General Anesthesia Practice Questions

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

Halothane. ***Halothane*** - **Halothane** is known to significantly **sensitize the myocardium to circulating catecholamines**, increasing the risk of arrhythmias, particularly ventricular extrasystoles. - This effect is due to its interaction with calcium channels and other cellular mechanisms that alter cardiac excitability. *Desflurane* - While Desflurane can cause a **transient increase in heart rate and blood pressure** upon rapid increase in concentration, it does not sensitize the myocardium to catecholamines to the same extent as halothane. - Its cardiovascular effects are usually mediated by sympathetic nervous system activation rather than enhanced myocardial sensitivity. *Nitrous Oxide* - **Nitrous oxide** has minimal direct effects on the myocardium and does not sensitize it to catecholamines. - It tends to have a mild sympathomimetic effect, but its impact on cardiac excitability is generally considered benign. *Enflurane* - **Enflurane** has a moderate effect on the cardiovascular system, causing dose-dependent myocardial depression. - However, it does not significantly sensitize the myocardium to catecholamines in the same problematic way that halothane does.

Q: Which anesthetic gas is known for causing maximum respiratory irritation?

Desflurane. ***Desflurane*** - **Desflurane** is known for its **pungent odor** and tendency to cause significant **respiratory irritation** (e.g., coughing, breath-holding, laryngospasm) upon induction, especially at higher concentrations. - This irritation is exacerbated by its **low blood-gas solubility**, leading to rapid increases in alveolar concentration and rapid achievement of brain partial pressure. *Halothane* - **Halothane** is a potent anesthetic but is generally associated with less respiratory irritation compared to desflurane due to its **less pungent odor**. - Its main concerns include **hepatotoxicity** (halothane hepatitis) and cardiac arrhythmias, not primary respiratory irritation. *Enflurane* - **Enflurane** can cause some respiratory irritation, but it is generally less irritating than desflurane. - It is also associated with a risk of **seizures** at higher concentrations, making it less commonly used. *Sevoflurane* - **Sevoflurane** is known for its **non-pungent odor** and minimal respiratory-irritant properties, making it an excellent choice for **inhalational induction**, especially in pediatric patients. - While it can generate compound A (a nephrotoxic substance) with CO2 absorbents, it is very well tolerated by the respiratory system.

Q: IV administration of which anesthetic drug is most painful among the following?

Propofol. ***Propofol*** - **Propofol** is notoriously known for causing **significant pain on injection** due to its formulation with **soybean oil emulsion** and its direct irritation of venous free nerve endings. - This pain is often described as a **burning sensation** and can be severe enough to require pre-treatment with lidocaine or administering it in a larger vein. *Methohexital* - While **methohexital** can cause localized pain and sometimes **thrombophlebitis** during intravenous administration, it is generally considered less painful than propofol. - It is a **barbiturate** and its discomfort is typically related to its alkaline pH and potential for venous irritation. *Ketamine* - **Ketamine** typically causes **minimal pain on injection** when administered intravenously. - Its mechanism of action as an **NMDA receptor antagonist** does not generally involve direct irritation of venous endothelium in the same way as propofol. *Etomidate* - **Etomidate**, like methohexital, can cause some **pain and irritation on injection**, and poses a risk of **thrombophlebitis**. - However, the severity of pain is generally **less pronounced** compared to the distinct and often intense burning sensation associated with propofol.

Q: All of the following statements about neuromuscular blockage produced by succinylcholine are true, except for:

Fade on tetanic stimulation. ***Fade on tetanic stimulation*** - Succinylcholine is a **depolarizing neuromuscular blocker** that initially causes fasciculations and then sustained depolarization. - In a typical depolarizing block (Phase I), there is **no fade** with tetanic or train-of-four (TOF) stimulation due to continuous activation of nicotinic receptors. *Sustained contraction during tetany* - **Sustained contraction during tetany** is characteristic of a depolarizing block (Phase I) where the muscle remains depolarized and unresponsive. - The muscle fibers are continuously stimulated, leading to a prolonged contractile state or paralysis without fade. *Train of four ratio < 0.4* - A **Train-of-Four (TOF) ratio < 0.4** indicates a **fade** in muscle response, which is a hallmark of a **non-depolarizing block (Phase II block)**. - In a typical depolarizing block (Phase I), the TOF ratio is close to 1 because there is no fade. *No fade on Train of four stimulation* - **No fade on Train-of-Four (TOF) stimulation** is a characteristic of a **depolarizing neuromuscular block (Phase I block)**. - This occurs because succinylcholine continuously activates the acetylcholine receptors, maintaining a persistent depolarization throughout the TOF stimuli.

