General Anesthesia Practice Questions

Q: What is true about midazolam as an inducing agent?

Does not produce pain on intravenous injection.. **Explanation:** Midazolam is a water-soluble benzodiazepine frequently used for preoperative sedation and induction of anesthesia. **Why Option B is Correct:** Unlike its predecessor Diazepam, which is insoluble in water and requires a propylene glycol solvent (causing significant venous irritation and thrombophlebitis), **Midazolam contains an imidazole ring**. At a pH of less than 4.0, this ring remains open, making the drug **water-soluble**. This eliminates the need for irritating solvents, ensuring that it **does not produce pain on intravenous injection**. Once injected, the physiological pH of the blood (7.4) causes the ring to close, making the drug lipid-soluble so it can cross the blood-brain barrier. **Analysis of Incorrect Options:** * **Option A & D:** Midazolam typically causes a **decrease in systemic vascular resistance (SVR)** and a modest **decrease in blood pressure**. It does not increase peripheral vascular resistance; rather, it has a mild vasodilatory effect. * **Option C:** Benzodiazepines, including midazolam, **decrease cerebral metabolic rate of oxygen consumption (CMRO2)** and cerebral blood flow (CBF) while maintaining the CO2 reactivity of the cerebral vasculature. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Potentiates GABA-A receptors by increasing the **frequency** of chloride channel opening. * **Metabolism:** Metabolized by hepatic CYP3A4 enzymes; its active metabolite is 1-hydroxymidazolam. * **Specific Antagonist:** **Flumazenil** (competitive antagonist) is used to reverse its effects. * **Anterograde Amnesia:** Midazolam is highly effective at producing anterograde amnesia, making it ideal for premedication.

Q: Which of the following is a non-depolarizing muscle relaxant?

Mivacurium. **Explanation:** **Mivacurium** is the correct answer because it is a short-acting **benzylisoquinolinium** derivative belonging to the class of **non-depolarizing neuromuscular blocking agents (NDMRs)**. These drugs act as competitive antagonists at the nicotinic acetylcholine receptors (nAChR) at the neuromuscular junction, preventing muscle contraction without causing initial fasciculations. **Analysis of Incorrect Options:** * **Halothane, Desflurane, and Isoflurane (Options B, C, and D):** These are all **volatile inhalation anesthetics** used for the induction and maintenance of general anesthesia. While they can provide some degree of skeletal muscle relaxation by acting on the central nervous system and spinal cord, they are not classified as muscle relaxants or neuromuscular blockers. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolism:** Mivacurium is unique among NDMRs because it is metabolized by **plasma cholinesterase (pseudocholinesterase)**, similar to Succinylcholine. This results in a very short duration of action (approx. 15–20 minutes). * **Prolonged Block:** Patients with **atypical plasma cholinesterase** deficiency will experience a significantly prolonged duration of action when given Mivacurium. * **Side Effects:** It is known for causing **histamine release**, which can lead to cutaneous flushing, hypotension, and bronchospasm if injected rapidly. * **Classification Tip:** Remember that most non-depolarizing relaxants end in **"-curium"** (atracurium, mivacurium) or **"-onium"** (vecuronium, rocuronium, pancuronium).

Q: All of the following are false statements regarding Nitrous Oxide (N2O) EXCEPT:

