Pain management in the intensive care unit

Critically ill patients often experience pain from an underlying illness or injury, a recent surgical or other invasive procedure, or various interventions in the intensive care unit (ICU), e.g., endotracheal intubation, vascular access devices, nasogastric tubes, urinary catheters, mechanical ventilation, and routine nursing care, such as repositioning. Opioids remain the mainstay medication for pain control in the ICU; however, they can have adverse effects, including over-sedation, respiratory depression, opioid-induced constipation, opioid dependence and withdrawal, which result in increased length of ICU/hospital stay, health care costs, morbidity, and mortality. In this review, we summarize the mechanism of action, usual doses, side effects, recent studies of opioids that are frequently used in adult ICUs, and pain assessment tools for monitoring pain in adult ICU patients.   Keywords: analgesia, opioids, intensive care unit, pain assessment tools