Q: At the end of anaesthesia after discontinuation of nitrous oxide and removal of endotracheal tube, 100% oxygen is administered to the patient to prevent:

Diffusion Hypoxia. ***Diffusion Hypoxia*** - Post-anaesthesia administration of 100% oxygen prevents **diffusion hypoxia**, a phenomenon where **nitrous oxide** rapidly diffuses out of the blood into the alveoli, diluting alveolar oxygen and carbon dioxide. - This rapid outflow of nitrous oxide can lead to a significant drop in **partial pressure of oxygen** in the alveoli, causing hypoxemia if not counteracted with high inspired oxygen. *Second gas effect* - The **second gas effect** refers to the phenomenon where the rapid uptake of a highly soluble anesthetic (like nitrous oxide) accelerates the uptake of a co-administered less soluble anesthetic. - This is an effect related to the **induction phase** of anesthesia, not emergence, and is distinct from the issues arising from nitrous oxide washout. *Bronchospasm* - **Bronchospasm** is an acute constriction of the bronchioles, often triggered by irritants, allergens, or certain medications. - While it can occur during emergence from anesthesia, it is not directly prevented by administering 100% oxygen and is typically managed with bronchodilators. *Hyperoxia* - **Hyperoxia** is a condition of excess oxygen in the body, which can be detrimental, but it is not the primary concern immediately following the discontinuation of nitrous oxide. - Administering 100% oxygen in this context is a **controlled, short-term measure** to prevent a more immediate and severe issue (hypoxia) rather than causing chronic hyperoxia.

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

Halothane. ***Halothane*** - **Halothane** sensitizes the myocardium to the arrhythmogenic effects of **catecholamines**, leading to an increased risk of ventricular arrhythmias, especially in the presence of exogenous adrenaline. - This sensitization occurs due to its effect on myocardial **calcium ion** regulation and increased automaticity in cardiac pacemaker cells. *Isoflurane* - **Isoflurane** causes minimal sensitization of the myocardium to catecholamines compared to halothane. - It maintains **cardiac output** with a dose-dependent decrease in systemic vascular resistance. *Ether* - **Diethylether** historically caused sympathetic stimulation, which could mask some depressant effects but did not primarily sensitize the myocardium to arrhythmias from exogenous catecholamines. - Its use has largely been replaced due to its flammability and slower induction/recovery. *Propofol* - **Propofol** generally causes myocardial depression and vasodilation, but it does **not sensitize** the myocardium to catecholamines in a clinically significant way that increases arrhythmogenic risk. - It often leads to a decrease in **blood pressure** and heart rate.

Q: What is the ionized calcium (IC) content of Ringer's lactate in mmol/L, and why is it clinically significant?

4 mmol/L. ***4 mmol/L*** - Ringer's lactate contains **calcium chloride**, contributing to its ionized calcium content of **4 mmol/L**. - This calcium is a critical component for **blood clotting** and **cardiac function**, making it clinically significant, particularly in large volume resuscitation. *130 mmol/L* - This value is close to the **sodium content** of Ringer's lactate, not its ionized calcium. - Sodium is the primary determinant of **fluid balance** and **osmolarity**, distinct from calcium's roles. *109 mmol/L* - This value approximates the **chloride content** of Ringer's lactate, which is important for acid-base balance but not its ionized calcium. - Chloride's primary role is in maintaining **electrical neutrality** and fluid distribution. *0 mmol/L* - Ringer's lactate is a **balanced electrolyte solution** and definitely contains calcium. - A value of 0 would indicate the absence of calcium, which would contradict its formulation and clinical utility, especially in scenarios requiring **electrolyte repletion**.

Q: What is the definition of conscious sedation?

Sedation with ability to respond to verbal commands. ***Sedation with ability to respond to verbal commands*** - Conscious sedation involves a drug-induced depression of consciousness during which the patient **retains the ability to respond purposefully to verbal commands**. - This level of sedation ensures that the patient's **airway reflexes** and **ventilatory function** remain intact. *CNS depression with unconsciousness* - This describes **general anesthesia** or **deep sedation**, where the patient is unable to respond purposefully to verbal commands. - In such states, spontaneous ventilation may be **inadequate**, and **airway support** is often required. *Sedation with inability to respond to verbal commands* - This definition aligns with **deep sedation** or **general anesthesia**, where the patient's consciousness is significantly depressed. - At this level, patients may require assistance in maintaining a **patent airway** and adequate ventilation. *None of the options* - This option is incorrect because one of the provided definitions accurately describes conscious sedation. - The definition of conscious sedation is well-established in clinical practice, emphasizing the **preservation of responsiveness**.

