Hi Sz,
In the worst case scenario section (2.2) it is a judgement call, however there may be literature to back this up that you can use as a reference in the Usability File. I regularly scan medical device alerts (MHRA [UK], FDA [USA - MAUDE], Afssps [France], Salute [Italy], MDCO [Hong Kong] etc). These can illustrate a worst case e.g. an event leading to death or serious injury. An example from MAUDE database (FDA - ID 1712843) indicated that a portable suction device did not operate, so a patient’s airway could not be cleared leading to death. The reason for lack of function being that the (battery) device was not kept on charge.
Steve