A method of detecting occlusions in a medical fluid communication system comprising a fluid reservoir, a fluid path connected between the fluid reservoir and a patient, a fluid delivery device, and a pressure sensor within the fluid path in contact with the medical fluid for directly measuring a pressure of the fluid within the fluid path, the method comprising the steps of: measuring pressure of a medication fluid in a fluid path of a medical fluid communication system during the current interval with the in-line pressure sensor directly sensing pressure of the medication fluid; based on the pressure measurements, determining if a flow of the medication fluid is successful or unsuccessful, wherein determining if the medication fluid is flowing further comprises: calculating a minimum pressure of the current interval; and comparing the minimum pressure of the current interval to pressure data of a previous interval, wherein the flow of the medication fluid is not successful if the minimum pressure exceeds the pressure data of the previous interval; characterized in that, the pressure data of the previous interval is based on a calculation of a peak pressure of the previous interval and a minimum pressure of the previous interval; and the calculation is W*P MAX + (1 - W)*P MIN, where P MAX is the maximum pressure of the previous interval, P MIN is the minimum pressure of the previous interval, and W is a weighting factor set based on the sensitivity. measuring pressure of a medication fluid in a fluid path of a medical fluid communication system during the current interval with the in-line pressure sensor directly sensing pressure of the medication fluid; based on the pressure measurements, determining if a flow of the medication fluid is successful or unsuccessful, wherein determining if the medication fluid is flowing further comprises: calculating a minimum pressure of the current interval; and comparing the minimum pressure of the current interval to pressure data of a previous interval, wherein the flow of the medication fluid is not successful if the minimum pressure exceeds the pressure data of the previous interval; characterized in that, the pressure data of the previous interval is based on a calculation of a peak pressure of the previous interval and a minimum pressure of the previous interval; and the calculation is W*P MAX + (1 - W)*P MIN, where P MAX is the maximum pressure of the previous interval, P MIN is the minimum pressure of the previous interval, and W is a weighting factor set based on the sensitivity. calculating a minimum pressure of the current interval; and comparing the minimum pressure of the current interval to pressure data of a previous interval, wherein the flow of the medication fluid is not successful if the minimum pressure exceeds the pressure data of the previous interval; characterized in that, the pressure data of the previous interval is based on a calculation of a peak pressure of the previous interval and a minimum pressure of the previous interval; and the calculation is W*P MAX + (1 - W)*P MIN, where P MAX is the maximum pressure of the previous interval, P MIN is the minimum pressure of the previous interval, and W is a weighting factor set based on the sensitivity.