1. A method for respiratory support, the method comprising: delivering a measured pressure; calculating a net flow based on at least one measured inlet flow and at least one measured outlet flow; using a relationship between a first value related to the measured pressure, a second value related to the net flow and a third value related to patient effort to provide an estimate of patient effort, wherein the third value related to patient effort represents at least one unknown value, and wherein the estimate of patient effort is determined based on the unknown value being characterized by a smooth signal; updating an interim value used to calculate a previous computed patient effort based at least in part on the estimate of patient effort, wherein the interim value is represented by a composite parameter that does not directly correspond to a particular respiratory parameter; calculating a computed patient effort based at least in part on the updated interim value; and utilizing the computed patient effort to trigger a ventilation cycle.