patient access device (20) is dislodged from the patient (12)； and a logic implementer (100) configured to determine that the patient access device (20) has been dislodged from the patient (12) when the second characteristic of the parameter is detected..
