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Principles 2 > Regional Anesthesia Basic Overview (pt 1) > Flashcards

Regional Anesthesia Basic Overview (pt 1) Flashcards

1
Q

What is the definition of Regional Anesthesia?

A

Selective anesthesia and analgesia achieved by exposing selected nerves to LA.

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2
Q

What is a Field Block?

A

Uses local infiltration, but specifically identifying a nerve root/bundle

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3
Q

Describe the advantages/disadvantages of Topical Regional Anesthesia

A

Advantages:
-Easy
-Low skill
-Low risk
-Great for mucus membranes

Disadvantages:
-Short duration 1-4 hours
-Slow onset over skin (needs soak time)
-Doesn’t work well or at all on inflamed/infected tissues

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4
Q

Describe the uses for Topical Regional Anesthesia

A

-IV placement
-Eye procedures
-ENT procedures
-Awake fiberoptic intubation
-Dental pain
-Surgical wound closure
-Acute/chronic pain mgmt

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5
Q

What is EMLA cream?

A

A Eutectic mixture of local anesthetics.
-Mixture of 2.5% Lido and 2.5% Prilocaine

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6
Q

What is a concern with Benzocaine spray?

A

Methemoglobinemia

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7
Q

What is local infiltration?

A

The injection of LA directly into a tissue.
-Used for traumatic wound closure, surgical wound closure, and pre-emptive analgesia (Trocar sites, joint injection)

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8
Q

What are the advantages and disadvantages of Local Infiltration?

A

Advantages:
-Fast and easy
-Low skill
-Lower risk

Disadvantages:
-Short duration 1-6 hrs
-Doesn’t work well or at all on inflamed/infected tissues
-Requires provider to place injections systematically to ensure good coverage (patchy coverage is common)

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9
Q

What is a Field Block?

A

Infiltration of LA around an area that you wish to anesthetize.
-Know the path in which the nerves innervate that area.

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10
Q

What are some uses of Field Blocks?

A

-Carotid endarterectomy (Superficial Cervical Plexus)
-I&D of wounds
-Intercostobrachial and medial brachial cutaneous nerves
-Dentistry
-Plastic surgery (Breast reduction/augmentation)

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11
Q

What are the advantages/disadvantages of Field Blocks?

A

Advantages:
-Easy to perform
-Low risk procedure
-Multiple LA options
-Can be used to supplement patchy peripheral or NA blocks

Disadvantages:
-Inconsistent coverage
-Only covers superficial structures
-Relatively short DOA

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12
Q

What is a Bier Block?

A

The injection of LA into the venous system of an exsanguinated extremity to produce surgical anesthesia for short periods.
-Exsanguinate an entire limb via a tourniquet
-Fill venous system of that extremity using an IV with a large volume (50 mL) of a dilute local solution (LIDOCAINE ONLY).
-Gives you full anesthesia of the arm
-Very short procedures (ex: Carpal tunnel)
-If surgeon takes a long time, can’t really use it. In about 30 minutes, will see tourniquet pain issues.

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13
Q

What are the uses of a Bier Block?

A

-Best suited for short soft tissue upper extremity procedures
-Can be used for lower extremity.

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14
Q

What are the advantages of a Bier Block?

A

-Relatively easy to perform
-Provides surgical anesthesia quickly

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15
Q

What are the disadvantages of a Bier Block?

A

-Tourniquet pain limits useful duration
-Tourniquet must be inflated for at least 20 minutes
-Will start to see Tourniquet pain after about 30 minutes
-Must be able to obtain IV access on operative limb
-Pt habitus must be suitable for proper tourniquet fit
-Failed tourniquets risk large volume LA immediately entering central circulation
-Acute LA Toxicity

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16
Q

Where should the IV be placed for a Bier Block?

A

Preferably, in the hand of the operative arm.

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17
Q

Describe the procedure of placing a Bier Block.

A

1) Establish IV access
2) Apply DOUBLE pneumatic tourniquet to upper arm (pad arm with cotton)
3) Exsanguinate arm (raise arm up, apply Esmarch bandage in a spiral from hand to proximal cuff of tourniquet)
4) Inflate distal cuff first to 50-100 mmHg above SBP (usually 200-250 mmHg for an arm)
5) Inflate proximal cuff
6) Deflate distal cuff (allows local to seep underneath distal cuff)
7) Inject LA (ONLY LIDO ALWAYS)
-Want venous distention, LA all over extremity.
8) Remove IV

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18
Q

What local anesthetic do you use for a Bier Block?

