General 1 Flashcards

Question

25. Blockade of the superficial cervical plexus is performed at which location? (A) At the midposterior border of the sternocleidomastoid muscle (B) In the interscalene groove (C) Over Chassaignac tubercle (D) Over the mastoid process (E) Over the transverse process of C2

Answer 1

A Antidepressants such as amitriptyline can be given for diabetic neuropathy. Corticosteroids are for pain associated with inflammation. Methylphenidate is given to counteract sedation if the client is on opioids. Lorazepam is an anxiolytic.

Answer 2

C Question 4 Explanation: Cancer pain generally worsens with disease progression and the use of opioids is more generous. Fibromyalgia is more likely to be treated with non-opioid and adjuvant medications. Trigeminal neuralgia is treated with anti-seizure medications such as carbamazepine (Tegretol). Phantom limb pain usually subsides after ambulation begins.

Answer 3

C The Faces pain rating scale (depicting smiling, neutral, frowning, crying, etc.) is appropriate for young children who may have difficulty describing pain or understanding the correlation of pain to numerical or verbal descriptors. The other tools require abstract reasoning abilities to make analogies and use of advanced vocabulary.

Answer 4

C the IV route is preferred as the fastest and most amenable to titration. A PCA bolus can be delivered; however, the pump will limit the dosage that can be delivered unless the parameters are changed. Intraspinal administration requires special catheter placement and there are more potential complications with this route. Sublingual is reasonably fast, but not a good route for titration, medication variety in this form is limited.

Answer 5

A the goal is to control pain while minimizing side effects. For severe pain, the medication can be titrated upward until pain is controlled. Downward titration occurs when the pain begins to subside. Adequate dosing is important; however, the concept of controlled dosing applies more to potent vasoactive drugs.

Answer 6

B Use of heat and cold applications is a standard therapy with guidelines for safe use and predictable outcomes, and an LPN/LVN will be implementing this therapy in the hospital, under the supervision of an RN. Therapeutic touch requires additional training and practice. Meditation is not acceptable to all clients and an assessment of spiritual beliefs should be conducted. Transcutaneous electrical stimulation is usually applied by a physical therapist.

Answer 7

C Step 1 includes non-opioids and adjuvant drugs. Step 2 includes opioids for mild pain plus Step 1 drugs and adjuvant drugs as needed. Step 3 includes opioids for severe pain (replacing Step 2 opioids) and continuing Step 1 drugs and adjuvant drugs as needed.

Answer 8

D at greatest risk are elderly clients, opiate naïve clients, and those with underlying pulmonary disease. The child has two of the three risk factors

Answer 9

A This client has strong beliefs and emotions related to the issue of sibling addiction. First, encourage expression. This indicated to the client that the feelings are real and valid. It is also an opportunity to assess beliefs and fears. Giving facts and information is appropriate at the right time. Family involvement is important, bearing in mind that their beliefs about drug addiction may be similar to those of the client.

Answer 10

C Diaphoresis is one of the early signs that occur between 6 and 12 hours. Fever, nausea, and abdominal cramps are late signs that occur between 48 and 72 hours.

Answer 11

A The nursing assistant is able to assist the client with hygiene issues and knows the principles of safety and comfort for this procedure. Monitoring the client, teaching techniques, and evaluating outcomes are nursing responsibilities.

Answer 12

B Complete information from the family should be obtained during the initial comprehensive history and assessment. If this information is not obtained, the nursing staff will have to rely on observation of nonverbal behavior and careful documentation to determine pain and relief patterns

Answer 13

C If the gastrointestinal system is function, the oral route is preferred for routine analgesics because of lower cost and ease of administration. Oral route is also less painful and less invasive than the IV, IM, subcutaneous, or PCA routes. Transdermal route is slower and medication availability is limited compared to oral forms.

Answer 14

D Assess the pain for changes in location, quality, and intensity, as well as changes in response to medication. This assessment will guide the next steps.

Answer 15

C The side-lying, knee-chest position opens retroperitoneal space and provides relief. The pillow provides a splinting action. Diversional therapy is not the best choice for acute pain, especially if the activity requires concentration. TENS is more appropriate for chronic muscular pain. The additional stimulation of massage may be distressing to the client.

Answer 16

D IF the pain is constant, the best schedule is around-the-clock, to provide steady analgesia and pain control. The other options may actually require higher doses to achieve control

Answer 17

B/C Question 22 Explanation: The clients with the cast and the toe amputation are stable clients and need ongoing assessment and pain management that are within the scope of practice for an LPN/LVN under the supervision of an RN. The RN should take responsibility for pre-operative teaching, and the terminal cancer needs a comprehensive assessment to determine the reason for refusal of medication.

Answer 18

C When a client takes aspirin, monitor for increases in PT (normal range 11.0-12.5 seconds in 85%-100%). Also monitor for possible decreases in potassium (normal range 3.5-5.0 mEq/L). If bleeding signs are noted, hematocrit should be monitored (normal range male 42%-52%, female 37%-47%). An elevated BUN could be seen if the client is having chronic gastrointestinal bleeding (normal range 10-20 mg/dL)

Answer 19

B A second day postoperative client who needs medication prior to dressing changes has predictable and routine care that a new nurse can manage. Although chronic pain clients can be relatively stable, the interaction with this client will be time consuming and may cause the new nurse to fall behind. The HIV client has complex complaints that require expert assessment skills. The client pending discharge will need special and detailed instructions.

Answer 20

C directly ask the client about the pain and do a complete pain assessment. This information will determine which action to take next.

Answer 21

1. (D) Straight leg raising test. This patient likely has a compressed nerve. The straight leg raising test is used to elicit nerve impingement from a herniated disk in the lumbar spine, which frequently results in sciatica or posterior hip pain. Internal and external rotation of the hip and Patrick’s maneuver both elicit causes of anterior hip pain. Ober’s test is used to detect iliotibial band syndrome, a cause of lateral hip pain.

Answer 22

2. (A) AVN. In Figure 1, decreased signal intensity is observed in the femoral head (wedge shape), which strongly suggests AVN. MRI is the most sensitive test for detecting AVN. Plain radiographs can be negative in early AVN. There is no evidence of hip fracture on this patient’s MRI, and she had no history of recent trauma. Osteoarthritis has a more insidious course and would not progress this rapidly (this patient’s hip pain developed over 5 days). Trochanteric bursitis causes lateral hip pain; Patrick’s maneuver would not be positive in trochanteric bursitis

Answer 23

3. (B) Hip fracture. This patient likely has a right hip fracture. In Figure 2, note the displaced femoral neck. Plain radiography is a good initial study but is not sensitive for diagnosing acute nondisplaced fractures. If this patient’s initial radiograph did not show hip fracture, further studies would be indicated given this patient’s recent fall, inability to walk, and history of osteoporosis. Computed tomography or MRI likely would reveal a nondisplaced acute fracture. Osteoarthritis has a more insidious course and would not cause acute pain. Trochanteric bursitis causes lateral hip pain

Answer 24

4. (A) Adenocarcinoma. Because this patient is a nonsmoker, adenocarcinoma is the most likely diagnosis. Patients with a history of smoking are more likely to develop small cell carcinoma, squamous cell carcinoma, and large cell carcinoma. It is not uncommon for patients to present with bone pain from metastasis as their initial manifestation of lung cancer.

Answer 25

5. (C) Osteoarthritis. Crepitus is the hallmark finding of osteoarthritis. Patrick’s maneuver confirms an anterior cause of the hip pain. This patient developed symptoms over 6 months, and AVN would likely have a more rapid course. Without a history of trauma, hip fracture is unlikely in this patient. Trochanteric bursitis causes lateral hip pain, not anterior hip pain.

Answer 26

6. (A) Iliotibial band syndrome. Ober’s test is performed by having the patient lie on the unaffected side, and the affected leg is then abducted with the knee flexed to 90 degrees and released. Ober’s test is considered positive for iliotibial band syndrome if the thigh remains abducted when it is released. Sciatica causes posterior hip pain and is most likely due to a herniated disk in the lumbar spine. Meralgia paresthetica causes anterolateral thigh numbness and pain and is due to an entrapped lateral femoral cutaneous nerve. Trochanteric bursitis also causes lateral hip pain but is diagnosed by simple palpation of the lateral hip over the greater trochanter.