Q: Regarding propofol, which one of the following statements is false?

It causes severe vomiting. ***It causes severe vomiting*** - Propofol is actually known for its **antiemetic properties**, meaning it helps *prevent* rather than cause nausea and vomiting. - This makes it a preferred anesthetic for procedures where **postoperative nausea and vomiting (PONV)** are a concern. *It is used as an intravenous induction agent* - **Propofol** is a widely used **intravenous anesthetic** for the **induction and maintenance of general anesthesia**. - It provides a rapid onset of unconsciousness due to its high lipid solubility. *It is painful on injecting intravenously* - Injection of propofol can often cause **pain at the injection site**, particularly when administered into smaller veins. - This pain can be mitigated by co-administering **lidocaine** or using larger veins. *It has no muscle relaxant property* - Propofol does **not possess intrinsic muscle relaxant properties**; patients require additional neuromuscular blocking agents for surgical relaxation. - It facilitates intubation by causing **loss of consciousness** and **reducing airway reflexes**, but does not directly relax skeletal muscles.

Q: What is a significant disadvantage of ketamine?

Delirium. ***Delirium*** - Ketamine is known to cause **emergence phenomena**, which include **vivid dreams, hallucinations**, and **delirium**, particularly during recovery from anesthesia. - This psychotomimetic effect can be distressing for patients and may necessitate the co-administration of a **benzodiazepine** to mitigate these symptoms. *Increased heart rate* - While ketamine does cause an **increase in heart rate** and **blood pressure** due to sympathetic stimulation, this is often considered a disadvantage but not the *most significant* when compared to the unique cognitive side effects. - This effect can be beneficial in patients with **hemodynamic instability**, but can be problematic in those with **cardiovascular disease**. *Increased ICT* - It is often considered a contraindication in patients with **elevated intracranial pressure (ICP)** as it can potentially increase **cerebral blood flow** and thus ICP. - However, recent studies suggest that in adequately ventilated patients, the effect on ICP may be less pronounced than previously thought, making delirium a more consistent and prominent disadvantage for many patients. *All of the options* - While ketamine can cause an **increased heart rate** and potentially affect **intracranial pressure**, **delirium** and other emergence phenomena are often highlighted as a unique and significant disadvantage because they are highly distressing and difficult to manage. - The psychotomimetic effects are a hallmark side effect that often governs its cautious use without concurrent medication.

Question 1

Which of the following inhalational agents sensitizes myocardium to catecholamines

Accepted Answer

Halothane

Answer

Desflurane

Answer

Nitrous Oxide

Answer

Enflurane

Question 2

Which anesthetic gas is known for causing maximum respiratory irritation?

Accepted Answer

Desflurane

Answer

Halothane

Answer

Enflurane

Answer

Sevoflurane

Question 3

IV administration of which anesthetic drug is most painful among the following?

Accepted Answer

Propofol

Answer

Ketamine

Answer

Etomidate

Answer

Methohexital

Question 4

All of the following statements about neuromuscular blockage produced by succinylcholine are true, except for:

Accepted Answer

Fade on tetanic stimulation

Answer

Sustained contraction during tetany

Answer

Train of four ratio < 0.4

Answer

No fade on Train of four stimulation

Question 5

At the end of anaesthesia after discontinuation of nitrous oxide and removal of endotracheal tube, 100% oxygen is administered to the patient to prevent:

Accepted Answer

Diffusion Hypoxia

Answer

Second gas effect

Answer

Bronchospasm

Answer

Hyperoxia

Question 6

Which one of the following agents sensitizes the myocardium to catecholamines?

Accepted Answer

Halothane

Answer

Isoflurane

Answer

Ether

Answer

Propofol

Question 7

What is the ionized calcium (IC) content of Ringer's lactate in mmol/L, and why is it clinically significant?

Accepted Answer

4 mmol/L

Answer

0 mmol/L

Answer

130 mmol/L

Answer

109 mmol/L

Question 8

What is the definition of conscious sedation?

Accepted Answer

Sedation with ability to respond to verbal commands

Answer

CNS depression with unconsciousness

Answer

Sedation with inability to respond to verbal commands

Answer

None of the options

Question 9

Regarding propofol, which one of the following statements is false?

Accepted Answer

It causes severe vomiting

Answer

It is painful on injecting intravenously

Answer

It has no muscle relaxant property

Answer

It is used as an intravenous induction agent

Question 10

What is a significant disadvantage of ketamine?

Accepted Answer

Delirium

Answer

Increased heart rate

Answer

Increased ICT

Answer

All of the options

General Anesthesia — MCQs

General Anesthesia — MCQs

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