General Anesthesia Practice Questions

Q: Which of the following drugs produces dissociative anesthesia?

Ketamine. ***Ketamine*** - **Ketamine** is a **dissociative anesthetic** that causes a trance-like state characterized by profound analgesia, amnesia, and catatonia, with the patient appearing to be awake but unresponsive. - It works by antagonizing the **NMDA receptor**, leading to a functional dissociation between the limbic and cortical systems. *Propofol* - **Propofol** is a short-acting intravenous anesthetic that produces a rapid loss of consciousness and has sedative-hypnotic properties. - It functions primarily by enhancing the activity of the **GABA-A receptor**, leading to central nervous system depression, not dissociation. *Thiopentone* - **Thiopentone** (Thiopental) is a barbiturate that induces rapid anesthesia and is used for induction and short procedures. - Its mechanism involves potentiation of the **GABA-A receptor**, causing global central nervous system depression without dissociative effects. *Enflurane* - **Enflurane** is an inhaled halogenated ether anesthetic that provides excellent muscle relaxation and analgesia. - It primarily acts by enhancing **GABAergic inhibition** and inhibiting excitatory neurotransmission, producing general anesthesia rather than a dissociative state.

Q: After suxamethonium 50mg, apnea persists for one hour.

Probably an atypical cholinesterase is present. ***Probably an atypical cholinesterase is present*** - Prolonged apnea after suxamethonium administration is a classic sign of **pseudocholinesterase deficiency**, potentially due to an atypical variant. - An atypical (or inherited deficient) **pseudocholinesterase** cannot metabolize suxamethonium effectively, leading to prolonged neuromuscular blockade. *treatment with cholinesterase is indicated* - Administering cholinesterase is not a standard treatment; rather, treatment focuses on **supportive care** until the drug is metabolized. - Adding more cholinesterase in the presence of an atypical enzyme would not be effective and might even worsen the situation by altering the enzyme's activity. *Treatment with stored blood is indicated* - **Stored blood** containing normal plasma cholinesterase can be considered in very severe, prolonged cases of pseudocholinesterase deficiency. - However, it is not the primary or immediate treatment and is reserved for extreme situations, not merely for "an hour" of apnea, which still typically resolves with supportive care. *Apnea may be due to low serum potassium concentration* - While **hypokalemia** can exacerbate muscle weakness and potentially prolong neuromuscular blockade, it is not the most likely cause of prolonged apnea specifically following suxamethonium. - Myasthenia gravis or other neuromuscular disorders, rather than isolated hypokalemia, are more commonly associated with prolonged apnea independent of pseudocholinesterase deficiency.

Q: Which stage of surgical anesthesia is optimal for surgery?

Stage III. ***Stage III*** - This stage, also known as **surgical anesthesia**, is characterized by stable vital signs, loss of consciousness, and adequate muscle relaxation, making it ideal for performing surgical procedures. - During this stage, the patient's reflexes are suppressed, and pain perception is abolished, ensuring a smooth and pain-free surgical experience. *Stage I* - This is the **analgesia stage**, where the patient is conscious but drowsy and may experience some pain relief. Incisions are typically not made during this stage. - Reflexes are still present, and the patient may be able to communicate, meaning surgical pain would still be experienced. *Stage II* - Often referred to as the **delirium stage** or **excitement stage**, this phase is characterized by involuntary movements, struggling, and potentially vomiting. - It is an undesirable stage for surgery due to the risk of injury to the patient and staff, and the instability of vital signs. *Stage IV* - This stage, known as **medullary depression**, represents an overdose of anesthetic agents, leading to severe depression of respiratory and cardiovascular centers. - It is a life-threatening stage characterized by complete respiratory arrest, cardiovascular collapse, and potential death, requiring immediate intervention.

Q: Which inducing agent is associated with the highest incidence of postoperative vomiting?

Ketamine. ***Ketamine*** - While **ketamine** is a valuable anesthetic, it is associated with a higher incidence of **postoperative nausea and vomiting (PONV)** due to its effects on the central nervous system. - This is particularly noted in adult patients undergoing procedures where ketamine is used as the primary inducing agent or for maintenance. *Etomidate* - **Etomidate** is known for its **hemodynamic stability**, making it a good choice for patients with cardiovascular disease. - It has a moderate incidence of **PONV**, generally considered lower than ketamine but higher than propofol. *Thiopentone* - **Thiopentone** (now less commonly used) was a traditional barbiturate inducing agent. - Its incidence of **PONV** is generally considered moderate and not the highest among common inducing agents. *Propofol* - **Propofol** is well-known for its **antiemetic properties**, which contribute to a significantly lower incidence of **PONV**. - It is often favored in patients at high risk for PONV precisely because of this beneficial side effect.

