There are a great many data missing from this question, but I'm going to make some basic assumptions (if they are wrong, then the answer may be also). First, I'm assuming that the patient is a mentally competent adult who is capable of understanding both the disease and the treatment. Secondly, I'm assuming that when he refused surgery, he was cogent, not under duress, nor under the influence of drugs or alcohol. Finally, I'm assuming that while the situation may be emergent, the patient has remained mentally alert.

After making all of these assumptions, it is both unethical AND illegal to perform surgery upon an adult who has refused it. I understand the feelings of the children who want the best treatment for their father, but it simply is not allowed. Perhaps if you or his physician explained the disease and treatment to him, he might give in and allow it but, either way, you cannot proceed without his consent or a court order.

As a final part to this answer, if the patient becomes unconscious, his condition changes, and the family is re-approached by the surgeon, there are circumstances in which the children can giver permission, but they would need to be specific and well documented.

I agree with Eric. Even in an emergency situation, if the patient has shown mental capacity to make his or her own decision at the time the decision is to be made and if the patient has received information from the physician about the patient's disorder, treatment, risks and possible outcomes and shows understanding of the information, then if the patient refuses the treatment, such refusal cannot be overturned by any family member. The physician may, if appropriate, present to the patient alternate approaches to treatment for the patient's consideration. If the patient refuses all and any specific treatment for the emergent condition, the physician still must provide for the patient's comfort until some final disposition of the patient is made. If the patient, who had capacity and refused treatment, subsequently becomes unconscious, the family cannot reverse the patient's previously expressed decision. However, if the patient's diagnosis has substantially changed in the interval and the information which had been given to the patient was no longer pertinent, in an emergent situation, the family could give informed consent for the new condition and new treatment (as under substituted judgment) but first having considered the possible reasons for the previous rejection by the patient. If that previous rejection was for general reasons including quality of life, which could apply to the patient's current status, then those reasons may preclude the family's decision for consent. It is the responsibility of the attending physician to consider whether any decision by family surrogates most likely represents a substituted judgment of what the patient would have said he or she wanted. That means that the physician must question the family regarding their understanding of the patient's wishes and the basis for their decision. ..Maurice.

Eric, but I just want to emphasize (from your second paragraph) that any consent made by the family of that now unconscious patient would have to be based not only on the new condition and information provided by the doctor but also based and decided upon by the family's understanding of the meaning and intent of the patient's initial refusal decision. The patient's underlying philosophy regarding treatment has to be considered. ..Maurice.