General Anesthesia Practice Questions

Q: Anesthetic agents causing bradycardia are all except:

Ketamine. ***Ketamine*** - Ketamine characteristically causes **sympathetic stimulation**, leading to an increase in **heart rate** and blood pressure, rather than bradycardia. - Its effects can be beneficial in patients with **hemodynamic instability** or compromised cardiac function. *Procaine* - Procaine, like other local anesthetics, can cause **bradycardia** and other cardiac depressant effects, especially at higher doses or with systemic absorption. - This effect is due to its action on **cardiac ion channels**, impairing impulse generation and conduction. *Prilocaine* - Prilocaine can induce **bradycardia**, similar to other amide-type local anesthetics, due to its direct depressant effects on myocardial function and conduction. - High doses can also lead to **methemoglobinemia**, which, while not directly causing bradycardia, complicates cardiovascular status. *Bupivacaine* - Bupivacaine is particularly known for its **cardiotoxic potential**, including severe **bradycardia** and arrhythmias, especially with accidental intravascular injection. - Its prolonged binding to **cardiac sodium channels** makes it more difficult to resuscitate from bupivacaine-induced cardiac arrest.

Q: Train of four fade is a characteristic feature of:

Non depolarizing block. ***Non depolarizing block*** - A **train-of-four (TOF) fade** is a hallmark of **non-depolarizing neuromuscular block**, due to the competitive antagonism of acetylcholine at the postsynaptic receptor. - The first twitch depletes a portion of readily releasable acetylcholine, and the subsequent twitches show progressive fade because less acetylcholine is released with each successive stimulus. *Depolarizing block* - In a **Phase I depolarizing block**, there is **no fade** with TOF stimulation because the acetylcholine receptor is continuously activated, leading to sustained depolarization. - During prolonged exposure to a depolarizing agent, a Phase II block may develop which *can* exhibit fade, but this is a secondary phenomenon, and the primary characteristic of a depolarizing block is lack of fade. *Both depolarizing and non-depolarizing block* - While a **Phase II depolarizing block** can show fade, it is not a *characteristic* feature of all depolarizing blocks, distinguishing it from the consistent fade seen in non-depolarizing blocks. - The primary action of depolarizing agents (Phase I block) does not involve fade, making this option incorrect as a universal characteristic. *Malignant hyperthermia* - **Malignant hyperthermia** is a hypermetabolic crisis triggered by certain anesthetic agents, primarily involving uncontrolled calcium release from the sarcoplasmic reticulum, not directly related to neuromuscular blockade monitoring patterns. - While muscle rigidity can be a symptom, it does not manifest as a **train-of-four fade**, which is specific to postsynaptic acetylcholine receptor interactions.

Q: Stage 2 block (Phase II block) is seen with:

Suxamethonium. ***Suxamethonium*** - **Suxamethonium** (succinylcholine) is a depolarizing neuromuscular blocker that can cause a **Phase II block** with prolonged or high-dose administration. - Phase II block, also known as **desensitization block**, clinically resembles a non-depolarizing block and can be antagonized by **anticholinesterases**. *Isoflurane* - **Isoflurane** is an inhaled anesthetic that causes muscle relaxation by enhancing the effects of non-depolarizing neuromuscular blockers, but does not directly induce a Phase II block. - It primarily acts on GABA receptors in the CNS to produce anesthesia and has minimal direct effect on **nicotinic acetylcholine receptors** at the neuromuscular junction. *Enflurane* - **Enflurane** is another inhaled anesthetic that, similar to isoflurane, potentiates neuromuscular blockade but does not directly cause a **Phase II block**. - Its effects are primarily on the **central nervous system**, contributing to anesthesia and muscle relaxation through central mechanisms. *Sevoflurane* - **Sevoflurane** is a commonly used inhaled anesthetic that also enhances the effects of neuromuscular blockers but does not cause a unique **Phase II block** itself. - Like other volatile anesthetics, it facilitates muscle relaxation, thereby reducing the dose of neuromuscular blockers required.

Q: Which of the following intravenous anaesthetic agent causes decrease in postoperative nausea and vomiting :

Propofol. ***Propofol*** - **Propofol** has antiemetic properties, which contributes to a reduced incidence of **postoperative nausea and vomiting (PONV)**. - Its mechanism of action in reducing PONV is thought to involve effects on **dopaminergic receptors** and **serotonin pathways** in the brain. *Etomidate* - **Etomidate** is not known to significantly reduce PONV and may even have a neutral effect or slightly increase it compared to propofol. - Its primary advantages include **cardiovascular stability**, which is unrelated to antiemetic effects. *Ketamine* - **Ketamine** is associated with a higher incidence of PONV, especially at higher doses, due to its **psychedelic side effects** and stimulation of the chemoreceptor trigger zone. - It is known for causing **emergence delirium** and does not possess antiemetic properties. *Thiopentone* - **Thiopentone** (Thiopental) does not have any significant antiemetic properties and is not typically used for its effect on PONV. - It was historically used as an induction agent but has largely been replaced by newer drugs like propofol.