Q: Bradycardia is common after the injection of

Fentanyl. ***Fentanyl*** - Fentanyl is an **opioid analgesic** that **consistently and commonly** causes **bradycardia** [1] by directly stimulating the **vagal nerve** nuclei in the brainstem. - This effect is mediated through increased **parasympathetic activity**, reliably slowing the heart rate. - Bradycardia is a **predictable and dose-dependent** side effect of fentanyl administration. *Succinylcholine* - Succinylcholine is a **depolarizing neuromuscular blocker** that **can** cause **bradycardia**, particularly with **repeat dosing**, in **children**, or with **higher doses** due to stimulation of **muscarinic receptors** at the SA node. - However, its cardiac effects are **variable and context-dependent** - it can also cause **tachycardia** in some patients due to sympathetic ganglion stimulation. - The bradycardia is **less predictable** compared to fentanyl. *Atropine* - Atropine is an **anticholinergic drug** that acts as a **muscarinic receptor antagonist**, therefore it typically causes **tachycardia**, not bradycardia [2]. - It works by blocking the effects of **acetylcholine** on the **vagus nerve**, thereby increasing heart rate. *Adrenaline* - Adrenaline (epinephrine) is a **sympathomimetic drug** that stimulates **alpha and beta-adrenergic receptors**. - Its primary cardiac effects are **increased heart rate**, **contractility**, and **blood pressure**, directly opposing bradycardia.

Q: Nitrous oxide alone is not used as a general anaesthetic agent because of

Inability to maintain adequate depth of anesthesia. ***Inability to maintain adequate depth of anesthesia*** - **Nitrous oxide** has a relatively **high minimum alveolar concentration (MAC)** (104%), meaning it cannot achieve surgical depths of anesthesia when administered alone (even at 100% concentration, which would be hypoxic). - Its **low potency** necessitates co-administration with more potent inhalational agents or intravenous anesthetics to ensure appropriate analgesia and muscular relaxation for surgical procedures. *Cost and exposure hazards* - While prolonged exposure to **nitrous oxide** can pose an occupational hazard to healthcare workers and it is an environmental pollutant, these are not the primary reasons it is unsuitable as a sole general anesthetic. - The cost of **nitrous oxide** itself is generally moderate and not prohibitive for its use, especially in combination. *Potential adverse effects on liver function* - **Nitrous oxide** is primarily eliminated by the lungs and undergoes minimal metabolism, making **hepatic toxicity** not a significant concern. - Hepatic adverse effects are more commonly associated with other halogenated anesthetics like halothane. *Rapid onset and offset leading to unstable anesthesia* - The **rapid onset and offset** of **nitrous oxide** are actually advantageous in many clinical situations, contributing to rapid induction and recovery from anesthesia. - While it has a rapid effect, this characteristic does not inherently lead to "unstable anesthesia" in the context of its overall suitability as a sole agent; rather, its low potency is the limiting factor.

Q: Propofol and thiopentone are:

Anesthesia induction agents. ***Anesthesia induction agents*** - Propofol and thiopentone are **intravenous anesthetic agents** primarily used to rapidly induce a state of unconsciousness for surgery and other medical procedures. - They produce a **quick onset of action** allowing for a smooth and controlled intubation if needed, initiating the anesthetic process. *Anesthesia maintenance agents* - While propofol can be used for maintenance as a continuous infusion, its primary role, as well as that of thiopentone, is **induction due to their rapid onset and short duration** when given as a bolus. - Anesthesia maintenance typically involves volatile anesthetics (e.g., sevoflurane, isoflurane) or continuous infusions of drugs like propofol or remifentanil. *Anesthesia reversal agents* - Reversal agents are used to **counteract the effects of muscle relaxants** (e.g., neostigmine, sugammadex) or benzodiazepines (e.g., flumazenil) used during anesthesia. - Propofol and thiopentone do not have a role in reversing general anesthesia; their effects simply wear off as they are metabolized. *Local anesthetics* - Local anesthetics (e.g., lidocaine, bupivacaine) block nerve conduction in a **specific region of the body** without affecting consciousness. - Propofol and thiopentone are **general anesthetics** that induce a state of unconsciousness, affecting the entire central nervous system.

Q: Which anesthetic agent does not cause bradycardia?

Ketamine. ***Ketamine*** - Unlike other anesthetic agents, **ketamine** directly stimulates the sympathetic nervous system and inhibits norepinephrine reuptake, which often leads to **tachycardia** and increased blood pressure, rather than bradycardia. - This sympathetic stimulation makes it a useful agent in trauma or hypovolemic patients where maintaining hemodynamic stability is crucial. *Halothane* - **Halothane** is known to directly depress the myocardium and sensitize the heart to catecholamines, often leading to **bradycardia** and arrhythmogenicity. - It also reduces adrenergic outflow from the central nervous system, further contributing to a slower heart rate. *Isoflurane* - While generally considered more hemodynamically stable than halothane, **isoflurane** can cause **dose-dependent myocardial depression** and a reduction in heart rate at higher concentrations. - It can cause vasodilation, which may initially trigger a reflex tachycardia, but direct myocardial effects can predominate, leading to bradycardia. *Thiopentone* - **Thiopentone**, a barbiturate, causes dose-dependent depression of the central nervous system, including the cardiovascular centers, leading to reduced cardiac output and **bradycardia**. - It also has a direct myocardial depressant effect, contributing to a slower heart rate and hypotension.

