Regional Anesthesia Practice Questions

Q: A 30-year-old lady is to undergo surgery under intravenous regional anesthesia for her left trigger finger. Which one of the following should not be used for the patient?

Bupivacaine. **Explanation:** The question describes **Intravenous Regional Anesthesia (IVRA)**, also known as a **Bier Block**. This technique involves injecting local anesthetic into the venous system of a limb distal to a double-tourniquet. **Why Bupivacaine is contraindicated (The Correct Answer):** Bupivacaine is strictly contraindicated in IVRA due to its high **cardiotoxicity**. It has a high affinity for myocardial sodium channels and dissociates slowly during diastole ("fast-in, slow-out" kinetics). If the tourniquet fails or is released prematurely, a large bolus of bupivacaine enters the systemic circulation, potentially causing refractory ventricular arrhythmias and cardiac arrest that is notoriously difficult to resuscitate. **Analysis of Incorrect Options:** * **Lignocaine (A):** This is the **gold standard** and most commonly used drug for IVRA (usually 0.5% preservative-free). It has a rapid onset and a safer systemic profile compared to bupivacaine. * **Prilocaine (C):** This is considered the **safest** drug for IVRA due to its high therapeutic index and rapid metabolism. However, in high doses (>600mg), it carries a risk of methemoglobinemia. * **Lignocaine + Ketorolac (D):** Adjuvants are often added to lignocaine in IVRA to improve the quality of the block and provide post-operative analgesia. Ketorolac (an NSAID) is a common and safe additive for this purpose. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** IVRA works by the diffusion of anesthetic from the vascular bed into adjacent nerve endings. * **Tourniquet Time:** Minimum inflation time is **20 minutes** (to prevent systemic toxicity) and maximum is **90 minutes** (to prevent nerve injury/ischemia). * **Chloroprocaine:** Not used in IVRA due to a high incidence of thrombophlebitis. * **Ropivacaine:** Generally avoided in IVRA as it is also associated with potential CNS and cardiac toxicity, though less so than bupivacaine.

Q: Which of the following is NOT an approach used for a brachial plexus block?

3 in 1 block. **Explanation:** The **3-in-1 block** (Winnie’s technique) is an approach used for the **lumbar plexus**, not the brachial plexus. It involves injecting local anesthetic into the femoral nerve sheath, where it is intended to track cranially to block the **femoral, lateral femoral cutaneous, and obturator nerves**. In modern practice, this has largely been superseded by the Fascia Iliaca Compartment Block (FICB). **Analysis of Brachial Plexus Approaches:** The brachial plexus (C5-T1) can be blocked at various levels depending on the surgical site: * **Interscalene (Option B):** Performed at the level of the roots/trunks between the anterior and middle scalene muscles. It is the gold standard for shoulder surgeries but often misses the ulnar nerve (C8-T1). * **Supraclavicular:** Performed at the level of the divisions ("Spinal of the upper limb"). It provides the most dense block for the entire arm. * **Infraclavicular:** Performed at the level of the cords. * **Axillary (Option D):** Performed at the level of the terminal branches. It is safest for forearm and hand surgery as it avoids the risk of phrenic nerve palsy or pneumothorax. * **Suprascapular (Option A):** While often used as an adjunct for shoulder pain, it targets a specific branch arising from the upper trunk of the brachial plexus. **High-Yield Clinical Pearls for NEET-PG:** * **Phrenic Nerve Palsy:** Occurs in 100% of cases with the Interscalene approach; therefore, it is contraindicated in patients with severe COPD. * **Horner’s Syndrome:** A common side effect of interscalene and supraclavicular blocks due to the proximity of the stellate ganglion. * **Pneumothorax:** The most dreaded complication of the supraclavicular approach. * **Ulnar Sparing:** Most common in the Interscalene approach.

Q: In spinal anesthesia, the drug is deposited between which anatomical layers?

Pia mater and arachnoid mater. **Explanation:** In spinal anesthesia (Subarachnoid Block), the local anesthetic is injected into the **subarachnoid space**, which contains cerebrospinal fluid (CSF). Anatomically, this space is located between the **Pia mater** (the innermost layer closely adherent to the spinal cord) and the **Arachnoid mater** (the middle layer). **Analysis of Options:** * **Option A (Correct):** The subarachnoid space lies between the pia and arachnoid mater. Depositing the drug here allows it to mix with CSF and act directly on the spinal nerve roots. * **Option B (Incorrect):** The space between the dura mater and arachnoid mater is the **subdural space**. This is a potential space; accidental injection here results in a "failed spinal" or an unpredictable, patchy block. * **Option C (Incorrect):** The space between the dura mater and the vertebrae (ligamentum flavum) is the **epidural space**. This is the site for epidural anesthesia, not spinal anesthesia. * **Option D (Incorrect):** Injecting directly into the spinal cord would cause permanent neurological damage (conus medullaris injury). To avoid this, spinal anesthesia is typically performed below the level of **L2** in adults (where the cord ends). **High-Yield Clinical Pearls for NEET-PG:** * **Layers pierced during Spinal Anesthesia (Outside to Inside):** Skin → Subcutaneous tissue → Supraspinous ligament → Interspinous ligament → Ligamentum flavum → Epidural space → Dura mater → Arachnoid mater → **Subarachnoid space**. * **Endpoint:** The hallmark of successful entry into the subarachnoid space is the **clear backflow of CSF** from the needle hub. * **Level of Termination:** Spinal cord ends at **L1-L2** in adults and **L3** in infants. The dural sac ends at **S2**.

