Neuroanesthesia Practice Questions

Q: Which of the following is the best cerebroprotective drug?

Thiopentone. ***Thiopentone*** - **Thiopentone** is a barbiturate that can significantly reduce cerebral metabolic rate for oxygen (**CMRO2**) and cerebral blood flow (**CBF**), leading to a reduction in intracranial pressure (**ICP**). - It achieves neuroprotection by decreasing brain metabolism, scavenging free radicals, and stabilizing neuronal membranes. *Propofol* - **Propofol** also reduces **CMRO2** and **CBF**, thus decreasing **ICP**, but its neuroprotective effects are less profound and consistent compared to barbiturates like thiopentone. - While it has some neuroprotective properties, such as antioxidant effects, it is not considered the **best** cerebroprotective agent, especially in severe cases where maximum cerebral protection is needed. *Etomidate* - **Etomidate** is known for its minimal cardiovascular effects and its ability to reduce **CMRO2** and **CBF**, which can lower **ICP**. - However, its use is limited by its potential to cause adrenal suppression with prolonged or repeated administration, making it less suitable for continuous cerebroprotection. *Ketamine* - **Ketamine** typically increases **CBF** and **CMRO2**, which can lead to an increase in **ICP**, making it generally unsuitable as a cerebroprotective agent in patients with elevated ICP or acute cerebral injury. - While it has analgesic and dissociative properties, its impact on cerebral hemodynamics often contraindicates its use in situations requiring brain protection.

Q: Thiopentone has cerebroprotective effect because of –

Decrease cerebral metabolism. ***Decrease cerebral metabolism*** - Thiopentone significantly **reduces cerebral metabolic rate** of oxygen consumption (CMRO2) by depressing neuronal activity. - This reduction in metabolic demand makes the brain more resilient to **ischemic injury**, offering a cerebroprotective effect. *Calcium channel blockage* - While some anesthetic agents have calcium channel blocking properties, this is not the primary mechanism behind thiopentone's **cerebroprotective effects**. - Calcium channel blockers are more commonly used for conditions like **hypertension** or certain arrhythmias. *Reduction of vasospasm* - Thiopentone does not primarily act as a **vasodilator** or antispasmodic agent to directly reduce cerebral vasospasm. - Vasospasm reduction is often targeted by therapies like **nimodipine** in specific conditions like subarachnoid hemorrhage. *Free radical removal* - Although **barbiturates** may have some antioxidant properties, free radical scavenging is not the main mechanism for thiopentone's significant cerebroprotection. - The cerebroprotective effect is predominantly due to its **metabolic suppression**.

Q: All of the following decrease cerebral blood flow and intracranial pressure except:

Ketamine. ***Ketamine*** - Ketamine is an exception as it is known to **increase cerebral blood flow (CBF)** and **intracranial pressure (ICP)** due to its dissociative anesthetic properties. - It causes cerebral vasodilation and increased cerebral metabolic rate, making it generally avoided in patients with elevated ICP or head trauma. *Thiopentone* - Thiopentone (a barbiturate) is a potent cerebral vasoconstrictor that **decreases cerebral blood flow (CBF)** and **intracranial pressure (ICP)**. - It achieves this by reducing the cerebral metabolic rate of oxygen consumption (CMRO2), thus coupling metabolism and flow. *Propofol* - Propofol significantly **reduces cerebral blood flow (CBF)** and **intracranial pressure (ICP)** by causing widespread cerebral vasoconstriction. - Its rapid onset and offset, along with its neuroprotective properties, make it a favorable agent for neuroanesthesia. *Etomidate* - Etomidate is an imidazole derivative that causes a significant **reduction in cerebral blood flow (CBF)** and **intracranial pressure (ICP)** comparable to barbiturates. - It achieves this by reducing cerebral metabolic rate and causing cerebral vasoconstriction, without significantly altering systemic hemodynamics.