Answer 27

7. (B) Meralgia paresthetica. Meralgia paresthetica causes numbness and pain in the anterolateral thigh as a result of an entrapped lateral femoral cutaneous nerve. Risk factors for meralgia paresthetica include obesity, pregnancy, and ascites. In this case, the patient’s weight gain likely caused nerve entrapment. Upon further history, the patient reported that he was still wearing the same size of clothing; nerve entrapment may be due to wearing clothes that are too tight. Trochanteric bursitis and iliotibial band syndrome cause lateral hip pain as a result of overuse rather than compression. Sciatica is unlikely because it causes posterior hip pain.

Answer 28

788. (B) Tachyphylaxis is a well-known phenomenon associated with repeated injections of local anesthetics leading to decreased effectiveness. Interestingly, the dosing interval seems most important in the development of tachyphylaxis. If the dosing interval is short (and no pain between injections) tachyphylaxis does not develop. However, with longer dosing intervals (and pain between injections) tachyphylaxis develops

Answer 29

789. (B) The treatment of pruritus, the most common side effect of neuraxial opiates, is primarily with opioid antagonists, mixed opioid agonist-antagonist, and antihistamine drugs (by their sedating effects). Nalbuphine is a mixed opioid agonist-antagonist; diphenhydramine and hydroxyzine have antihistamine properties. Propofol at very low doses (e.g., 10 mg) has been useful to treat pruritus not only induced by neuraxial opiates but also the pruritus associated with cholestatic liver disease. Propofol does not affect analgesia, whereas opioid antagonists and mixed agonist-antagonist may reverse some or all of the analgesia, depending upon dose. Dexmedetomidine is a highly selective α2-receptor agonist that has a faster onset and shorter duration of action compared with clonidine. Dexmedetomidine has analgesic properties, can potentiate neuraxial analgesia when injected spinally, and can perhaps decrease the incidence of pruritus by reducing the narcotic dose is used. It does not treat pruritus

Answer 30

790. (D) The maximum dose of local anesthetics containing 1:200,000 epinephrine that can be used for major nerve blocks is lidocaine, 500 mg; mepivacaine, 500 mg; prilocaine, 600 mg; bupivacaine, 225 mg; etidocaine, 400 mg; and tetracaine, 200 mg

Answer 31

791. (B) 1:200,000 means 1 g = 1000 mg = 1,000,000 μg per 200,000 mL 1,000,000 μg/200,000 mL = 5 μg/mL

Answer 32

792. (E) The early signs of digitalis toxicity include loss of appetite and nausea and vomiting. In some patients there may be pain that is similar to trigeminal neuralgia. Pain or discomfort in the feet and pain and discomfort in the extremities may be a feature of digitalis toxicity. Transient visual disturbances (e.g., amblyopia, scotomata) have been reported in patients with digitalis toxicity. In this patient, it would be prudent to obtain a digoxin level as an early part of the workup for these complaints. He may also have true trigeminal neuralgia, and workup for this condition can be undertaken after digitalis toxicity has been ruled out

Answer 33

793. (C) Toxic reactions to local anesthetics are usually due to intravascular or intrathecal injection or to an excessive dosage. The initial symptoms of local anesthetic toxicity are lightheadedness and dizziness. Patients also may note perioral numbness and tinnitus. Progressive central nervous system (CNS) excitatory effects include visual and auditory disturbances, shivering, muscular twitching, and ultimately, generalized tonic-clonic seizures. CNS depression can ensue, leading to respiratory depression or arrest

Answer 34

794. (B) The site of action of spinally administered opiates is the substantia gelatinosa of the spinal cord. Epidural administration is complicated by factors related to dural penetration, absorption in fat, and systemic uptake; therefore, the quantity of intrathecally administered opioid required to achieve effective analgesia is typically much smaller. The ratio of epidural to intrathecal dose of morphine is approximately 10:1. Morphine is typically given in doses of 3 to 10 mg in the lumbar epidural space. Intrathecal morphine dosage is 0.2 to 1.0 mg. Onset time for epidural administration is 30 to 60 minutes with a peak effect in 90 to 120 minutes. Onset time for intrathecal administration is shorter than epidural administration. Duration of 12 to 24 hours of analgesic effect can be expected by either route

Answer 35

795. (A) Commonly injected local anesthetics are divided chemically into two groups: the aminoesters (esters) and the aminoamides (amides). The esters include procaine, chloroprocaine and tetracaine (all have one letter i in the name). The amides are lidocaine, mepivacaine, prilocaine, bupivacaine, levobupivacaine, etidocaine and ropivacaine (all have two i’s in the name). The esters undergo plasma clearance by cholinesterases and have relatively short half-lives, whereas the amides undergo hepatic clearance and have longer half-lives

Answer 36

796. (C) The major disadvantage of the interscalene block for hand and forearm surgery is that blockade of the inferior trunk (C8-T1) is often incomplete. Supplementation of the ulnar nerve often is required. The risk of pneumothorax is quite low, but blockade of the ipsilateral phrenic nerve occurs in up to 100% of blocks. This can cause respiratory compromise in patients with significant lung disease

Answer 37

797. (C) Surgical trauma includes a wide variety of physiologic responses. General anesthesia has no or only a slight inhibitory effect on endocrine and metabolic responses to surgery. Regional anesthesia inhibits the nociceptive signal from reaching the CNS and, therefore, has a significant inhibitory effect on the stress response, including adrenergic, cardiovascular, metabolic, immunologic, and pituitary. This effect is most pronounced with procedures on the lower part of the body and less with major abdominal and thoracic procedures. The variable effect is probably due to unblocked afferents, i.e., vagal, phrenic, or sympathetic

Answer 38

798. (C) The structures that are traversed by a needle placed in the midline prior to the epidural space are as follows: skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, and ligamentum flavum. The ligamentum flavum is tough and dense and a change in the resistance to advancing the needle is often perceived and to many feels like a “snap.” The anterior and posterior longitudinal ligaments bind the vertebral bodies together. See also explanation and diagram in question 870

Answer 39

799. (B) The symptoms of cauda equina syndrome include low back pain, bilateral lower extremity weakness, saddle anesthesia and loss of bowel and bladder control. Pooling of local anesthetics in dependent areas of the spine within the subarachnoid space has been identified as the causative factor in cases of cauda equina syndrome. Microlumen catheters may enhance the nonuniform distribution of solutions within the intrathecal space, but cauda equina syndrome has been associated with the use of larger catheters, 5% lidocaine with dextrose, and 2% lidocaine, as well as 0.5% tetracaine

Answer 40

800. (B) Differential nerve blockade is a complex process where anatomic and chemical factors determine the susceptibility of fibers to blockade by local anesthetics. Diameter, myelinization, and location within the nerve trunk affect the onset and regression time. In general, the small unmyelinated sympathetic fibers are blocked first, followed by unmyelinated C fibers (pain and temp), then small myelinated fibers (proprioception, touch, pressure), and finally the large myelinated fibers (motor)

Answer 41

801. B Acute herpes zoster is due to the reactivation of the varicella-zoster virus. Acute treatment includes symptomatic pain treatment and antiviral drugs (e.g., acyclovir). It is typically a benign and self-limiting disease in patients younger than 50 years of age. As one gets older, the incidence of postherpetic neuralgia (PHN) defined as pain persisting beyond the healing of the herpes zoster lesions increases. The incidence of PHN is about 50% in patients older than 50 years. Treatment of established PHN has been shown to be resistant to interventions and, thus, can be difficult. However, proven therapies include tricyclic antidepressants, anticonvulsants, topical local anesthetics (e.g., 5% lidocaine patch), topical capsaicin and TENS. Sympathetic blocks can provide excellent analgesia but are most useful during the more acute stages of the disease rather than during the late chronic stages. Sympathetic blocks in the acute stages may decrease the incidence of PHN. Oral clonidine, which is used to treat hypertension and opioid withdrawal, has not been shown to be an effective treatment for postherpetic neuralgia

Answer 42

802. (C) The deep peroneal nerve innervates the short extensors of the toes and the skin of the web space between the great and second toe. The deep peroneal nerve is blocked at the ankle by infiltration between the tendons of the anterior tibial and extensor hallucis longus muscle

Answer 43

803. (B) Central nervous system (CNS) toxicity from local anesthetics generally parallels anesthetic potency (e.g., bupivacaine is four times as potent as lidocaine, ropivacaine is three times as potent as lidocaine). Cardiovascular (CV) toxicity occurs at a higher blood level than CNS toxicity. For bupivacaine and ropivacaine, CV toxicity occurs at two times the CNS dose, whereas for lidocaine the CV toxicity occurs at seven times the CNS toxicity levels, making lidocaine the least cardiotoxic, and bupivacaine the most cardiotoxic of the listed local anesthetics

