(a) Notwithstanding the provisions of sections 19a-571, 19a-572, 19a-575, 19a-575a, 19a-577, 19a-580a and 19a-580b, comfort care and pain alleviation shall be provided in all cases.

(b) Any document executed prior to October 1, 1991, in accordance with § 19a-575, revision of 1958, revised to January 1, 1991, and § 19a-575a shall not be invalidated by any provision of public act 91-283*. Any document executed prior to October 1, 1991, shall not be presumed to prohibit withholding or withdrawal of life support systems as defined in § 19a-570, revision of 1958, revised to January 1, 1991, unless such prior document specifically addresses such withholding or withdrawal.