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Anesthesiology > Anatomy, Regional, and Pain > Flashcards

Anatomy, Regional, and Pain Flashcards

1
Q

What are the signs of local anesthetic toxicity

A

Initial symptoms are lightheadedness and dizziness then perioral numbness and tinnitus

Progressive CNS excitatory effects include visual/auditory disturbances, shivering, and ultimately tonic-clinic seizures

CNS depression can ensue, resulting in respiratory depression

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2
Q

Where do spinally administered opiates exert their action?

A

The substantia gelatinosa of the spinal cord

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3
Q

What are the classifications of local anesthetics?

A

Esters (only 1 i in name):
Procaine
Chlorprocaine
Tetracaine

Amides (2 i's in name):
Lidocaine
Mepivacaine
Prilocaine
Bupivacaine
Etidocaine
Ropivacaine
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3
Q

Describe local anesthetic metabolism

A

Esters undergo plasma clearance by cholinesterases and have short half-lives
- PABA is a metabolic breakdown product of esters and can be responsible for allergic reactions

Amides undergo hepatic clearance and have longer half-lives

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4
Q

What is the major disadvantage of the interscalene block for hand/forearm surgery as opposed to other approaches to the brachial plexus?

A

Ulnar nerve is often spared

Blockade of the ipsilateral phrenic nerve also commonly occurs, which can cause respiratory distress in patients with lung disease

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5
Q

What are the symptoms of cauda equina syndrome? What is thought to be the cause?

A

Low back pain, bilateral lower extremity weakness, saddle anesthesia, and loss of bowel/bladder function

Thought to be caused by maldistribution of local anesthetic (pooling in dependent areas of the spine)

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7
Q

What are the structures (in order) traversed by a midline needle prior to reaching the epidural space? What about during a paramedian approach?

A 
Midline approach:
Skin
Subcutaneous tissue
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Paramedian approach:
Skin
Subcutaneous tissue
Paraspinous muscles
Ligamentum flavum
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8
Q

Describe the order of differential nerve block

A

Small, unmyelinated sympathetic fibers

Unmyelinated C fibers (pain and temperature)

Small, myelinated fibers (proprioception, touch, pressure)

Large, myelinated fibers (motor)

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9
Q

Which nerves are blocked in an ankle block?

A

Deep Peroneal Nerve:

  • located on the dorsum surface of the foot just lateral to the extensor hallucis longus tendon
  • sensory between the 1st/2nd toes
  • motor to extend the toes

Superficial Peroneal Nerve:

  • located just above the lateral malleolus
  • sensory to the dorsum of the foot

Posterior Tibial Nerve:

  • located posterior to the medial malleolus
  • sensory for the sole of the foot
  • motor to flex the toes

Sural Nerve:

  • located between the lateral malleolus and the Achilles’ tendon
  • sensory to the lateral foot

Saphenous Nerve:

  • located anterior to the medial malleolus
  • sensory to the medial foot
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9
Q

What are the symptoms of complex regional pain syndrome (CRPS)? What are the two types? What is the treatment?

A

Syndrome of continuous burning pain exacerbated by normal movement, cutaneous stimulation or stress, usually weeks after a trauma. May have cool, red, and clammy skin. Chronic cases may lead to atrophy and osteoporosis.

CRPS I (reflex sympathetic dystrophy) - caused by non-nerve specific trauma

CRPS II (causalgia) - similar to type I but after a nerve-related injury

1st line treatment - physical therapy
2nd line - amitriptyline, gabapentin, opioids
3rd line - sympathetic blocks
4th line - spinal cord stimulators

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10
Q

What is anesthesia dolorosa?

A

A complication of neurolytic blocks for the treatment of trigeminal neuralgia
- numbness and pain in an area that lacks sensation

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11
Q

For local anesthetics:
What determines potency?
What determines speed of onset?
What determines duration of action?

A

Potency - lipid solubility

Onset - pKA

Duration - protein binding

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12
Q

What is the progression of epidural abscess symptoms? How do they differ from an epidural hematoma?

A
  1. Localized back pain
  2. Nerve root / radicular pain
  3. Motor and sensory deficit
  4. Paraplegia

Epidural hematoma pts complain of severe back pain rather than radicular pain

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14
Q

What nerves are blocked by a retrobulbar block? How does it compare to a peribulbar block?

A

Cranial nerves III, IV, and VI (eye movement)

Ciliary nerves (anesthesia to conjunctiva, cornea, and uvea)

Ophthalmic branch of trigeminal nerve

Main advantage over a peribulbar block is the reduced onset time, but it does not cover the eyelid which a peribulbar block will

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14
Q

What is the innervation of the larynx?