Answer 44

804. (E) The International Association for the Study of Pain (IASP) has defined several pain terms. Anesthesia dolorosa refers to spontaneous pain in an area or region that is anesthetic. Neuropathic pain is pain initiated or caused by a primary lesion or dysfunction in the nervous system. Dysesthesia is an unpleasant abnormal sensation, whether spontaneous or evoked. Hyperalgesia is an increased response to a stimulus that is normally painful. Allodynia is pain caused by a stimulus that does not normally provoke pain

Answer 45

805. (A) Ester local anesthetics are hydrolyzed by cholinesterase enzymes that are present mainly in plasma and, in a smaller amount, in the liver. Because there are no cholinesterase enzymes present in cerebrospinal fluid (CSF), the anesthetic effect of tetracaine will persist until it is absorbed into systemic circulation. The rate of hydrolysis varies, with chloroprocaine being fastest, procaine intermediate, and tetracaine the slowest. Toxicity is inversely related to the rate of hydrolysis; tetracaine is, therefore, the most toxic

Answer 46

806. (A) Complex regional pain syndrome type I or CRPS type I also called reflex sympathetic dystrophy (RSD) is a clinical syndrome of continuous burning pain, usually occurring after minor trauma. Patients present with variable sensory, motor, autonomic, and trophic changes. Complex regional pain syndrome type II or CRPS type II (causalgia) exhibits the same features of reflex sympathetic dystrophy, but the etiology is usually major traumatic damage to large nerves (e.g., median nerve of the upper extremity or tibial division of the sciatic nerve in the lower extremity)

Answer 47

807. (C) The potency of local anesthetics is directly related to their lipid solubility. In general, the speed or onset of action of local anesthetics is related to the pKa of the drug. Drugs with lower pKa values have a higher amount of non-ionized molecules at physiologic pH and penetrate the lipid portion of nerves faster (an exception is chloroprocaine, which has a fast onset of action that may be related to the higher concentration of drug used). The amount of protein binding seems related to the duration of action of local anesthetics (more protein binding has longer duration of action)

Answer 48

808. (E) Many factors have an effect on the sensory level after a subarachnoid injection. The baricity of the solution and the patient position are the most important determinants of sensory level. The other listed options have little to no effect on sensory level. Patient height also has little effect on sensory level

Answer 49

809. (D) Chloroprocaine is an ester local anesthetic that is rapidly metabolized by pseudocholinesterase. With the epidural injection of chloroprocaine, very little drug is available to cross the placenta, because the half-life is about 45 seconds (and that which crosses is also rapidly metabolized making fetal effects essentially non-significant). The amide local anesthetics undergo liver metabolism and have relatively long half-lives, but with prolonged epidural administration may accumulate in the fetus

Answer 50

810. (A) Hypotension with a high spinal anesthesia is related to sympathetic blockade; venodilation (decreases preload), arterial dilation (decreases afterload) and a decrease in heart rate (cardioaccelerator fibers T1-T4 blockade and a fall in right atrial filling that affects the intrinsic chronotropic stretch receptors). With a high spinal, the decrease in venous dilation is the predominant cause of hypotension

Answer 51

811. (C) The incidence of phantom limb pain is estimated to be 60% to 85%. The incidence of phantom limb pain does not differ between traumatic and nontraumatic amputees. The incidence of phantom pain increases with more proximal amputation. Although very difficult to treat, nerve blocks are commonly used in an attempt to treat phantom pain. These include trigger point injections, peripheral and central nerve blocks, and sympathetic blocks

Answer 52

812. (D) Prilocaine is the most rapidly metabolized of the amide local anesthetics and therefore least toxic. 2- Chloroprocaine is hydrolyzed rapidly in the blood and, therefore, would appear to be ideal, but it has been associated with a high incidence of thrombophlebitis and is therefore not recommended. To avoid toxicity, maximum doses are as follows: prilocaine, 3 to 4 mg/kg; lidocaine, 1.5 to 3 mg/kg; ropivacaine, 1.2 to 1.8 mg/kg. Bupivacaine is not recommended for Bier blocks because of reports of cardiovascular toxicity and death that have occurred

Answer 53

813. (D) Both phenylephrine and epinephrine will prolong a spinal anesthetic when administering lidocaine. The Taylor approach for spinal anesthesia uses a paramedian approach to the L5-S1 interspace—the largest interspace of the vertebral column. The sympathetic nervous system originates in the thoracic and lumbar spinal cord T1- L3; therefore, a high thoracic sensory level can cause a complete sympathetic block. The dural sac extends to S2-S3, not S4-S5. The spinal cord extends to L3 in the infant and L1-L2 in adults

Answer 54

814. (A) Development of an epidural abscess is fortunately an exceedingly rare complication of spinal and epidural anesthesia. Most anesthetic related epidural abscesses are associated with epidural catheters. When an epidural abscess is developing, prompt recognition and treatment are essential if permanent sequelae are to be avoided. Symptoms from an epidural abscess may not become apparent until several days (mean 5 days) after placement of the block. There are four clinical stages of epidural abscess symptom progression. Initially, localized back pain develops. Second stage includes nerve root or radicular pain. The third stage involves motor and sensory deficits followed by the last stage of paraplegia. Unlike an epidural hematoma, in which severe back pain is the key feature, patients with epidural abscesses will complain of radicular pain approximately 3 days after development of the back pain. Anterior spinal artery syndrome is characterized predominantly by motor weakness or paralysis of the lower extremities. Meralgia paresthetica is related to entrapment of the lateral femoral cutaneous nerve as it courses below the inguinal ligament and is associated with burning pain over the lateral aspect of the thigh. It is not a complication of epidural anesthesia

Answer 55

815. (C) Complex regional pain syndromes are associated with trauma. The main feature is burning and continuous pain that is exacerbated by normal movement, cutaneous stimulation, or stress, usually weeks after the injury. The pain is not anatomically distributed. Other associated features include cool, red, clammy skin and hair loss in the involved extremity. Chronic cases may be associated with atrophy and osteoporosis

Answer 56

816. (D) Neurolytic blockade with phenol (6% to 10% in glycerine) is painless because phenol has a dual action as both a local anesthetic and a neurolytic agent. The initial block wears off over a 24-hour period, during which time neurolysis occurs. For this reason you must wait a day to determine effectiveness of the neurolytic block. Alcohol (100% ethanol) is painful on injection and should be preceded by local anesthetic injection. Unfortunately, there is no neurolytic agent that affects only sympathetic fibers

Answer 57

817. (C) In general, each 1-2 mL of local anesthetic will anesthetize about one spinal segment in the 20 to 40-year-old patient. Because of the negative intrathoracic pressure transmitted to the epidural space with breathing, about two thirds of the segments are blocked above the level of the lumbar placement and one third of segments are blocked below the injection. For example, to achieve a T4 block when an epidural is placed at the L2-L3 space about 10 segments above and 5 segments below the epidural would be needed (15 segments) or about 20-25 mL. As one gets older, the dose of local anesthetic mL/segment decreases (e.g., 80 year old may need 0.75-1.5 mL/segment). Also, pregnant patients are more sensitive to local anesthetics and reduced doses are needed

Answer 58

818. (C) The artery of Adamkiewicz is also called the arteria radicularis magna and is one of the “feeder” arteries for the anterior spinal artery. Damage to this artery can lead to ischemia in the thoracolumbar region and may result in paraplegia. The origin of this artery is variable

Answer 59

819. (E) The one anterior spinal artery supplies about 75% of the blood flow to the spinal cord (motor tracts) and arises from the vertebral arteries and radicular arteries from the aorta. It descends in front of the anterior longitudinal sulcus of the spinal cord. The two posterior spinal arteries supply about 25% of the blood flow to the spinal cord (sensory tracts) and arise from the posterior and inferior cerebellar arteries, the vertebral arteries, and the radicular arteries

Answer 60

820. (D) To perform a sciatic nerve block, first draw a line from the posterior superior iliac spine to the greater trochanter, then draw a 5-cm line perpendicular from the midpoint of this line caudally and a second line from the sacral hiatus to the greater trochanter. The intersection of the second line with the perpendicular line marks the point of entry

