General Anesthesia Practice Questions

Q: Characteristic EEG pattern seen in surgical tolerance stage of anesthesia is?

Delta. ***Delta*** - The surgical tolerance stage of anesthesia is characterized by a **depressed central nervous system**, which manifests as **slow-wave activity** on EEG. - **Delta waves**, defined as 0.5-4 Hz, are indicative of deep sleep or profound CNS depression and are therefore characteristic of surgical anesthesia. *Alpha* - **Alpha waves** (8-13 Hz) are typically associated with a **relaxed, wakeful state** with closed eyes, not surgical anesthesia. - Their presence would indicate insufficient depth of anesthesia, risking intraoperative awareness. *Beta* - **Beta waves** (14-30 Hz) are characteristic of an **awake, alert, and active brain**, or light anesthesia. - Their predominance during surgery would suggest the patient is not adequately anesthetized. *Theta* - **Theta waves** (4-8 Hz) are typically associated with **light sleep**, drowsiness, or certain meditative states. - While slower than alpha waves, they do not signify the deep CNS depression required for surgical tolerance.

Q: Which muscle relaxant has the longest duration of action?

Doxacurium. ***Doxacurium*** - **Doxacurium** is a long-acting, non-depolarizing neuromuscular blocker, meaning it typically has the longest duration of action among the options provided. - Its prolonged effect is due to its **slow metabolism** and **renal excretion**, leading to an estimated duration of action of 90-120 minutes. *Rocuronium* - **Rocuronium** is an intermediate-acting non-depolarizing neuromuscular blocker, with a typical duration of action of 30-40 minutes after an intubating dose. - It has a rapid onset, making it suitable for **rapid sequence intubation**, but its duration is significantly shorter than doxacurium. *Vecuronium* - **Vecuronium** is an intermediate-acting non-depolarizing neuromuscular blocker, similar to rocuronium, with a duration of action around 25-40 minutes. - It is often favored in patients with **renal insufficiency** as it undergoes significant hepatic metabolism and biliary excretion, but its duration is not as long as doxacurium. *Atracurium* - **Atracurium** is an intermediate-acting non-depolarizing neuromuscular blocker, known for its unique metabolism via **Hofmann elimination** and ester hydrolysis, independent of renal or hepatic function. - Its duration of action is typically 20-35 minutes, making it shorter-acting than doxacurium.

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: 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.

Q: Intraocular pressure is increased by which anaesthetic?

Ketamine. ***Ketamine*** - **Ketamine** is known to increase **intraocular pressure (IOP)**, making it generally avoided in patients with glaucoma or penetrating eye injuries. - This effect is thought to be due to its dissociative properties, causing **nystagmus**, and stimulating extraocular muscles. *Nitrous Oxide* - **Nitrous oxide** by itself has minimal or no direct effect on **intraocular pressure (IOP)**. - However, in cases of an air-filled globe (e.g., after retinal detachment surgery), it can increase IOP by expanding the gas bubble. *Isoflurane* - **Isoflurane**, like most volatile anesthetics, typically **decreases intraocular pressure (IOP)**. - This reduction is generally due to its effects on reducing aqueous humor production and increasing uveoscleral outflow. *Propofol* - **Propofol** is known for its ability to **decrease intraocular pressure (IOP)**. - This effect is mediated by a reduction in aqueous humor production and an increase in uveoscleral outflow, making it a favorable choice in ophthalmic surgery.

Q: Which of the following statements about Nitrous Oxide (N2O) is true?

Least potent inhalational anesthetic. **Least potent inhalational anesthetic** - Nitrous oxide has a **high Minimum Alveolar Concentration (MAC)** of approximately 104%, making it the least potent of the commonly used inhalational anesthetics. - Its high MAC means a very high concentration is required to achieve surgical anesthesia, which is why it is typically used as an adjunct to more potent agents. *Lighter than air* - The molecular weight of nitrous oxide (N2O) is 44, which is **heavier than air** (average molecular weight approximately 29 g/mol). - Its density is greater than air, meaning it would tend to sink rather than rise. *Effective muscle relaxant* - Nitrous oxide provides **minimal to no skeletal muscle relaxation** benefits. - If muscle relaxation is required, a neuromuscular blocking agent must be administered separately. *Does not cause diffusion hypoxia* - Nitrous oxide rapidly diffuses out of the blood into the alveoli during emergence, diluting the oxygen and carbon dioxide there. - This rapid diffusion can lead to **diffusion hypoxia** (also known as the "second gas effect"), necessitating the administration of 100% oxygen during recovery to prevent this complication.

Q: Which anesthetic agent is known for providing smooth induction?

