Colo. Rev. Stat. § 15-18-107
In the event that an attending physician is presented with an unrevoked declaration executed by a declarant whom the physician believes has a terminal condition or is in a persistent vegetative state, and lacks decisional capacity to accept or reject medical or surgical treatment, the attending physician shall order the declarant to be examined by one other physician. If both physicians find that the declarant has a terminal condition or is in a persistent vegetative state, and lacks decisional capacity to accept or reject medical or surgical treatment, they shall certify such fact in writing and enter such in the qualified patient's medical record of the hospital in which the withholding or withdrawal of life-sustaining procedures or artificial nutrition and hydration may occur, together with a copy of the declaration. If the attending physician has actual knowledge of the whereabouts of either the qualified patient's agent under a medical power of attorney or, without regard to order, the patient's spouse, a person designated under the "Colorado Designated Beneficiary Agreement Act", as described in article 22 of this title, any of his or her adult children, a parent, sibling, or any other person designated in writing by the qualified patient, the attending physician shall immediately make a reasonable effort to notify at least one of said persons that a certificate has been signed. If no action to challenge the validity of a declaration has been filed within forty-eight hours after the certification is made by the physicians, the attending physician shall then withdraw or withhold all life-sustaining procedures or artificial nutrition and hydration pursuant to the terms of the declaration.
C.R.S. § 15-18-107