Q: Increased intracranial pressure occurs with:

Succinylcholine. ***Succinylcholine*** - **Succinylcholine** is known to cause a transient increase in **intracranial pressure (ICP)** due to its fasciculations, which can increase cerebral blood flow and metabolic demand. - This effect is particularly relevant in patients with pre-existing elevated ICP or those at risk of brain herniation. *None of the options* - This option is incorrect because **succinylcholine** does indeed cause an increase in ICP, making one of the listed drugs relevant. *Rocuronium* - **Rocuronium** is a **nondepolarizing neuromuscular blocker** and typically does not significantly increase ICP; it is often considered safe for use in patients with intracranial pathology. - Its mechanism of action does not involve muscle fasciculations, which are the primary reason for ICP elevation with succinylcholine. *Vecuronium* - **Vecuronium** is also a **nondepolarizing neuromuscular blocker** and, like rocuronium, does not typically cause a significant increase in ICP. - It works by blocking acetylcholine receptors at the neuromuscular junction without stimulating them, thus avoiding the fasciculations seen with succinylcholine.

Q: Which of the following anaesthetic agents causes a rise in the Intracranial pressure:

Sevoflurane.. ***Sevoflurane*** - **Sevoflurane** is an inhaled anesthetic that causes cerebral vasodilation, leading to an increase in **cerebral blood flow** and consequently, a rise in **intracranial pressure (ICP)**. - This effect is dose-dependent and can be attenuated by maintaining normocapnia or mild hypocapnia to cause cerebral vasoconstriction. *Propofol* - **Propofol** is an intravenous anesthetic that typically causes a dose-dependent decrease in **cerebral metabolic rate** and **cerebral blood flow**, leading to a reduction in **intracranial pressure (ICP)**. - It is often used for induction and maintenance of anesthesia in critically ill patients with elevated ICP due to its favorable cerebral effects. *Thiopentone sodium* - **Thiopentone sodium** (thiopental) is a barbiturate that significantly reduces **cerebral metabolic rate** and **cerebral blood flow**, thereby **decreasing intracranial pressure (ICP)**. - It is used in neuroanesthesia to protect the brain and lower ICP, particularly in cases of head injury or intracranial hemorrhage. *Lignocaine* - **Lignocaine** (lidocaine) is a local anesthetic that, when administered intravenously, can decrease **cerebral metabolic rate** and **cerebral blood flow**, leading to a **reduction in intracranial pressure (ICP)**. - It is sometimes used as an adjunct in neuroanesthesia for its cerebral protective effects and to blunt airway reflexes, which can otherwise transiently increase ICP.

Q: Increase in ICP is due to:

Ketamine. ***Ketamine*** - **Ketamine** is known to increase **cerebral blood flow** and metabolic rate, which can lead to an increase in **intracranial pressure (ICP)**. - This effect makes ketamine generally contraindicated in patients with pre-existing elevated ICP or neurotrauma. *Prilocaine* - **Prilocaine** is a **local anesthetic** that does not directly cause increases in ICP. - Its metabolism can produce **o-toluidine**, which can cause **methemoglobinemia**, a side effect unrelated to ICP. *Procaine* - **Procaine** is an **ester-type local anesthetic** that primarily functions by blocking nerve impulses. - It does not have a direct mechanism that would lead to increased **intracranial pressure**. *Bupivacaine* - **Bupivacaine** is a **long-acting local anesthetic** commonly used for regional anesthesia. - While it can cause **cardiovascular depression** and **CNS toxicity** in high doses, it does not typically increase **intracranial pressure**.

