General Anesthesia Practice Questions

Q: Which anesthetic agent affects laryngeal and pharyngeal reflexes minimally?

Ketamine. **Explanation:** **Ketamine** is a unique "dissociative" anesthetic agent that acts primarily as an NMDA receptor antagonist. Unlike most intravenous anesthetics that cause generalized central nervous system depression, ketamine creates a state of "dissociation" between the thalamocortical and limbic systems. One of its most significant clinical characteristics is the **preservation of protective airway reflexes** (laryngeal and pharyngeal reflexes). While the patient is unconscious, the cough and gag reflexes remain largely intact, and spontaneous respiration is usually maintained. This makes it a preferred agent in emergency situations where the patient has a "full stomach" or when performing procedures without endotracheal intubation. **Why the other options are incorrect:** * **Thiopental and Methohexital (Barbiturates):** These agents cause dose-dependent depression of the central nervous system, leading to the significant suppression of laryngeal and pharyngeal reflexes. Methohexital, in particular, is known to occasionally cause hiccups or laryngospasm during induction. * **Propanidid:** An older eugenol derivative (now largely obsolete) that causes rapid loss of consciousness and significant respiratory depression, leading to the loss of protective reflexes. **High-Yield Clinical Pearls for NEET-PG:** * **Airway:** Although reflexes are preserved, the risk of aspiration still exists; ketamine also increases **salivation** (sialagogue effect), which may require pretreatment with glycopyrrolate. * **Hemodynamics:** Ketamine is **sympathomimetic** (increases HR, BP, and CO), making it the induction agent of choice for patients in **hypovolemic shock**. * **Contraindications:** Avoid in patients with raised intracranial pressure (ICP) or intraocular pressure (IOP), and those with severe hypertension or ischemic heart disease. * **Emergence Delirium:** Can be minimized by co-administering benzodiazepines (e.g., Midazolam).

Q: To minimize the effects of diffusion hypoxia during N2O-O2 analgesia, for how long should the patient be oxygenated?

3 to 5 minutes. **Explanation:** **1. Why Option B is Correct (The Underlying Concept):** Diffusion hypoxia (the **Fink Effect**) occurs at the end of nitrous oxide (N₂O) administration. N₂O is 31 times more soluble in blood than nitrogen. When the N₂O supply is stopped and the patient breathes room air, N₂O rapidly diffuses out of the blood and into the alveoli. This massive influx of N₂O dilutes the alveolar concentration of oxygen (O₂) and carbon dioxide (CO₂). The dilution of O₂ leads to hypoxia, while the dilution of CO₂ reduces the respiratory drive. To counteract this, **100% oxygen must be administered for 3 to 5 minutes** to wash out the N₂O and maintain adequate alveolar oxygen tension. **2. Why Other Options are Wrong:** * **Option A (30s – 1 min):** This duration is insufficient to clear the large volume of N₂O exiting the blood, leaving the patient at high risk for transient hypoxemia. * **Options C & D (10 – 45 mins):** While safe, these durations are clinically unnecessary. The majority of N₂O is eliminated within the first few minutes due to its low blood-gas partition coefficient (0.47). Prolonged oxygenation unnecessarily delays recovery and room turnover. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Second Gas Effect:** N₂O (the "First Gas") speeds up the uptake of a companion volatile anesthetic (the "Second Gas") by creating a negative pressure in the alveoli. * **Concentration Effect:** The higher the concentration of N₂O inhaled, the more rapidly the arterial tension of the gas rises. * **Contraindications:** Avoid N₂O in cases of pneumothorax, intestinal obstruction, air embolism, or middle ear surgery, as it expands closed air-filled spaces. * **Blood-Gas Partition Coefficient:** For N₂O, it is **0.47**, explaining its rapid onset and recovery.

Q: What is neurolept analgesia?

