144B.2  Durable power of attorney for health care.
  A durable power of attorney for health care authorizes the attorney in fact to make health care decisions for the principal if the durable power of attorney for health care substantially complies with the requirements of this chapter. A document executed prior to May 8, 1991, purporting to create a durable power of attorney for health care shall be deemed valid if the document specifically authorizes the attorney in fact to make health care decisions and is signed by the principal.
91 Acts, ch 140, §2