Answer 61

821. (D) Complications of deep cervical plexus block include injection of the local anesthetic into the vertebral artery, subarachnoid space, or epidural space. Other nerves that may be anesthetized include the phrenic nerve (which is why bilateral deep cervical plexus blocks should be performed with caution, if at all), and the recurrent laryngeal nerve

Answer 62

822. (E) A retrobulbar block anesthetizes the three cranial nerves responsible for movement of the eye. The ciliary nerves are also blocked, providing anesthesia to the conjunctiva, cornea, and uvea. The ophthalmic branch of the trigeminal nerve provides sensory innervation to the skin of the forehead, cornea, and eyelid. This branch of the trigeminal nerve may be blocked, but the maxillary branch would be spared

Answer 63

823. (E) The vagus nerve innervates the airway by two branches: the superior laryngeal nerves and the recurrent laryngeal nerves. All the muscles of the larynx are innervated by the recurrent laryngeal nerve except for the cricothyroid muscle. The superior laryngeal nerve divides into the internal and external laryngeal branches. The external laryngeal branch innervates the cricothyroid muscle. The internal laryngeal branch provides sensory fibers to the cords, epiglottis and the arytenoids

Answer 64

824. (E) Because of the potential for cardiotoxicity and because bupivacaine has no advantages over other local anesthetics in this setting, it is no longer recommended for use in intravenous regional anesthesia

Answer 65

825. (C)The stellate ganglion usually lies in front of the neck of the first rib. The vertebral artery lies anterior to the ganglion as it has just originated from the subclavian artery. After passing over the ganglion, it enters the vertebral foramen and lies posterior to the anterior tubercle of C6

Answer 66

826. (D) The median nerve is the most medial structure in the antecubital fossa. To block this nerve, first the brachial artery is palpated at the level of the intercondylar line between the medial and lateral epicondyles, and then a needle is inserted just medial to the artery and directed perpendicularly to the skin

Answer 67

827. (D) When an epidural catheter is placed without fluoroscopic guidance, the exact location of the needle tip relative to the anatomic structures of the back can only be surmised. If malposition of either the needle or the catheter is suspected, it is prudent to withdraw the entire apparatus and reinsert a second time. In this case, it is possible that the catheter tip has found its way into a nerve root. Under these circumstances, injection of a local anesthetic or narcotic could produce pressure that would lead to ischemia and possible neurologic damage. During placement or injection of an epidural catheter, a paresthesia is always a warning sign that should be heeded

Answer 68

828. (B) There are five nerves that supply the ankle and foot: the posterior tibial, sural, superficial and deep peroneal, and saphenous nerves. These nerves are superficial at the level of the ankle and are easy to block. The posterior branch of the tibial nerve gives rise to the medial and lateral plantar nerves, which supply the plantar surface of the foot

Answer 69

829. (C) In general, in both in vivo and in vitro studies there is an overall direct correlation between anesthetic’s potency and its direct depressant effect on myocardial contractility. The ratio of dosage required for cardiovascular collapse in animal models compared with that required to produce neurologic symptoms is the lowest for bupivacaine, levo-bupivacaine and ropivacaine (2.0). Ratios for other local anesthetics are as follows: prilocaine, 3.1; procaine and chloroprocaine, 3.7; etidocaine, 4.4; lidocaine and mepivacaine, 7.1

Answer 70

830. (E) Reactivation of phantom limb sensations has been reported in patients who have received both spinal and epidural anesthetics (90% in some series). In the majority of these cases (80%), phantom limb sensation persisted until the block receded. With a history of a phantom limb sensations that drove this patient to attempt suicide, it is probably wise to avoid spinal and epidural anesthetics. Phenelzine (Nardil) is a monoamine oxidase (MAO) inhibitor that is occasionally used for the treatment of depression. Any anesthetic or combination of techniques that involves meperidine is contraindicated in patients receiving MAO inhibitors. The combination of meperidine and MAO inhibitors has been associated with hyperthermia, hypotension, hypertension, ventilatory depression, skeletal muscle rigidity, seizures, and coma. Because of this unfavorable drug interaction, meperidine should be avoided in patients receiving MAO inhibitors. Accordingly, the only acceptable choice in this question would be general anesthesia with propofol, succinylcholine, nitrous oxide, and fentanyl. As an interesting side point, the drug phenelzine prolongs the duration of action of succinylcholine by decreasing plasma cholinesterase activity

Answer 71

831. (C) The recurrent laryngeal nerve innervates all the muscles of the larynx except the cricothyroid muscle, which tenses the vocal cords and is innervated by the external branch of the superior laryngeal nerve. With bilateral transections of the recurrent laryngeal nerve, the vocal cords lie within 2 to 3 mm of the midline. The airway maybe inadequate and a tracheostomy may be needed

Answer 72

832. (E) Postdural puncture headache (PDPH) will have a postural component. When supine, the headache is usually gone but may be mild in some cases. When the head is elevated the headache may be severe, is bilateral and may be associated with diplopia, nausea and vomiting. The headache pain is typically frontal and/or occipital in location

Answer 73

833. (C) VAN (Vein, Artery, Nerve) describes the anatomical relationship of the intercostal structures deep to the lower border of the ribs from cephalad to caudal direction. The block is performed by walking off the inferior edge of the rib typically about 5 to 7 cm from midline. The two principle risks are pneumothorax and intravascular injection of local anesthetics. Because of the close proximity of the vein and artery to the nerve, intercostal blocks have relatively high blood levels as compared to other blocks (e.g., epidural, brachial plexus, infiltration) and caution with dose is needed if many levels are blocked

Answer 74

834. (A) The site of injection of the local anesthetic is one of the most important factors influencing systemic local anesthetic absorption and toxicity. The degree of absorption from the site of injection depends on the blood supply to that site. Areas that have the greatest blood supply have the greatest systemic absorption. For this reason, the greatest plasma concentration of local anesthetic occurs after an intercostal block, followed by caudal epidural, lumbar epidural, brachial plexus, sciatic/femoral nerve block, and subcutaneous

Answer 75

835. (D) Local anesthetics are weak bases. The neutral (non-ionized) form of the molecule is able to pass through the lipid nerve cell membrane, whereas the ionized (protonated) form actually produces anesthesia. Chloroprocaine has the highest pKa of local anesthetics, meaning that a greater percentage of it will exist in the ionized form at any given pH than any of the other local anesthetics. Despite this fact, 3% chloroprocaine has a more rapid onset than 2% lidocaine, presumably because of the greater number of molecules (concentration). If one compares onset time for 1.5% lidocaine against 1.5% chloroprocaine, the former will have a more rapid onset

Answer 76

836. (B) The risk of pneumothorax is a significant limitation for supraclavicular brachial plexus blocks (incidence 0.5%- 6% depending upon experience). Furthermore, the technique is difficult to teach and describe. For these reasons, this block should not be performed in patients in whom a pneumothorax or phrenic nerve block (40%-60% of patients) would result in significant dyspnea or respiratory distress. A pneumothorax should be considered if the patient begins to complain of chest pain or shortness of breath or begins to cough during placement of supraclavicular brachial plexus block

Answer 77

837. (B) The structures in the neck from medial to lateral are the recurrent laryngeal nerve, carotid artery, vagus nerve, internal jugular vein, and phrenic nerve

Answer 78

838. (A) The obturator nerve provides variable cutaneous innervation of the thigh. An obturator nerve block is achieved by placement of the needle 1 to 2 cm lateral to and 1 to 2 cm below the pubic tubercle. After contact with the pubic bone, the needle is withdrawn and walked cephalad to identify the obturator canal. Between 10 and 15 mL of local anesthetic should be placed in the canal. If a nerve stimulator is used, contraction of the adductor muscles with nerve stimulation indicates proximity to the nerve

Answer 79

839. (A) The most serious complication associated with a supraclavicular brachial plexus block is pneumothorax. The most common complication is a phrenic nerve block which is usually mild and relatively common (40%-60% of blocks). Bilateral supraclavicular blocks however, are not recommended due to the possibility of bilateral phrenic nerve paralysis or pneumothoraces. Other potential complications include Horner’s syndrome, nerve damage or neuritis, or intravascular injection

Answer 80

840. (A) The arm receives sensory innervation from the brachial plexus except for the shoulder, which is innervated by the cervical plexus, and the posterior medial aspect of the arm, which is supplied by the intercostobrachial nerve

