By signing the paperwork, the non-patient spouse is also made responsible for the debt, not solely mad responsible for the debt. A guarantor is nothing more than an additional pocket to whom the hospital may look for payment. That does not in any way release the debtor, i.e., the patient, from his/her obligation. No, you do not have a cause of action against the hospital for attempting to collect the debt by sending the case to a collection agency.
----The advice given here is not intended to, and does not, establish an attorney-client relationship. Also, the advice given is general, based solely on the facts stated in the question. Other facts, not listed here, as well as the contents of any documentation involved in your case may substantially affect your rights/obligations. The only way to know for sure is to schedule and appointment with an attorney to discuss your case in detail.----