It is useful for minor surgical procedures.. **Explanation:** **Neurolept analgesia** is a state of profound sedation and analgesia produced by the combination of a neuroleptic (typically **Droperidol**) and a potent opioid analgesic (typically **Fentanyl**). **Why Option D is Correct:** Neurolept analgesia induces a state of "quietude" where the patient is calm, indifferent to surroundings, and free from pain, but remains conscious and capable of following simple commands. This makes it ideal for **minor surgical procedures** or diagnostic interventions (e.g., endoscopies, burn dressings) where patient cooperation is beneficial but pain relief is essential. **Analysis of Incorrect Options:** * **Option A:** It is **contraindicated** in Parkinson’s disease. Droperidol is a dopamine (D2) receptor antagonist, which would exacerbate the motor symptoms of Parkinsonism. * **Option B:** It does **not** preclude the use of succinylcholine. If the combination is supplemented with Nitrous Oxide (N₂O), it becomes **Neurolept anesthesia**, which may require muscle relaxants like succinylcholine for intubation. * **Option C:** Neurolept analgesia specifically **does not induce unconsciousness**. The patient remains in a state of "dissociated" sedation. If consciousness is lost, the state has progressed to neurolept anesthesia. **High-Yield Clinical Pearls for NEET-PG:** * **Standard Combination:** Droperidol (50 parts) + Fentanyl (1 part). A common premixed preparation is **Innovar**. * **Clinical Features:** Characterized by "psychic indifference," intense analgesia, and decreased motor activity. * **Side Effects:** Droperidol can cause extrapyramidal symptoms (EPS) and QT prolongation. Fentanyl can cause chest wall rigidity (Wooden Chest Syndrome) if administered rapidly. * **Neurolept Anesthesia:** Neurolept analgesia + N₂O in Oxygen.

Q: Surgical anaesthesia is defined as which stage?

Stage III. **Explanation:** The stages of anesthesia were originally described by **Arthur Guedel** in 1920, primarily based on the effects of inhaled diethyl ether. **Correct Option: C (Stage III)** Stage III is known as the **Stage of Surgical Anesthesia**. It begins with the onset of regular rhythmic breathing and ends with the cessation of spontaneous respiration. This stage is characterized by the loss of the lash reflex and the depression of various protective reflexes. It is further divided into four planes (Plane 1 to 4) based on ocular movements, pupil size, and respiratory effort. Most surgical procedures are performed during this stage because it provides sufficient analgesia, amnesia, and muscle relaxation. **Incorrect Options:** * **Stage I (Analgesia):** Extends from the induction of anesthesia to the loss of consciousness. The patient remains conscious but feels less pain. * **Stage II (Delirium/Excitement):** Extends from the loss of consciousness to the onset of regular breathing. It is characterized by agitation, irregular respiration, and risk of laryngospasm. It is a "danger zone" that clinicians aim to bypass quickly. * **Stage IV (Medullary Paralysis):** This is an overdose stage. It begins with the cessation of respiration and ends with circulatory collapse/death due to extreme CNS depression. **High-Yield Clinical Pearls for NEET-PG:** * **Guedel’s Classification** is most accurate for slow-acting agents like Ether; it is less distinct with modern rapid-acting IV agents (e.g., Propofol). * **Loss of Eyelash Reflex** is the classic clinical marker for the transition from Stage II to Stage III. * **Plane 2 of Stage III** is generally considered the ideal depth for most abdominal surgeries. * **Stage II** is the period where the risk of vomiting and aspiration is highest.

Q: Which of the following is NOT true about propofol?

Acts as a cardiac stimulant.. **Explanation:** Propofol (2,6-diisopropylphenol) is the most commonly used intravenous induction agent. The correct answer is **D** because propofol is a **potent cardiovascular depressant**, not a stimulant. **1. Why Option D is the Correct Answer (The Concept):** Propofol causes a significant decrease in systemic vascular resistance (vasodilation) and myocardial contractility. It also blunts the baroreceptor reflex, meaning the heart rate often stays the same or decreases despite a drop in blood pressure. This makes it potentially dangerous in hemodynamically unstable or hypovolemic patients. **2. Why the other options are incorrect (True statements about Propofol):** * **Option A:** Propofol is known for "clear-headed" recovery with minimal hangover effect due to its rapid metabolism and redistribution. This makes it the gold standard for day-care surgeries. * **Option B:** Unlike barbiturates (e.g., Thiopentone), propofol does not induce the enzyme ALA synthetase, making it safe for patients with **Porphyria**. * **Option C:** Propofol possesses unique **antiemetic properties** (at sub-hypnotic doses of 10–20 mg), making it ideal for patients prone to Postoperative Nausea and Vomiting (PONV). **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Facilitates inhibitory neurotransmission via **GABA-A receptors**. * **Pain on Injection:** Common; can be mitigated by using larger veins or pre-treatment with Lidocaine. * **Propofol Infusion Syndrome (PRIS):** A rare, fatal complication of long-term high-dose infusion characterized by metabolic acidosis, rhabdomyolysis, and cardiac failure. * **Preservative:** Formulated in a lipid emulsion (soybean oil, egg lecithin); must be used within 6–12 hours of opening due to risk of bacterial growth. * **Drug of Choice:** For **TIVA** (Total Intravenous Anesthesia) and **Malignant Hyperthermia** susceptible patients.

Q: Which of the following is a recognized side effect of halothane?