Answer 81

841. (B) The brachial plexus starts out at the root level from the ventral rami of C5-T1 with a small amount from C4 and T2. These roots at the level of the scalene muscle become the 3 trunks: superior, middle and inferior. The trunks then divide into the dorsal and ventral divisions at the lateral edge of the first rib. When the divisions enter the axilla, they become the cords: posterior, lateral and medial. At the lateral border of the pectoralis muscle they become the five peripheral nerves: radial, musculocutaneous, median, ulnar and axillary. The plexus is blocked at the distal level of the trunks just before they become divisions. Here a small volume of anesthetic is required and no part of the plexus is spared, as with axillary or interscalene block. The block can be performed with the arm in any position

Answer 82

842. (A) The celiac plexus innervates most of the abdominal viscera, including the lower esophagus, stomach, all of the small intestine and the large intestine up to the splenic flexure as well as the pancreas, liver, biliary tract, spleen, kidneys, adrenal glands and omentum. The pelvic organs (e.g., uterus, ovaries, prostate, distal colon) are supplied by the hypogastric plexus

Answer 83

843. (D) The great toe is innervated by the deep peroneal, posterior tibial, superficial peroneal, and occasionally the saphenous nerve. All four of these nerves should be blocked for surgery on the great toe

Answer 84

844. (D) Frequent dosing by a patient receiving postoperative analgesia through a PCA pump suggests the need to increase the magnitude of the dose. It is important to keep in mind that a patient should be given a sufficient loading dose of narcotic before initiative therapy with a PCA pump. Otherwise, the patient will be playing the frustrating game of “catch up”

Answer 85

845. (D) Transcutaneous electrical nerve stimulation (TENS) is low-intensity electrical stimuli (2 and 100 Hz,) that produces a tingling or vibratory sensation. It is thought that TENS units produce analgesia by releasing endogenous endorphins. These endorphins have an inhibitory effect at the spinal cord level and augment descending inhibitory pathways

Answer 86

846. (C) Although the more hydrophilic drugs such as morphine have a longer duration of action of analgesia, they also have a higher potential for inducing delayed respiratory depression through cephalad migration in the CNS, as compared with the more lipid-soluble drugs listed in this question

Answer 87

847. (C) The thumb corresponds to dermatome C6, the second and middle fingers correspond to dermatome C7, and the fourth and little fingers correspond to dermatome C8

Answer 88

848. (D) Increasing the total dose (mass) of local anesthetic is more efficacious in hastening the onset and increasing the duration of an epidural anesthetic than increasing the volume or increasing the concentration (while holding the total dose constant)

Answer 89

849. (D) Alcohol and phenol are similar in their ability to cause nonselective damage to neural tissues. Alcohol causes pain when injected and sometimes is mixed with bupivacaine, whereas phenol is relatively painless. Neural tissue will regenerate; therefore, neurolytic blocks are never “permanent” and neurolysis can lead to a denervation hypersensitivity, which can be extremely painful

Answer 90

850. (B) Epinephrine’s effect on the duration of anesthesia depends on the local anesthetic and the site. Infiltration and peripheral block duration with most agents will be prolonged with epinephrine. The addition of epinephrine to epidural 0.5% or 0.75% bupivacaine has not been shown to increase the duration of the motor blockade but does extend the duration of the sensory block. The effect of epinephrine is greater for the intermediate duration local anesthetics lidocaine and mepivacaine

Answer 91

851. (E) Mixtures of local anesthetics have been used to take advantage of the short latency of certain agents (chloroprocaine) and the long duration of other agents (bupivacaine). Duration of epidural anesthesia by mixtures of chloroprocaine and bupivacaine has been shown to be shorter than bupivacaine alone and onset time longer than chloroprocaine alone

Answer 92

852. (C) Younger adults have a higher incidence of PDPH than older adults. Women have a slightly higher incidence than men. Pregnant women have a higher incidence than nonpregnant women. Since the incidence and severity of PDPH relates to the amount of CSF leakage through the dural hole, it makes sense that the larger the needle and the more holes in the dura the greater incidence of PDPH. In addition, the shape of the tip of the needle is important; a cutting needle (e.g.. Quincke) has a greater incidence of PDPH than noncutting needles (e.g., Whitacre, Sprotte). The incidence of headache has been shown to be less when the dural fibers are split longitudinally rather than when they are cut while the needle is held in a transverse direction. The timing of ambulation relative to dural puncture has not been shown to affect the incidence of postspinal headache. The block should wear off before ambulation is attempted

Answer 93

853. (A) Virtually all pain arising in the thoracic or abdominal viscera is transmitted via the sympathetic nervous system in unmyelinated type C fibers. Visceral pain is dull, aching, burning, and nonspecific. Visceral pain is caused by any stimulus that excites nociceptive nerve endings in diffuse areas. In this regard, distention of a hollow viscus causes a greater sensation of pain than does the highly localized damage produced by transecting the gut

Answer 94

854. (E) The brachial plexus is not normally retracted during repair of an anterior shoulder dislocation. Prolonged pressure on the brachial plexus will result in hand or arm numbness. This may occur if this structure becomes pinched between the clavicle and the head of the humerus, as seen in patients placed in steep Trendelenburg position with the shoulders resting against shoulder braces. Prolonged pressure on the medial epicondyle may produce an ulnar neuropathy, whereas prolonged pressure against the posterior surface of the humerus may produce a radial neuropathy. Bupivacaine is a long-acting local anesthetic and may cause numbness for 8 to 12 hours

Answer 95

855. (D) The cardiac accelerator fibers originate in the T1-T4 segments. A high spinal, above T1, can cause bradycardia by anesthetizing these fibers. Diabetic patients who display orthostatic hypotension have an autonomic neuropathy. The cardiac accelerator fibers are essentially ablated in these patients and therefore, the slowing of heart rate does not ordinarily develop with high spinals. Pilocarpine, a parasympathomimetic agent, will not prevent bradycardia with spinal anesthesia. Patients with Wolff-Parkinson-White syndrome will become bradycardic when the autonomic accelerator fibers are interrupted, as will patients with a spinal cord transection below T4. Recent myocardial infarction does not eliminate susceptibility to bradycardia with sympatholysis unless the patient has a complete heart block

Answer 96

856. (D) All of the nerves of the foot with the exception of the saphenous are derived from the sciatic nerve. The sciatic nerve distally becomes the tibial and peroneal nerves which can be blocked at the popliteal fossa for surgery below the knee. The saphenous nerve is a branch of the femoral nerve and provides sensory innervation along the medial aspect of the lower leg between the knee and the medial malleolus and must also be blocked for surgery below the knee

Answer 97

857. (A) The sympathectomy produced by a celiac plexus block causes hypotension by decreasing preload to the heart. This complication can be avoided by volume loading the patient with lactated Ringer’s solution. Subarachnoid injection is the most serious complication of celiac plexus block. Seizure is possible with an intravascular injection. Retroperitoneal hematoma is also possible, but extremely rare. This block frequently relieves constipation by interrupting the sympathetic fibers and leaving the parasympathetic fibers unopposed

Answer 98

858. (E) The occiput receives sensory innervation from the greater and lesser occipital nerves, which are terminal branches of the cervical plexus. Blockade of these nerves is usually carried out as a diagnostic step in the evaluation of head and neck pain

Answer 99

859. (D) Potential complications from lumbar sympathetic block include subarachnoid injection, puncture of a major vessel (e.g., aorta) or renal pelvis, neuralgia, somatic nerve damage, perforation of a disk, infection, ejaculatory failure, and chronic back pain. Blockade of nerves arising from the lumbar plexus is possible, but given the anatomic location of the sacral plexus, blockade of an S1 nerve would be extremely unlikely if not impossible

Answer 100

860. (D) With the unintentional injection of an epidural dose of local anesthetic into the subarachnoid space, spinal anesthesia develops rapidly. Blockade of the sympathetic fibers (T1-L2) produces hypotension, particularly if the patient is hypovolemic. Bradycardia is produced by blocking the cardiac accelerator fibers (T1-T4). Respiratory arrest is due to hypoperfusion of the respiratory centers as well as paralysis of the phrenic nerve (C3-C5). The pupils become dilated after intrathecal injection of large quantities of local anesthetics; they will return to normal size after the block recedes. Cauda equina syndrome has occasionally developed when the epidural dose was unintentionally administered into the subarachnoid space (most commonly with chloroprocaine). If one suspects an unintentional placement of the epidural dose subarachnoid, supportive methods are initially done (the basic ABC’s of resuscitation). One can also aspirate CSF from the epidural catheter (if it was inserted) to help remove some of the drug as well as reducing the pressure in the subarachnoid space, which might help better perfuse the spinal cord and decrease the chance of cauda equina syndrome developing

