"improving intensive care in Scotland"

Other sedative agents used in the ICU

Etomidate:

  • Is contraindicated as a sedative in ICU patients.

  • It abolishes adrenal cortical steroid production and was found to increase mortality when administered to critically ill patients by infusion.

Thiopentone:

  • Is still used by continuous intravenous infusion for refractory status epilepticus andintractable intracranial hypertension. This is predominately in children and less commonly in adults.

  • Thiopentone obeys saturation kinetics (i.e. the liver enzymes metabolizing it become completely saturated and thus the drug accumulates markedly) during continuous infusion, resulting in an extremely protracted duration of action.

Ketamine:

  • Is an NMDA-receptor antagonist.

  • Produces dissociative anaesthesia (profound analgesia, mild sedation, amnesia and reduced motor activity), making it very useful for procedural analgesia (e.g. burns dressings).

  • Produces sympathetic stimulation with its benefits being related to this (and therefore its lack of cardiovascular and respiratory depression) leading to its use as a treatment for life threatening asthma/severe unresponsive bronchospasm and anaesthesia for shocked patients.

  • Ketamine does have notable side effects:

    - Unpleasant dreams, emergence delirium, hallucinations

    • Increased cerebral metabolic rate (contraindicated in raised ICP)

    • Increased myocardial oxygen consumption (cautious use in patients with coronary artery disease).

Inhalational anaesthetics:

  • E.G. sevoflurane, desflurane, isoflurane

  • Can and have been used for sedation in ICU, though their use is not common place.

  • Their main limitations are with difficult/non-practical administration and scavenging and high cost.

  • They may have a role in managing life threatening asthma/severe unresponsive bronchospasm in mechanically ventilated patients in the ICU.

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