This has come up in Question 11.1from the second paper of 2017 and in Question 18 from the second paper of 2015. The college wanted a thorough discussion of the mechanisms of triggering and cycling. Overall, the question seemed like a refugee from the primary exam. The trainees answered it well (maximum mark was 8.5 and 77% passed), but the college still complained that "overall there was a lack of knowledge". Triggering of ventilation is subjected to a more thorough dissection in the Mechanical Ventilation section among the core topics. The best published resource on this topic is probably the 2011 article by Catherine Sassoon. Here, only a brief summary is offered. As many of these things, it works best in a tabulated format.
|Pressure||triggered by a patient-generated drop in pressure, from PEEP.|
|Flow||Triggered by a patient-generated change in fresh gas flow though a circuit|
|NAVA||Triggered by a change in diaphragmatic EMG, detected by a properly positioned electrode array on a special NGT|