Q: Which of the following anesthetic agents may have cerebroprotective effect:

All show cerebroprotective effect. ***All show cerebroprotective effect*** - **Barbiturates**, such as **thiopental**, are known for their profound **cerebroprotective effects** by significantly reducing **cerebral metabolic rate** and **intracranial pressure (ICP)**, particularly beneficial during neurological insults. - **Ketamine** can maintain **cerebral blood flow (CBF)** and **metabolic activity**, potentially offering protection against **ischemic damage** in certain contexts. - **Etomidate** is a short-acting hypnotic agent that can effectively lower **cerebral metabolic rate for oxygen (CMRO2)** and ICP, making it useful for neurosurgical procedures. *Ketamine* - While it can be considered **cerebroprotective** in some situations, particularly by maintaining **cerebral blood flow** and thus oxygen delivery, it is typically associated with increased **cerebral blood flow** and **intracranial pressure** which can be detrimental in cases of head injury or space-occupying lesions. - Its effects on **cerebral metabolism** are complex; while it can decrease overall **metabolic demand**, it can paradoxically increase CMRO2 in certain brain regions. *Etomidate* - **Etomidate** is excellent at reducing **cerebral metabolic rate** and **intracranial pressure**, thus offering protection against **ischemic damage**. - Its **cerebroprotective** properties are primarily linked to its ability to decrease global brain metabolic activity without significantly changing **cerebral blood flow**. *Barbiturates* - **Barbiturates** induce a **dose-dependent reduction** in **cerebral metabolic rate of oxygen (CMRO2)** and **cerebral blood flow (CBF)**, leading to a significant decrease in **intracranial pressure (ICP)**. - This property makes them highly valuable for **cerebroprotection** in conditions like **traumatic brain injury** or **ischemic stroke**.

Q: 5 year old child going for sitting craniotomy, while positioning in O.T. developed end tidal CO2- Zero mmHg, PO2- 80 mm Hg implies that :

Venous air embolism. ***Venous air embolism*** - A sudden drop in **end-tidal CO2 (ETCO2)** to zero, coupled with a normal or mildly decreased PO2, in a patient undergoing a sitting craniotomy strongly suggests a venous air embolism. The sitting position and open venous sinuses in neurosurgery create a pressure gradient favoring air entrainment. - While pulmonary issues can cause some ETCO2 changes, a **sudden complete loss** (zero mmHg) is characteristic of a circulatory collapse or severe obstruction to pulmonary blood flow, as seen with significant air emboli. *Left lung collapse* - A left lung collapse (atelectasis) would primarily cause a **decrease in PO2** due to ventilation-perfusion mismatch, and a subsequent **increase in ETCO2** due to increased dead space and shunting, rather than a sudden drop to zero. - While lung collapse can lead to some ETCO2 variations, it would not typically result in a **complete absence** of exhaled CO2. *Endotracheal tube blocked with secretions* - An endotracheal tube blocked with secretions would lead to a significant **increase in peak inspiratory pressures**, **decreased tidal volumes**, and a gradual rather than sudden drop in ETCO2, often to a measurable but low level, not zero. - The patient would also likely exhibit signs of **respiratory distress** and difficulty ventilating, which is not directly indicated by the isolated ETCO2 reading. *Endotracheal tube in Oesophagus* - If the endotracheal tube were in the esophagus, there would be no CO2 entering the breathing circuit from the lungs, leading to an **ETCO2 of zero**. - However, this would also be immediately accompanied by **very low or unmeasurable PO2** because no oxygen would be entering the lungs. The given PO2 of 80 mmHg makes this less likely.

Q: All of the following causes decrease in CMRO2, CBF and ICP except:-

Ketamine. ***Ketamine*** - Ketamine is a dissociative anesthetic that typically causes an **increase in cerebral blood flow (CBF)** and **intracranial pressure (ICP)**, while its effect on cerebral metabolic rate of oxygen (CMRO2) can be variable but often does not decrease significantly. - It works by antagonizing **NMDA receptors**, inducing a state of dissociation rather than global cerebral depression. *Etomidate* - Etomidate is an anesthetic agent that effectively **decreases CMRO2, CBF, and ICP**, making it suitable for neurosurgical procedures. - Its mechanism involves enhancing **GABA-A receptor activity**, leading to global central nervous system depression. *Propofol* - Propofol is a commonly used intravenous anesthetic that significantly **reduces CMRO2, CBF, and ICP**. - It primarily acts on **GABA-A receptors** to induce sedation and anesthesia, making it a good choice for patients with elevated ICP. *Thiopentone* - Thiopentone, a barbiturate, is known to produce a dose-dependent decrease in **CMRO2, CBF, and ICP**. - It also enhances **GABA-A receptor-mediated inhibition**, resulting in cerebral vasoconstriction and metabolic suppression.

