Dr. Ernesto Torres told reporters the 50-year-old Camacho has been comatose since being shot Tuesday night. The fighter went into cardiac arrest early Wednesday, the Primera Hora newspaper reported from San Juan.
Torres said it was up to a neurologist to make an official proclamation of brain death, although he used the term "clinically brain dead" in his media appearance.
The doctor said medical staff had spoken to Camacho's mother, Maria Matias, about organ donation.
Camacho was shot while sitting in a car with a childhood friend, who was killed in the attack. A bullet entered Camacho's left jaw, severed his brain stem and ended up in his right shoulder, the report said.
Police said numerous packets of cocaine were found in the car where the men were shot.