Regional Anesthesia Practice Questions

Q: For which surgical area is a supraclavicular block indicated?

Arm. **Explanation:** The **supraclavicular block** is often referred to as the "spinal of the upper limb" because it provides dense, rapid-onset anesthesia for the entire arm. At the level of the supraclavicular fossa, the brachial plexus is most compact, consisting of three divisions. This anatomical arrangement allows for a reliable block of the **arm, elbow, forearm, and hand**. **Why the options are correct/incorrect:** * **Arm (Correct):** The supraclavicular approach targets the plexus where the divisions are tightly bundled, ensuring anesthesia of the musculocutaneous, radial, ulnar, and median nerves. It is the gold standard for surgeries involving the mid-humerus down to the hand. * **Shoulder (Incorrect):** While it can provide some coverage, the **interscalene block** is the preferred choice for shoulder surgery. The supraclavicular block often misses the suprascapular nerve and the cervical plexus branches (C3-C4) required for complete shoulder anesthesia. * **Neck (Incorrect):** The neck is supplied by the **cervical plexus**, not the brachial plexus. * **Forearm (Incorrect):** While the block *does* cover the forearm, the question asks for the primary surgical area indication. In NEET-PG contexts, if "Arm" is an option, it represents the most proximal extent of the block's reliable coverage compared to more distal blocks like the infraclavicular or axillary blocks. **High-Yield Clinical Pearls for NEET-PG:** 1. **Anatomy:** The plexus is located posterior and superior to the **subclavian artery**. 2. **Complications:** The most classic complication is **pneumothorax** (due to the proximity of the cupula of the lung). Other risks include Horner’s syndrome and phrenic nerve palsy (though less common than in interscalene blocks). 3. **Contraindication:** It should be avoided in patients with severe underlying lung disease (COPD) due to the risk of accidental phrenic nerve block or pneumothorax.

Q: Following injection of local anesthesia for lower molar extraction using a classical inferior alveolar nerve block, which space has the highest chance of infection?

Pterygomandibular space. **Explanation:** The **Pterygomandibular space** is the correct answer because it is the specific anatomical site where the local anesthetic is deposited during a classical inferior alveolar nerve block (IANB). **1. Why Pterygomandibular Space is Correct:** The IANB aims to deposit anesthesia near the mandibular foramen. This foramen is located within the pterygomandibular space, which is bounded laterally by the ramus of the mandible and medially by the medial pterygoid muscle. If the needle is contaminated or if an infection is present at the injection site, the needle can track microorganisms directly into this potential space, leading to a pterygomandibular space abscess. **2. Why Other Options are Incorrect:** * **Lateral pharyngeal / Parapharyngeal space:** These terms are often used interchangeably. While the pterygomandibular space communicates posteriorly with the parapharyngeal space, it is not the primary site of deposition. Infection here is usually a secondary spread from the pterygomandibular space or tonsillar infections. * **Pretracheal space:** This is located in the neck, anterior to the trachea. It is anatomically distant from the site of a dental block and is typically involved in infections originating from the thyroid, esophagus, or trachea. **High-Yield Clinical Pearls for NEET-PG:** * **Boundaries:** Pterygomandibular space contains the Inferior Alveolar Nerve, Artery, and Vein, and the Lingual Nerve. * **Trismus:** A common sign of infection or hematoma in this space is trismus (difficulty opening the mouth) due to irritation of the medial pterygoid muscle. * **Needle Landmark:** The needle passes through the buccinator muscle to reach this space during an IANB.

Q: Levo-bupivacaine is administered by which of the following routes?

Epidural. **Explanation:** **Levo-bupivacaine** is the S-enantiomer of the amide local anesthetic bupivacaine. It is primarily used for **regional anesthesia**, specifically via the **epidural route**, spinal anesthesia, and peripheral nerve blocks. **Why Epidural is Correct:** Levo-bupivacaine works by blocking sodium channels in nerve fibers, preventing the propagation of action potentials. It is preferred for epidural administration in obstetrics and major surgeries because it provides excellent sensory blockade with a longer duration of action. Crucially, it has a **lower risk of cardiotoxicity and neurotoxicity** compared to racemic bupivacaine, making it a safer profile for high-volume regional blocks. **Why Other Options are Incorrect:** * **Nasogastric:** Local anesthetics are not administered via NG tubes as they are intended for site-specific nerve blockade, not systemic absorption through the GI tract. * **Intravenous:** Intravenous administration of potent local anesthetics like bupivacaine is strictly avoided (except for specific uses of Lidocaine) because it can lead to **Local Anesthetic Systemic Toxicity (LAST)**, resulting in seizures and fatal cardiac arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Safety Profile:** Levo-bupivacaine and Ropivacaine are "pure isomers" developed to reduce the cardiac side effects associated with the R-isomer of bupivacaine. * **Differential Block:** It provides a better "differential block" (sensory block > motor block), which is ideal for "walking epidurals" in labor analgesia. * **Toxicity Management:** If accidental IV injection occurs leading to toxicity, the antidote of choice is **20% Intralipid (Lipid Emulsion Therapy)**.

