Did you have at least two hours of time for orientation by a nurse who is working the same case? If not, you must insist on it. You should also have accurate contact information for the RN who is managing the patient. That's what they are there for. If you aren't feeling sure of yourself as far as the specific skills you need with the patient, call your agency and schedule an appointment with the DON there to address your concerns.
Never go to take care of a client and just "hope for the best" if you're scared. I don't know if that is the case here, just saying that as a general rule.
Go online and research the heck out of every piece of machinery and equipment your patient uses.
You should never feel like you've been cast out to sea on an ice floe.
If the agency tries to brush you off, I would seriously consider not working for them anymore. I know we hear this over and over, but it's your license that can be at risk, and trust me. Your agency will not care about backing you up in most cases.