Q: A 32-year-old male is a known hypertensive and is being planned for cholecystectomy. Which of the following anesthetic agents is contraindicated in this person?

Ketamine. ***Ketamine*** - **Ketamine** can cause significant increases in **heart rate** and **blood pressure**, which are undesirable in a hypertensive patient undergoing surgery. - Its **sympathomimetic effects** can exacerbate pre-existing hypertension and increase the risk of perioperative cardiovascular complications. *Etomidate* - **Etomidate** is known for its **cardiovascular stability**, making it a good choice for hypertensive patients as it has minimal effects on heart rate and blood pressure. - It can, however, suppress adrenal steroid synthesis, which is generally not a contraindication for a single dose in a healthy hypertensive patient. *Propofol* - **Propofol** often causes a **dose-dependent decrease in blood pressure** due to vasodilation and myocardial depression. - While this can be a concern, it is usually managed by careful titration and is less likely to exacerbate hypertension than ketamine. *Midazolam* - **Midazolam** is a benzodiazepine that provides **sedation and anxiolysis**; it has minimal effects on hemodynamics at typical anesthetic induction doses. - It is often used as a co-induction agent, not as a primary induction agent, and generally does not worsen hypertension.

Q: Hallucinations are seen after _______ anaesthesia:

Ketamine. ***Ketamine*** - Ketamine is known for its **dissociative anesthetic** properties, which can lead to vivid **hallucinations** and disturbing dreams during emergence from anesthesia, especially in adults. - This effect is due to its action as an **NMDA receptor antagonist**, disrupting normal sensory and cognitive processing. *Nitrous oxide* - While nitrous oxide can cause a sense of **euphoria** and altered perception, it is less commonly associated with vivid, distressing hallucinations typical of ketamine. - It is often used as an adjunct to other anesthetics to reduce their dose and enhance **analgesia**. *Fentanyl* - Fentanyl is a potent **opioid analgesic** primarily used for pain relief and sedation, and does not typically cause hallucinations. - Its main side effects include **respiratory depression**, nausea, and constipation. *Thiopentone* - Thiopentone is a **barbiturate** used for rapid induction of anesthesia, causing loss of consciousness quickly to facilitate intubation. - It primarily acts as a **GABA-A receptor agonist** and is not associated with hallucinogenic effects during emergence.

Q: Which of the following inhalational agents sensitizes myocardium to catecholamines?

Halothane. ***Halothane*** - **Halothane** significantly sensitizes the myocardium to the dysrhythmogenic effects of **exogenous and endogenous catecholamines**, leading to an increased risk of ventricular arrhythmias. - This effect is due to its interaction with myocardial ion channels and adrenergic receptors, making the heart more susceptible to the arrhythmogenic actions of **norepinephrine** and **epinephrine**. *Ether* - **Diethylether** does not significantly sensitize the myocardium to catecholamines; in fact, it tends to have a more stable cardiovascular profile in this regard. - While it can cause some sympathetic stimulation, its arrhythmogenic potential with catecholamines is much lower compared to halothane. *Isoflurane* - **Isoflurane** has a minimal effect on myocardial sensitization to catecholamines, making it a safer option for patients with pre-existing cardiac conditions or those requiring exogenous catecholamine administration. - It maintains cardiac rhythm stability much better than halothane in the presence of adrenergic stimulation. *Sevoflurane* - **Sevoflurane**, similar to isoflurane, causes very little myocardial sensitization to catecholamines and is considered to be a **cardiac-friendly** inhalational agent. - It maintains **hemodynamic stability** and has a low incidence of arrhythmias even with concurrent use of epinephrine.

Q: Stage of analgesia in anaesthesia is ?

Stage-1. ***Stage-1*** - This stage is known as the **stage of analgesia** or disorientation, lasting from the initial administration of anesthetic agents to the loss of consciousness. - During this stage, the patient may experience **analgesia** (pain relief) and amnesia, though they are still conscious. *Stage-2* - This is the **stage of delirium**, characterized by excitement, involuntary movements, and irregular breathing. - Patients are at risk of **laryngospasm** and vomiting during this stage, making it crucial to transition through it quickly. *Stage-4* - This is the **stage of medullary depression** or respiratory arrest, indicating an overdose of anesthetic. - It is characterized by severe cardiovascular and respiratory depression, leading to **circulatory collapse** and death if not immediately rectified. *Stage-3* - This is the **stage of surgical anesthesia**, subdivided into four planes based on depth of anesthesia, ranging from light to deep surgical anesthesia. - Key signs include regular respiration, loss of reflexes, and muscle relaxation, making it suitable for **surgical procedures**.