Q: What is the maximum safe dose of bupivacaine?

2 mg/kg. **Explanation:** Bupivacaine is a potent, long-acting amide local anesthetic. The maximum safe dose of bupivacaine is **2 mg/kg** (without epinephrine) and up to **2.5–3 mg/kg** (with epinephrine). This limit is strictly observed because bupivacaine is significantly more **cardiotoxic** than other local anesthetics like lidocaine. It binds strongly to sodium channels in the myocardium and dissociates slowly during diastole (the "fast-in, slow-out" phenomenon), leading to refractory ventricular arrhythmias and cardiovascular collapse. **Analysis of Options:** * **Option A (1 mg/kg):** This is an underestimation. While conservative, it is below the established clinical safety threshold for a healthy adult. * **Option B (2 mg/kg):** **Correct.** This is the standard maximum recommended dose for plain bupivacaine to avoid Local Anesthetic Systemic Toxicity (LAST). * **Option C (3 mg/kg):** This dose is generally considered the upper limit only when bupivacaine is combined with **epinephrine**, which slows systemic absorption through vasoconstriction. * **Option D (5 mg/kg):** This is the maximum safe dose for **Lidocaine (plain)**. Using this dose for bupivacaine would almost certainly result in fatal toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Cardiotoxicity:** Bupivacaine has a low therapeutic index. The CC/CNS ratio (dose required for cardiovascular collapse vs. seizures) is lower for bupivacaine (~2.0) than lidocaine (~7.0). * **Antidote:** In case of LAST, the specific treatment is **20% Intravenous Lipid Emulsion (ILE)** therapy. * **Levobupivacaine & Ropivacaine:** These are S-enantiomers developed to provide similar anesthesia with significantly reduced cardio- and neurotoxicity compared to racemic bupivacaine. * **Maximum Dose of Lidocaine:** 5 mg/kg (plain) and 7 mg/kg (with epinephrine).

Q: The segmental level of spinal anesthesia depends on which of the following factors?

All of the above. The level of a spinal block (the dermatomal spread of local anesthetic within the subarachnoid space) is determined by a complex interplay of drug characteristics, patient factors, and procedural techniques. **Explanation of Factors:** 1. **Specific Gravity (Baricity):** This is the most critical factor. The relationship between the density of the local anesthetic and the density of cerebrospinal fluid (CSF) determines how the drug moves. **Hyperbaric** solutions (denser than CSF, usually containing glucose) sink to dependent areas, while **hypobaric** solutions rise. 2. **Posture of the Patient:** Because of baricity, the patient's position during and immediately after injection dictates the spread. For example, if a hyperbaric drug is injected while the patient is sitting, it will settle toward the sacral fibers (Saddle block). If the patient is placed in the Trendelenburg position, the drug will spread cephalad (toward the head). 3. **Volume and Dose:** While baricity is dominant, the total volume and dose of the local anesthetic also influence the height of the block. A larger volume creates a greater pressure gradient and physical displacement within the fixed space of the spinal canal, typically leading to a higher level. **High-Yield Clinical Pearls for NEET-PG:** * **Most Important Factor:** Baricity (Specific Gravity) is considered the single most important factor for determining spread. * **CSF Volume:** Low CSF volume (seen in obesity, pregnancy, or the elderly) is associated with a higher level of block for a given dose. * **Site of Injection:** Unlike epidural anesthesia, the site of injection (e.g., L3-L4 vs. L4-L5) has a minimal effect on the final level of spinal anesthesia. * **Drug Concentration:** Concentration alone does not affect the level of spread, but it does affect the **quality and duration** of the motor and sensory block.

Q: Which was the first local anesthetic used for spinal block?

Cocaine. **Explanation:** The correct answer is **Cocaine (Option A)**. Cocaine, an alkaloid derived from the coca leaf, was the first local anesthetic discovered. Its journey into spinal anesthesia began after **Carl Koller** first demonstrated its topical analgesic properties in ophthalmology (1884). In **1898, August Bier** performed the first successful clinical spinal anesthetic using intrathecal cocaine, famously testing it on himself and his assistant. **Analysis of Incorrect Options:** * **B. Procaine:** Synthesized by Alfred Einhorn in 1905 (as Novocaine), it was the first synthetic ester local anesthetic. While it replaced cocaine due to lower toxicity and lack of addiction potential, it was not the first used. * **C. Prilocaine:** An amide local anesthetic developed much later (1950s). It is clinically significant for its association with methemoglobinemia but has no role in the history of the first spinal block. * **D. Lignocaine (Lidocaine):** Synthesized by Nils Löfgren in 1943, it is the "gold standard" amide anesthetic. While widely used for spinal anesthesia today, it was developed decades after the initial discovery of spinal blocks. **High-Yield Clinical Pearls for NEET-PG:** * **August Bier** is known as the "Father of Spinal Anesthesia." * **Corning** (1885) is often credited with the first experimental (though likely peridural) injection, but Bier (1898) is credited with the first intentional spinal block. * **Cocaine** is the only naturally occurring local anesthetic and the only one with significant **vasoconstrictive** properties (inhibits norepinephrine reuptake). * **Sequence of discovery:** Cocaine (1884) → Procaine (1905) → Lidocaine (1943) → Bupivacaine (1957).

