The level of pain and sedation will be assessed between groups randomized to either methadone or placebo in addition to current intravenous sedative and analgesic agents. The duration of mechanical ventilation will be assessed between both groups. Opioid withdrawal symptoms may manifest or be mistaken for delirium symptoms. ICU delirium is often managed with antipsychotic medications. To assess if methadone can reduce the need for antipsychotic medication, all administered antipsychotic doses will be recorded and total consumption will be compared between the two groups. Methadone has been associated with abnormal heart rhythms in rare instances. To ensure patient safety, data from the heart monitor will be collected and compared between the two groups to assess for QT interval prolongation.