Impact of Methadone on Prolonged Mechanical Ventilation in Patients on Continuous Treatment With Opioids

Inclusion Criteria: * Patients on Intermittent mandatory ventilation (IMV) for more than 72 hours * Patients infused Fentanyl or Hydromorphone for more than 72 hours * Patients with evidence of reversal of process that caused respiratory failure, adequate oxygenation (PaO2/fraction of inspired oxygen (FiO2)\>200; Positive end expiratory pressure (PEEP)≤8 and Ph≥7.2 * Patients hemodynamically stable * Patients with a failed single or multiple attempts at spontaneous breathing trials Exclusion Criteria: * Patients with history of opioid drug abuse * Patients receiving schedule II narcotics on a chronic basis for longer than 6 months prior to ICU admission or on other analgesic infusions other than Fentanyl or Hydromorphone * Patients with cervical spinal cord injury or neuromuscular disease * Patients with end stage liver disease at ICU admission (ie, International normalized ratio ≥2and not taking warfarin and/or a total serum bilirubin ≥1.5 times above normal limits * Patients with prolonged QTc interval ≥500 * Patients with prior history of cardiac conduction defects or sudden death * Patients with QTc increase of ≥60 milliseconds above the value of prior EKGs measured during current ICU admission * Patients with more than 5 days on IV analgesia * Patients intubated for more than 3 days * Patients without feeding tubes * Patients not receiving enteral feeding