Ultrasound for Regional Anesthesia — MCQs
What is the primary instrument used for creating endodontic access cavity during endodontic procedures?
Which of the following is the best in-vivo screening choice for carotid artery stenosis?
Which is not echogenic while doing ultrasonography:
What is the name of the nerve block technique shown in the image?
Intravenous regional anesthesia is suitable for :
Interscalene approach to brachial plexus block does not provide optimal surgical anaesthesia in the area of distribution of which of the following nerve?
During ultrasound-guided internal jugular vein cannulation, you observe the vein collapsing with minimal probe pressure while the artery remains patent. The vein appears enlarged and the artery-to-vein ratio is 1:3. A spontaneously breathing patient shows respiratory variation. Evaluate the most appropriate interpretation and management strategy.
A 55-year-old patient with previous lumbar spine surgery requires epidural catheter placement for postoperative analgesia. Pre-procedure ultrasound shows loss of normal posterior complex and irregular acoustic shadowing at L3-L4 and L4-L5 levels. The L2-L3 level shows preserved anatomy with a depth of 6 cm to the epidural space. Which technical modification would provide the best success rate?
A 28-year-old ASA I patient undergoes ultrasound-guided axillary block. Despite clear visualization of local anesthetic spread around all three major nerves, the patient develops incomplete block in the distribution of musculocutaneous nerve. What is the most likely anatomical explanation?
During ultrasound-guided supraclavicular block, you observe the brachial plexus as a 'bunch of grapes' appearance. The subclavian artery appears pulsatile underneath. You notice a hyperechoic line moving with respiration above the artery. What does this structure represent and what is its clinical significance?
Ultrasound for Regional Anesthesia Indian Medical PG Practice Questions and MCQs
Question 1: What is the primary instrument used for creating endodontic access cavity during endodontic procedures?
- A. K-File
- B. K-reamer
- C. Gates glidden drill
- D. Round bur (Correct Answer)
Explanation: ***Round bur*** - A **round bur** is the primary choice for creating the initial opening of the access cavity due to its ability to create a smooth, rounded entry point and remove caries effectively. - Its design allows for controlled penetration into the tooth and the removal of the **pulp chamber roof**, which is crucial for endodontic access. *Gates Glidden drill* - **Gates Glidden drills** are primarily used for widening the coronal portion of the root canal, not for creating the initial access cavity. - They are designed to be used in a **crown-down technique** to remove restrictive dentin in the canal's orifice. *K-File* - **K-files** are hand instruments used for initial negotiation, enlargement, and cleaning of the root canal system, not for creating the access cavity. - They are characterized by their **tightly twisted square or triangular cross-sectional blades**, which facilitate cutting and debris removal inside the canal. *K-reamer* - **K-reamers** are primarily used for shaping and enlarging the root canals through a reaming, or rotational, motion. - Similar to files, they are designed to work within the canal space and are not suitable for the initial opening of the **access cavity**.
Question 2: Which of the following is the best in-vivo screening choice for carotid artery stenosis?
- A. Digital Subtraction Angiography (DSA)
- B. CT
- C. MRI
- D. USG (Correct Answer)
Explanation: ***USG*** - **Ultrasound** (USG), specifically **carotid duplex ultrasonography**, is the **safest**, most cost-effective, and readily available initial screening tool for carotid artery stenosis due to its non-invasive nature and ability to visualize blood flow and vessel morphology. - It combines **B-mode imaging** with **Doppler flow analysis** to provide real-time images and flow velocity measurements, allowing for assessment of the degree of **stenosis** and plaque characteristics without radiation or contrast agents. - Sensitivity and specificity exceed 85-90% for detecting significant stenosis, making it the preferred first-line screening modality. *Digital Subtraction Angiography (DSA)* - **DSA** is the **gold standard** for anatomical detail and remains the most accurate method for quantifying carotid stenosis, but it is **invasive** and requires arterial catheterization. - It involves **ionizing radiation** and **iodinated contrast agents**, carrying risks of stroke (0.5-1%), arterial dissection, nephrotoxicity, and contrast allergic reactions. - Due to its invasive nature and associated risks, DSA is reserved for **pre-surgical planning** or when non-invasive imaging is inconclusive, not for initial screening. *CT* - **Computed tomography angiography (CTA)** involves **ionizing radiation** and typically requires an **iodinated contrast agent**, which carries risks of allergy and nephrotoxicity. - Though CTA provides excellent anatomical detail and can visualize vessel wall calcification, it is generally reserved for confirmation or surgical planning rather than initial screening due to its higher cost, radiation exposure, and contrast-related risks. *MRI* - **Magnetic resonance angiography (MRA)** can visualize carotid arteries well but is more expensive, less accessible than ultrasound, and may require a **gadolinium-based contrast agent**, which can have adverse effects (nephrogenic systemic fibrosis in renal impairment). - It is often used when ultrasound findings are equivocal or in cases where CTA is contraindicated, but it's not the preferred initial screening method due to its complexity, cost, longer examination time, and contraindications (pacemakers, metallic implants).