It is the least potent inhalational anesthetic agent.. **Explanation:** Nitrous Oxide ($N_2O$) is a unique inorganic inhalational anesthetic. To identify the correct statement, we must evaluate its physical and pharmacological properties. **1. Why Option A is Correct:** Potency of an inhalational agent is inversely proportional to its **Minimum Alveolar Concentration (MAC)**. $N_2O$ has a MAC of approximately **104%**, which is the highest among all anesthetic gases. Since it cannot achieve surgical anesthesia at 1 atmosphere without causing hypoxia, it is clinically the **least potent** agent. **2. Why Other Options are Incorrect:** * **Option B:** $N_2O$ provides excellent analgesia but has **no significant muscle relaxant properties**. It is often used alongside neuromuscular blockers for this reason. * **Option C:** $N_2O$ is **heavier than air** (Specific gravity of 1.5). This is clinically relevant as it can accumulate in low-lying areas. * **Option D:** $N_2O$ is highly insoluble in blood. When discontinued, it rushes out of the blood into the alveoli, diluting oxygen concentration. This phenomenon is known as **Diffusion Hypoxia (Fink Effect)**. It is prevented by administering 100% $O_2$ for 5–10 minutes after stopping $N_2O$. **High-Yield Clinical Pearls for NEET-PG:** * **Second Gas Effect:** $N_2O$ accelerates the uptake of a companion volatile anesthetic (like Halothane or Isoflurane). * **Closed Spaces:** $N_2O$ is 34 times more soluble than Nitrogen. It diffuses into air-filled cavities faster than Nitrogen can leave, causing **expansion of closed spaces**. It is strictly **contraindicated** in pneumothorax, air embolism, intestinal obstruction, and middle ear surgeries (tympanoplasty). * **Toxicity:** Chronic exposure inhibits **Vitamin B12** (Methionine Synthase), leading to megaloblastic anemia and peripheral neuropathy. * **Storage:** Stored in **Blue Cylinders** as a liquid under pressure.

Q: Which of the following induction agents may cause adrenal cortex suppression?

Etomidate. **Explanation:** **Etomidate** is the correct answer because it causes dose-dependent inhibition of the enzyme **11-beta-hydroxylase**. This enzyme is essential for converting 11-deoxycortisol to cortisol in the adrenal cortex. Even a single induction dose can suppress adrenal steroidogenesis for 6–24 hours, leading to decreased plasma cortisol levels. While this makes it less ideal for patients in septic shock, it remains a popular choice for hemodynamically unstable patients due to its minimal cardiovascular impact. **Analysis of Incorrect Options:** * **Propofol (A):** The most common induction agent; it acts via GABA-A receptors. Its primary side effects are hypotension and respiratory depression, not adrenal suppression. * **Ketamine (B):** A dissociative anesthetic that acts as an NMDA receptor antagonist. It actually stimulates the sympathetic nervous system, increasing heart rate and blood pressure, and does not affect the adrenal cortex. * **Thiopentone (D):** An ultra-short-acting barbiturate. While it can cause cardiovascular and respiratory depression, it has no specific inhibitory effect on adrenal enzymes. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Etomidate is the induction agent of choice for patients with **cardiovascular disease** or **hemodynamic instability** (e.g., trauma, hypovolemia) because it maintains heart rate and blood pressure. * **Myoclonus:** Etomidate is frequently associated with involuntary muscle movements (myoclonus) during induction, which can be prevented by premedication with opioids or benzodiazepines. * **Avoidance:** Due to adrenal suppression, etomidate is generally avoided as a continuous infusion in the ICU.

Q: Which of the following is true about halothane?

Causes bronchodilation. **Explanation:** Halothane is a potent volatile anesthetic agent that belongs to the halogenated hydrocarbon group. **1. Why Option A is Correct:** Halothane is a potent **bronchodilator**. It achieves this by directly relaxing bronchial smooth muscle and inhibiting the release of bronchoconstricting mediators like histamine. Because it is non-irritating to the airways and has a pleasant odor, it was historically the agent of choice for **inhalation induction**, especially in pediatric patients and those with reactive airway diseases like asthma or COPD. **2. Why the Other Options are Incorrect:** * **Option B:** Halothane is actually **arrhythmogenic**. It sensitizes the myocardium to the effects of endogenous and exogenous catecholamines (epinephrine), which can lead to ventricular arrhythmias. * **Option C:** Halothane is associated with **"Halothane Hepatitis."** About 20% of the drug undergoes hepatic metabolism, producing trifluoroacetylated proteins that can trigger an immune-mediated hepatotoxicity. It is contraindicated in patients with pre-existing liver disease or a history of unexplained jaundice after previous exposure. * **Option D:** Halothane causes **uterine relaxation**, not contraction. This can lead to increased postpartum hemorrhage (PPH) if used in high concentrations during obstetric procedures. **High-Yield Clinical Pearls for NEET-PG:** * **Blood-Gas Partition Coefficient:** 2.4 (Slower induction/recovery compared to Sevoflurane). * **Halothane Shake:** Post-operative shivering is a common side effect. * **Malignant Hyperthermia:** Like all volatile anesthetics, Halothane is a known trigger. * **Preservation:** It is stored in amber-colored bottles with **Thymol (0.01%)** as a preservative to prevent spontaneous decomposition.

