Anatomy

Question 1

Which of the following reflects the LEAST amount of beam rays during ultrasound imaging?

Answer 1

Structures such as blood, which have a high water content, reflect little of an ultrasound’s beam and thus appear hypoechoic. Structures with low water content such as bone and tendon, reflect more of an ultrasound’s beam and appear hyperechoic. Air reflects a significant amount of the beam back, making the use of ultrasound gel important.

TrueLearn Insight : A curved array ultrasound probe maximizes returning ultrasound waves and is better at deeper structures compared to a linear array ultrasound. At the same time, a linear array will have higher resolution at the expense of less penetration.

Question 2

A 90% stenotic lesion along which of the following can cause atrioventricular nodal blockade?

Answer 2

A high-grade stenotic lesion along the posterior descending artery (PDA) may result in atrioventricular (AV) nodal blockade. This is due to the indirect blockage of the PDA’s AV nodal branch.

Question 3

Which of the following factors, within typical ranges, has the LEAST effect on the spread of neural blockade with spinal anesthesia?

Answer 3

Drug dosage, drug baricity, and patient positioning are the most important factors influencing level of spinal blockade. Drug volume is an important factor during epidural blockade.

Question 4

Regarding the larynx, which of the following groupings of innervation, muscle, and action is correct?

Answer 4

The recurrent laryngeal nerve (RLN) innervates the posterior cricoarytenoid muscles, which are responsible for vocal cord abduction. The posterior cricoarytenoid muscles are the only laryngeal muscles to open the true vocal folds.
The cricothyroid muscle is the exception because it is innervated by the superior laryngeal nerve (external branch). It primarily functions as a tensor, elongating the cords and raising the pitch of the sound produced.

Question 5

The below images are from an ultrasound transducer that was placed on the right neck of a volunteer. The transducer was oriented perpendicular to the trachea at the level of the cricoid cartilage, with the orientation marker dot of the image being lateral. In the image on the left, the transducer is resting lightly on the skin, and in the image on the right the transducer is pressed down gently. Which structure is demonstrated in the figure as B?

Answer 5

Ultrasound is often used for central line placement to decrease the incidence of complications. Veins and arteries can be distinguished using ultrasonography by the collapsibility of veins. The internal jugular vein runs near the internal carotid artery and is deep to the sternocleidomastoid muscle.

TrueLearn Insight : Ease of pulmonary artery catheter placement can be a reason for choosing different areas for central line placement. A pulmonary artery catheter is most easily placed from the right internal jugular vein. Following the right internal jugular vein, placement is then easiest in the left subclavian vein, then the left internal jugular vein, and finally the right subclavian vein. Axillary central line placement provides similar benefits as subclavian central line placement, but with some reduced risks due to the use of ultrasound.

Question 6

Which of the following statements about spinal cord anatomy is FALSE?

Answer 6

In newborns, the dural sac typically ends at S3 and the conus medullaris at L3. In adults, the dural sac typically ends at S1-S2 and the conus medullaris at L1-L2.

Question 7

Subcutaneous infiltration of the entire width of the medial axillary fossa will block which of the following nerves?

Answer 7

Supplementation of brachial plexus blocks with an intercostobrachial nerve block may help to prevent tourniquet pain.

Question 8

A spinal drain is placed preoperatively to help prevent spinal cord ischemia in a patient undergoing an open thoracoabdominal aortic aneurysm repair. At which of the following spinal levels does the great radicular artery MOST commonly originate?

Answer 8

The great radicular artery (aka arteria radicularis magna or artery of Adamkiewicz) originates from the aorta between the T9 and T12 vertebral segments in 75% of the population. The anterior spinal cord is perfused by a single ASA with collateralization from the radicular arteries. Interruption of the great radicular artery may result in ASA syndrome, which includes bilateral lower extremity paraplegia as well as bowel and bladder dysfunction. Sensation and proprioception are classically spared as the posterior portion of the spinal cord is supplied by two PSAs. SCPP = MAP - CSF pressure. CSF pressure is measured via a lumbar spinal drain. Arterial pressure augmentation and CSF pressure reduction are therefore the best methods by which SCPP may be optimized.