Question 3: Which is not echogenic while doing ultrasonography:
- A. Bile (Correct Answer)
- B. Bone
- C. Gas
- D. Gall stones
Explanation: ***Bile*** - Bile is largely composed of **water**, which allows ultrasound waves to pass through it with minimal reflection, appearing **anechoic** (black) on ultrasound. - This property makes the gallbladder lumen, when filled with bile, appear anechoic, which is crucial for identifying structures like gallstones. *Bone* - **Bone** is highly dense and reflects a significant portion of ultrasound waves, making it appear very **echogenic** (bright) on ultrasonography. - Due to its high reflectivity, bone often produces a strong **acoustic shadow** behind it, obscuring deeper structures. *Gas* - **Gas** (air) is a strong reflector of ultrasound waves and appears brightly echogenic, often with a characteristic **dirty shadowing** or **reverberation artifact**. - The presence of gas can significantly hinder visualization of underlying tissues due to its strong reflection and scatter of the ultrasound beam. *Gall stones* - **Gallstones** are solid concretions that are highly reflective of ultrasound waves, appearing as bright, **echogenic foci** within the gallbladder lumen. - A classic ultrasound sign of gallstones is an echogenic structure with strong **posterior acoustic shadowing**.
Question 4: What is the name of the nerve block technique shown in the image?
- A. Intra-arterial anesthesia (Correct Answer)
- B. Bier's block
- C. Regional anesthesia
- D. Axillary block
Explanation: ***Intra-arterial anesthesia*** - The image shows a **cannula inserted directly into an artery**, indicated by the blood reflux and the context of anesthesia, suggesting direct drug delivery into the arterial system. - This method is used for specific types of regional pain management or diagnostic procedures where direct arterial access is required for **localized drug distribution**. *Bier's block* - A Bier's block, or **intravenous regional anesthesia**, involves injecting local anesthetic into a **vein** in an extremity after it has been exsanguinated and isolated by a tourniquet. - The image clearly shows a **bright red blood flash**, characteristic of arterial cannulation, not venous. *Regional anesthesia* - This is a broad term referring to the **anesthesia of a specific region** of the body and encompasses various techniques. - While intra-arterial anesthesia is a type of regional anesthesia, "regional anesthesia" itself is too general to specifically describe the technique shown. *Axillary block* - An **axillary block** is a type of peripheral nerve block targeting the brachial plexus in the axilla to anesthetize the arm. - The image does not depict the axillary region or the characteristic needle placement for an axillary block; instead, it shows direct vascular access.
Question 5: Intravenous regional anesthesia is suitable for :
- A. Caesarian section
- B. Head and neck surgery
- C. Orthopedic manipulation on the upper limb (Correct Answer)
- D. Vascular surgery on the lower limb
Explanation: ***Orthopedic manipulation on the upper limb*** - **Intravenous regional anesthesia (IVRA)**, also known as a Bier block, is ideal for **short-duration procedures on the extremities**, especially the upper limb. - The technique involves isolating the limb with a **tourniquet** and injecting a local anesthetic intravenously, making it suitable for procedures like **orthopedic manipulations** that are typically less than an hour. *Caesarian section* - A Caesarian section requires **widespread anesthesia** to the lower abdomen and uterus, which cannot be achieved with IVRA. - It is typically performed under **spinal or epidural anesthesia**, or general anesthesia. *Head and neck surgery* - **IVRA** is a regional technique limited to the extremities below the tourniquet; it cannot provide anesthesia for the **head and neck region**. - Procedures in this area usually require **general anesthesia** or sometimes regional blocks like cervical plexus blocks. *Vascular surgery on the lower limb* - While IVRA can be used on the lower limb, **vascular surgery** often involves **longer durations** and may require more profound muscle relaxation and sensory blockade than IVRA can reliably provide. - Additionally, the use of a **tourniquet for extended periods** in vascular surgery patients can be contraindicated due to potential ischemic complications.
Question 6: Interscalene approach to brachial plexus block does not provide optimal surgical anaesthesia in the area of distribution of which of the following nerve?
