General Anesthesia Practice Questions

Q: What is the intubation dose of pancuronium?

0.08 mg/Kg. ***0.08 mg/Kg*** - The standard **intubating dose** of pancuronium is typically **0.08-0.1 mg/kg intravenously**. - This dose provides adequate **neuromuscular blockade** for endotracheal intubation. *0.02 mg/Kg* - This dose is too low and would likely result in **insufficient neuromuscular blockade** for successful intubation. - Sub-therapeutic doses would lead to **incomplete muscle relaxation**, making intubation difficult and risky. *0.04 mg/Kg* - While higher than 0.02 mg/kg, this dose is still generally considered **sub-optimal** for intubation with pancuronium. - It may prolong the onset of action or provide **inadequate depth of block** for optimal intubating conditions. *0.06 mg/Kg* - This dose is approaching the lower end of an effective range for some neuromuscular blocking agents, but it is typically **not sufficient** for reliable intubation with pancuronium. - It might lead to a longer **onset time** and compromised intubating conditions compared to the recommended dose.

Q: Which of the following intravenous agents is known to cause pain upon injection?

Propofol. ***Propofol*** - **Propofol** is notoriously known to cause significant **pain upon injection**, especially when administered into smaller veins. - This is attributed to its **lipid emulsion formulation** and activation of **TRPA1 receptors** on sensory neurons. *Methohexital* - While **methohexital** can cause localized pain and venous irritation, it is generally less pronounced and less frequent than with propofol. - It is known more for causing **hiccups** and **muscle twitching** upon induction, rather than severe injection pain. *Ketamine* - **Ketamine** typically causes minimal to no pain upon intravenous injection. - Its side effects are often related to its **dissociative anesthetic** properties, such as psychomimetic effects and increased sympathetic activity. *Etomidate* - **Etomidate** is generally considered to be low in causing injection site pain. - Its primary concern is the potential for **adrenocortical suppression** and a high incidence of **myoclonus**.

Q: Which organ is most resistant to general anesthesia?

Heart. ***Heart*** - The heart is highly resistant to the direct suppressive effects of **general anesthetics** because its primary function is to maintain circulation, and it has intrinsic automaticity. - While anesthetic agents can influence heart rate and contractility, the heart itself continues to function even at deep anesthetic planes, unlike the brain or spinal cord which are targets of anesthesia. *Spinal Cord* - The spinal cord is particularly sensitive to general anesthetics, as they are crucial in producing the immobility component of anesthesia by **depressing spinal reflexes**. - High concentrations of anesthetics can directly suppress spinal cord activity, leading to muscle relaxation and loss of motor response. *Medulla oblongata* - The medulla oblongata contains vital centers for **respiration** and **cardiovascular control** that are highly sensitive to anesthetic agents. - Anesthetic overdose can lead to profound depression of these centers, resulting in respiratory arrest and severe cardiovascular collapse due to direct effects on neurons located there. *Liver* - The liver is primarily involved in the **metabolism of many anesthetic drugs**, rather than being a direct target for their central depressant effects. - While anesthetic agents can impact hepatic blood flow and function, the liver itself does not exhibit the same level of resistance to the *direct pharmacological effects* of anesthesia as the heart.

Q: What is the percentage of halothane that is metabolized in the human body?

25%. **Correct: 25%** - Approximately **25%** of administered halothane is metabolized in the liver, which is a relatively high percentage compared to other volatile anesthetics. - This extensive metabolism can lead to the formation of reactive intermediates, contributing to its potential for **hepatotoxicity** (halothane hepatitis). *Incorrect: 50%* - **50%** metabolism is significantly higher than what is observed for halothane and would imply even greater risk of significant metabolic byproduct accumulation and toxicity. - Most volatile anesthetics are metabolized to a much lesser extent, with desflurane having the least metabolism (<0.02%). *Incorrect: 5%* - **5%** metabolism is too low for halothane; while some volatile anesthetics like isoflurane fall into this range (~0.2-2%), halothane is known for its considerably higher metabolic rate. - A 5% metabolism rate would result in less concern for and incidence of **halothane hepatitis**. *Incorrect: 2.50%* - **2.50%** metabolism is an underestimation of halothane's metabolic activity within the body. - Anesthetic agents such as **enflurane** have a metabolism rate closer to this value (~2-5%), whereas halothane is much higher.

Q: Which of the following determines the speed of recovery from intravenous anesthesia?