Isoflurane. ***Isoflurane*** - **Isoflurane** is frequently chosen for its capacity to induce a **smooth and rapid loss of consciousness**, primarily due to its low blood solubility which facilitates quick changes in anesthetic depth. - Its **minimal irritation** to the respiratory tract and **stable cardiovascular profile** during induction contribute to a smoother process for the patient. *Sevoflurane* - While sevoflurane also offers a **smooth and rapid induction** due to its low solubility, it is sometimes associated with a higher incidence of **airway irritation** (e.g., coughing) compared to isoflurane, especially in children. - It is known for its **pleasant odor**, making it a good choice for mask induction in pediatric patients. *Halothane* - **Halothane** provides a relatively smooth induction but has a higher risk of **hepatotoxicity** and cardiac arrhythmias, which have led to its decreased use. - Its higher blood solubility means a **slower onset and offset** compared to modern volatile agents like isoflurane. *Enflurane* - **Enflurane** can cause **CNS excitation** at deeper levels of anesthesia, potentially leading to seizures, making its induction less smooth and predictable. - It also has a greater potential to cause **myocardial depression** and arrhythmias than isoflurane.

Q: Which inhalational anesthetic agent is known to be hepatotoxic?

Halothane. ***Halothane*** - Halothane is historically known for causing **halothane hepatitis**, a severe and sometimes fatal liver injury. - This toxicity is thought to be due to its metabolism to **trifluoroacetyl (TFA) halides**, which can bind to hepatocyte proteins, leading to an immune reaction. *Enflurane* - Enflurane can cause a small amount of **nephrotoxicity** due to fluoride ion production, but it is not typically associated with significant hepatotoxicity. - Its metabolism is limited, resulting in lower fluoride levels compared to older agents but still can be a concern in patients with renal impairment. *Desflurane* - Desflurane is minimally metabolized and is considered one of the safest inhalational agents in terms of organ toxicity. - Due to its low solubility and rapid elimination, it has a very low risk of causing **organ damage**, including the liver. *Sevoflurane* - Sevoflurane is generally considered safe for the liver and is widely used, particularly in pediatric anesthesia. - While it undergoes some metabolism to fluoride ions, it is not associated with significant **hepatotoxicity** in clinical practice, though it can interact with desiccated CO2 absorbents to produce Compound A.

Q: Which anaesthetic is contraindicated in renal failure?

Methoxyflurane. ***Methoxyflurane*** - Methoxyflurane undergoes significant **metabolism** to produce inorganic **fluoride ions**, which are directly **nephrotoxic**. - This nephrotoxicity can cause **high-output renal failure** with reduced concentrating ability, making it contraindicated in patients with pre-existing renal impairment. *Isoflurane* - Isoflurane is minimally metabolized and produces very low levels of **fluoride ions**, making it generally **safe** for use in patients with renal failure. - Its elimination is primarily via the **lungs**, with very little hepatic metabolism or renal excretion of active compounds. *Desflurane* - Desflurane is also minimally metabolized, similar to isoflurane, and therefore produces negligible amounts of **fluoride ions**. - It is considered a **safe option** for patients with renal impairment due to its predominantly pulmonary elimination and lack of nephrotoxic metabolites. *Halothane* - While halothane can cause **hepatotoxicity**, it is generally **not directly nephrotoxic** in the way methoxyflurane is. - Its metabolism, though more extensive than isoflurane or desflurane, does not produce clinically significant levels of nephrotoxic fluoride ions to contraindicate its use in renal failure.

Question 1

Characteristic EEG pattern seen in surgical tolerance stage of anesthesia is?

Accepted Answer

Delta

Answer

Alpha

Answer

Beta

Answer

Theta

Question 2

Which muscle relaxant has the longest duration of action?

Accepted Answer

Doxacurium

Answer

Rocuronium

Answer

Vecuronium

Answer

Atracurium

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

What is a significant disadvantage of ketamine?

Accepted Answer

Delirium

Answer

Increased heart rate

Answer

Increased ICT

Answer

All of the options

Question 6

Intraocular pressure is increased by which anaesthetic?

Accepted Answer

Ketamine

Answer

Nitrous Oxide

Answer

Isoflurane

Answer

Propofol

Question 7

Which of the following statements about Nitrous Oxide (N2O) is true?

Accepted Answer

Least potent inhalational anesthetic

Answer

Lighter than air

Answer

Effective muscle relaxant

Answer

Does not cause diffusion hypoxia

Question 8

Which anesthetic agent is known for providing smooth induction?

Accepted Answer

Isoflurane

Answer

Halothane

Answer

Enflurane

Answer

Sevoflurane

Question 9

Which inhalational anesthetic agent is known to be hepatotoxic?

Accepted Answer

Halothane

Answer

Enflurane

Answer

Desflurane

Answer

Sevoflurane

Question 10

Which anaesthetic is contraindicated in renal failure?

Accepted Answer

Methoxyflurane

Answer

Isoflurane

Answer

Desflurane

Answer

Halothane

General Anesthesia — MCQs

General Anesthesia — MCQs

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