Answer 101

861. (B) Somatic pain in the extremities is relieved with spinal anesthesia. If a patient fails to obtain pain relief despite complete sympathetic, sensory, and motor blockade, a “central” mechanism for the pain is likely or the lesion causing the pain is higher in the CNS than the level of blockade achieved by the spinal. Central pain states may include encephalization, psychogenic pain, or malingering. Persistence of pain in the lower extremities after successful spinal blockade suggests a central source or psychological source of pain

Answer 102

862. (E) During a seizure, administration of 100% O2 helps to prevent and treat hypoxia in a patient who otherwise might not be breathing. Hyperventilation also causes cerebral vasoconstriction and decreased delivery of local anesthetic to the brain. Hyperventilation induces hypokalemia and respiratory alkalosis, both of which result in hyperpolarization of nerve membranes and elevation of the seizure threshold. Hyperventilation also raises the patient’s pH (respiratory alkalosis) and converts lidocaine into the non-ionized (nonprotonated) form, which crosses the membrane more easily than the ionized form, which is detrimental

Answer 103

863. (D) Para-aminobenzoic acid is a metabolite of the ester-type local anesthetics. Local anesthetics may be placed into two distinct categories based on their chemical structure: ester or amide. The amides, which are ropivacaine lidocaine, etidocaine, prilocaine, mepivacaine and bupivacaine, are metabolized in the liver. The ester local anesthetics are cocaine, procaine, chloroprocaine, tetracaine, and benzocaine. These drugs are metabolized by the enzyme pseudocholinesterase found in the blood. Para-aminobenzoic acid is a metabolic breakdown product of ester anesthetic and is responsible for allergic reactions in some individuals

Answer 104

864. (E) Peripheral nerve axons are always enveloped by a Schwann cell. The myelinated nerves may be enveloped many times by the same Schwann cell. Transmission of nerve impulses (i.e., action potentials) along nonmyelinated nerves occurs in a continuous fashion, whereas transmission along myelinated nerves occurs by saltatory conduction from one node of Ranvier to the next. Myelination speeds transmission of neurological impulses; it also renders nerves more susceptible to local anesthetic blockade. An action potential is associated with an inward flux of sodium that occurs after a certain membrane threshold has been exceeded

Answer 105

865. (C) The needle insertion site for an interscalene block is C6. Local anesthetics usually spread to C5, C6 and C7 which supply much, but not all, of the cutaneous innervation to the shoulder. With low-to-moderate volume blocks there will be sparing of the (C3-C4) nerve roots, which supply some of the innervation to the anterior shoulder. Of note, C8 and T1 may also be spared, often resulting in the need for ulnar nerve supplementation if this block were used for a hand operation. Complete anesthesia for shoulder arthroscopy may require a supplemental superficial cervical plexus with use of low to moderate volumes of a local anesthetic

Answer 106

866. (B) Hand washing is one of the most important techniques to prevent infections especially when alcohol-based antiseptic solutions are used with sterile gloves. Although soap and water remove bacteria, they do not effectively kill organisms. Antiseptic solutions with alcohol appear better than nonalcoholic antiseptics (e.g., povidone iodine). Nail length does not appear to be a risk factor for infections, because the majority of bacterial growth occurs along the proximal 1 mm of nail adjacent to the subungual skin. Universal use of gowns and gloves does not appear to be better than gloves alone in preventing infections in ICUs and presumably is less important than adequate hand washing and use of sterile gloves (Hebl JR: Infections complications:

Answer 107

867. (A) In patients taking low-molecular weight heparin, or LMWH (e.g., enoxaparin, dalteparin, tinzaparin), caution should be exercised before proceeding with an epidural or spinal anesthetic because of the risk of producing an epidural or spinal hematoma. The amount of time between the last dose of the LMWH and the relative safety of starting a central neuraxial block depends on the dose of the LMWH. At the lower doses, used for thromboprophylaxis, the LMWH should be held at least 10 to 12 hours prior to the block. At the higher doses, used to treat an established DVT, one should wait at least 24 hours after the last dose of LMWH prior to the block

Answer 108

868. (C) Patients taking nonsteroidal anti-inflammatory drugs (NSAIDs), ticlopidine and clopidogrel, exert effects on platelet function. Nonsteroidal anti-inflammatory drugs (NSAIDs) are not a problem if given alone before epidural or spinal anesthesia. But patients taking ticlopidine should wait 14 days and patients taking clopidogrel should wait 7 days before having a neuraxial block placed, because of the increased risk of spinal hematoma formation. Keep in mind that caution is always needed and the ASRA statement of “Careful preoperative assessment of the patient to identify alterations of health that might contribute to bleeding is crucial” is important

Answer 109

869. (E) Adding sodium bicarbonate to local anesthetic solutions hastens the onset of action of the local anesthetics, especially when the local anesthetic solution contains epinephrine (which is produced at a lower pH). By raising the pH, more of the local anesthetic is in the non-ionized, more lipid-soluble state. Raising the pH too much (i.e., >6.05-8) would cause precipitation of the local anesthetic. It also seems to decrease pain with skin infiltration. Pain on injection can also be decreased by a slow injection of the local anesthetic

Answer 110

870. (D) This figure shows the anatomic structures that must be traversed by the spinal needle during performance of a subarachnoid block. The structures include the skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, the ligamentum flavum, and finally the dura (posterior). If you were to continue to advance the spinal needle, you would encounter the dura (anteriorly) while exiting the subarachnoid space, the posterior longitudinal ligament, the periosteum of the vertebral body, and finally, bone

Answer 111

871. (D) In the epidural space, bupivacaine is four times more potent than lidocaine, so 0.5% bupivacaine is similar to 2% lidocaine. The duration of the bupivacaine block will be longer because bupivacaine has a long duration of action and lidocaine has an intermediate duration of action

Answer 112

872. (E) Drugs with α-agonist activity (phenylephrine/epinephrine) possess some analgesic activity but less than narcotics and local anesthetics. In addition, intrathecal epinephrine will reduce systemic/vascular uptake of local anesthetics, thereby enhancing their effects, including hypotension. Clonidine alone, when administered neuraxially, is an effective analgesic. Neostigmine has some mild analgesia properties but experience is limited. Opioids added to the spinal solution enhance surgical anesthesia and provide postoperative pain. Fentanyl 25 μg is commonly added for short surgical procedures (outpatient) whereas morphine can be used when longer postoperative analgesia is desired for inpatients

Answer 113

873. (B) For topical anesthesia, lidocaine, tetracaine, dibucaine and benzocaine are effective, as well as the combination of lidocaine and prilocaine or EMLA cream. For intravenous regional anesthesia or Bier blocks, many drugs have been used. Ester local anesthetics are not used for IV regional blocks because they can be broken down in the blood stream (by plasma ester hydrolysis) which can shorten the drug’s duration of action and can also cause thrombophlebitis of the vein (reported with chloroprocaine). Because cardiovascular collapse has been reported with bupivacaine, and would likely also occur with etidocaine and ropivacaine, if the tourniquet unintentionally is released while the block is setting up, they are not used for intravenous regional anesthesia. Lidocaine and prilocaine are used for Bier blocks because of their relative safety. For infiltrative anesthesia, all local anesthetics can be used. All local anesthetics can be used in the epidural space, although procaine and tetracaine are rarely used (procaine has a slow onset and tetracaine has marked motor block)

Answer 114

874. (A) Procaine and 2-chloroprocaine have a short duration of action; lidocaine, mepivacaine and prilocaine have an intermediate duration of action; etidocaine, bupivacaine, levobupivacaine, tetracaine and ropivacaine have a long duration of action. For similar sensory anesthesia, a higher concentration of local anesthetic is needed for the short duration of local anesthetics compared with both the intermediate and long duration agents, because they are less potent

Answer 115

875. (B) A change in the T-wave amplitude of 25 percent, an increase in heart rate of 10 beats per minutes, or systolic blood pressure greater than 15 mm Hg is considered a positive response to an epinephrine containing local anesthetic solution. A slight drop in heart rate may result if the block is properly performed and no intravascular injection occurs

Answer 116

876. (E) All of the choices listed are potential complications of stellate ganglion blockade except an increase in heart rate. The stellate ganglion supplies sympathetic fibers to the upper extremity and head and some to the heart. Loss of the cardiac acceleratory fibers may slow the heart rate, not speed it up. Other potential complications of stellate ganglion blockade include accidental injection of the local anesthetic into a vertebral artery resulting in seizure and inadvertent cervical epidural