Malignant hyperthermia. **Explanation:** **Malignant Hyperthermia (MH)** is a life-threatening pharmacogenetic hypermetabolic state triggered by volatile anesthetic agents (like halothane) and the depolarizing muscle relaxant succinylcholine. In susceptible individuals (often with mutations in the **RYR1 receptor**), halothane causes an uncontrolled release of calcium from the sarcoplasmic reticulum. This leads to sustained muscle contraction, massive heat production, and metabolic acidosis. Management requires immediate cessation of the trigger and administration of **Dantrolene**. **Analysis of Incorrect Options:** * **A & C (Hypertension and Tachycardia):** Halothane actually causes **hypotension** (via direct myocardial depression) and **bradycardia** (due to its vagomimetic effect). It is notorious for sensitizing the myocardium to catecholamines, which can lead to arrhythmias, but its primary hemodynamic profile is depressant. * **D (Uterine contraction):** Halothane is a potent **uterine relaxant**. While this is useful for intrauterine fetal manipulation, it is contraindicated during the third stage of labor as it can lead to significant postpartum hemorrhage. **High-Yield Clinical Pearls for NEET-PG:** * **Halothane Hepatitis:** A rare but severe immune-mediated hepatotoxicity ("Halothane shakes" or fever often precede it). * **Sweet Smell:** It is non-pungent, making it the agent of choice for **smooth inhalation induction** in pediatric patients. * **Blood-Gas Partition Coefficient:** 2.4 (slower induction/recovery compared to Sevoflurane). * **Preservation:** It is stored in amber-colored bottles with **thymol** to prevent spontaneous decomposition.

Q: Which of the following statements about Total Intravenous Anesthesia (TIVA) is false?

It is contraindicated in neurosurgery.. **Explanation:** **1. Why Option A is the Correct Answer (The False Statement):** Contrary to the statement, TIVA (specifically using Propofol) is often the **technique of choice in neurosurgery**. Propofol reduces the Cerebral Metabolic Rate of Oxygen ($CMRO_2$) and Cerebral Blood Flow (CBF), which leads to a decrease in **Intracranial Pressure (ICP)**. Unlike volatile inhalational agents, which can cause cerebral vasodilation and increase ICP at higher concentrations, TIVA maintains favorable cerebral hemodynamics and allows for better intraoperative neuromonitoring (SSEP/MEP). **2. Analysis of Incorrect Options (True Statements):** * **Option B:** TIVA is the gold standard for patients with a history of **Malignant Hyperthermia (MH)**. MH is triggered by volatile halogenated anesthetics and succinylcholine; since TIVA avoids these triggers, it is perfectly safe. * **Option C:** Inhalational agents inhibit **Hypoxic Pulmonary Vasoconstriction (HPV)**, potentially worsening shunting. TIVA agents (like Propofol) do not interfere with this protective reflex, thus maintaining better oxygenation in certain clinical scenarios. * **Option D:** **Propofol** is indeed the most common agent used for TIVA due to its rapid onset, short duration of action (favorable pharmacokinetics), and smooth recovery profile with minimal postoperative nausea and vomiting (PONV). **Clinical Pearls for NEET-PG:** * **Context-Sensitive Half-Time:** Propofol has a relatively short context-sensitive half-time even after prolonged infusion, making it ideal for TIVA. * **Target Controlled Infusion (TCI):** Often used in TIVA to achieve steady-state plasma concentrations using the **Marsh or Schnider models**. * **Triad of TIVA:** Usually consists of Propofol (hypnotic), an Opioid (usually Remifentanil/Fentanyl for analgesia), and a muscle relaxant if required.

Q: Which muscle relaxant should not be used in a patient with liver failure?

Pancuronium. **Explanation:** The liver plays a critical role in the metabolism and excretion of several neuromuscular blocking agents (NMBAs). **Pancuronium** is a long-acting aminosteroid muscle relaxant that is primarily dependent on the liver for its metabolism (deacetylation) and the kidneys for excretion. In patients with liver failure, the clearance of Pancuronium is significantly reduced, and its volume of distribution is increased. This leads to a prolonged half-life and an unpredictable, extended duration of neuromuscular blockade, making it unsuitable for patients with hepatic impairment. **Analysis of Incorrect Options:** * **d-Tubocurarine:** While it undergoes some biliary excretion, it is primarily excreted unchanged in the urine. It is rarely used today due to significant histamine release, but it is not as strictly contraindicated in liver failure as Pancuronium. * **Suxamethonium (Succinylcholine):** This is a depolarizing NMBA metabolized by **pseudocholinesterase** (produced by the liver). While liver failure can decrease enzyme levels and slightly prolong its action, it is not "avoided" as a rule, though caution is required. * **Decamethonium:** A historical depolarizing agent primarily excreted unchanged by the kidneys. **NEET-PG High-Yield Pearls:** * **Drug of Choice in Liver/Renal Failure:** **Atracurium** or **Cisatracurium**. They undergo **Hofmann elimination** (spontaneous non-enzymatic degradation), making their clearance independent of organ function. * **Vecuronium & Rocuronium:** These are also aminosteroids (like Pancuronium) but have shorter durations; however, their action is still significantly prolonged in hepatic cirrhosis. * **Mnemonic:** Remember **"P"** for **P**ancuronium is **P**rolonged in **P**ortal hypertension/Liver failure.

