Hi Alex,
Not necessarily. Breathing is regulated by the brainstem; as long as the brainstem is intact, the person will likely be able to breathe independently. Many patients in a coma are dependent on mechanical ventilation – but being in a state of unarousable unconsciousness (coma) does not necessarily mean the person cannot breathe independently. People in vegetative states (or unresponsive wakefulness syndrome) can often breathe on their own.