TrueLearn Insight : Delayed-onset paraplegia is the new onset of neurologic dysfunction several hours to days following surgery in a patient who otherwise woke up without neurologic deficits. The same principles of SCPP optimization persist and include increasing MAP via vasopressors and/or emergent placement of a spinal drain. This is an important concept since a spinal cord that was adequately protected during surgery is still at risk for ischemia and infarction postoperatively.

Question 9

Which of the following nerve blocks carries the HIGHEST risk of pneumothorax when performed using the anatomic landmarks technique?

Answer 9

Most practitioners utilize the SCB for surgery below the mid-humerus level. The risk of PTX is approximately 1-6% but use of ultrasound may improve this safety profile by allowing direct visualization of the needle tip. While the most serious complication of a SCB is PTX, the most common complication is phrenic nerve blockade. The block is performed by visualizing the ScA within the supraclavicular fossa. The brachial plexus lies lateral, superior and posterior to the ScA. Visualization of the first rib and “shimmery” pleura deep to the plexus is mandatory prior to placing the needle in plane. The first rib may serve as a barrier between the needle tip and the pleura. The SAX in-plane view is utilized to perform ultrasound-guided SCB.

TrueLearn Insight : Although the ulnar nerve is not located inside the brachial plexus trunk sheath at the supraclavicular level, it is anesthetized >90% of the time during SCB due to its close proximity to the subclavian artery and the easy hydrodissection of local anesthetic in this region. This is in comparison to the interscalene block where 50% of cases neglect ulnar nerve blockade

Question 10

Injury to which of the following nerves would MOST likely result in numbness and paresthesias along the medial lower leg?

Answer 10

The saphenous nerve is a major sensory branch of the femoral nerve that is primarily responsible for cutaneous innervation of the medial lower leg.

Question 11

Which of the following is decreased the MOST from lumbar or low thoracic epidural anesthesia with a local anesthetic?

Answer 11

In healthy patients, lumbar or low thoracic epidural anesthesia produces small (≤ 10%) changes in most pulmonary function parameters. However, PEP and cough strength are significantly reduced (10-40% and up to 50%, respectively) from baseline. These two parameters are more dependent on abdominal musculature which has a higher degree of motor blockade than thoracic musculature from a lumbar or low thoracic epidural. Note a disproportionately greater decrease in peak expiratory pressure with only a small decrease in FEV1 is in line with FEV1 being relatively effort-independent (lower peak expiratory pressure in a weaker patient is conceptually equivalent to lower effort).

Question 12

A solution of 10 mL of 8.4% sodium bicarbonate (1 mEq/mL) is added to 100 mL of 0.125% ropivacaine for infusion in a femoral nerve catheter. This mix was prepared to create an alkaline solution and promote an increased non-ionized fraction of ropivacaine. Which of the following is the MOST likely to occur with this mixture?

Answer 12

Often bicarbonate is added to local anesthetic (often in a 1:10 ratio) to increase the pH of the solution. This increase of pH decreases pain on injection into peripheral tissues and also speeds the onset time of the local anesthetic by increasing the unionized portion of local anesthetic. Lidocaine remains relatively soluble in its unionized form. However ropivacaine and levobupivacaine are not, and therefore it is not recommended to have bicarbonate added for infusions. Recommendations for ropivacaine state that if bicarbonate is added the solution should be used within 5-10 minutes of mixing.

Question 13

A 25-year-old female is scheduled for right femoral osteotomy under spinal anesthesia. She has a history of arthritis secondary to congenital hip dysplasia. Shortly after spinal injection, the patient becomes bradycardic with a heart rate of 33 beats per minute. Which of the following is NOT a contributing cause of bradycardia following an intrathecal anesthetic?

Answer 13

Bradycardia following spinal anesthetic injection is more common in patients with high baseline vagal tone, anesthetic levels above T5, and is associated with decreased cardiac preload. Brainstem ischemia may be the result of hypotension and leads to apnea. The treatment of bradycardia should be prompt and epinephrine should be used early if necessary.

Question 14

In a normal adult, at what level does the dural sac terminate?

Answer 14

In adults, the spinal cord ends at about L1-L2 and the dural sac ends at about S1-S2. In an infant, these landmarks are shifted slightly caudad with the spinal cord ending at L3-L4 and the dural sac terminating at S3-S4.