Q: High spinal anesthesia is associated with which of the following hemodynamic changes?

Decreased blood pressure and decreased heart rate. **Explanation:** High spinal anesthesia (typically defined as a block extending above the T4 level) results in a dual mechanism of hemodynamic depression: 1. **Decreased Blood Pressure:** The primary cause is the blockade of **preganglionic sympathetic fibers (T1–L2)**. This leads to arterial and venous vasodilation. Venous pooling reduces venous return (preload), which subsequently decreases cardiac output and blood pressure. 2. **Decreased Heart Rate:** While low spinal blocks often cause a compensatory tachycardia, a **high spinal** blocks the **cardioaccelerator fibers (T1–T4)**. This removes sympathetic drive to the heart, allowing parasympathetic (vagal) tone to dominate, resulting in bradycardia. Additionally, decreased venous return reduces stretch on right atrial baroreceptors (Bainbridge reflex), further lowering the heart rate. **Analysis of Incorrect Options:** * **Option B & D:** These are incorrect because sympathetic blockade inherently causes vasodilation, making an increase in blood pressure physiologically impossible under normal spinal anesthesia. * **Option C:** This describes the typical compensatory response seen in *low* spinal or hypovolemic states. In a *high* spinal, the blockade of T1–T4 prevents this compensatory tachycardia from occurring. **High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of Threes":** Sympathetic block is usually 2–3 segments higher than the sensory block, which is 2–3 segments higher than the motor block. * **Bezold-Jarisch Reflex:** This triad of bradycardia, hypotension, and cardiovascular collapse can occur during spinal anesthesia due to low ventricular volume triggering inhibitory receptors. * **Treatment:** The drug of choice for hypotension with bradycardia in high spinal is **Ephedrine** (indirect-acting sympathomimetic) or **Atropine**. If only BP is low but HR is normal/high, **Phenylephrine** may be used.

Q: Which of the following is NOT an advantage of epidural anesthesia?

Slow onset. **Explanation:** In the context of anesthesia, an "advantage" refers to a beneficial clinical outcome. **Slow onset** is considered a **disadvantage** or a limitation of epidural anesthesia compared to spinal anesthesia. While spinal anesthesia acts almost instantly, an epidural requires 15–20 minutes for the drug to diffuse across the dural cuff and reach the nerve roots. **Analysis of Options:** * **A. Adequate analgesia:** This is a primary advantage. Epidurals provide excellent sensory blockade and can be maintained postoperatively via a catheter for continuous pain relief. * **B. Reduced blood loss:** Regional anesthesia (both spinal and epidural) causes sympathetic blockade leading to vasodilation and hypotension in the surgical field, which significantly reduces intraoperative blood loss compared to general anesthesia. * **C. Reduced stress response:** By blocking afferent painful stimuli from reaching the brain, epidurals blunt the neuroendocrine "stress response" (release of catecholamines, cortisol, and ADH), leading to better metabolic stability and reduced cardiac demand. **High-Yield NEET-PG Pearls:** * **Site of Action:** The primary site of action for epidural anesthesia is the **spinal nerve roots** as they exit the dura. * **Segmental Block:** Unlike spinal anesthesia, epidurals allow for a "segmental block," where only specific dermatomes are targeted (e.g., thoracic epidural for abdominal surgery). * **Test Dose:** A standard test dose (3 mL of 1.5% Lignocaine with 1:200,000 Adrenaline) is used to rule out accidental intravascular or intrathecal injection. * **Comparison:** Spinal anesthesia has a faster onset, denser block, and higher risk of PDPH (Post-Dural Puncture Headache), whereas epidural anesthesia offers more hemodynamic stability due to its slower onset of sympathetic block.

Q: Which anesthetic agent is contraindicated for intrathecal use?

