Which intravenous anaesthetic agent has high incidence of pychomimetic reactions during early recovery period-
First, I recall that psychomimetic reactions are hallucinations, illusions, or other psychiatric-like symptoms that occur post-anesthesia. Which agents are known for this? Ketamine comes to mind. It's an NMDA receptor antagonist and is infamous for causing dissociative anesthesia and psychotomimetic effects. Patients might experience vivid dreams or hallucinations upon waking.
Other agents like propofol are usually associated with smooth induction and fewer emergence reactions. Etomidate is another one, but I think it's more linked to adrenocortical suppression and myoclonus, not psychomimetic effects. Thiopental, a barbiturate, is less likely to cause such reactions. So the answer is likely ketamine.
Now, the options must have included ketamine. Let me check the distractors. If the options were A. Propofol, B. Etomidate, C. Ketamine, D. Thiopental, then C is correct. I need to explain why ketamine causes these reactions. It's due to its action on the NMDA receptors, which can lead to a dissociative state. The other agents don't have this mechanism. For each wrong option, I should note their side effects instead. Propofol might cause pain on injection, etomidate myoclonus, thiopental hypotension. The clinical pearl is that ketamine's psychomimetic effects are dose-related and can be mitigated with premedication. The correct answer is C. Ketamine.
**Core Concept**
Psychomimetic reactions during early recovery from anesthesia are characterized by hallucinations, illusions, or dissociative states. These are most commonly associated with **ketamine**, an NMDA receptor antagonist that induces a dissociative anesthetic state by disrupting glutamatergic neurotransmission.
**Why the Correct Answer is Right**
Ketamine blocks NMDA receptors in the brain, leading to a decoupling of thalamic and cortical activity. This mechanism results in a "dissociative anesthesia" state, marked by vivid dreams, hallucinations, and psychotomimetic effects during emergence. These effects are dose-dependent and more pronounced in pediatric patients or those with anxiety. Ketamine's unique pharmacology distinguishes it from other intravenous anesthetics.
**Why Each Wrong Option is Incorrect**
**Option A: Propofol** – Causes smooth induction and emergence without psychomimetic effects; associated with pain on injection and postoperative delirium in some cases.
**Option B: Etomidate** – Linked to myoclonus during induction and adrenocortical suppression, not psychomimetic reactions.
**Option D: Thiopental** – A barbiturate with minimal emergence reactions; more commonly causes hypotension and prolonged sedation.
**Clinical Pearl / High-Yield Fact**
Ketamine's psychomimetic effects can be mitigated with premedication (e.g., benzodiazepines) or co-administration with anticholinergics. Remember: *“Ketamine = Krazy Dreams”