Question 15

A patient undergoes spinal anesthesia for lower extremity orthopedic surgery. Unfortunately, the anesthetic results in a high spinal blockade. The patient is given a fluid bolus and started on a phenylephrine infusion, but the patient still endorses significant nausea. Which of the following medications is the BEST treatment for nausea after high spinal blockade?

Answer 15

Nausea and vomiting may be associated with a neuraxial block in up to 20% of patients and atropine is almost universally effective in treating nausea associated with high (T5) neuraxial anesthesia. Nausea can occur with normal blood pressure and glycopyrrolate may be considered as an alternative to atropine for nausea associated with neuraxial anesthesia.

Question 16

An 86-year-old man is undergoing surgery under regional anesthesia for a fractured wrist. The patient received an axillary block, but upon nerve testing he is noted to have sensation on the lateral palm of his hand and is able to flex his hand at the wrist. If a supplemental nerve block were to be performed to provide coverage for this patient, where would the nerve be located?

Answer 16

The median nerve supplies sensation to the lateral palm of the hand and motor to the wrist flexor muscles. It can be located and blocked in the antecubital fossa medial to the brachial artery.

Question 17

Which of the following innervates the cricothyroid muscle?

Answer 17

The cricothyroid muscle is innervated by the external branch of the superior laryngeal nerve, the external laryngeal nerve.

TrueLearn Insight : The cricothyroid muscle is the only tensor muscle of the larynx aiding with phonation, which works by tilting the thyroid forward to tense the vocal cords. The posterior cricoarytenoid muscles abduct the vocal cords and the lateral cricoarytenoid muscle adduct the vocal cords.

Question 18

Transtracheal injection of lidocaine blocks which of the following nerves?

Answer 18

Transtracheal injection of local anesthetic will block the recurrent laryngeal nerve.

Question 19

Which of the following statements about the superior laryngeal nerve is TRUE?

Answer 19

The external branch of the superior laryngeal nerve innervates the cricothyroid muscle. The internal branch provides sensory innervation to the larynx above the vocal cords.

Question 20

A 62-year-old female is undergoing wrist surgery with intravenous regional anesthesia (Bier block). Five minutes after the local anesthetic injection, the tourniquet malfunctions and fully deflates. The patient becomes agitated and tachycardic, but shortly thereafter suffers cardiac arrest. According to the American Society of Regional Anesthesia and Pain Medicine, which of the following BEST describes how epinephrine should be administered during advanced cardiac life support resuscitation in the setting of LA toxicity?

Answer 20

The dose of epinephrine in ACLS guided resuscitation of LAST should be reduced to < 1 mcg/kg per dose. Vasopressin use should be avoided.

Question 21

Which of the following is the afferent limb for the laryngospasm reflex?

Answer 21

The internal branch of the superior laryngeal nerve (SLN) provides sensation to the entire larynx above the glottis. Laryngospasm can result from stimulation of this nerve.

Question 22

Which of the following local anesthetics has the LOWEST cardiac-to-CNS dose toxicity ratio and the HIGHEST relative potency for cardiac toxicity?

Answer 22

Bupivacaine has the lowest cardiac-to-CNS dose toxicity ratio (2:1) AND the highest relative potency for cardiac toxicity of all local anesthetics. Bupivacaine’s higher relative lipophilicity and potency promote stronger affinity for both resting and inactivated sodium channels within the myocardium.

Question 23

Which of the following is NOT associated with spinal anesthesia?

Answer 23

Spinal anesthesia is associated with an incidence of PDPH as high as 25%. Other common complications or side effects include increased gastrointestinal secretions and mobility, increased ventilatory response to hypercapnia, hypothermia from peripheral vasodilation, and a transient decrease in hearing ability.

Question 24

Which of the following nerve block combinations would best prevent coughing?

Answer 24

Coughing during awake intubation can be prevented by blockade of the superior laryngeal nerve and recurrent laryngeal nerve. The glossopharyngeal nerve also provides airway innervation but is involved in the gag, not the cough reflex.

Question 25

Which of the following nerves innervates the cricothyroid muscle?

Answer 25

The cricothyroid muscle is innervated by the external branch of the SLN. All other laryngeal muscles are innervated by the RLN. Bilateral RLN palsy or injury results in respiratory distress but unilateral injury or palsy typically does not.