Q: Which of the following is NOT contained in Ringer's lactate solution?

Bicarbonate. **Explanation:** Ringer’s Lactate (RL), also known as Hartmann’s solution, is a balanced salt solution used for fluid resuscitation. The correct answer is **Bicarbonate** because RL does not contain pre-formed bicarbonate. Instead, it contains **Sodium Lactate**. Once infused, the lactate is metabolized by the liver into bicarbonate, providing a buffering effect against metabolic acidosis. **Breakdown of Options:** * **Sodium (A):** RL contains approximately **130 mEq/L** of Sodium. This is slightly hyponatremic compared to plasma (135–145 mEq/L). * **Potassium (B):** RL contains **4 mEq/L** of Potassium, which mimics physiological plasma levels. * **Chloride (C):** RL contains **109 mEq/L** of Chloride. This is lower than Normal Saline (154 mEq/L), making RL less likely to cause hyperchloremic metabolic acidosis. * **Bicarbonate (D):** Bicarbonate is unstable in plastic bags and can precipitate with calcium. Therefore, lactate is used as a stable precursor. **High-Yield Clinical Pearls for NEET-PG:** 1. **Composition:** Na⁺ (130), Cl⁻ (109), Lactate (28), K⁺ (4), and **Calcium (3)**. 2. **Osmolarity:** RL is slightly **hypotonic** (273 mOsm/L) compared to plasma (285–295 mOsm/L). 3. **Contraindications:** * Avoid in **Traumatic Brain Injury (TBI)** due to hypotonicity (may increase cerebral edema). * Do not co-administer with **blood transfusions** in the same line; the Calcium in RL can bind with the Citrate anticoagulant in blood, leading to clot formation. * Use with caution in severe liver failure (impaired lactate metabolism).

Question 1

Which of the following diseases is associated with resistance to succinylcholine?

Accepted Answer

Myasthenia gravis

Answer

Polymyositis

Answer

Lambert-Eaton myasthenic syndrome

Answer

Muscular dystrophy

Question 2

Which anesthetic agent affects laryngeal and pharyngeal reflexes minimally?

Accepted Answer

Ketamine

Answer

Propanidid

Answer

Methohexital

Answer

Thiopental

Question 3

To minimize the effects of diffusion hypoxia during N2O-O2 analgesia, for how long should the patient be oxygenated?

Accepted Answer

3 to 5 minutes

Answer

30 seconds to 1 minute

Answer

10 to 30 minutes

Answer

30 to 45 minutes

Question 4

What is neurolept analgesia?

Accepted Answer

It is useful for minor surgical procedures.

Answer

It is used in patients with Parkinson's disease.

Answer

It precludes the use of succinylcholine.

Answer

It induces unconsciousness.

Question 5

Surgical anaesthesia is defined as which stage?

Accepted Answer

Stage III

Answer

Stage I

Answer

Stage II

Answer

Stage IV

Question 6

Which of the following is NOT true about propofol?

Accepted Answer

Acts as a cardiac stimulant.

Answer

Provides pleasant sedation and rapid recovery.

Answer

Is safe to use in patients with porphyria.

Answer

Has an antiemetic effect.

Question 7

Which of the following is a recognized side effect of halothane?

Accepted Answer

Malignant hyperthermia

Answer

Hypertension

Answer

Tachycardia

Answer

Uterine contraction

Question 8

Which of the following statements about Total Intravenous Anesthesia (TIVA) is false?

Accepted Answer

It is contraindicated in neurosurgery.

Answer

It can be safely used in individuals with a history of malignant hyperthermia.

Answer

Pulmonary vasoconstriction is maintained by it.

Answer

Propofol is the commonest used agent for it.

Question 9

Which muscle relaxant should not be used in a patient with liver failure?

Accepted Answer

Pancuronium

Answer

d-Tubocurarine

Answer

Suxamethonium

Answer

Decamethonium

Question 10

Which of the following is NOT contained in Ringer's lactate solution?

Accepted Answer

Bicarbonate

Answer

Sodium

Answer

Potassium

Answer

Chloride

General Anesthesia — MCQs

General Anesthesia — MCQs

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