General Anesthesia Practice Questions

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.

Q: Suxamethonium is available as a clear, colourless aqueous solution. What is the shelf life of suxamethonium when stored correctly?

2 years. ***2 years*** - When **stored correctly** (refrigerated between 2-8°C and protected from light), the typical shelf life of suxamethonium is **2 years**. [1] - This stability ensures its effectiveness as a **neuromuscular blocking agent** when needed for medical procedures. [1] *6 months* - A 6-month shelf life is generally too short for the refrigerated, unopened vials of **suxamethonium** from the manufacturer. - This period is more commonly associated with the stability of certain reconstituted or diluted medications. *1 year* - While some medications might have a 1-year shelf life, **suxamethonium** typically has a longer stability period when stored under optimal conditions. - A 1-year shelf life would be relatively short for an unopened, stock solution of this drug. *3 years* - A 3-year shelf life is generally considered too long for **suxamethonium** under standard refrigerated storage conditions. - Most manufacturers specify a 2-year shelf life to maintain drug efficacy and safety.

Q: Action of succinylcholine is potentiated by.

Halothane. ***Halothane*** - **Halothane** is a potent **volatile anesthetic** that inhibits acetylcholinesterase, thus prolonging the presence of **acetylcholine** at the neuromuscular junction. - This inhibition leads to increased **depolarization** and **flaccid paralysis**, thereby enhancing the effects of depolarizing muscle relaxants like succinylcholine. *Nitrous oxide* - **Nitrous oxide** is a weak anesthetic and lacks significant muscle relaxant properties; it does not directly affect the neuromuscular junction or interact with succinylcholine in a potentiating manner. - It is typically used as a **carrier gas** or for its **analgesic** effects rather than for muscle relaxation. *Sevoflurane* - **Sevoflurane** is a volatile anesthetic that produces muscle relaxation but primarily by central mechanisms and by causing some direct effects on muscle cells, rather than through potentiation of succinylcholine at the neuromuscular junction. - While it can be used with neuromuscular blockers, its mechanism of interaction with succinylcholine is not one of direct potentiation in the same way as halothane. *Isoflurane* - **Isoflurane** is a volatile anesthetic that causes muscle relaxation through both central nervous system depression and some direct action on skeletal muscle. - While it can facilitate the action of non-depolarizing muscle relaxants, it does not significantly potentiate the depolarizing effects of succinylcholine like halothane does.

Q: Which inhalational anesthetic is most commonly used for induction in general anesthesia?

Sevoflurane. ***Sevoflurane*** - **Sevoflurane** is preferred for inhalational induction due to its **low pungency** and **rapid onset** and offset of action. - Its favorable pharmacokinetic profile makes it suitable for patients of all ages, including children, for quick and smooth induction without airway irritation. *Desflurane* - **Desflurane** has a **very low blood-gas solubility**, leading to rapid onset and offset, but it is **too pungent** for inhalational induction. - Its high pungency often causes **coughing, salivation, and laryngospasm**, making it unsuitable forawake induction *Enflurane* - **Enflurane** is an older inhalational anesthetic that is **rarely used today** due to its side effects, including the potential for **seizures** and **arrhythmias**. - Its slower onset and higher incidence of adverse effects make it inferior to newer agents for induction. *Nitrous oxide* - **Nitrous oxide** is a weak anesthetic and is typically used as an adjunct to other more potent inhalational agents, not as a primary induction agent. - It has a high **MAC (Minimum Alveolar Concentration)**, meaning it cannot produce surgical anesthesia on its own.

Q: Probable indicators of reversal of neuromuscular blockade are all EXCEPT:

Leg lift for 10 seconds. ***Leg lift for 10 seconds*** - A **leg lift for 10 seconds** is a test of lower limb strength, which can be affected by residual neuromuscular blockade, but it is **not a primary or standard indicator** used to assess the reversal of neuromuscular blockade for airway protection and overall recovery. - While it demonstrates muscle strength, it isn't as critical for assessing readiness for extubation as upper airway and respiratory muscle function tests. *Sustained hand grip for 5 seconds* - **Sustained hand grip for 5 seconds** demonstrates adequate neuromuscular transmission in the forearm muscles and is a generally accepted indicator of reversal of neuromuscular blockade. - It suggests sufficient recovery of peripheral muscles to perform voluntary movements effectively. *Lift head for 5 seconds* - The **ability to lift the head off the bed for 5 seconds** is a crucial clinical test indicating significant recovery of the neck and upper airway muscles, which are vital for maintaining airway patency. - This demonstrates adequate strength in the diaphragm, intercostals, and upper airway muscles, suggesting readiness for extubation. *Ability to perform sustained tongue depressor test* - The **sustained tongue depressor test** involves the patient holding an object between their teeth, indicating sufficient strength of the jaw musculature. - This test is a reliable indicator of adequate neuromuscular recovery in the muscles essential for airway protection and swallowing.

Q: Which of the following statements about propofol is false?