Question 26

A patient received an L3-4 spinal anesthetic injection with anesthetic levels up to T5. Which of the following nerves should be blocked for a transurethral resection of a lateral wall bladder tumor?

Answer 26

Transurethral surgery of the bladder usually can be performed with spinal anesthesia without further consideration. If the tumor is along the lateral aspect of the bladder then the obturator nerve may be stimulated and the jerk reflex initiated even under spinal anesthesia. An obturator nerve block should be performed to help prevent this. Alternatively, general anesthesia with muscle relaxation can also be performed to prevent the reflex. If neuromuscular blocking agents are not used during general anesthesia, the obturator nerve block will still need to be performed.

TrueLearn Insight : The femoral nerve arises from the anterior rami of L2-L4, it provides sensory innervation to the anterior thigh and motor innervation to the flexor muscles of the hip and thigh. A “3-in-1-block” can be performed which will block the femoral, lateral femoral cutaneous, and the obturator nerves (although the obturator nerve is often missed during this block thus it would not be an appropriate block to prevent the knee jerk).

Question 27

Which of the following anesthetic complications is NOT associated with parturients that have ankylosing spondylitis?

Answer 27

Ankylosing spondylitis is associated with difficult airway and epidural hematoma secondary to epidural attempts, but is not associated with peripheral neuropathy.

Question 28

A 59-year-old male is admitted with a 3-day history of retrosternal chest discomfort and troponin elevation. On transthoracic echocardiogram, the patient is found to have severe acute mitral regurgitation with an anteriorly directed regurgitant jet. Which of the following is the MOST likely involved ischemic vessel?

Answer 28

In the setting of non-ST elevation myocardial infarction and acute mitral regurgitation, there is high suspicion for papillary muscle rupture. The posteromedial papillary muscle receives a single blood supply from the right coronary artery in about two-thirds of patients. It is more susceptible to infarct than the anterolateral papillary muscle, which receives dual blood supply from the left anterior descending artery and left circumflex coronary artery.

Question 29

Which of the following is in the correct order from GREATEST to LEAST with regard to local anesthetic systemic absorption based on injection site?

Answer 29

Local anesthetics have a higher rate of absorption when injected in areas of higher vascularity. Areas with high absorption rates are intercostal > caudal > epidural > brachial plexus > lower extremity nerve blocks.

TrueLearn Insight : There are several mnemonics to help recall the order of absorption.
ICEBaLLS: Intercostal, Caudal, Epidural, Brachial plexus, Lower Limb, Subcutaneous.
BICEPS: Blood, Intercostal, Caudal, Epidural, Plexus (brachial), Sciatic, Subcutaneous.

Question 30

A 67-year-old male is being prepped for an awake oral fiberoptic intubation. 3 mL of 2% lidocaine is injected into the base of the palatoglossal fold. Which nerve is anesthetized as part of this block?

Answer 30

The glossopharyngeal nerve is blocked at the palatoglossal folds. The recurrent laryngeal nerve can be blocked with a transtracheal injection through the cricothyroid membrane. The superior laryngeal nerve can be blocked by either injection at the horn of the hyoid bone or by placing a pledget in the pyriform sinus. The mandibular portion of the trigeminal nerve is blocked topically.

TrueLearn Insight : Resting tone of airway smooth muscle is primarily mediated by parasympathetic neurons.

Question 31

A 48-year-old male with factor V Leiden deficiency is scheduled to undergo a right knee replacement. The patient takes aspirin, rivaroxaban, and acetaminophen daily. The decision was made to perform this procedure under epidural anesthesia as it is efficacious for postoperative analgesia as well. The case proceeded uneventfully and on the second postoperative day, the epidural catheter was pulled. Three hours later, the provider was called to the bedside for progressive lower extremity weakness and paresthesias. Which of the following is MOST likely?

Answer 31

During consideration of neuraxial anesthesia, coagulopathies must be ruled out in order to decrease the potential for the development of an epidural hematoma and neurologic sequelae.

Question 32

Which of the following statements regarding spinal cord blood supply is CORRECT?