Q: All of the following are signs of successful stellate ganglion block, except:

Mydriasis. **Explanation:** A **Stellate Ganglion Block (SGB)** involves injecting local anesthetic near the stellate ganglion (formed by the fusion of the inferior cervical and first thoracic sympathetic ganglia). This procedure results in a **sympathetic blockade** of the head, neck, and upper extremity. **Why Mydriasis is the Correct Answer:** The sympathetic nervous system is responsible for pupillary dilation (mydriasis). When the stellate ganglion is blocked, sympathetic outflow is interrupted, leading to the dominance of parasympathetic activity. This results in **Miosis** (constriction of the pupil), not mydriasis. Miosis is a hallmark component of **Horner’s Syndrome**, which signifies a successful block. **Analysis of Incorrect Options:** * **Flushing of the face (A):** Sympathetic blockade causes vasodilation of the cutaneous blood vessels in the head and neck, leading to facial flushing and increased skin temperature. * **Conjunctival congestion (B):** Vasodilation of the conjunctival vessels occurs due to the loss of sympathetic vasoconstrictor tone. * **Nasal stuffiness (D):** Also known as **Guttman’s sign**, this occurs due to the engorgement of the nasal mucosa following sympathetic blockade. **High-Yield Clinical Pearls for NEET-PG:** * **Horner’s Syndrome Tetrad:** Miosis (constricted pupil), Ptosis (drooping eyelid), Anhidrosis (lack of sweating), and Enophthalmos (apparent sinking of the eyeball). * **Anatomical Landmark:** The block is typically performed at the level of the **C6 transverse process (Chassaignac’s tubercle)**. * **Complications:** Accidental vertebral artery injection (seizures), phrenic nerve block (diaphragmatic palsy), and recurrent laryngeal nerve block (hoarseness).

Question 1

For which surgical area is a supraclavicular block indicated?

Accepted Answer

Arm

Answer

Shoulder

Answer

Neck

Answer

Forearm

Question 2

What is the most commonly used local anesthetic for intravenous regional anesthesia (Bier's block)?

Accepted Answer

Lignocaine

Answer

Bupivacaine

Answer

Prilocaine

Answer

Chloroprocaine

Question 3

Following injection of local anesthesia for lower molar extraction using a classical inferior alveolar nerve block, which space has the highest chance of infection?

Accepted Answer

Pterygomandibular space

Answer

Lateral pharyngeal space

Answer

Parapharyngeal space

Answer

Pretracheal space

Question 4

A patient presents with trismus. Which of the following techniques will block the mylohyoid nerve, incisive nerve, and long buccal nerve?

Accepted Answer

Akinosi technique

Answer

Gow-Gates technique

Answer

V-block technique

Answer

Conventional inferior alveolar nerve block

Question 5

Levo-bupivacaine is administered by which of the following routes?

Accepted Answer

Epidural

Answer

Nasogastric

Answer

Intravenous

Answer

All

Question 6

What is the maximum safe dose of bupivacaine?

Accepted Answer

2 mg/kg

Answer

1 mg/kg

Answer

3 mg/kg

Answer

5 mg/kg

Question 7

A 48-year-old male with triple vessel disease and longstanding diabetes developed gangrene in his left lower foot. Which is the best mode of anesthesia?

Accepted Answer

Popliteal block

Answer

Sciatic block

Answer

Femoral block

Answer

Saphenous nerve block

Question 8

The segmental level of spinal anesthesia depends on which of the following factors?

Accepted Answer

All of the above

Answer

Volume of the local anesthetic injected

Answer

Specific gravity of the local anesthetic solution

Answer

Posture of the patient

Question 9

Which was the first local anesthetic used for spinal block?

Accepted Answer

Cocaine

Answer

Procaine

Answer

Prilocaine

Answer

Lignocaine

Question 10

All of the following are signs of successful stellate ganglion block, except:

Accepted Answer

Mydriasis

Answer

Flushing of face

Answer

Conjunctival congestion

Answer

Nasal stuffiness

Regional Anesthesia — MCQs

Regional Anesthesia — MCQs

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