Depending on the make, the lifetimes of the currently available indwelling voice prostheses range from weeks to months. That is why the prostheses have to be replaced at regular intervals. This is usually effected through the tracheostoma with the patient awake, and having been given local anesthesia if desired. Just how demanding changing the voice prosthesis is for the patient and for the doctor depends on how many times it has already been changed, the size of the tracheostoma, where the esophagotracheal fistula is, what method of insertion was used, whether there are any complications to control, and how sensitive the patient is to manipulation of the wind pipe.