Famous Vietnamese hospital: I am impatient and I am an in-patient (2,3,4)

'famous vietnamese' is the definition.
The definition suggests a singular noun which matches the answer.

'hospital i am impatient and i am an in-patient' is the wordplay.
I cannot really see how this works, but
'hospital' could be 'h' (abbreviation for hospital on maps) and 'h' is present in the answer.
'i' is found in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
'an' could be 'i' (Roman numeral for one) and 'i' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?