| Element | Key point |
| Opioid dosing | ICU clinicians responsible for pain management should have knowledge of equianalgesic opioid dosing Dosing regimens should be based on a risks/benefits ration for an individual patient There is no maximum dose or duration of effect; these must be individualized The "normal dose" for an individual patient is that which adequately relieves pain without unacceptable adverse effects |
| Opioid administration | The preferred mode of initial therapy is rapid titration of opioids with small incremental IV doses Both remifentanil and sufentanil can be considered for use since both are short-acting opioids and may decrease the duration of mechanical ventilation and ICU length of stay and improve procedural pain management Dose and rate-related histamine release does not occur with fentanyl analogues and can be limited by slowing the rate of IV administration of opioids Methadone has unpredictable pharmacokinetics and pharmacodynamics in opiate-naïve patients. The Patient's Q-T interval (corrected) of the electrocardiographic tracing should be monitored carefully if methadone is used at all. |
| Opioids - other considerations | It is necessary to institute a bowel regimen with stimulant or osmotic laxative in all patients receiving sustained opioid administration unless there are contraindications such as small bowel obstruction Use of opioids in liver failure can be complicated since most opioids are at least partially metabolized in the liver, reducing opioid clearance. Fentanyl may be preferred opioid in liver failure although its half-life is prolonged with repeated dosing or use of high doses. Use opioids cautiously in patient with end-stage liver disease. Longer dosing intervals may be needed. Use of opioids in renal failure is associated with complex drug absorption, metabolism, and renal clearance. Meperidine has been removed from many hospital formularies and, even if available, potential toxicity contraindicates its use in renal failure. Use of codine and morphine is not recommended. Hydromorphone should be used cautiously; an active metabolite can accumulate between dialysis treatments. Fentanyl and methadone are relatively safe in renal failure since they have no active metabolites. However, neither is removed by dialysis. Opioids, especially when used chronically or in patients with renal failure, electrolyte disturbances, and dehydration, may cause neuroexcitatory effects, such as myoclonus. Myoclonus may resolve over a few days with decrease in opioid dose. Myoclonus, especially if mild, should not interfere with good pain control. Rotating opioid to a lower dose of another opioid with a different structure may reduce myoclonus within 24 hours. Fentanyl might be a better choice in this case since it has no active metabolites. Certain opioids such as fentanyl distribute in fat which can prolong the opioid effects |