Q: Which of the following is a non-opioid intravenous anesthetic agent?

Ketamine. **Explanation:** The question asks to identify a **non-opioid** intravenous (IV) anesthetic agent. **Correct Answer: D. Ketamine** Ketamine is a phencyclidine derivative that acts primarily as an **NMDA receptor antagonist**. It is classified as a "dissociative anesthetic" because it induces a state where the patient appears awake (eyes open, intact cough reflex) but is dissociated from the environment and feels no pain. Unlike opioids, it does not act on the mu-opioid receptors for its primary anesthetic effect. It is unique among IV anesthetics for causing sympathetic stimulation (increased HR, BP, and CO) and bronchodilation. **Incorrect Options:** * **A. Tramadol:** A synthetic analogue of codeine. It is a weak opioid agonist and also inhibits the reuptake of serotonin and norepinephrine. It is used for analgesia, not for the induction of anesthesia. * **B. Pethidine (Meperidine):** A synthetic opioid agonist acting on mu and kappa receptors. It is known for its anticholinergic side effects and its metabolite, *normeperidine*, which can cause seizures. * **C. Fentanyl:** A potent synthetic phenylpiperidine derivative. It is a pure mu-opioid agonist used extensively in anesthesia for analgesia and blunting the intubation response, but it belongs to the opioid class. **High-Yield Clinical Pearls for NEET-PG:** * **Ketamine** is the drug of choice for induction in patients with **bronchial asthma** and **hypovolemic shock**. * It is **contraindicated** in patients with head injuries (increases ICP) and hypertensive heart disease. * **Emergence delirium** is a common side effect of Ketamine, which can be prevented by co-administering benzodiazepines (e.g., Midazolam).

Q: Which stage of anesthesia is known as the stage of analgesia?

Stage 1. **Explanation:** The stages of anesthesia were originally described by **Arthur Guedel** in 1920, based on the effects of inhaled diethyl ether. Understanding these stages is crucial for identifying the depth of anesthesia. **Correct Option: A. Stage 1 (Stage of Analgesia)** This stage begins with the induction of anesthesia and lasts until the loss of consciousness. It is characterized by the patient feeling drowsy and experiencing a significant reduction in pain perception (analgesia) while remaining conscious and able to follow commands. **Incorrect Options:** * **B. Stage 2 (Stage of Excitement/Delirium):** This stage starts from the loss of consciousness to the onset of automatic breathing. It is characterized by agitation, struggling, irregular respiration, and risk of laryngospasm or vomiting. * **C. Stage 3 (Stage of Surgical Anesthesia):** This is the goal for most surgeries. It is divided into four planes based on eye movements, pupil size, and respiratory patterns. It extends from the onset of regular breathing to respiratory paralysis. * **D. Stage 4 (Stage of Medullary Paralysis/Overdose):** This is a critical stage where severe depression of the vasomotor and respiratory centers in the medulla occurs. Without immediate support, it leads to circulatory collapse and death. **High-Yield Clinical Pearls for NEET-PG:** * **Guedel’s Classification** is most clearly seen with slow-acting agents like Ether; modern IV agents (Propofol) bypass Stages 1 and 2 almost instantaneously. * **Stage 2 Danger:** Always avoid stimulating a patient in Stage 2 due to the high risk of **laryngospasm**. * **Surgical Plane:** Plane 2 of Stage 3 is generally considered the ideal depth for most surgical procedures.

Q: Which muscle is most resistant to non-depolarizing neuromuscular blockade?