Causes vomiting after use. ***Causes vomiting after use*** - Propofol is actually known for its **antiemetic properties**, meaning it helps reduce or prevent nausea and vomiting after anesthesia. - This statement is false because propofol's effect is typically the opposite of causing vomiting, often being used to mitigate postoperative nausea and vomiting. *Has a rapid recovery rate* - Propofol is indeed characterized by a **rapid onset** and **rapid recovery** profile, making it a popular choice for procedures requiring quick patient awakening. - Its short duration of action is due to its **rapid redistribution** from the brain to other tissues and its high metabolic clearance. *Used for induction & maintenance of anesthesia* - Propofol is widely used as an intravenous anesthetic agent for both the **induction of general anesthesia** and for the **maintenance of anesthesia** through continuous infusion. - It provides a smooth induction and allows for dose-dependent control of anesthetic depth during maintenance. *Causes sedation* - Propofol is a potent sedative-hypnotic agent that causes dose-dependent **central nervous system depression**, leading to sedation and loss of consciousness. - This property is fundamental to its use in anesthesia and conscious sedation procedures.

Q: Which of the following is the most clinically significant statement about propofol?

Safe to use in porphyria. ***Safe to use in porphyria*** - Propofol is considered **safe** for use in patients with **porphyria**, as it does not induce the enzymes involved in heme biosynthesis that can precipitate **porphyric crises**. - This represents the most **clinically significant** information about propofol, as using contraindicated anesthetics in porphyria patients can be life-threatening. *None of the options* - This option is incorrect because "Safe to use in porphyria" is a factually correct and clinically relevant statement about propofol. - Multiple statements about propofol can be correct, making this blanket dismissal inappropriate. *Not indicated in egg allergy* - While propofol contains **egg lecithin** as an emulsifier, **mild egg allergy** is not an absolute contraindication according to current guidelines. - **Severe egg allergy** may require caution and consideration of alternatives, but the statement oversimplifies the clinical reality. *It belongs to the alkyl phenol group* - This statement is **chemically correct** - propofol is indeed an **alkylphenol** compound (2,6-diisopropylphenol). - However, this pharmacological classification has limited **clinical relevance** compared to safety considerations in specific patient populations like those with porphyria.

Q: Which of the following inhalation anesthetics should be avoided in middle ear surgery?

Nitrous oxide. ***Nitrous oxide*** - **Nitrous oxide** rapidly diffuses into air-containing cavities, such as the middle ear, causing an increase in pressure that can disrupt grafts and ossicles, leading to **hearing loss** or **facial nerve damage**. - Its use during tympanoplasty or stapedectomy can lead to **barotrauma** and potential complications for graft survival and successful middle ear reconstruction. *Ether* - **Ether** is an older anesthetic not commonly used today in developed countries due to its flammability, pungency, and slow onset/offset. - While it doesn't specifically cause middle ear pressure changes like nitrous oxide, its general disadvantages make it an unsuitable choice for modern surgical anesthesia. *Isoflurane* - **Isoflurane** is a volatile anesthetic that does not readily diffuse into air-filled cavities in a manner that would significantly increase middle ear pressure. - It is a commonly used intravenous anesthetic for maintaining general anesthesia and would not typically be avoided for middle ear surgery. *Halothane* - **Halothane** is a potent volatile anesthetic but is rarely used now due to concerns about **hepatotoxicity** (halothane hepatitis). - Like other volatile anesthetics (except nitrous oxide), it does not cause rapid and problematic pressure changes within the middle ear.

Question 1

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 2

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

Question 3

Suxamethonium is available as a clear, colourless aqueous solution. What is the shelf life of suxamethonium when stored correctly?

Accepted Answer

2 years

Answer

1 year

Answer

3 years

Answer

6 months

Question 4

Action of succinylcholine is potentiated by.

Accepted Answer

Halothane

Answer

Sevoflurane

Answer

Isoflurane

Answer

Nitrous oxide

Question 5

Which inhalational anesthetic is most commonly used for induction in general anesthesia?

Accepted Answer

Sevoflurane

Answer

Desflurane

Answer

Enflurane

Answer

Nitrous oxide

Question 6

Probable indicators of reversal of neuromuscular blockade are all EXCEPT:

Accepted Answer

Leg lift for 10 seconds

Answer

Sustained hand grip for 5 seconds

Answer

Lift head for 5 seconds

Answer

Ability to perform sustained tongue depressor test

Question 7

Which of the following statements about propofol is false?

Accepted Answer

Causes vomiting after use

Answer

Used for induction & maintenance of anesthesia

Answer

Causes sedation

Answer

Has a rapid recovery rate

Question 8

Which of the following is the most clinically significant statement about propofol?

Accepted Answer

Safe to use in porphyria

Answer

None of the options

Answer

It belongs to the alkyl phenol group

Answer

Contraindicated in patients with egg allergy

Question 9

Which of the following inhalation anesthetics should be avoided in middle ear surgery?

Accepted Answer

Nitrous oxide

Answer

Isoflurane

Answer

Ether

Answer

Halothane

Question 10

What is the electrolyte composition of Ringer's lactate?

Accepted Answer

Na+ 130 mEq/L, Cl- 109 mEq/L, K+ 4 mEq/L, Ca2+ 3 mEq/L, Lactate 29 mEq/L

Answer

Na+ 140 mEq/L, Cl- 103 mEq/L, K+ 4 mEq/L, Lactate 29 mEq/L

Answer

Na+ 135 mEq/L, Cl- 110 mEq/L, K+ 5 mEq/L, Ca2+ 2 mEq/L, Lactate 28 mEq/L

Answer

Na+ 130 mEq/L, Cl- 109 mEq/L, K+ 4 mEq/L, Mg2+ 1.5 mEq/L, Lactate 29 mEq/L

General Anesthesia — MCQs

General Anesthesia — MCQs

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