A medication infusion system comprising: a pump controller for providing medication fluid to a patient via a fluid path connected between a fluid reservoir of the pump controller and a patient; and an in-line fluid detector for measuring pressure of the medication fluid in the fluid path and transmitting the measured pressure to the pump controller, wherein the pump controller determines if a flow of the medication fluid is successful or unsuccessful based on the pressure measurements in the current interval; wherein the pump controller determines if a flow of the medication fluid is successful or unsuccessful and wherein the pump controller 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, wherein 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, characterized in that the calculation is W ∗ P MAX + (1 - W) ∗ P MIN, where P MAX is the maximum pressure of the previous interval, P MIN is a minimum pressure of a previous interval, and W is a weighting factor set based on the sensitivity a pump controller for providing medication fluid to a patient via a fluid path connected between a fluid reservoir of the pump controller and a patient; and an in-line fluid detector for measuring pressure of the medication fluid in the fluid path and transmitting the measured pressure to the pump controller, wherein the pump controller determines if a flow of the medication fluid is successful or unsuccessful based on the pressure measurements in the current interval; wherein the pump controller determines if a flow of the medication fluid is successful or unsuccessful and wherein the pump controller 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, wherein 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, characterized in that the calculation is W ∗ P MAX + (1 - W) ∗ P MIN, where P MAX is the maximum pressure of the previous interval, P MIN is a minimum pressure of a 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, wherein 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, characterized in that the calculation is W ∗ P MAX + (1 - W) ∗ P MIN, where P MAX is the maximum pressure of the previous interval, P MIN is a minimum pressure of a previous interval, and W is a weighting factor set based on the sensitivity