Answer 32

The anterior two-thirds of the spinal cord is supplied by the anterior spinal artery and contributing radicular vessels, including the artery of Adamkiewicz (which most commonly arises between T9 and T12). The posterior one-third of the spinal cord is supplied by the two PSAs, along with collateral radicular vessels.

Question 33

A patient with which of the following diseases or injuries is MOST likely to develop permanent neurologic injury from a spinal anesthetic?

Answer 33

Patients with space-occupying extradural lesions or those that reduce the cross-sectional area of the spinal cord are most at risk for new or worsening neurologic injury from a neuraxial anesthetic. Although neurologic injury from neuraxial anesthesia is very rare, they tend to result in permanent deficits.

Question 34

Which type of nerve fiber is responsible for the fastest transmission of nociception?

Answer 34

Nerve fibers that conduct nociceptive information are A-delta fibers and C fibers. C fibers are small and unmyelinated. A-alpha fibers are large and myelinated. A-alpha fibers carry proprioceptive and motor fibers.

TrueLearn Insight : A mnemonic for differential blockade is “Sympathetic People Matter”: Sympathetics > Pain > Motor for neuraxial blockade levels.

Question 35

A 3-year-old male develops an episode of laryngospasm during emergence from general anesthesia. Which of the following descriptions BEST describes this mechanism?

Answer 35

Laryngospasm is a protective airway reflex resulting in closure of the true and false vocal cords or the true cords only. It typically occurs during stage 2 (excitation phase) of anesthesia and may occur during both induction and emergence. Glottic closure results by the involuntary contraction of the lateral cricoarytenoid, the thyroarytenoid, and the cricothyroid muscles. It is more common in pediatric populations, particularly those with GERD or recent upper respiratory infections.

Question 36

A patient is receiving twice daily prophylactic dosing of enoxaparin for deep venous thrombosis prophylaxis. The patient is not on any other anticoagulant medications and has a normal platelet count. The patient is scheduled for a thoracotomy the following day and the anesthesiologist would like to place an epidural for postoperative pain management. What should be done prior to epidural placement in this patient?

Answer 36

For patients receiving prophylactic doses of LMWH, ASRA guidelines recommend waiting 12 hours between the last dose of LMWH and neuraxial needle placement.

Question 37

An axillary block is performed for repair of a distal radius fracture under monitored anesthesia care. During the procedure, the patient complains of pain in the lateral forearm. To alleviate the patient’s pain, local anesthetic should be injected into which of the following muscles?

Answer 37

The musculocutaneous nerve travels within the belly of the coracobrachialis muscle. The nerve may therefore be neglected during an axillary brachial plexus block for distal upper extremity surgery since it is not contained within the axillary sheath. The median, ulnar, and radial nerves (as well as the axillary artery) are contained within the sheath.

Question 38

Which of the following myocardial regions is MOST commonly supplied by the right coronary artery?

Answer 38

The left main coronary artery provides blood supply to the apices of the left ventricle (LV) and right ventricle (RV), the anterolateral LV, and the anterior two-thirds of the interventricular septum. The right coronary artery (RCA) supplies the anterior and posterior RV, the RA, the upper atrial septum, the posterior third of the interventricular septum, and the inferior and posterior LV. Right-dominant hearts have an RCA that gives rise to the posterior descending artery (PDA) and therefore supplies blood to the AV node, but the PDA can also arise from the left circumflex coronary artery

Question 39

When performing a caudal epidural, which of the following structures should a needle traverse just prior to the epidural space?

Answer 39

The sacrococcygeal ligament covers the opening of the sacral hiatus. Landmarks for caudal blockade include the triangle with vertices at the posterior superior iliac spines and the sacral hiatus. The sacral hiatus lies directly superior to the coccyx bone. The sacral hiatus is created by the non-union of the S4 and S5 lamina. In infants, the dural sac extends to S3/S4 and makes dural puncture more likely. In adults, the sacrococcygeal ligament becomes heavily calcified, making caudal anesthesia difficult.

Question 40

Which of the following structures are MOST likely traversed during a paramedian thoracic epidural?

Answer 40

Paramedian approach: skin -> subcutaneous fat -> paraspinous muscles -> ligamentum flavum. Midline approach: skin -> subcutaneous fat -> supraspinous ligament -> interspinous ligament -> ligamentum flavum.

