General Anesthesia Practice Questions

Q: Thiopentone is contraindicated in which of the following conditions?

Acute intermittent porphyria. **Explanation:** **1. Why Acute Intermittent Porphyria (AIP) is the Correct Answer:** Thiopentone (a barbiturate) is an absolute contraindication in patients with Porphyria. Barbiturates are potent inducers of the hepatic enzyme **ALA synthetase** (Aminolevulinic acid synthetase). This enzyme is the rate-limiting step in heme synthesis. Induction of ALA synthetase leads to the overproduction and accumulation of porphyrins and their precursors (like porphobilinogen), which can precipitate a life-threatening **acute neurovisceral crisis** characterized by abdominal pain, psychiatric symptoms, and paralysis. **2. Analysis of Incorrect Options:** * **Bronchial Asthma:** While Thiopentone causes histamine release and can theoretically cause bronchospasm, it is a **relative contraindication**, not an absolute one. In modern practice, Propofol or Ketamine are preferred for asthmatics, but Thiopentone is not strictly prohibited if the airway is managed carefully. * **Both/None:** Since AIP is a definitive absolute contraindication and Asthma is only relative, "Both" is incorrect in the context of standard NEET-PG questioning where the most "absolute" contraindication is sought. **3. High-Yield Clinical Pearls for NEET-PG:** * **Absolute Contraindications of Thiopentone:** Porphyria, Status Asthmaticus (severe acute asthma), and known hypersensitivity. * **Cardiovascular Effects:** Thiopentone causes peripheral vasodilation and myocardial depression; it should be used with extreme caution in **hypovolemic shock**. * **pH Fact:** Thiopentone is highly alkaline (pH 10.5). Accidental **intra-arterial injection** causes severe pain and gangrene due to crystal formation (Treatment: Papaverine/Lidocaine and Heparin). * **Recovery:** Recovery from a single dose occurs due to **redistribution** from the brain to skeletal muscle, not metabolism.

Q: Which of the following anesthetic agents causes hypertension on injection?

Ketamine. **Explanation:** **Ketamine** is the correct answer because it is a unique induction agent that acts as a **sympathomimetic**. Unlike most other anesthetics, it stimulates the sympathetic nervous system, leading to an increase in heart rate, cardiac output, and arterial blood pressure (hypertension). This occurs due to the inhibition of neuronal catecholamine reuptake and direct central stimulation. **Why the other options are incorrect:** * **Propofol:** Known for causing significant **hypotension** due to profound peripheral vasodilation and mild myocardial depression. * **Thiopentone:** A barbiturate that causes **hypotension** primarily through peripheral venodilation (pooling of blood) and direct myocardial depression. * **Halothane:** An inhalational agent that causes **hypotension** by decreasing cardiac output and sensitizing the myocardium to catecholamines (which can lead to arrhythmias, but not hypertension). **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Ketamine is the induction agent of choice in **hypovolemic shock** and **bronchial asthma** (due to its bronchodilatory properties). * **Contraindications:** Avoid Ketamine in patients with hypertension, ischemic heart disease (increases myocardial oxygen demand), and raised intracranial or intraocular pressure. * **Dissociative Anesthesia:** Ketamine produces a state where the patient appears awake (eyes open) but is unconscious and feels no pain, characterized by electroencephalographic dissociation between the thalamocortical and limbic systems. * **Emergence Delirium:** A common side effect of Ketamine, which can be mitigated by co-administering benzodiazepines like Midazolam.

Q: A 74-year-old woman with a history of a previous total abdominal hysterectomy presents with abdominal pain and distention for 3 days. Plain films reveal dilated small bowel and air-fluid levels. She is taken to the operating room for a small-bowel obstruction. Which of the following inhalational anesthetics should be avoided because of accumulation in air-filled cavities during general anesthesia?