Answer 117

877. (D) A total of 60 mL of 0.5% bupivacaine with epinephrine (1:200,000) was used. A 0.5% solution = 0.5 g in 100 mL of fluid = 500 mg/100 mL = 5 mg/mL. A 1:200,000 solution means 1 gram in 200,000 mL = 1000 mg/200,000 mL = 1 mg/200 mL = 1000 μg/200 mL = 5 μg/mL. Therefore 60 mL of 0.5% bupivacaine with 1:200,000 epinephrine contains 60 mL × 5 mg/mL or 300 mg bupivacaine and 60 mL × 5 μg/mL or 300 μg of epinephrine. For a major nerve block the maximum recommended dose with epinephrine (1:200,000) is 500 mg for lidocaine and mepivacaine, 600 mg with prilocaine, and 225 mg with bupivacaine. Epinephrine is used in the local anesthetic to check for intravascular injection of the incremental doses and is not contraindicated but should be used for this block

Answer 118

878. (A) Post dural puncture headaches (spinal headaches) usually develop within 12 to 48 hours after a dural puncture, but may develop immediately or take months to develop. The most characteristic symptom is a postural component where the headache occurs in the upright position and is usually completely gone when the patient is in the supine position. The headache is typically frontal and/or occipital in location. Other symptoms include nausea, vomiting, anorexia, visual disturbances (blurred vision, double vision, photophobia) and occasionally hearing loss (routinely found with auditory testing)

Answer 119

879. (D) Ipsilateral phrenic nerve block with diaphragmatic paralysis occurs is virtually 100% of patients receiving an interscalene block. This produces a 25% reduction in pulmonary function, making this block a contraindication in patients with borderline pulmonary function. Blockage of the recurrent laryngeal nerve can occur but is rare; however, if the patient has contralateral vocal cord palsy and develops a recurrent laryngeal nerve block, complete airway obstruction can occur. With this block, the inferior trunk of the brachial plexus where the ulnar nerve is derived may be spared

Answer 120

880. (A) Five nerves are blocked when performing an ankle block. The saphenous, superficial peroneal, and sural nerves are all sensory below the ankle and electrical stimulation would have no effect. Stimulation of the posterior tibial nerve causes flexion of the toes by stimulating the flexor digitorum brevis muscles and abduction of the first toe by stimulating the abductor hallucis muscles. The posterior tibial nerve also is sensory to most of the plantar part of the foot. Stimulation of the deep peroneal nerve causes extension of the toes by stimulating the extensor digitorum brevis muscles. The deep peroneal nerve has a small sensory branch for the first interdigital cleft. From the practical standpoint, many anesthesiologists perform a purely infiltration block of these nerves. If a nerve stimulator is used, it is mainly used to find the posterior tibial nerve, which can be hard to anesthetize if small volumes of local anesthetic are administered. The posterior tibial nerve can be difficult to stimulate in diabetics with diabetic neuropathy

Answer 121

881. (B) The motor responses include: arm flexion at the elbow (musculocutaneous nerve), arm extension at the elbow (radial nerve), forearm pronation, wrist flexion and thumb opposition (median nerve), ulnar deviation of the wrist, little finger flexion, thumb adduction and flaring of the fingers (ulnar nerve), wrist and finger extension (radial nerve). The sensory response (includes some variations) is: back of the arm, forearm and radial side dorsal side of the hand (radial nerve), skin of the lateral forearm (musculocutaneous nerve), ulnar side of the hand and both surfaces of the ulnar one and one-half fingers (ulnar nerve), the radial side of the palm of the hand as well as the dorsal aspect of the radial three and one-half fingers (median nerve). To evaluate the setup of a brachial plexus block, a common technique is to perform the four P’s (Push, Pull, Pinch, Pinch). Have the patient push or extend the forearm (radial), pull or flex the forearm (musculocutaneous nerve), pinch the index or second finger (median nerve), pinch the little finger (ulnar nerve)

Answer 122

882. (C) Unilateral numbness or paresthesia in the upper extremity during extension of the neck usually represents nerve root impingement at the vertebral foramina. Specifically, unilateral degenerative changes restrict the foramen to such a degree that it compresses and irritates the nerve root traversing the vertebral foramen when the head is extended. Treatment ranges from NSAIDs, to steroids and may require surgical intervention if there is muscle weakness

Answer 123

883. (D) Although a successful interscalene block causes ipsilateral phrenic nerve paralysis in almost 100% of patients, identifying the phrenic nerve means you are anterior to the brachial plexus and you should reposition your needle. You should redirect the needle in a posterior direction

Answer 124

884. (D) With an intravascular injection, the main symptoms would most likely be CNS toxicity (e.g., seizures) as blood flow is directly to the brain. The Bezold-Jarish reflex (hypotension and bradycardia) has been reported in awake, sitting patients undergoing shoulder surgery with an interscalene block. This maybe related to intracardiac mechanoreceptors being stimulated by the decreased venous return in the sitting position. This leads to decreased sympathetic tone and increased parasympathetic tone. Breathing is still present with this reflex. Block of the stellate ganglion would produce a Horner’s syndrome, which is not associated with breathing abnormalities. Injection into the intrathecal space is uncommon, but possible, especially if the needle is not pointed in the caudal direction, and would lead to a total spinal block with little local anesthetic injected (e.g., hypotension, bradycardia respiratory paralysis that would lead to cyanosis)

Answer 125

885. (C) The pipecoloxylidide local anesthetics (mepivacaine, bupivacaine, ropivacaine and levobupivacaine) are chiral drugs, which means they have an asymmetric carbon atom (i.e., have a left- or S and a right- or R hand configuration). Mepivacaine and bupivacaine are racemic mixtures (50% S: 50% R mixture). The pure S forms show reduced neurotoxicity and reduced cardiotoxicity (e.g., ropivacaine and levobupivacaine). Lidocaine is an achiral compound (i.e., has no chiral carbon atom)

Answer 126

886. (A) Nerves to the lower extremity emerge from the L2 to S3 nerve roots. The upper roots (mainly L2-L4) form the lumbar plexus which gives rise to the femoral, obturator, and lateral femoral cutaneous nerves. A branch from the lumbar plexus along with the sacral plexus gives rise to the sciatic nerve. Branches of the sciatic nerve include the common peroneal (branches to make the superficial and deep) and the tibial, and the sural nerves

Answer 127

887. (E) Anesthetic-related nerve injuries to the brachial plexus are rare and poorly understood. The only way to minimize nerve injury is to minimize trauma to neural fibers. Although ultrasound-guided technique is promising, currently there is no clinical evidence for this

Answer 128

888. (C) Local anesthetic toxicity is a multisystem phenomenon, but the most crucial manifestation involves the heart (atrioventricular conduction block, arrhythmias, myocardial depression, and cardiac arrest). In isolated cardiac tissue hypercarbia, acidosis and hypoxia will augment the negative inotropic and chronotropic effects of bupivacaine. In the event of seizure and ventricular fibrillation, hypercarbia and hypotension would cause a severe acidosis and hypoxia, which would potentiate the toxicity of bupivacaine. To reduce these cardiotoxic effects, the initial resuscitation efforts are aimed at maximizing oxygen delivery, increasing tissue perfusion and ventilation. This is accomplished through chest compressions, assisted ventilation with oxygen, intravenous sodium bicarbonate, and inotropic and chronotropic support with pharmacological agents such as atropine, epinephrine, dopamine, and dobutamine. Standard cardiopulmonary resuscitation may not be successful in some cases, and placement of the patient on cardiopulmonary bypass may be necessary. Recently, lipid infusions have been shown to reduce the toxicity of intravascularly injected bupivacaine. Propofol is formulated as a lipid emulsion, and as such would bind bupivacaine to some degree, but this effect would be overshadowed by the substantial cardiac depressant of the anesthetic

Answer 129

889. (E) When performing an interscalene block, the needle is usually placed at the line extending lateral to the cricoid cartilage that intersects the interscalene groove at the C6 level. The needle in inserted in a slightly posterior and a 45° caudad direction. The caudad direction is used to decrease the chance of injecting the local anesthetic into the vertebral artery, or obtaining a spinal or epidural block. The phrenic nerve is routinely blocked (100% of the time) and occasionally the recurrent laryngeal nerve is blocked