Q: Which of the following drugs is contraindicated in a patient with raised intracranial pressure ?

Ketamine. ***Ketamine*** - **Ketamine** typically causes an increase in **cerebral blood flow** and **intracranial pressure (ICP)**, making it contraindicated in patients with raised ICP. - This effect is due to its action as a **dissociative anesthetic** which can lead to cerebral vasodilation. *Midazolam* - **Midazolam**, a benzodiazepine, can decrease **cerebral metabolic rate** and **cerebral blood flow**, thereby reducing ICP, making it a suitable option for sedation in patients with raised ICP. - It provides **sedation** and **anxiolysis** without significantly increasing ICP. *Propofol* - **Propofol** is a common choice for sedation in patients with raised ICP because it significantly reduces **cerebral blood flow**, **cerebral metabolic rate**, and thus **intracranial pressure**. - Its rapid onset and offset allow for precise control of depth of sedation and neurological assessment. *Thiopentone* - **Thiopentone**, a barbiturate, effectively reduces **cerebral blood flow** and **cerebral metabolic rate**, leading to a decrease in **intracranial pressure**. - It is often used for inducing anesthesia and as a neuroprotective agent in situations with acute brain injury.

Question 1

Which of the following is the best cerebroprotective drug?

Accepted Answer

Thiopentone

Answer

Propofol

Answer

Etomidate

Answer

Ketamine

Question 2

Thiopentone has cerebroprotective effect because of –

Accepted Answer

Decrease cerebral metabolism

Answer

Calcium channel blockage

Answer

Reduction of vasospasm

Answer

Free radical removal

Question 3

All of the following decrease cerebral blood flow and intracranial pressure except:

Accepted Answer

Ketamine

Answer

Thiopentone

Answer

Propofol

Answer

Etomidate

Question 4

Increased intracranial pressure occurs with:

Accepted Answer

Succinylcholine

Answer

None of the options

Answer

Rocuronium

Answer

Vecuronium

Question 5

Which of the following anaesthetic agents causes a rise in the Intracranial pressure:

Accepted Answer

Sevoflurane.

Answer

Propofol.

Answer

Thiopentone sodium.

Answer

Lignocaine.

Question 6

Increase in ICP is due to:

Accepted Answer

Ketamine

Answer

Procaine

Answer

Prilocaine

Answer

Bupivacaine

Question 7

Which of the following anesthetic agents may have cerebroprotective effect:

Accepted Answer

All show cerebroprotective effect

Answer

Ketamine

Answer

Etomidate

Answer

Barbiturates

Question 8

5 year old child going for sitting craniotomy, while positioning in O.T. developed end tidal CO2- Zero mmHg, PO2- 80 mm Hg implies that :

Accepted Answer

Venous air embolism

Answer

Left lung collapse

Answer

Endotracheal tube blocked with secretions

Answer

Endotracheal tube in Oesophagus

Question 9

All of the following causes decrease in CMRO2, CBF and ICP except:-

Accepted Answer

Ketamine

Answer

Etomidate

Answer

Propofol

Answer

Thiopentone

Question 10

Which of the following drugs is contraindicated in a patient with raised intracranial pressure ?

Accepted Answer

Ketamine

Answer

Midazolam

Answer

Propofol

Answer

Thiopentone

Neuroanesthesia — MCQs

Neuroanesthesia — MCQs

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