Nitrous oxide. **Explanation:** The correct answer is **Nitrous oxide (N₂O)**. This question tests the intersection of surgical pathology (Small Bowel Obstruction - SBO) and anesthetic pharmacology. **1. Why Nitrous Oxide is the Correct Answer:** Nitrous oxide is significantly more soluble in blood (blood-gas partition coefficient 0.47) than nitrogen (0.015). In a patient with SBO, the bowel contains trapped air (mostly nitrogen). When N₂O is administered, it diffuses from the blood into the air-filled bowel lumen much faster than nitrogen can diffuse out. This leads to a rapid increase in the volume and pressure within the obstructed bowel segments. This can worsen bowel distention, compromise blood flow to the gut wall, and make surgical closure of the abdomen difficult. **2. Why the Other Options are Incorrect:** * **Diethyl ether, Halothane, and Methoxyflurane:** These are volatile liquid anesthetics. While they have varying degrees of solubility and potency (MAC values), they do not possess the specific property of rapid diffusion into closed gas spaces that N₂O does. They do not cause significant expansion of air-filled cavities. **3. Clinical Pearls for NEET-PG:** * **Contraindications for N₂O:** Due to its ability to expand closed gas spaces, N₂O is strictly contraindicated in: * Intestinal obstruction * Pneumothorax * Air embolism * Tympanic membrane grafting (Middle ear surgery) * Pneumocephalus * Intraocular gas bubbles (e.g., after retinal detachment surgery) * **Second Gas Effect:** N₂O is often used to speed up the induction of other volatile agents. * **Diffusion Hypoxia:** Always administer 100% oxygen for 5–10 minutes after discontinuing N₂O to prevent dilution of alveolar oxygen.

Q: Tachypnoea is associated with which of the following anesthetic agents?

Trilene. **Explanation:** The correct answer is **Trilene (Trichloroethylene)**. **Why Trilene causes Tachypnoea:** Trilene is a potent analgesic but a weak anesthetic agent. It is unique among volatile anesthetics because it significantly increases the respiratory rate (tachypnoea) while decreasing the tidal volume. This occurs due to the **sensitization of pulmonary stretch receptors** (Hering-Breuer reflex), which triggers rapid, shallow breathing. If the concentration of Trilene is increased too rapidly, it can lead to severe tachypnoea and cardiac arrhythmias. **Analysis of Incorrect Options:** * **Ether:** Diethyl ether is a respiratory irritant that stimulates secretions and initially increases minute ventilation, but it does not characteristically produce the rapid, shallow tachypnoea seen with Trilene. * **Halothane:** Halothane is a potent respiratory depressant. It typically decreases tidal volume and can increase respiratory rate slightly to compensate, but it is more famously associated with **bronchodilation** and sensitization of the myocardium to catecholamines. * **Cyclopropane:** This agent generally maintains or slightly depresses respiration. It is better known for causing "cyclopropane hypertension" and emergence delirium. **High-Yield Clinical Pearls for NEET-PG:** * **Trilene & Soda Lime:** Trilene must **never** be used in a closed circuit with soda lime. It reacts with soda lime to form **Dichloroacetylene** (neurotoxic, causing cranial nerve palsies, especially the Trigeminal nerve) and **Phosgene** (highly pulmonary toxic). * **Metabolism:** Trilene is metabolized to **Trichloroacetic acid**, which can be detected in urine. * **Analgesia:** It was historically favored for obstetric analgesia (self-administration via the **Minitt’s apparatus**) due to its potent analgesic properties.

Q: Inadequate depth of anesthesia leads to all of the following physiological responses except:

Bradycardia. **Explanation:** Inadequate depth of anesthesia (light anesthesia) triggers a **sympathetic nervous system (SNS) surge** as a physiological response to surgical stress and noxious stimuli. **1. Why Bradycardia is the Correct Answer:** In response to surgical stimulation under light anesthesia, the body releases catecholamines (epinephrine and norepinephrine). This leads to **tachycardia** (increased heart rate), not bradycardia. Bradycardia is typically associated with deep anesthesia (halothane effects), high spinal blocks, or specific reflexes (like the oculocardiac reflex), rather than inadequate depth. **2. Analysis of Incorrect Options:** * **Lacrimation (A):** Tearing is a classic clinical sign of light anesthesia. It occurs due to autonomic stimulation and is often used by anesthesiologists to gauge the need for more analgesia or anesthetic agents. * **Mydriasis (C):** Pupillary dilation occurs during light anesthesia due to sympathetic overactivity. (Note: Very deep anesthesia can also cause mydriasis due to medullary depression, but in the context of surgical stimulation, it indicates inadequacy). * **Hypertension (D):** Increased systemic vascular resistance and cardiac output due to catecholamine release lead to a rise in blood pressure. **3. Clinical Pearls for NEET-PG:** * **Signs of Light Anesthesia:** Tachycardia, hypertension, lacrimation, sweating (diaphoresis), tachypnea, and purposeful movement. * **PRST Score:** A clinical tool used to assess anesthetic depth based on **P**ressure (BP), **R**ate (HR), **S**weating, and **T**ears. * **Gold Standard:** While clinical signs are vital, **Bispectral Index (BIS) monitoring** is the most objective way to prevent intraoperative awareness; a BIS value between 40–60 indicates an adequate depth for general anesthesia.