Redistribution of the drug from sites in the CNS. ***Redistribution of the drug from sites in the CNS*** - For many intravenous anesthetic agents, **redistribution** from highly perfused central nervous system (CNS) tissues to less perfused peripheral tissues is the primary mechanism for the termination of drug action and recovery from anesthesia. - This rapid decrease in the drug concentration at the site of action (brain) leads to the patient waking up, even before significant metabolism or excretion has occurred. *Liver metabolism of drug* - While liver metabolism is crucial for the **elimination** of many anesthetic drugs from the body, it is typically a slower process and contributes more to the overall drug clearance than to the immediate termination of the anesthetic effect. - Significant metabolism usually occurs after redistribution has already caused the patient to awaken. *Protein binding of drug* - **Protein binding** affects the free fraction of the drug available to act on receptors and to be metabolized or excreted. - However, it does not directly determine the speed of recovery, which is more dependent on the drug's movement between tissue compartments. *Plasma clearance of the drug* - **Plasma clearance** refers to the volume of plasma cleared of the drug per unit time, encompassing both metabolism and excretion. - While important for overall drug removal, it is generally a slower process compared to redistribution in determining the immediate end of intravenous anesthetic action.

Q: Ketamine is the preferred anesthetic for the following conditions except:

Hypertensives. ***Hypertensives*** - Ketamine can cause a significant **increase in blood pressure and heart rate** due to its sympathomimetic effects. - This makes it a less desirable agent for patients with **uncontrolled hypertension**, as it could exacerbate their condition. *Trauma cases that have bled significantly* - Ketamine is preferred in trauma patients with significant blood loss because it **maintains cardiovascular stability** by increasing heart rate and blood pressure, which helps preserve organ perfusion. - Its **sympathomimetic properties** counteract the hypotensive effects of hypovolemia, making it beneficial in these critical situations. *Burn dressing* - Ketamine is well-suited for painful procedures like burn dressing changes because it provides **potent analgesia and amnesia** while largely preserving airway reflexes. - Its ability to maintain **hemodynamic stability** and respiratory function is advantageous for patients undergoing repeated painful interventions. *Short operations on asthmatics* - Ketamine is a good choice for asthmatic patients because it has **bronchodilatory properties**, which can help prevent or ameliorate bronchospasm. - It also **preserves respiratory drive** and airway reflexes, making it safer for patients with reactive airway disease undergoing short procedures.

Q: Which of the following should be considered as the cause of generalized convulsions 20 minutes postoperatively?

Enflurane. ***Enflurane*** - **Enflurane** is well-known to cause **generalized convulsions** or seizure-like activity during emergence from anesthesia, particularly when inspired concentrations exceed 3.0% or with hypocapnia. - The risk of seizures is a significant reason why enflurane is rarely used in modern anesthetic practice compared to newer volatile agents. *Halothane* - **Halothane** is associated with cardiac arrhythmias and hepatotoxicity but generally does not cause generalized convulsions as a primary side effect. - While it can lower the seizure threshold, overt seizures are not a common complication of halothane administration. *Isoflurane* - **Isoflurane** is associated with CNS depression and can, in rare cases, cause myoclonus, but it is not typically linked to generalized tonic-clonic convulsions. - It is often used in neurosurgery due to its beneficial effects on cerebral blood flow and minimal seizure-inducing potential. *Sevoflurane* - **Sevoflurane**, while capable of causing excitatory movements or myoclonus during induction and emergence, is not a common cause of clear-cut generalized convulsions in healthy patients. - High concentrations in pediatric patients or those with pre-existing seizure disorders might slightly increase the risk of seizure-like EEG changes, but it is less epileptogenic than enflurane.

Q: Which anesthetic agent is considered the least cardiotoxic?

Sevoflurane. ***Sevoflurane*** - Sevoflurane is known for its **smooth induction** and rapid recovery, making it a common choice, especially in pediatric anesthesia [3]. - It has a relatively **low pungency** and minimal cardiovascular depressant effects compared to other volatile anesthetics, contributing to its favorable cardiotoxicity profile [1], [4]. *Enflurane* - Enflurane can cause **myocardial depression** and may induce **seizures** at higher concentrations, limiting its use [1]. - Its widespread use has decreased due to concerns about its **cardiovascular effects** and potential for **renal toxicity**. *Isoflurane* - While Isoflurane is a commonly used anesthetic, it can cause **coronary steal phenomenon** in patients with coronary artery disease due to its potent vasodilatory effects. - It also causes dose-dependent **myocardial depression** and can increase heart rate, which may be detrimental in some patients [4]. *Halothane* - Halothane is known for significant **myocardial depression**, causing a decrease in cardiac output and systemic vascular resistance [2]. - It also sensitizes the myocardium to **catecholamines**, increasing the risk of arrhythmias, and is associated with **halothane hepatitis**, a rare but severe liver injury [3].

