Explain each of these modes of BIPAP therapy.
1. spontaneous- pt triggered only
2. spontaneous/times- pt triggered w/ a back up rate if the pt fails to initiate a breath
3. timed- unit cycles between the IPAP and EPAP levels based soley on a timing mechanism as determined by the BPM and % IPAP
4. CPAP- CPAP pressure level only, pt must be ventilating spontaneously