Q: The drug combination which produces neuroleptanalgesia is?

Droperidol + Fentanyl. **Explanation:** **1. Understanding the Concept:** Neuroleptanalgesia is a state of profound sedation and intense analgesia produced by the combined administration of a **neuroleptic (antipsychotic)** drug and a **narcotic analgesic**. In this state, the patient remains quiet, indifferent to surroundings, and pain-free, yet can often respond to simple commands. * **Droperidol** (a butyrophenone) acts as the neuroleptic, providing sedation and antiemetic effects. * **Fentanyl** (a potent opioid) provides intense analgesia. When a 65% mixture of **Nitrous Oxide (N₂O)** is added to this combination, it is termed **Neuroleptanesthesia**. **2. Analysis of Options:** * **Option A (Correct):** Droperidol + Fentanyl is the classic combination (often available in a fixed 50:1 ratio known as Innovar). * **Option B:** Ketamine produces "Dissociative Anesthesia," not neuroleptanalgesia. It is characterized by a functional dissociation between the thalamoneocortical and limbic systems. * **Option C:** Ether is an inhalational anesthetic used for general anesthesia; it does not fall under the neuroleptic category. * **Option D:** This combination describes a balanced anesthesia technique or neuroleptanesthesia (due to N₂O), but the specific term "neuroleptanalgesia" refers strictly to the neuroleptic + opioid duo. **3. High-Yield Clinical Pearls for NEET-PG:** * **Innovar:** Contains Droperidol (2.5 mg/mL) and Fentanyl (0.05 mg/mL). * **Key Features:** Patients exhibit a "waxy rigidity" (catalepsy), suppressed reflexes, and profound calmness. * **Contraindication:** Avoid Droperidol in patients with **Parkinson’s disease** because it is a dopamine antagonist and can worsen extrapyramidal symptoms. * **Side Effect:** Droperidol can cause **QT interval prolongation**; ECG monitoring is recommended.

Q: All of the following are true regarding the effect of inhalational anesthetic agents on the respiratory tract EXCEPT?

They increase ciliary movement.. **Explanation:** The correct answer is **D (They increase ciliary movement)** because inhalational anesthetic agents actually **depress or inhibit** mucociliary clearance. **1. Why Option D is the Correct Answer (The Exception):** Volatile anesthetics (like Sevoflurane, Isoflurane, and Desflurane) cause dose-dependent **inhibition of ciliary beat frequency** and alter the properties of mucus. This impairment of the mucociliary blanket leads to the pooling of secretions in the tracheobronchial tree, increasing the risk of postoperative atelectasis and pulmonary infections. **2. Why the other options are incorrect (True statements):** * **Option A (Relax airway smooth muscle):** Volatile agents are potent bronchodilators. They act by reducing intracellular calcium and inhibiting vagal pathways. **Sevoflurane** is the agent of choice for inhalational induction in patients with reactive airways (asthma/COPD) due to its non-pungency and bronchodilatory properties. * **Options B & C (Blunt respiratory drive/Suppress center):** All inhalational agents cause dose-dependent respiratory depression. They decrease the sensitivity of the medullary respiratory center to Carbon Dioxide (CO₂) and blunt the peripheral chemoreceptor response to Hypoxia. This results in a decreased tidal volume and a compensatory (but insufficient) increase in respiratory rate. **Clinical Pearls for NEET-PG:** * **Halothane** is the most potent bronchodilator but sensitizes the myocardium to catecholamines (risk of arrhythmias). * **Desflurane and Isoflurane** are pungent and can cause airway irritation (coughing, laryngospasm), making them unsuitable for smooth inhalational induction. * **Dead Space:** Inhalational agents increase the ratio of dead space to tidal volume (Vd/Vt). * **Hypoxic Pulmonary Vasoconstriction (HPV):** All volatile agents inhibit HPV, which can potentially worsen V/Q mismatch.

