Advance Directive to document your wishes for your care 

Every person over the age of 18 should complete an Advance Directive or a Durable Power of Attorney for Healthcare.The Advance Directive form allows you to designate who would make medical decisions if you are unable to do so, and also allows you to state your wishes about prolonging life and under what circumstances.
You should provide signed copies to the person you've designated and to your doctor's office, and bring a copy with you whenever you are admitted to a hospital.

Please be aware that hospital employees are not permitted to witness your signature on these documents.

If you don't have either an Advance Directive/Durable Power of Attorney for Healthcare, or documents prepared by an attorney for this purpose, the law specifies who among your immediate family are the ones legally authorized to make medical decisions for you if you are unable to do so.
In addition to signing an Advance Directive, you should also speak with your family to make your wishes clear about organ and tissue donation. The surest way to indicate that you want to be an organ and tissue donor is to sign up on the Michigan Organ Donor Registry and receive a heart sticker for the front of your driver's license or state ID. This makes it clear what your wishes are after you die.

American Hospital Association - Put It In Writing

Michigan Advance Directive Advance Directive Form