- A. Median
- B. Musculocutaneous
- C. Radial
- D. Ulnar (Correct Answer)
Explanation: ***Ulnar*** - The **ulnar nerve** (C8-T1) emerges from the lower trunk of the brachial plexus. During an **interscalene block**, the local anesthetic is typically deposited at the level of the roots and trunks (C5-C7), which is superior to the origin of the lower trunk that gives rise to the ulnar nerve. - Due to the **cephalad spread** of the local anesthetic from an interscalene block, the **C8 and T1** nerve roots (and thus the ulnar nerve) are often not adequately blocked, leading to suboptimal anesthesia in its distribution. *Median* - The **median nerve** (C5-T1) originates from the lateral and medial cords, which are typically well-covered by the spread of local anesthetic in an interscalene block due to its formation from the middle and upper trunks. - Optimal anesthesia in the distribution of the median nerve is generally achieved with an interscalene block, as its nerve roots are within the targeted antegrade spread. *Musculocutaneous* - The **musculocutaneous nerve** (C5-C7) arises from the lateral cord, which is formed by the upper and middle trunks. These structures are reliably blocked during an interscalene approach. - Sensory and motor functions of the musculocutaneous nerve, such as **biceps contraction** and lateral forearm sensation, are usually well anesthetized. *Radial* - The **radial nerve** (C5-T1) is a branch of the posterior cord, which receives fibers from all three trunks. Its upper and middle trunk components are generally well-blocked by an interscalene approach. - While complete anesthesia of the entire brachial plexus can be variable, the radial nerve is more consistently affected by an interscalene block than the ulnar nerve due to its more extensive proximal root contributions which are within the typical spread.
Question 7: During ultrasound-guided internal jugular vein cannulation, you observe the vein collapsing with minimal probe pressure while the artery remains patent. The vein appears enlarged and the artery-to-vein ratio is 1:3. A spontaneously breathing patient shows respiratory variation. Evaluate the most appropriate interpretation and management strategy.
- A. This indicates hypovolemia; fluid resuscitation should be considered before central line insertion (Correct Answer)
- B. This is normal anatomy; proceed with cannulation using standard technique
- C. This suggests venous thrombosis; consider alternative site
- D. This indicates increased central venous pressure; use ultrasound compression technique
Explanation: ***This indicates hypovolemia; fluid resuscitation should be considered before central line insertion*** - Significant **respiratory variation** and ease of **venous collapse** with minimal probe pressure are classic ultrasound indicators of a **low intravascular volume state**. - Managing the **hypovolemia** first improves the safety of the procedure by increasing the target vessel size, thereby reducing the risk of **accidental arterial puncture**. *This is normal anatomy; proceed with cannulation using standard technique* - While the **internal jugular vein** is normally larger than the artery, excessive **compressibility** and collapse indicate an abnormal physiological state that complicates cannulation. - Proceeding without addressing the **underfilled vein** increases the technical difficulty and the likelihood of a **transfixion injury** where the needle passes through both walls. *This suggests venous thrombosis; consider alternative site* - **Venous thrombosis** would manifest as a **non-compressible** vein, often containing visible **distal echoes** or intraluminal clots. - In this scenario, the vein is noted to be **highly compressible**, which is the physiological opposite of what is seen in **deep vein thrombosis (DVT)**. *This indicates increased central venous pressure; use ultrasound compression technique* - High **central venous pressure (CVP)** would result in a **distended, non-collapsible** vein that does not vary significantly with the respiratory cycle. - An **artery-to-vein ratio** where the vein is excessively small or collapses easily specifically contradicts the diagnosis of **fluid overload** or **right heart failure**.
Question 8: A 55-year-old patient with previous lumbar spine surgery requires epidural catheter placement for postoperative analgesia. Pre-procedure ultrasound shows loss of normal posterior complex and irregular acoustic shadowing at L3-L4 and L4-L5 levels. The L2-L3 level shows preserved anatomy with a depth of 6 cm to the epidural space. Which technical modification would provide the best success rate?