A

NO LA OTHER THAN LIDOCAINE USED.
30-50 mL of 0.5% Lidocaine.
-3 mg/kg max dose
-Never ever use bupivicaine or anything other than Lido for a Bier Block

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19
Q

What should you do if tourniquet pain starts during a Bier Block?

A

Can inflate distal cuff and then deflate proximal.
-Never deflate cuff less than 20 minutes from injection

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20
Q

How do you deflate the tourniquets at the end of a Bier Block?

A

If you’re worried about toxicity:
-Deflate cuff for 10 seconds
-Reinflate for 1 minute
-Allows initial bolus of lidocaine that entered systemic circulation to dissipate and get soaked up before the rest is let out (Gradual LA Washout)

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21
Q

What are the advantages of Peripheral Nerve Blocks?

A

-Specific control of what is being blocked
-And possibly more important, what is not blocked. Requires working knowledge of fine anatomic detail
-Can avoid systemic side effects of neuraxial techniques
-Continuous Perineural catheters can be used

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22
Q

What are the disadvantages of Peripheral Nerve Blocks?

A

-Anatomical variability and technical difficulty can lead to failure (Especially in landmark techniques)
-Inadvertent blockade of nerves due to proximity (ex: Phrenic nerve block)

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23
Q

What are the advantages of Neuraxial Anesthesia?

A

-Provide coverage to large sections of the body
-Catheter placement allows for analgesic control

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24
Q

What are the disadvantages of Neuraxial Anesthesia?

A

-Can be technically difficult
-Sympathectomy
-Contraindicated for many comorbidities and pt specific factors (Coagulopathy/anticoagulation, Uncooperative pt, Stenotic heart valve lesions, etc.)

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25
Q

What things do you need to consider when forming an anesthetic plan?

A

-Surgical procedure (intensity, positioning, length)
-Patient (consent, comorbidities, any c/i like coagulopathy, Aortic Stenosis, etc.)
-Anesthetist (skill, comfort level)
-Surgeon (surgical skill, comfort with blocks)
-Facility resources
-Pre-op and PACU Staff

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26
Q

What characteristics do you need to consider when selecting a LA?

A

-Onset
-Duration
-Depth of blockade desired
-Additives

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27
Q

Which two local anesthetics have a fast onset, short duration, and create a dense block?

A

-Lidocaine
-Mepivicaine

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28
Q

Which two local anesthetics have a slower onset and longer duration?

A

-Bupivicaine (dense block)
-Ropivicaine (less profound block)

29
Q

Why is epinephrine added to LAs?

A

-Intravascular marker
-Decreases uptake, prolonging duration?

30
Q

Which other additive is added to LAs in order to decrease uptake, prolonging duration?

A

Phenylephrine

31
Q

What is the purpose of adding Dexamethasone and Clonidine to LA?

A

To prolong the duration

32
Q

What is the purpose of adding Sodium Bicarb to a LA?

A

To speed up the onset

33
Q

What puts you at increased risk for infection with RA?

A

-Continuous > single shot
-Femoral or Axillary site used
-Recent trauma
-Recent ICU admission
-Compromised immunity (Diabetes)
-Catheter in place for >48 hours
-Absence of ABX use

34
Q

How can you lower the risk of infection with RA?

A

-Avoid puncture of infected tissue
-Ensure good aseptic technique: Good skin prep (Betadine – vs – Chlorhexadine), Sterile technique, Catheter dressed well (Biopatch, chlorhexadine dressing)
-Judicious Pt selection
-Reduce trauma r/t block placement

35
Q

What increases the risk of hematoma?

A

-Prolonged needling
-Larger needle size
-Trans-arterial technique
-Pt with coagulopathy (Rx and patho): Current Neuraxial Anticoagulation guidelines apply to RA. Caveat – Common and well accepted to judiciously practice outside of guideline. Different blocks carry different risks

36
Q

How can you decrease the risk of hematoma?

A

-Consciously avoid vascular structures, both deep and superficial structures.
-Veins collapse easily with minimal pressure from needle or US
-May be piercing vein and not see it, or get bloody aspiration
-Hold pressure after inadvertent vascular puncture. >5 minutes if arterial

37
Q

Why are hematomas bad?