A

Motor:
All muscles of the larynx are innervated by the recurrent laryngeal nerve, except for the cricothyroid muscle, which is innervated by the external branch of the superior laryngeal nerve

Sensory:

  • The internal branch of the laryngeal nerve provides sensory above the cords
  • The recurrent laryngeal nerve provides sensory below the cords
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15
Q

What dermatome covers the thumb? The 2nd and 3rd fingers? The 4th and 5th fingers?

A

Thumb - C6
2nd and 3rd fingers - C7
4th and 5th fingers - C8

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16
Q

How do TENS units work? What are the indications for its use?

A

Transcutaneous electrical nerve stimulation (TENS) is thought to produce analgesia by releasing endogenous endorphins that have an inhibitory effect at the spinal cord

Indications for use:

  • chronic intractable pain
  • acute post-surgical or post-traumatic pain
  • arthritis pain
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17
Q

List the sites in order (greatest to least) of LA uptake after regional anesthesia

A 
Intravascular
Endotracheal
Intercostal
Caudal epidural
Lumbar epidural
Brachial plexus
Sciatic/femoral
Subcutaneous
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18
Q

When doing a popliteal block for an ankle/foot surgery, which other nerve must be blocked? Why?

A

Saphenous nerve

The popliteal block will block the tibial and peroneal nerves (both originating from the sciatic nerve). However, the Saphenous nerve is a branch of the femoral nerve and is not covered in a popliteal block.

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19
Q

What are the risk factors for post-dural puncture headache?

A

Young age (20 - 40 years)
Female
Pregnancy
Large needle

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20
Q

What effect does adding sodium bicarbonate to local anesthetics solutions cause? Which local anesthetics will precipitate when bicarbonate is added?

A

It hastens the onset of action, since raising the pH causes more of the local anesthetic to be in the non-ionized, lipid-soluble state

It also decreases pain with skin infiltration

Cannot be added to Ropivacaine or Bupivacaine due to precipitation

22
Q

Describe the anatomy of the axillary block

A

With the humerus at the bottom of the screen:

Median nerve is located superficially and lateral to the artery

Ulnar nerve is medial to the artery

Radial nerve is inferior to the artery

Musculocutaneous nerve is far lateral to the artery

23
Q

What is meralgia paresthetica?

A

Compression of the lateral femoral cutaneous nerve by the inguinal ligament producing pain, numbness, and parathesias over the anterolateral thigh

24
Q

Which nerve is commonly missed during an axillary block? How can it be anesthetized?

A 
Musculocutaneous nerve (lateral forearm)
- can be anesthetized by injecting local anesthetic into the belly of the coracobrachialis muscle
25
Q

Describe IV regional anesthesia (Bier block)

A

Can provide complete motor and sensory anesthesia for up to approximately 90 minutes

Performed by:

1) placing a small IV in operative extremity
2) placing a double tourniquet on extremity
3) exsanguinating extremity
4) injecting 40-50 mL of 0.5% lidocaine

Mechanism of block is diffusion of LA from veins into capillaries surrounding peripheral nerves and then into the vasa nervora

  • LA will also diffuse extravascularly into the nerves supplying the skin
  • tourniquet causes distal ischemia which also contributes to anesthesia and analgesia
26
Q

What is considered a positive test dose during placement of an epidural?

A

An increase in HR by 10 beats indicates intravascular injection

Tinnitus, odd taste, perioral numbness are all signs of intrathecal injection

27
Q

What blocks can be done to block the coughing reflex? Where are they performed?

A

Superior laryngeal nerve:
Blocked at the cornu of the hyoid

Recurrent laryngeal nerve:
Blocked via transtracheal block

28
Q

What is Naltrexone? How should it be handled peri-operatively?

A

Naltrexone is an oral opioid antagonist for treatment of alcohol or opioid dependency
- blocks downstream events that contribute to euphoria and reinforcing effects

Will block the effects of opioids so must be stopped pre-operatively
- Does not need to be tapered

29
Q

What is Gabapentin used for? How does it work? What are it’s side effects?

A

Used to treat neuropathic pain

Works via calcium channel modulation

Side effects of chronic use:

  • Weight gain
  • Cognitive effects
  • Peripheral edema
  • Sedation
30
Q

Which local anesthetic has been implicated in causing transient neurologic symptoms (TNS)? What factor has the largest impact on the risk?

A

Lidocaine has an incidence 5 to 10 times greater than other LAs

Patient position confers the greatest impact on risk
- lithotomy > supine

31
Q

What are the effects of epidurals on the GI system?

A

It is thought that epidurals can shorten duration of post-op ileus and ultimately decrease morbidity, hospital stay, and overall cost

Sympathectomy induced by epidural removes the tonic sympathetic inhibition resulting in increased gut motility

Decreased post-op pain results in less systemic opioids and also reducing amount of circulating catecholamines, promoting better gut contraction

32
Q

During spinal anesthesia, what factors are most important in determining the level of blockade?

A

Total dose of LA
Baricity
Patient position

33
Q

What is the difference in pain transmitted by A-delta fibers and C fibers?