Remifentanyl. **Explanation:** The correct answer is **Remifentanil**. The primary reason Remifentanil is contraindicated for intrathecal (spinal) or epidural administration is its formulation. Remifentanil is buffered with **glycine**, an inhibitory neurotransmitter. When injected into the subarachnoid space, glycine can cause profound **neurotoxicity**, leading to motor dysfunction and potential spinal cord damage. Furthermore, Remifentanil’s unique pharmacokinetic profile—ultra-short duration due to rapid metabolism by non-specific plasma esterases—makes it impractical for regional anesthesia, where a sustained effect is usually desired. **Analysis of Incorrect Options:** * **Fentanyl (Option A):** A highly lipophilic opioid commonly used as an adjuvant in spinal anesthesia. It provides rapid onset of analgesia and reduces the dose requirement of local anesthetics. * **Sufentanil (Option C):** Even more lipophilic than fentanyl, it is frequently used intrathecally, especially in obstetric analgesia, due to its high potency and rapid onset. * **Alfentanil (Option D):** While less common than fentanyl, it is preservative-free and can be used neuraxially without the neurotoxic risks associated with Remifentanil. **High-Yield Clinical Pearls for NEET-PG:** * **The "Glycine" Rule:** Always remember that Remifentanil = Glycine = Neurotoxicity in the CNS. * **Metabolism:** Remifentanil is the only opioid metabolized by **plasma and tissue esterases**, giving it a predictable context-sensitive half-life of ~3–4 minutes, regardless of infusion duration. * **Preservatives:** Many drugs (like certain formulations of Lidocaine or Bupivacaine) are contraindicated intrathecally if they contain preservatives like **methylparaben** or **sodium metabisulfite** due to the risk of arachnoiditis.

Q: What is the drug of choice for Bier's block?

Lidocaine. **Explanation:** **Bier’s Block (Intravenous Regional Anesthesia - IVRA)** involves the injection of a local anesthetic into the venous system of an extremity that has been isolated from the systemic circulation using a pneumatic tourniquet. **Why Lidocaine is the Correct Answer:** Lidocaine (0.5%) is the **drug of choice** for Bier’s block due to its excellent safety profile, rapid onset, and moderate duration of action. It provides reliable sensory and motor blockade with a low risk of systemic toxicity once the tourniquet is deflated, as it rapidly redistributes and is metabolized. **Analysis of Incorrect Options:** * **Prilocaine:** While Prilocaine is actually considered the safest drug for IVRA in many international guidelines (due to its high therapeutic index), it is **not** the most commonly used or the standard "textbook" answer in the context of Indian medical exams unless specifically asked for the "safest" drug. Furthermore, it carries a risk of **methemoglobinemia**. * **Bupivacaine:** This is **strictly contraindicated** in Bier’s block. Bupivacaine is highly cardiotoxic; if the tourniquet fails or is released prematurely, the sudden systemic bolus can lead to fatal arrhythmias and cardiac arrest that is notoriously difficult to resuscitate. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** The anesthetic works by diffusing from the vascular bed into adjacent nerve endings and trunks. * **Tourniquet Time:** The tourniquet must remain inflated for at least **20 minutes** to allow for tissue fixation of the drug, preventing a toxic systemic bolus upon release. * **Maximum Time:** Should not exceed 90 minutes to avoid nerve injury and ischemia. * **Chloroprocaine:** Avoided in IVRA due to a high incidence of thrombophlebitis.

Q: Which technique is used for a closed mouth mandibular nerve block?

Akinosi-Vazarani technique. The **Akinosi-Vazirani technique** is the correct answer as it is specifically designed as a **closed-mouth approach** to the mandibular nerve block. ### 1. Why Akinosi-Vazirani is Correct This technique is primarily indicated for patients with **trismus** (limited mouth opening) or when the landmarks for a standard inferior alveolar nerve block (IANB) are obscured. The needle is inserted at the level of the maxillary mucogingival junction, parallel to the occlusal plane, into the pterygomandibular space while the teeth are in occlusion. It anesthetizes the inferior alveolar, lingual, and mylohyoid nerves. ### 2. Analysis of Incorrect Options * **Gow-Gates Technique:** This is an **open-mouth** technique. It is considered a "true" mandibular block because it targets the neck of the mandibular condyle, anesthetizing almost all branches of the mandibular nerve (V3). It has a higher success rate than IANB but requires the patient to open wide. * **Clark and Holmes Technique:** This is a variation of the IANB but is not the standard closed-mouth approach. * **Angelo Sargenti Technique:** This refers to a controversial endodontic method (N2 paste) involving root canal filling materials containing formaldehyde, unrelated to nerve block techniques. ### 3. Clinical Pearls for NEET-PG * **Landmark for Akinosi:** Maxillary tuberosity at the level of the mucogingival junction. * **Landmark for Gow-Gates:** Intertragic notch and the mesiopalatal cusp of the maxillary second molar. * **Highest Success Rate:** Gow-Gates (due to lower anatomical variation at the condyle). * **Highest Aspiration Risk:** Standard IANB (approx. 10–15%). * **Nerves spared in IANB but caught in Gow-Gates:** Buccal nerve and auriculotemporal nerve.