Q: Which of the following is/are hepatotoxic anesthetic agent(s)?

Both Chloroform and Halothane. ***Both Chloroform and Halothane*** - Both agents are well-established hepatotoxins used historically in anesthesia - **Chloroform** causes direct hepatotoxicity through centrilobular necrosis due to reactive metabolites (CYP2E1-mediated) - **Halothane** causes halothane hepatitis, a rare but potentially fatal immune-mediated hepatotoxicity (occurs in 1:10,000-35,000 exposures) - This is the **most complete answer** as it includes all hepatotoxic agents listed *Halothane* - This is medically correct - halothane is indeed hepatotoxic - However, this is **incomplete** as it omits chloroform, another hepatotoxic anesthetic agent in the options - When multiple correct agents are listed, the most comprehensive answer is preferred *Chloroform* - This is medically correct - chloroform is indeed hepatotoxic - However, this is **incomplete** as it omits halothane, another hepatotoxic anesthetic agent in the options - Chloroform was historically used but abandoned due to hepatotoxicity and cardiac arrhythmias *None of the above* - This is incorrect as both chloroform and halothane have well-documented hepatotoxic effects - Both agents can cause liver damage ranging from transient enzyme elevation to fulminant hepatic failure

Q: Second gas effect is exaggerated by which of the following gases when co-administered with halothane?

Nitrous oxide. ***Nitrous oxide*** - **Nitrous oxide** has a high partial pressure and low blood solubility, leading to its rapid uptake into the blood and then into the alveoli. - This rapid absorption concentrates the remaining inspired gases, including halothane, thereby exacerbating the **second gas effect** and leading to a more rapid increase in halothane's partial pressure in the alveoli. *Cyclopropane* - While cyclopropane is an anesthetic gas with quick induction, it is no longer widely used and its physiological interaction with other gases in exaggerating the second gas effect is not as pronounced or clinically relevant as that of nitrous oxide. - It has a low MAC and high potency, but its role in the **second gas effect** is not primarily due to its rapid tissue uptake and concentration of other gases in the same manner as nitrous oxide. *Nitrogen (inert gas)* - Nitrogen is an **inert gas** and does not readily participate in physiological processes or anesthetic effects. - Its presence in the inspired gas mixture does not significantly affect the uptake of other anesthetic gases to exaggerate the **second gas effect**. *Helium (low solubility)* - Helium has very **low blood solubility** but is not an anesthetic gas. - Although its low solubility might suggest rapid movement, it would not concentrate other anesthetic gases or directly contribute to the **second gas effect** in the manner of nitrous oxide, which is itself an anesthetic agent with high partial pressure.

Question 1

Which of the following drugs produces dissociative anesthesia?

Accepted Answer

Ketamine

Answer

Propofol

Answer

Thiopentone

Answer

Enflurane

Question 2

After suxamethonium 50mg, apnea persists for one hour.

Accepted Answer

Probably an atypical cholinesterase is present

Answer

Treatment with stored blood is indicated

Answer

Apnea may be due to low serum potassium concentration

Answer

treatment with cholinesterase is indicated

Question 3

Which stage of surgical anesthesia is optimal for surgery?

Accepted Answer

Stage III

Answer

Stage I

Answer

Stage II

Answer

Stage IV

Question 4

Which inducing agent is associated with the highest incidence of postoperative vomiting?

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Propofol

Answer

Etomidate

Question 5

Bradycardia is common after the injection of

Accepted Answer

Fentanyl

Answer

Succinylcholine

Answer

Atropine

Answer

Adrenaline

Question 6

Nitrous oxide alone is not used as a general anaesthetic agent because of

Accepted Answer

Inability to maintain adequate depth of anesthesia

Answer

Cost and exposure hazards

Answer

Potential adverse effects on liver function

Answer

Rapid onset and offset leading to unstable anesthesia

Question 7

Propofol and thiopentone are:

Accepted Answer

Anesthesia induction agents

Answer

Anesthesia maintenance agents

Answer

Anesthesia reversal agents

Answer

Local anesthetics

Question 8

Which anesthetic agent does not cause bradycardia?

Accepted Answer

Ketamine

Answer

Isoflurane

Answer

Thiopentone

Answer

Halothane

Question 9

Which of the following is/are hepatotoxic anesthetic agent(s)?

Accepted Answer

Both Chloroform and Halothane

Answer

Halothane

Answer

None of the above

Answer

Chloroform

Question 10

Second gas effect is exaggerated by which of the following gases when co-administered with halothane?

Accepted Answer

Nitrous oxide

Answer

Cyclopropane

Answer

Nitrogen (inert gas)

Answer

Helium (low solubility)

General Anesthesia — MCQs

General Anesthesia — MCQs

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