Q: Which of the following factors does not affect the Minimum Alveolar Concentration (MAC) of anesthetics?

Duration of anesthesia. ***Duration of anesthesia*** - **MAC remains constant** once steady state is achieved, regardless of how long the anesthetic has been administered during the procedure. - The concentration needed to prevent movement to surgical stimulus does not change with prolonged exposure, making duration irrelevant to MAC determination. *Species variability* - Different species have **significantly different MAC values** due to variations in receptor sensitivity and CNS organization. - For example, MAC for halothane varies considerably between humans, dogs, and rodents, making species a crucial factor in MAC determination. *Sex differences* - While **minor physiological differences** exist between sexes, sex alone does not significantly alter baseline MAC requirements. - Hormonal influences may cause subtle variations, but sex is not considered a primary determinant of MAC in clinical practice. *Age of the patient* - **MAC significantly decreases with increasing age**, particularly after infancy, due to age-related CNS changes and reduced anesthetic requirements. - **MAC peaks around 6 months of age** in infants, then gradually decreases throughout life, making age one of the most important factors affecting MAC.

Q: Etomidate is not used for long-term infusion because?

Causes adrenal suppression. ***Causes adrenal suppression*** - Etomidate is a **GABA-A agonist** that inhibits the enzyme **11-beta-hydroxylase**, crucial for cortisol synthesis in the adrenal cortex. - This inhibition leads to a dose-dependent and prolonged **adrenal suppression**, making it unsuitable for long-term infusions due to the risk of **adrenal insufficiency** and increased mortality. *May cause vasodilation* - Etomidate is known for its **hemodynamic stability**, causing minimal changes in **heart rate** or **blood pressure**, rather than vasodilation. - It generally maintains **cardiac output** and **systemic vascular resistance**, which is why it's often favored in patients with cardiovascular instability for induction. *Can lead to bradycardia* - Etomidate typically has **minimal effects on heart rate** and sympathetic nervous system activity. - It does not commonly cause **bradycardia** and is often used in patients where myocardial depression or significant heart rate changes are undesirable. *May cause increased intracranial pressure* - Etomidate is known to **reduce cerebral blood flow (CBF)** and **cerebral metabolic rate of oxygen (CMRO2)**. - This action usually leads to a **reduction, not an increase, in intracranial pressure (ICP)**, making it a suitable choice for induction in patients with neurological concerns.

Question 1

What is the intubation dose of pancuronium?

Accepted Answer

0.08 mg/Kg

Answer

0.02 mg/Kg

Answer

0.04 mg/Kg

Answer

0.06 mg/Kg

Question 2

Which of the following intravenous agents is known to cause pain upon injection?

Accepted Answer

Propofol

Answer

Ketamine

Answer

Etomidate

Answer

Methohexital

Question 3

Which organ is most resistant to general anesthesia?

Accepted Answer

Heart

Answer

Spinal Cord

Answer

Medulla oblongata

Answer

Liver

Question 4

What is the percentage of halothane that is metabolized in the human body?

Accepted Answer

25%

Answer

50%

Answer

5%

Answer

2.50%

Question 5

Which of the following determines the speed of recovery from intravenous anesthesia?

Accepted Answer

Redistribution of the drug from sites in the CNS

Answer

Liver metabolism of drug

Answer

Protein binding of drug

Answer

Plasma clearance of the drug

Question 6

Ketamine is the preferred anesthetic for the following conditions except:

Accepted Answer

Hypertensives

Answer

Trauma cases that have bled significantly

Answer

Burn dressing

Answer

Short operations on asthmatics

Question 7

Which of the following should be considered as the cause of generalized convulsions 20 minutes postoperatively?

Accepted Answer

Enflurane

Answer

Halothane

Answer

Isoflurane

Answer

Sevoflurane

Question 8

Which anesthetic agent is considered the least cardiotoxic?

Accepted Answer

Sevoflurane

Answer

Isoflurane

Answer

Enflurane

Answer

Halothane

Question 9

Which of the following factors does not affect the Minimum Alveolar Concentration (MAC) of anesthetics?

Accepted Answer

Duration of anesthesia

Answer

Species variability

Answer

Sex differences

Answer

Age of the patient

Question 10

Etomidate is not used for long-term infusion because?

Accepted Answer

Causes adrenal suppression

Answer

May cause vasodilation

Answer

Can lead to bradycardia

Answer

May cause increased intracranial pressure

General Anesthesia — MCQs

General Anesthesia — MCQs

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