Promissory note not enough to discharge patient with unpaid hospital bill

Dear PAO,

My brother is confined in the hospital, and my parents would like to have him checked out already because the bill is piling up and has ballooned to such an amount that our family is having a hard time settling. My parents are willing to sign a promissory note, but my uncle said that the hospital might not allow them. Is this true? My friend’s father told me though that hospitals could not refuse patients who wish to leave. Please advise.