The use of sedative agents in critically ill patients.

The main aim of sedation in the critically ill patient is to provide relief from anxiety and pain. The current, ideal level of sedation should leave a patient who is lightly asleep but easily roused. No single regimen is suitable for all patients. The level of sedation should be monitored, and the choice of agent, the dose and the route of administration adjusted appropriately. Midazolam is often used to provide sleep and anxiolysis. Alternatives include propofol and isoflurane. Propofol is easily titrated to achieve the desired level of sedation, and its effects rapidly end when the infusion is stopped. Isoflurane also appears promising, but special equipment is needed for its administration. Morphine is the standard analgesic agent. The principal metabolites, morphine-6-glucuronide, is also a potent opioid agonist and may accumulate in renal failure. Of the newer analgesic agents, alfentanil is an ideal agent for infusion, and may be the agent of choice in renal failure. Neuromuscular blocking agents are indicated only in specific circumstances, and used only once it is known patients are asleep and pain free. The actions of these agents are unpredictable in the critically ill patient. Alterations in drug effect and elimination may occur, especially in the patient with hepatic and renal failure. This may also apply to active metabolites of the parent drug. When planning sedation regimens, specific patient needs and staffing levels must be remembered. Attention to the environment is also important. Midazolam and morphine given by intermittent bolus or by infusion are the mainstay of most regimens. Propofol is ideal for short periods of care on the ICU, and during weaning when longer acting agents are being eliminated.