Question 41

Subarachnoid anesthesia can lead to hypotension via multiple physiologic effects. Which of the following is NOT a contributing cause of hypotension in this setting?

Answer 41

An elevated fractional area change correlates with an above normal ejection fraction and increased cardiac output, which is not associated with spinal anesthesia
Spinal anesthesia causes a sympathectomy that often results in hypotension via three main mechanisms: arterial dilation (decreased afterload), venodilation (decreased preload), and bradycardia (parasympathetic dominance and/or the Bezold-Jarisch reflex).

Question 42

A 28-year-old woman is undergoing an open colectomy for ulcerative colitis. Preoperatively an epidural is placed using the paramedian approach. Which of the following structures would be encountered with the needle during this epidural placement, in order of superficial to deep?

Answer 42

With the paramedian epidural approach the needle will pass through the skin, subcutaneous tissue, and then ligamentum flavum.

TrueLearn Insight : The Taylor approach is a paramedian approach to the epidural or spinal space at the L5-S1 interspace. This is the largest interspace of the spine, and therefore a reliable approach. The general approach is to place the needle 1cm medial and 1cm inferior to the posterior superior iliac spine. The needle is angled about 50 degrees cephalic medial.

Question 43

A patient reports acute circumoral numbness and tinnitus immediately after a regional procedure is performed following the proper technique. Which of the following blocks was MOST likely performed a few minutes before the onset of these symptoms?

Answer 43

Intercostal blocks are associated with the highest plasma levels of local anesthetic following completion due to the high vascularity of the area. Plasma local anesthetic concentrations following regional techniques, from highest to lowest, are: intravenous > intercostal blocks > caudal > epidural > brachial plexus > intravenous regional > lower extremity blockade.

Question 44

The spread of hyperbaric bupivacaine in the spinal canal is MOST affected by which of the following?

Answer 44

Spread of local anesthetic within the CSF is primarily determined by the baricity of the local anesthetic solution and patient position.

Question 45

The medial calf has sensory innervation from which of the following nerves?

Answer 45

The medial lower leg is innervated by the saphenous nerve, which is a branch of the femoral nerve.

Question 46

Which of the following is NOT an indication for emergent magnetic resonance imaging following neuraxial anesthesia?

Answer 46

An MRI is the best imaging modality in patients with possible neuraxial pathology. Indications include new onset motor weakness, progressive sensory loss, fever, or neurologic deficits including incontinence.

TrueLearn Insight : The presence of a ferromagnetic body in the patient is a contraindication for MRI. A common place for ferromagnetic foreign bodies is in the eye, such as in welders. Some medical implants contain ferromagnetic material like: implanted pacemakers and AICDs, cochlear implants, and tissue expanders. Intracranial coils and stents may or may not contain ferrous material. Coronary stents are made of non-ferromagnetic material and considered MRI safe.

Question 47

Which of the following is the APPROXIMATE maximum allowable dose of 2% lidocaine with 1:100,000 epinephrine that may be safely given via epidural catheter in a 70 kg female, assuming 7 mg/kg max dose?

Answer 47

It is important to know the approximate maximum allowable dose of the commonly used local anesthetic agents.  These maximum dosages are irrelevant of site of injection and toxicity may occur at lower dosages if inadvertent direct vascular injection is made.  However, note that not all sources agree on the maximum allowable dose, but these are generally quoted.
Lidocaine (plain): 5 mg/kg
Lidocaine (with epi): 7 mg/kg
Bupivacaine (plain): 2.5 mg/kg
Bupivacaine (with epi): 3 mg/kg
Ropivacaine (plain only): 3 mg/kg
Chloroprocaine (plain only): 12 mg/kg

Question 48

A 40-year-old trauma patient is taken to the operating room for external fixation of an open extremity fracture. Half an hour following endotracheal tube placement the patient becomes progressively more tachycardic and hypotensive. Focused assessment with sonography for trauma (FAST) was previously negative. A chest radiograph is reviewed from the patient’s initial arrival as well as a CT scan from an hour later, just before the patient was brought to the operating room. Which of the following interventions would best treat hemodynamic instability in this patient?

Answer 48

Tension pneumothorax should be high on the differential diagnosis in setting of hemodynamic collapse of the trauma patient. Recognizing this finding on CT scan and CXR can be life saving.