Diaphragm. **Explanation:** The sensitivity of muscles to non-depolarizing neuromuscular blocking agents (NMBAs) varies significantly based on muscle type, blood flow, and acetylcholine receptor density. **Why the Diaphragm is the Correct Answer:** The **diaphragm** is the most resistant muscle to NMBAs. It requires approximately **1.5 to 2 times** the dose needed to paralyze peripheral muscles (like the adductor pollicis). This resistance is attributed to its high density of acetylcholine receptors, high mitochondrial content, and excellent regional blood flow, which allows for rapid delivery and washout of the drug. Consequently, the diaphragm is the **last to be paralyzed** and the **first to recover** during anesthesia. **Analysis of Incorrect Options:** * **Intercostal and Abdominal Muscles (A & B):** These are considered "intermediate" in sensitivity. While they are more resistant than peripheral limb muscles, they are more sensitive than the diaphragm. They typically paralyze after the peripheral muscles but before the diaphragm. * **Adductor Muscles (D):** Peripheral muscles, such as the adductor pollicis (used in thumb twitch monitoring), are highly sensitive to NMBAs. They are among the first to be paralyzed and the last to recover. **NEET-PG High-Yield Pearls:** * **Sequence of Paralysis:** Small, rapid muscles (eyes, fingers) → Limbs → Trunk (Abdominal) → Intercostals → Diaphragm. * **Sequence of Recovery:** Reverse order (Diaphragm recovers first). * **Clinical Monitoring:** The **Adductor pollicis** is the standard for monitoring *recovery* (onset is slow), while the **Orbicularis oculi** better reflects the *onset* of blockade at the diaphragm/larynx. * **Laryngeal Muscles:** These are also relatively resistant (similar to the diaphragm), which is why profound blockade is needed for endotracheal intubation.

Question 1

What is true about midazolam as an inducing agent?

Accepted Answer

Does not produce pain on intravenous injection.

Answer

Causes an increase in blood pressure.

Answer

Increases cerebral oxygen consumption.

Answer

Increases peripheral vascular resistance.

Question 2

All are false about propofol except?

Accepted Answer

Propofol infusion at a rate >4 mg/hr can cause propofol infusion syndrome.

Answer

Propofol is the best bronchodilator.

Answer

Propofol is a cardiovascular stable drug.

Answer

Propofol causes malignant hyperthermia.

Question 3

Which of the following is a non-depolarizing muscle relaxant?

Accepted Answer

Mivacurium

Answer

Halothane

Answer

Desflurane

Answer

Isoflurane

Question 4

All of the following are false statements regarding Nitrous Oxide (N2O) EXCEPT:

Accepted Answer

It is the least potent inhalational anesthetic agent.

Answer

It possesses significant muscle relaxant properties.

Answer

It is lighter than air.

Answer

It does not cause diffusion hypoxia.

Question 5

Which of the following induction agents may cause adrenal cortex suppression?

Accepted Answer

Etomidate

Answer

Propofol

Answer

Ketamine

Answer

Thiopentone

Question 6

Which of the following is true about halothane?

Accepted Answer

Causes bronchodilation

Answer

Has anti-arrhythmic properties

Answer

Can be used in patients with hepatitis

Answer

Causes uterine contraction

Question 7

Which of the following is a non-opioid intravenous anesthetic agent?

Accepted Answer

Ketamine

Answer

Tramadol

Answer

Pethidine

Answer

Fentanyl

Question 8

Which stage of anesthesia is known as the stage of analgesia?

Accepted Answer

Stage 1

Answer

Stage 2

Answer

Stage 3

Answer

Stage 4

Question 9

Which of the following is FALSE regarding lumbar puncture in patients on anticoagulants or antiplatelets?

Accepted Answer

Intravenous heparin should be stopped 6 hours before lumbar puncture.

Answer

A patient on warfarin is contraindicated to lumbar puncture.

Answer

Low molecular weight heparin should be stopped 24 hours prior to lumbar puncture.

Answer

Aspirin is not an absolute contraindication to lumbar puncture.

Question 10

Which muscle is most resistant to non-depolarizing neuromuscular blockade?

Accepted Answer

Diaphragm

Answer

Intercostal muscles

Answer

Abdominal muscles

Answer

Adductor muscles

General Anesthesia — MCQs

General Anesthesia — MCQs

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