- A. Use paramedian approach at L3-L4 with fluoroscopy guidance
- B. Attempt midline approach at L2-L3 with ultrasound pre-scanning for trajectory (Correct Answer)
- C. Perform caudal epidural with threading of catheter to lumbar level
- D. Use loss of resistance to saline at L4-L5 with multiple attempts
Explanation: ***Attempt midline approach at L2-L3 with ultrasound pre-scanning for trajectory*** - Identifying a level with **preserved anatomy** (L2-L3) via ultrasound is the most reliable predictor of success in patients with prior **spinal surgery**. - **Pre-scanning** allows for precise measurement of **epidural depth** and determination of the optimal needle trajectory, bypassing levels with surgical scarring. *Use paramedian approach at L3-L4 with fluoroscopy guidance* - The L3-L4 level shows **irregular acoustic shadowing** and loss of normal complexes, indicating surgical distortion that makes access difficult despite a paramedian approach. - While **fluoroscopy** provides real-time imaging, it involves **radiation exposure** and is less desirable than utilizing a healthy adjacent level (L2-L3). *Perform caudal epidural with threading of catheter to lumbar level* - Threading a **caudal catheter** to the mid-lumbar levels is technically challenging and frequently results in **malpositioning** or inadequate analgesia. - This approach is generally reserved for patients where all **lumbar access** points are completely obliterated by extensive fusion or hardware. *Use loss of resistance to saline at L4-L5 with multiple attempts* - Multiple attempts at L4-L5, which shows **anatomical distortion**, significantly increase the risk of **dural puncture** and technical failure. - Relying solely on **loss of resistance** without respecting ultrasound signs of **posterior complex loss** is poor clinical practice in
Question 9: A 28-year-old ASA I patient undergoes ultrasound-guided axillary block. Despite clear visualization of local anesthetic spread around all three major nerves, the patient develops incomplete block in the distribution of musculocutaneous nerve. What is the most likely anatomical explanation?
- A. The musculocutaneous nerve has already entered the coracobrachialis muscle at the level of injection (Correct Answer)
- B. The nerve has anatomical variation with dual innervation
- C. Inadequate volume of local anesthetic was used
- D. The needle was placed too proximal in the axilla
Explanation: ***The musculocutaneous nerve has already entered the coracobrachialis muscle at the level of injection*** - The **musculocutaneous nerve** frequently exits the **neurovascular sheath** high in the axilla to enter the **coracobrachialis muscle**, often by the level of the pectoralis minor. - Because it travels separately from the **median, ulnar, and radial nerves**, it is often missed during a standard **axillary block** unless specifically identified and blocked within the muscle body. *The nerve has anatomical variation with dual innervation* - While **anatomical variations** exist, dual innervation from the **median nerve** is less common than simple proximal separation of the nerve. - This would not explain the failure of a block where local anesthetic spread was clearly visualized around the main nerves in the sheath. *Inadequate volume of local anesthetic was used* - The prompt states there was **clear visualization** of local anesthetic spread around the three major nerves, suggesting the volume was sufficient for the sheath compartments. - Increasing volume within the **axillary sheath** will not typically reach a nerve that has already anatomically deviated into a separate muscular plane. *The needle was placed too proximal in the axilla* - Placing the needle **proximal** would actually increase the likelihood of capturing the musculocutaneous nerve before it branches off. - Blocks performed more **distally** in the axilla are the ones most likely to miss the nerve as it moves laterally and deep into the **coracobrachialis**.
Question 10: During ultrasound-guided supraclavicular block, you observe the brachial plexus as a 'bunch of grapes' appearance. The subclavian artery appears pulsatile underneath. You notice a hyperechoic line moving with respiration above the artery. What does this structure represent and what is its clinical significance?
- A. First rib - landmark for needle placement
- B. Pleura - indicates risk of pneumothorax (Correct Answer)
- C. Prevertebral fascia - anatomical landmark
- D. Subclavian vein - vascular complication risk
Explanation: ***Pleura - indicates risk of pneumothorax*** - The **pleura** appears as a **hyperechoic**, shimmering line that exhibits **respiratory sliding**, located deep and lateral to the **subclavian artery**. - Identifying this structure is critical to avoid accidental needle puncture, which can lead to a **pneumothorax**, a classic complication of the supraclavicular approach. *First rib - landmark for needle placement* - The **first rib** is also **hyperechoic** but presents as a static, shadowing structure that does not move with respiration. - It serves as a safety barrier; keeping the needle tip above the **first rib** prevents it from entering the underlying lung tissue. *Prevertebral fascia - anatomical landmark* - The **prevertebral fascia** envelops the **brachial plexus** trunks but does not demonstrate the characteristic **sliding motion** seen with the pleura during breathing. - While it is a key landmark for identifying the **plexus sheath**, it does not correlate with the dynamic respiratory movement described in the prompt. *Subclavian vein - vascular complication risk* - The **subclavian vein** is typically located medial to the **subclavian artery** and appears as an **anechoic** (black), compressible oval. - It is not a hyperechoic line and does not possess the distinct **shimmering** appearance associated with the visceral and parietal pleural interface.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free