Q: Which of the following is true about spinal anesthesia?

Anesthesia is injected in the subarachnoid space. **Explanation:** **Correct Answer: B. Anesthesia is injected in the subarachnoid space** Spinal anesthesia (Subarachnoid Block) involves the injection of a local anesthetic into the **subarachnoid space** (between the arachnoid mater and pia mater), where it mixes with the cerebrospinal fluid (CSF). This results in a rapid, predictable, and dense sensory and motor blockade by acting directly on the spinal nerve roots. **Analysis of Incorrect Options:** * **Option A:** The onset of spinal anesthesia is very rapid, typically occurring within **2–5 minutes**. A 15-minute onset is more characteristic of epidural anesthesia. * **Option C:** While PDPH is a classic complication, the **most common** complication of spinal anesthesia is **hypotension** (due to sympathetic blockade causing peripheral vasodilation). * **Option D:** Spinal anesthesia typically leads to **bradycardia** (not tachycardia). This occurs due to the blockade of "cardio-accelerator" fibers (T1–T4) and a decrease in venous return (Bainbridge reflex). **High-Yield Clinical Pearls for NEET-PG:** * **Level of Injection:** Usually performed at L3-L4 or L4-L5 to avoid spinal cord injury (the cord ends at **L1** in adults and **L3** in infants). * **PDPH Management:** Characterized by a "postural" headache. Conservative management includes bed rest and hydration; the definitive treatment is an **Epidural Blood Patch**. * **Order of Blockade:** B-fibers (Sympathetic) > A-delta & C fibers (Pain/Temp) > A-gamma (Muscle spindle) > A-beta (Touch/Pressure) > A-alpha (Motor). * **Specific Gravity:** Hyperbaric solutions (dextrose added) are most commonly used to control the spread of the block via gravity.

Question 1

A 30-year-old lady is to undergo surgery under intravenous regional anesthesia for her left trigger finger. Which one of the following should not be used for the patient?

Accepted Answer

Bupivacaine

Answer

Lignocaine

Answer

Prilocaine

Answer

Lignocaine + ketorolac

Question 2

Which of the following is NOT an approach used for a brachial plexus block?

Accepted Answer

3 in 1 block

Answer

Suprascapular

Answer

Interscalene

Answer

Axillary

Question 3

In spinal anesthesia, the drug is deposited between which anatomical layers?

Accepted Answer

Pia mater and arachnoid mater

Answer

Dura mater and arachnoid mater

Answer

Dura mater and vertebrae

Answer

Into the spinal cord

Question 4

High spinal anesthesia is associated with which of the following hemodynamic changes?

Accepted Answer

Decreased blood pressure and decreased heart rate

Answer

Increased blood pressure and decreased heart rate

Answer

Decreased blood pressure and increased heart rate

Answer

Increased blood pressure and increased heart rate

Question 5

Which of the following is NOT an advantage of epidural anesthesia?

Accepted Answer

Slow onset

Answer

Adequate analgesia

Answer

Reduced blood loss

Answer

Reduced stress response of surgery

Question 6

A 28-year-old pregnant woman is admitted to the obstetrics department for delivery. During the final stages of labor, a caudal anesthetic is administered via the sacral hiatus. Into which of the following spaces in the sacral canal is the anesthetic placed?

Accepted Answer

Epidural space

Answer

Vertebral canal

Answer

Vertebral venous plexus

Answer

Subarachnoid space

Question 7

Which anesthetic agent is contraindicated for intrathecal use?

Accepted Answer

Remifentanyl

Answer

Fentanyl

Answer

Sufentanil

Answer

Alfentanil

Question 8

What is the drug of choice for Bier's block?

Accepted Answer

Lidocaine

Answer

Prilocaine

Answer

Bupivacaine

Answer

None of the above

Question 9

Which technique is used for a closed mouth mandibular nerve block?

Accepted Answer

Akinosi-Vazarani technique

Answer

Clark and Holmes technique

Answer

Gow gates technique

Answer

Angelio Sergenti technique

Question 10

Which of the following is true about spinal anesthesia?

Accepted Answer

Anesthesia is injected in the subarachnoid space

Answer

Onset of analgesia takes about 15 minutes

Answer

Most common complication is post-dural puncture headache (PDPH)

Answer

May lead to intra-operative tachycardia

Regional Anesthesia — MCQs

Regional Anesthesia — MCQs

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