At exida, we just finished a Failure Modes and Effects Analysis (FMEA) on a medical ventilator. This was done for a new manufacturer who needed independent design verification. It was a fascinating job. We found lots of pneumatic devices very similar if not identical to the kind used in automation. We were able to use our deep knowledge of failure rates and failure modes of this equipment. I guess it makes sense that the insides of a ventilator use the same proven technology of other automation systems, a ventilator automates human breathing.
An FMEA looks at each device in the system. Failure modes are listed for each device and the effect of that failure mode on system operation is identified. For this FMEA we added secondary failures if the first failure did not cause a life-threatening situation. Using that information, a probability of failure for each failure mode could be predicted for a given mission time. The probabilities of failure were quite low relative to normal life events like a snakebite or bee sting. I would personally feel quite comfortable to be using one of these machines if I needed one. And the job felt important in the middle of this COVID-19 pandemic.