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.