A

A-delta fibers are responsible for the “first” pain experienced after a stimulus
- generally easily localized and sharp

C fibers are responsible for the delayed “second” pain
- dull and achey

34
Q

What are the ASRA guidelines for anticoagulation and neuraxial anesthesia?

A

Antiplatelet agents:
ASA/NSAIDs - no restriction
Clopidgrel - 7 days

Prophylactic anticoagulation:
LMWH - 12 hours

Therapeutic anticoagulation:
LMWH - 24 hours
Coumadin - 5 days (or reversed with INR

35
Q

What are the potential side effects of NSAIDs?

A
  • renal vasoconstriction leading to renal failure
  • elevated blood pressure
  • edema
36
Q

What is the most common nerve injury associated with the lithotomy position?

A

Common peroneal nerve

- presents with foot drop

37
Q

What are the borders of the femoral triangle?

A

The femoral triangle is bordered by the inguinal ligament superiorly, the adductor longus muscle medially, and the sartorius muscle laterally.

38
Q

What are the conversions from intrathecal to epidural to IV to oral dosing for Morphine?

A

1mg of IT Morphine = 10mg Epidural = 100mg IV = 300mg oral

39
Q

List and describe some common sympathetic blocks

A

Stellate ganglion block

  • Located between C6-C7
  • Done for pain in upper extremities and thorax
  • Complications include Horner syndrome, recurrent laryngeal nerve injury

Celiac plexux block

  • Located beside the aorta and inferior vena cava at the level of L1
  • Done for pain relating to abdominal cancers
  • Complications include retroperitoneal hematoma

Lumbar sympathetic chain block

  • Located anterior to L1-L5, anteromedial to the psoas major muscle
  • Done for neuropathic pain in the lower extremities or visceral pain involving intestinal/urinary symptoms
  • Complications include genitofemoral nerve injury
40
Q

Describe myofascial pain syndromes

A

Characterized by localized pain in an area of repititive use or trauma with resultant trigger points that cause non-dermatomal pain radiation upon palpation

Autonomic dysfunction and spontaneous EMG activity can be seen in the affected region

41
Q

What are the potential complications from a retrobulbar block and how would they present?

A

Puncture of posterior globe - ocular pain and restlessness following block without an increase in intraocular pressure

Retrobulbar hemorrhage - closing of upper eyelid, proptosis, and increased intraocular pressure

Central retinal artery occlusion - painless loss of vision

Penetration of optic nerve - loss of vision or color vision

42
Q

What area does the lateral cutaneous femoral nerve cover? How is it blocked?

A

LCFN provides sensory innervation to the anterolateral thigh

Can be blocked by injecting ~10cc of LA at a spot 2.5cm medial and 2.5cm inferior to the ASIS

43
Q

What are the ASA practice guidelines for cancer pain?

A

Mild pain
- non-opioids

Mild to moderate pain

  • non-opioids
  • opioids

Moderate to severe pain

  • non-opioids
  • higher dose/frequency of opioids

At any point, adjuvants (antidepressants and neuromodulators) may be added

44
Q

What are the 5 criteria for the use of neurolytic blocks?

A
  1. presence of severe pain
  2. failure of less invasive techniques to relieve pain
  3. presence of well localized pain
  4. relief of pain with diagnostic local anesthetic block
  5. absence of adverse side effects after diagnostic block
45
Q

What is fibromyalgia? How is it diagnosed?

A

Fibromyalgia is a complex pain syndrome associated with widespread pain, sleep disturbances, fatigue, and depression

Diagnosed when:

  • pain cannot be attributed to other pain syndromes
  • pain has been present > 3 months
  • widespread pain index and symptom severity score criteria are met (WPI > 7 + SS > 5 OR WPI 3-6 + SS > 9)
46
Q

Which regional block carries the highest risk of pneumothorax?

A

Supraclavicular block

47
Q

What nerves are blocked by a transversus abdominal plexus (TAP) block?

A

Intercostal

Subcostal

Ilioinguinal

Iliohypogastric

48
Q

How do spinal cord stimulators work to treat chronic pain?

A

Spinal cord stimulators most significantly affect the dorsal horn of the spinal cord

They provide electrical stimulation to larger A-alpha and A-beta nerve fibers, closing the “gate” and impeding conduction of pain sensation

49
Q

For what type of patients should transdermal fentanyl be considered? In what patients is it contraindicated?

A

Should be considered in chronic pain patients (including cancer pain) who are taking more than 45 mg of morphine equivalents

Contraindicated for patients with acute pain or any pain states that have pain free intervals

50
Q

Describe discogenic back pain vs spinal stenosis

A

Discogenic back pain is usually worse when sitting or flexing and relieved by extension (standing upright or laying supine)

Spinal stenosis pain is worsened by extension (standing or walking), and is made better by flexion (sitting or walking uphill)

Anesthesiology (12 decks)

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