Q: The inducing agent of choice in shock -

Ketamine. **Ketamine** * **Ketamine** is preferred in shock due to its sympathomimetic properties, which maintain or increase blood pressure and heart rate, thus preserving **cardiovascular stability**. * It also has minimal respiratory depression and bronchodilatory effects, making it safer for patients with compromised respiratory function. * The cardiovascular stimulating effects of ketamine helps maintain haemodynamic stability in shocked patients. It maintains cerebral autoregulation and perfusion of vital organs. *Isoflurane* * **Isoflurane** is an inhaled anesthetic that typically causes **dose-dependent myocardial depression** and **vasodilation**, which can worsen hypotension in a shock state. * It can significantly decrease systemic vascular resistance, thereby exacerbating the already compromised cardiovascular status of a shock patient. *Desflurane* * **Desflurane** is an inhaled anesthetic known for its rapid onset and offset but can cause a **significant increase in heart rate and blood pressure** upon rapid concentration changes, which may be detrimental in an unstable patient. * Like isoflurane, it also causes dose-dependent peripheral vasodilation and myocardial depression, which can worsen hypotension in patients in shock. *Thiopentone* * **Thiopentone** is a barbiturate that causes significant **myocardial depression** and **peripheral vasodilation**, leading to a substantial drop in blood pressure. * Its use in shock would further compromise cardiovascular stability and is generally contraindicated due to its potent hemodynamic depressant effects.

Q: The fluoride level that can cause renal toxicity is

Above 50 micromol/litre. ***Above 50 micromol/litre*** - Clinically significant renal toxicity from fluoride is generally observed at plasma fluoride concentrations exceeding **50 micromol/L**, which is the established threshold in medical literature. - This level is particularly associated with **methoxyflurane anesthesia**, where fluoride metabolism leads to nephrotoxicity manifesting as **polyuria, polydipsia, and nephrogenic diabetes insipidus**. - At these concentrations, fluoride interferes with renal tubular function, causing **high-output renal failure** and electrolyte disturbances. *Above 20 micromol/litre* - While some subclinical renal effects may begin around 20 micromol/L, this is **below the threshold** for clinically significant renal toxicity. - This level may cause mild tubular dysfunction but does not typically result in the **overt nephrotoxicity** that characterizes fluoride-induced renal damage. - The consensus threshold for **clinical renal toxicity is 50 micromol/L**, not 20 micromol/L. *Above 5 micromol/litre* - A plasma fluoride level of 5 micromol/L is well within the **safe range** and is commonly seen with therapeutic fluoride exposure. - This level is associated with **dental prophylaxis** and normal environmental exposure without any renal toxicity. *Above 80 micromol/litre* - This represents a **severely toxic** fluoride level causing profound renal damage, but the threshold for **initial renal toxicity** is much lower at 50 micromol/L. - At 80 micromol/L, patients would experience severe systemic toxicity including **cardiac arrhythmias, CNS effects**, and potentially fatal complications.

Question 1

Anesthetic agents causing bradycardia are all except:

Accepted Answer

Ketamine

Answer

Procaine

Answer

Prilocaine

Answer

Bupivacaine

Question 2

Train of four fade is a characteristic feature of:

Accepted Answer

Non depolarizing block

Answer

Depolarizing block

Answer

Both depolarizing and non-depolarizing block

Answer

Malignant hyperthermia

Question 3

Stage 2 block (Phase II block) is seen with:

Accepted Answer

Suxamethonium

Answer

Isoflurane

Answer

Enflurane

Answer

Sevoflurane

Question 4

Which of the following intravenous anaesthetic agent causes decrease in postoperative nausea and vomiting :

Accepted Answer

Propofol

Answer

Etomidate

Answer

Ketamine

Answer

Thiopentone

Question 5

A 32-year-old male is a known hypertensive and is being planned for cholecystectomy. Which of the following anesthetic agents is contraindicated in this person?

Accepted Answer

Ketamine

Answer

Etomidate

Answer

Propofol

Answer

Midazolam

Question 6

Hallucinations are seen after _______ anaesthesia:

Accepted Answer

Ketamine

Answer

Nitrous oxide

Answer

Fentanyl

Answer

Thiopentone

Question 7

Which of the following inhalational agents sensitizes myocardium to catecholamines?

Accepted Answer

Halothane

Answer

Ether

Answer

Isoflurane

Answer

Sevoflurane

Question 8

Stage of analgesia in anaesthesia is ?

Accepted Answer

Stage-1

Answer

Stage-2

Answer

Stage-4

Answer

Stage-3

Question 9

The inducing agent of choice in shock -

Accepted Answer

Ketamine

Answer

Isoflurane

Answer

Desflurane

Answer

Thiopentone

Question 10

The fluoride level that can cause renal toxicity is

Accepted Answer

Above 50 micromol/litre

Answer

Above 5 micromol/litre

Answer

Above 20 micromol/litre

Answer

Above 80 micromol/litre

General Anesthesia — MCQs

General Anesthesia — MCQs

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