Where it is necessary, under the terms of a durable power of attorney to determine the mental or physical incapacity of a patient, a healthcare provider may release personal health information to a licensed physician or licensed attorney at law if the physician or attorney at law signs and furnishes the healthcare provider with an affidavit that the release of information is necessary to determine the mental or physical incapacity of the patient, or of the agent or other fiduciary under a durable power of attorney for health care that was signed by the patient where incapacity causes the document to come into effect, discontinues its effect or calls for a change in a fiduciary acting under the document.