Pharmacokinetics:

Special Circumstances:

• Children require higher doses (as they have larger Vd and higher clearance).
• Elderly require lower doses (as they have small Vd and decreased clearance).

• Neuro: Decreases cerebral metabolic O2 requirements, cerebral blood flow, intracranial pressure.
• CV: Decreases SVR, direct myocardial depressant.
• Pulm: Dose dependent respiratory depression (apnea in 25-35% of patients).

• Induction 2 mg/kg
• Sedation ~75 mcg/kg/min
• Hypnosis ~200 mcg/kg/min
• Also used to prevent post-op nausea/vomiting in high risk cases.

Increase frequency of Chloride channel opening, thereby increasing the efficiency of GABA-receptor and chloride ion channel coupling.

• Neuro: Decreases Cerebral Oxygen Requirements (CMRO2), Cerebral Blood Flow (CBF), and Intracranial Pressure (ICP) .
• CV: Decreases SVR and BP.
• Respiratory: Causes dose-dependent respiratory depression.

Anxiolysis, amnesia, sedative, hypnosis, anticonvulsant.

Flumazenil is a specific antagonist. Very short acting (~1 hr of action). May see re-sedation as benzodiazepine is eliminated more slowly compared to effects of flumazenil.

NMDA Antagonist

Produces a dissociative anesthetic state with profound analgesia and amnesia despite maintenance of consciousness.

Used for sedation, chronic pain patients.

• Neuro: Increases cerebral metabolic O2 requirements (CMRO2), Cerebral Blood Flow (CBF) and Intracranial Pressure (ICP). Contraindicated in neurosurgical procedures.
• CV: Cardio-stimulating effects 2/2 direct sympathetic stimulation (negatively affects myocardial supply-demand), but intrinsic myocardial depressant.
• Respiratory: Minimal respiratory depression; Bronchodilation: Protects Airway Reflexes; Increased secretions.

Sedation when hemodynamic stability is required. This is because etomidate does not induce histamine release like the other IV anesthetics do.

• Neuro: Decreases cerebral metabolic O2 requirements, cerebral blood flow, intracranial pressure.
• CV: Maintains hemodynamic stability (minimal cardiac depression as no histamine released)
• Respiratory: Minimal respiratory depression as no histamine released.

Myoclonus, pain on injection, inhibits adrenocortical synthetic function, PONV.

Selective α2 adrenergic agonist.

CV: Bradycardia, heart block, hypotension. Respiratory: Minimal effects (does not cause significant respiratory depression unlike other inhaled anesthetics).

Hypnotic, Analgesic. Used as an adjunct in general anesthesia to reduce opioid requirements without causing respiratory depression. Can also be used for sedation during awake fiberoptic intubations.

In the following clinical scenarios, what anesthetics would you use and why?