Altera FPGA in safety application

Life support is a different category. For a safety application it's usually sufficient to detect an error reliably and shutdown the monitored system. For a life support system, e.g. a pacemaker or an respiration apparatus it's not an option...

In my opinion, a safety application involving FPGA can be analysed similar to other digital logic applications, e.g. processor based. However, failure probability of complex devices is still calculated based on the transistor count.