Question 1

Q: What is the primary use of dexmedetomidine?

As a sedative agent for intubated patients.. **Explanation:** **Dexmedetomidine** is a highly selective **alpha-2 ($\alpha_2$) adrenergic agonist** (selectivity ratio of 1600:1 for $\alpha_2$ over $\alpha_1$). Its primary clinical utility is providing **"conscious sedation"** for patients in the Intensive Care Unit (ICU) who are intubated and undergoing mechanical ventilation. The drug acts on the **locus coeruleus** in the brainstem to induce a state of sedation that mimics natural sleep; patients remain easily rousable and cooperative, which is ideal for weaning from a ventilator. Unlike benzodiazepines or opioids, it provides sedation and analgesia **without causing significant respiratory depression.** **Analysis of Incorrect Options:** * **Option A:** While dexmedetomidine can prolong the duration of local anesthetics, it is generally avoided or used with extreme caution in hypertensive patients because its initial bolus can cause transient hypertension (via peripheral $\alpha_{2B}$ receptors), followed by prolonged bradycardia and hypotension. * **Option C:** Dexmedetomidine is used as an *adjuvant* to improve the quality and duration of regional blocks, but it does not technically increase the "bioavailability" (the fraction of drug reaching systemic circulation) of the local anesthetic. * **Option D:** While it does lower the Bispectral Index (BIS) as a consequence of sedation, its primary clinical indication is not specifically to "reduce the BIS" of low-potency agents. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Selective $\alpha_2$ agonist (8 times more selective than clonidine). * **Side Effects:** Bradycardia and hypotension are the most common adverse effects. * **Unique Feature:** It is the only sedative that does not cause respiratory depression. * **Other Uses:** Used for "awake" fiberoptic intubation and as an adjuvant in TIVA (Total Intravenous Anesthesia).

Question

What is the primary use of dexmedetomidine?

Accepted Answer

As a sedative agent for intubated patients.

Answer

To prolong the action of local anesthetics in hypertensive patients.

Answer

To increase the bioavailability of regional anesthetic drugs.

Answer

To reduce the bispectral index of general anesthetic drugs with low potency.

Critical Care Medicine — MCQs

Critical Care Medicine — MCQs

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