Answer 130

890. (E) Epidural hematomas are rare complications of spinal anesthesia (1:200,000) and epidural anesthesia (1:150,000). However, in the presence of LMWH the incidence is much higher: 1:40,000 with spinal anesthesia and 1:3000 with continuous epidural catheter. Clinical symptoms include radicular back pain, bowel and bladder dysfunction, sensory or motor deficits. An MRI is the diagnostic test of choice and prompt decompressive laminectomy is the treatment of choice

Answer 131

891. (D) Peripheral nerves are classified according to the fiber size and physiologic properties such as the presence or absence of myelin, conduction velocity, location, and function. Type A fibers range in diameter from 1 to 22 μm, are myelinated, and have moderate-to-fast conduction velocities. These fibers are subclassified into four groups based on their location and function. Type A-alpha and A-beta fibers provide motor and proprioception function to muscles and joints; type A-gamma fibers innervate muscle spindles and provide for muscle tone; and type A-delta fibers provide pain, temperature and touch sensation. Type B fibers are preganglionic sympathetic nerves that are less than 3 μm in diameter, myelinated, and have medium conduction velocities. Type C fibers are postganglionic sympathetic nerves that are very small in diameter, are not myelinated, and have slow conduction velocities. Type C fibers are also afferent sensory nerves involved in pain, temperature, and touch

Answer 132

892. (C) Overdose of intrathecal opiates would not be a sign of an intradural mass lesion. Granulomas at the tip of intrathecal catheters used with intrathecal drug delivery systems are gaining increased attention. Granulomas are more frequently associated with high concentrations and doses of either morphine (>10 mg/day) or hydromorphone (>10 mg/day). Most patients who will develop granulomas receive the intrathecal medications for more than 6 months. Presenting symptoms may include loss of drug effect, new pain or paresthesias or neurologic deficits. Patients should be routinely screened for signs and symptoms of granuloma formation at scheduled intrathecal pump refill appointments. Suspicious cases should undergo prompt diagnostic imaging and consideration of neurosurgical consultation

Answer 133

893. (A). In addition to benzocaine, tetracaine and lidocaine can also be used as topical anesthetics. Pseudocholinesterase, the enzyme responsible for the metabolism of succinylcholine, metabolizes all of the ester local anesthetics, benzocaine, procaine, chloroprocaine and tetracaine. Benzocaine does promote the formation of methemoglobin, but is not alone in that regard since prilocaine also causes formation of methemoglobin. The pKa of benzocaine is 3.5, which qualifies it as a weak acid and as such exists in uncharged at physiologic pH. All other local anesthetic pKa’s are higher than 7.4, meaning that some fraction of them exists in the protonated form

Answer 134

894. (D) The un-ionized form of the local anesthetic traverses the nerve membrane whereas the ionized form actually blocks conduction. About three nodes of Ranvier must be blocked to achieve anesthesia. The ability of a local anesthetic to block conduction is inversely proportional to the diameter of the fiber. The presence of myelin enhances the ability of a local anesthetic to block conduction, as does rapid firing. The local anesthetic blocks nerve transmission by inhibiting the voltage-gated sodium ion channels

Answer 135

895. (D) Postdural puncture headaches (PDPHs) typically appear within 12 to 48 hours of a dural puncture but may be immediate and occasionally have become delayed for several days or months after a dural puncture. The headaches are characterized by dull or throbbing frontal or occipital pain, which worsens with sitting and improves with reclining. Postspinal headaches may be associated with neurologic symptoms such as diplopia, tinnitus, and reduced hearing acuity. Very rarely, a subdural hematoma will develop. The etiology of postspinal headaches is believed to be caused by a reduction in CSF pressure and resulting tension on meningeal vessels and nerves (which results from leakage of CSF through the needle hole in the dura mater). Factors associated with an increased incidence of postspinal headaches include pregnancy, size and type of needle used to perform the block (larger needles and Quincke more common than smaller needles and Whitacre or Sprotte), and the number of dural punctures. They occur more frequently in young adults compared with children and the elderly. Conservative therapy for a postspinal headache includes bed rest, analgesics, and oral and intravenous hydration. If conservative therapy is not successful after 24 to 48 hours, an epidural “blood patch” with 10 to 20 mL of the patient’s blood can be performed. An epidural “blood patch” usually provides prompt relief of the postspinal headache

Answer 136

896. (C) When inserting a spinal cord stimulator, a 15 gauge needle is advanced into the epidural space via the paramedian approach. After confirmation of proper needle placement with AP and lateral fluoroscopic views, the stimulation electrode is passed through the needle and threaded to the desired vertebral level. The needle is then removed and the leads attached to the external programmer. Transcutaneous electrical nerve stimulation (TENS) unit electrodes are applied to the skin. With nucleoplasty, intradiskal electrothermal therapy and annuloplasty, the needle is inserted to access the intervertebral disk

Answer 137

897. (A) Many drugs have been used to treat neuropathic pain, including analgesics (NSAIDs and opioids), firstgeneration antiepileptic drugs (e.g., carbamazepine and phenytoin), second-generation antiepileptic drugs (e.g., gabapentin, pregabalin), topical agents (e.g., lidocaine, capsaicin), antiarrhythmics (e.g., mexiletine), tricyclic antidepressants (e.g., amitriptyline, nortriptyline, desipramine) as well as other antidepressants (e.g., duloxetine, venlafaxine). Duloxetine (Cymbalta) is a selective serotonin and norepinephrine reuptake inhibitor (SNRI) that is used for major depressive disorders, generalized anxiety disorders, fibromyalgia and diabetic peripheral neuropathic pain. Mexiletine is an orally effective amine analogue of lidocaine and may be effective in decreasing neuropathic pain when other drugs have failed. Gabapentin, a structural analogue of GABA, works by increasing the synthesis of the inhibitory neurotransmitter GABA. Tramadol is an opioid agonist that has moderate activity at the μ receptor and weak activity at the κ and δ opioid receptors. In addition, tramadol enhances the spinal inhibitory pathways by inhibiting the neuronal uptake of norepinephrine and serotonin as well as presynaptic stimulation of serotonin release. Carbamazepine (Tegretol) is an anticonvulsant with specific analgesic properties for trigeminal neuralgia. Carbamazepine seems to reduce polysynaptic responses by an unknown mechanism

Answer 138

898. (E) 899. (B) 900. (A) 901. (C)

Answer 139

902. (A) 903. (B) 904 (E) 905. (D) 906. (C) In the normal adult, breathing and coughing can be done exclusively by the diaphragm, which is innervated by the phrenic nerve (C3-C5). The heart rate is dependent upon intrinsic pacemaker activity of the SA node, which can be affected by the autonomic nervous systems sympathetic nervous systems cardiac accelerator fibers (T1-T4) as well as the parasympathetic nervous systems vagus nerve (cranial nerve 10). The first stage of labor pain is related to uterine contractions and dilation of the cervix (T10-L1). The second stage of labor is related to both uterine pain (T10-L1), as well as birth canal pain which is supplied by the pudendal nerves (S2-S4). The greater splanchnic (T5-T9) and the lesser splanchnic (T10-T12) nerves supply sympathetic fibers to the celiac plexus which inhibits much of the gastrointestinal tract

Answer 140

907. (E) 908. (C) 909. (D) 910. (B) 911. (A) 912. (A) 913. (D) 914. (E) When an awake intubation is needed, local anesthetics can be applied topically or by injection. Innervation of the airway includes the glossopharyngeal nerve, cranial nerve XI, and branches of the vagus nerve (internal and external branches of the superior laryngeal nerve and the recurrent laryngeal nerve). The glossopharyngeal nerve provides sensory innervation of the posterior one third of the tongue, the vallecula and the anterior surface of the epiglottis (lingual branch), the pharyngeal walls (pharyngeal branch) and the tonsils (tonsillar branch). With the exception of the cricothyroid muscle, the recurrent laryngeal nerve of the vagus provides motor innervation of all the intrinsic muscles of the larynx. The cricothyroid muscle is supplied by the external branch of the superior laryngeal nerve of the vagus. The sensory innervation of the mucosa of the larynx down to the vocal folds comes from the internal branch of the superior laryngeal nerve of the vagus, and the sensory innervation of the mucosa of the larynx below the vocal folds comes from the recurrent laryngeal nerve of the vagus. The muscles of the pharynx are supplied through the pharyngeal plexus from motor fibers from the eleventh cranial nerve (accessory nerve)

General 1 Flashcards

(253 cards)