Methadone Pharmacokinetics in End-stage Renal Disease

"* Explanation of the surgery and use of the IV-PCA pump.~* Signed informed consent."

Bolus of methadone 0.1mg/kg based on ideal body weight (up to a maximum dose of 20 mg), at the beginning of surgery.

Installation of IV-PCA of methadone. Program to be used with no background infusion, boluses of 1 mg, and the intervals between boluses of 8 minutes.