General Anesthesia Practice Questions

Q: What effect does Propofol have on the EEG?

Induces EEG depression. ***Induces EEG depression*** - Propofol, an intravenous anesthetic, primarily acts as a **GABA-A receptor agonist**, enhancing inhibitory neurotransmission in the brain. - This leads to a dose-dependent reduction in brain electrical activity, characterized by a decrease in the **amplitude and frequency of EEG waves**, effectively causing EEG depression. *Causes no significant change in EEG* - This statement is incorrect because propofol has profound effects on brain electrical activity, as measured by the EEG. - Its anesthetic properties are directly linked to its ability to alter neuronal excitability significantly. *Causes EEG activation* - EEG activation typically involves an increase in fast-frequency, low-amplitude waves, often associated with states of arousal or epileptic activity. - Propofol's primary effect is to depress brain activity, which is the opposite of activation. *None of the options* - This option is incorrect because propofol has a well-documented and significant effect on the EEG, which is precisely EEG depression.

Q: Which of the following agents is most commonly used to induce anesthesia?

Propofol. ***Propofol*** - **Propofol** is one of the most commonly used intravenous anesthetics for both induction and maintenance due to its rapid onset, short duration of action, and favorable recovery profile with less postoperative nausea and vomiting. - Its mechanism involves potentiation of **GABA-A receptors**, leading to CNS depression and anesthesia. *Thiopentone sodium* - **Thiopentone** is an ultrashort-acting barbiturate that was historically very popular for induction but has largely been replaced by propofol due to a slower recovery profile and higher incidence of cardiovascular depression. - It also acts on **GABA-A receptors**, enhancing chloride influx and hyperpolarizing neurons. *Methohexitone sodium* - **Methohexitone** is another ultrashort-acting barbiturate, similar to thiopentone, used for induction, particularly in electroconvulsive therapy (ECT) due to its lower incidence of post-ictal confusion. - However, it is associated with a higher risk of **muscle twitching** and **hiccups** compared to propofol. *Etomidate* - **Etomidate** is a short-acting intravenous anesthetic known for its excellent **cardiovascular stability**, making it a preferred choice in patients with compromised cardiac function or hemodynamic instability. - A significant drawback is its association with **adrenocortical suppression**, even after a single dose, which limits its widespread use for maintenance.

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: 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: 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 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 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

Question 1

What effect does Propofol have on the EEG?

Accepted Answer

Induces EEG depression

Answer

Causes no significant change in EEG

Answer

Causes EEG activation

Answer

None of the options

Question 2

Which of the following agents is most commonly used to induce anesthesia?

Accepted Answer

Propofol

Answer

Etomidate

Answer

Methohexitone sodium

Answer

Thiopentone sodium

Question 3

Which of the following drugs produces dissociative anesthesia?

Accepted Answer

Ketamine

Answer

Propofol

Answer

Thiopentone

Answer

Enflurane

Question 4

Which stage of surgical anesthesia is optimal for surgery?

Accepted Answer

Stage III

Answer

Stage I

Answer

Stage II

Answer

Stage IV

Question 5

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 6

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

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Propofol

Answer

Etomidate

Question 7

Bradycardia is common after the injection of

Accepted Answer

Fentanyl

Answer

Succinylcholine

Answer

Atropine

Answer

Adrenaline

Question 8

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 9

Propofol and thiopentone are:

Accepted Answer

Anesthesia induction agents

Answer

Anesthesia maintenance agents

Answer

Anesthesia reversal agents

Answer

Local anesthetics

Question 10

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

General Anesthesia — MCQs

General Anesthesia — MCQs

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