I have a relation in ICU ventillated

HI there! I just wanted to ask a few questions about a relation of mine whi is currently undergoing treatment in ICU. He had an accident three days back and he is unconsious. Doctors have hooked a "ventillator" to him. Now they are going to take it away. Please help me to understand this ventillator business. Thanks in advance

I don't know whether I am

I don't know whether I am too late. And you don't need this info now. But this is link to a pdf that tells a patient/relative all you wanna know about a ventilator.