Sedation in the intensive care unit (ICU) aims to improve patient comfort and 
facilitate treatment procedures. Most units still rely on a combination of 
opioid and benzodiazepines with the addition of other drugs for specific 
requirements. However, the effect of sedative agents in critically ill patients 
is often unpredictable, so frequent assessment of the depth of sedation is 
essential to match the depth to patient requirements. In the 1990s, heavy 
sedation and paralysis is not considered appropriate for many ICU patients; a 
minimum sedation approach limits cardiovascular or respiratory depression and 
enables earlier weaning and extubation of patients. Administering sedative 
agents by continuous infusion is convenient but, unless the level of sedation is 
reassessed regularly, many patients may become over-sedated. The use of propofol 
for short-term sedation in ICUs has allowed the maintenance of sedation to 
continue until just a few hours before extubation but the benefits of propofol 
for longer-term indications are more debatable. Closer titration of dose and 
desired effects could also be achieved by a patient-controlled system. The 
technique may not be suitable for a large number of patients, particularly early 
in their ICU stay but, for long-term sedation and in the weaning phase--of 
sedation as well as ventilation--the utility of a drug delivery system truly 
controlled by the patient should be further explored. The ICU has been 
succinctly described as an environment in which 'anxiety is prevalent, pain 
frequent, rest difficult and sleep impossible'. Sedation in the ICU has the 
double objective of relieving patient distress as well as facilitating treatment 
procedures.(ABSTRACT TRUNCATED AT 250 WORDS)