Q: Succinylcholine is used with caution in all conditions except which of the following?

Tachycardia. Succinylcholine is a depolarizing neuromuscular blocker that acts as an agonist at the nicotinic acetylcholine receptors. The correct answer is **Tachycardia** because Succinylcholine typically causes **bradycardia** (especially in children or with a second dose) due to its action on cardiac muscarinic receptors. It is not contraindicated in patients with pre-existing tachycardia; in fact, its vagomimetic effects might theoretically slow the heart rate. ### Why the other options require caution: * **Burns & Crush Injury:** These conditions lead to the "upregulation" of extrajunctional acetylcholine receptors. When Succinylcholine depolarizes these widespread receptors, it causes a massive efflux of potassium from the cells. This can lead to **severe hyperkalemia**, resulting in cardiac arrest. Caution (or absolute avoidance) is mandatory 24–48 hours post-injury. * **Myasthenia Gravis:** Patients with Myasthenia Gravis have a reduced number of functional acetylcholine receptors. They exhibit **extreme resistance** to Succinylcholine (requiring higher doses) but are hypersensitive to non-depolarizing agents. The unpredictable response necessitates extreme caution and monitoring. ### High-Yield Clinical Pearls for NEET-PG: * **Drug of Choice:** Succinylcholine remains the gold standard for **Rapid Sequence Induction (RSI)** due to its rapid onset (30–60s) and short duration (5–10 mins). * **Metabolism:** It is metabolized by **Pseudocholinesterase** (Plasma cholinesterase). * **Black Box Warning:** Avoid in children for routine intubation due to the risk of undiagnosed muscular dystrophy (Duchenne’s), which can lead to fatal hyperkalemia. * **Malignant Hyperthermia:** Succinylcholine is a known triggering agent.

Question 1

Thiopentone is contraindicated in which of the following conditions?

Accepted Answer

Acute intermittent porphyria

Answer

Bronchial Asthma

Answer

Both

Answer

None

Question 2

Which of the following anesthetic agents causes hypertension on injection?

Accepted Answer

Ketamine

Answer

Propofol

Answer

Halothane

Answer

Thiopentone

Question 3

A 74-year-old woman with a history of a previous total abdominal hysterectomy presents with abdominal pain and distention for 3 days. Plain films reveal dilated small bowel and air-fluid levels. She is taken to the operating room for a small-bowel obstruction. Which of the following inhalational anesthetics should be avoided because of accumulation in air-filled cavities during general anesthesia?

Accepted Answer

Nitrous oxide

Answer

Diethyl ether

Answer

Halothane

Answer

Methoxyflurane

Question 4

Tachypnoea is associated with which of the following anesthetic agents?

Accepted Answer

Trilene

Answer

Ether

Answer

Halothane

Answer

Cyclopropane

Question 5

Inadequate depth of anesthesia leads to all of the following physiological responses except:

Accepted Answer

Bradycardia

Answer

Lacrimation

Answer

Mydriasis

Answer

Hypertension

Question 6

Which drug is used to control secretions during general anesthesia?

Accepted Answer

Glycopyrrolate

Answer

Hyoscine

Answer

Pethidine

Answer

Lorazepam

Question 7

The drug combination which produces neuroleptanalgesia is?

Accepted Answer

Droperidol + Fentanyl

Answer

Droperidol + Ketamine

Answer

Droperidol + Ether

Answer

Droperidol + Thiopental sodium + Nitrous oxide

Question 8

Which patient position results in the least vital capacity under general anesthesia?

Accepted Answer

Trendelenburg

Answer

Lithotomy

Answer

Prone

Answer

Lateral

Question 9

All of the following are true regarding the effect of inhalational anesthetic agents on the respiratory tract EXCEPT?

Accepted Answer

They increase ciliary movement.

Answer

Volatile anesthetic agents relax airway smooth muscle.

Answer

They blunt respiratory drive.

Answer

They suppress the respiratory center.

Question 10

Succinylcholine is used with caution in all conditions except which of the following?

Accepted Answer

Tachycardia

Answer

Myasthenia gravis

Answer

Burns

Answer

Crush injury

General Anesthesia — MCQs

General Anesthesia — MCQs

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