Sedatives continue to be used on a routine basis in
critically ill patients. Although many agents are available and some approach an ideal, none are perfect. Patients require continuous reassessment of their
pain and need for sedation. Pathophysiologic abnormalities that cause agitation,
confusion, or
delirium must be identified and treated before unilateral administration of potent
sedative agents that may mask potentially lethal insufficiencies. The routine use of standardized and validated sedation scales and monitors is needed. It is hoped that reliable objective monitors of patients' level of consciousness and comfort will be forthcoming. Each
sedative agent discussed in this article seems to have a place in the ICU pharmacologic armamentarium to ensure the safe and comfortable delivery of care.
Etomidate is an attractive agent for short-term use to provide the rapid onset and offset of sedation in
critically ill patients who are at risk for hemodynamic instability but seem to need sedation or
anesthesia to perform a procedure or manipulate the airway.
Ketamine administered through
intramuscular injection or
intravenous infusion provides quick, intense
analgesia and anesthesia and allows patients to tolerate limited but painful procedures. The risk/benefit ratio associated with the use of this
neuroleptic agent must be weighed carefully.
Ketamine is contraindicated in patients who lack normal intracranial compliance or who have significant
myocardial ischemia.
Barbiturates are reserved mainly to induce
coma in patients at risk for severe CNS
ischemia, which frequently is associated with refractory
intracranial hypertension, or in patients with
status epilepticus. When administered in high doses, these drugs have prolonged
sedative and depressant effects. Judicious hemodynamic monitoring is required when
barbiturate coma is induced.
Haloperidol is indicated in the treatment of
delirium. Patients should be monitored for extrapyramidal side effects and, when they require higher doses, for potential electrocardiographic prolongation of the QT interval.
Dexmedetomidine may evolve into an agent with qualities comparable with
midazolam and
propofol, and it may even become a
drug of choice in select patients. Further study is required, however.
Propofol has many of the qualities of an ideal
sedative agent.
Benzodiazepines and
narcotics often are used in concert with
propofol to provide reliable
amnesia and to relieve
pain, respectively.
Propofol frequently causes
hypotension when administered as a bolus or infusion, particularly in patients with limited cardiac reserve or
hypovolemia. More data must be obtained to identify potential deleterious effects of
hypertriglyceridemia, and further evaluation of the potential benefits in certain patient populations, such as neurosurgical patients, is needed.