A

Increase pressure on the nerve, leading to injury.

38
Q

What incidental blockade can occur with ISB/SCB/Superficial Cervical Blocks?

A

1) Phrenic Nerve Blocks (occurs almost 100% of the time with ISB).
-Diaphragm paralysis, reduced ventilation
-CXR shows hemidiaphragm ipsilateral side of block. Doesn’t effect most healthy people
2) Recurrent Laryngeal Nerve
-Vocal cord paralysis
3) Sympathetic Cervical Ganglion (Horner’s Syndrome)

39
Q

What incidental blockade can occur with a Paravertebral Block?

A

Costal or Epidural spread

40
Q

What are the symptoms of intra-arterial injection of LA?

A

Most arteries flow to the periphery.
-Allows local some time to be absorbed by tissue
However, Vertebral and Carotid: direct flow to brain
-Even LA volumes 1-3ml cause almost immediate seizure, neurological LA toxicity S/Sx

41
Q

What are the symptoms of intra-venous injection of LA?

A

Most veins all flow directly to the heart
-Local Anesthetic Systemic Toxicity (LAST)
-Neuro s/sx may be delayed or absent
-CV instability is often first sign
-Compression of vessels during US/needling may hide IV puncture (no aspiration of blood)

42
Q

How do you prevent LAST?

A

-Continuous monitoring (ECG, BP, SpO2) for at least 30 minutes after high dose blocks
-Notify patient of symptoms to watch for (metal taste, ears ringing, circumoral numbness, anxiety)
-Frequent aspiration every 3-5 mL
-Slow injection of LA
-Avoid traumatic needling
-Judicious dosing of LA
-Epi marker in high volume blocks to detect increases in HR
-Have a plan (ASRA checklist or NYSORA flowchart)
-Have 20% Lipid Emulsion in area where blocks are performed.

43
Q

What conditions do you decrease the dose of LA?

A

-Advanced age
-Poor cardiac function
-Pre-existing conduction abnormalities
-Dec plasma proteins

44
Q

> ____% increase in HR may indicate intravascular injection (according to powerpoint)

A

> 10%

45
Q

Never use Epi in blocks in what areas?

A

-Fingers
-Toes
-Penis
-Nose
-Ears

46
Q

What are the CNS symptoms of LAST?

A

-Metal taste
-Tinnitus
-Double vision
-Dizziness
-Circumoral numbness
-Excitation (Agitation, confusion, twitching, seizure) or Depression (drowsy, obtunded, coma, apnea)
-Patient may be sedated from Benzo administration to report CNS symptoms
-Benzo may prevent seizure

47
Q

What are the cardiovascular signs of LAST?

A

May be the first/only signs.
-Excitation followed by depression
-Inc BP and inc HR
-Ventricular ectopy, multiform VT, VF (Hallmarks of cardiac toxicity of LA)
-Progressive BP decline, bradycardia leading to asystole (hallmark of severe LA toxicity)

48
Q

What is the treatment of LAST?

A

-Get help
-Lipid Emulsion
-ASRA checklist/NYSORA flowchart
-Alert cardiopulmonary bypass team
-Airway mgmt with ETT/vent
-Abolish seizure (Versed, avoid prop if CV unstable)
-Manage arrhythmias via ACLS (Epi, Amiodarine (300/150), Magnesium (1-2g)

49
Q

What drugs do you AVOID during tx of LAST?

A

-CCBs
-BBs
-Lidocaine
-Phenytoin
-Vasopressin (controversial)

50
Q

What is the dosage for administering 20% Lipid Emulsion therapy for tx of LAST?

A

-Bolus 1.5 mL/kg (lean body weight). Usually ~100 mL
-Infusion at 0.25 mL/kg/min (~18 mL/min)
-Repeat bolus q 5 min if persistent CV collapse
-Infusion doubled to 0.5 mL/kg if hypotension continues
-Continue infusion for at least 10 minutes after CV stable

51
Q

What is the upper limit for 20% Lipid Emulsion administration?

A

10 mL/kg over first 30 minutes.

52
Q

Which blocks have increased risk for Pneumothorax?

A

-Highest risk is Supraclavicular 0.5-6%
-Lower incidence occurs with ISB, ICV, and Suprascapular
-Also can occur with thoracic blocks like Paravertebral, PEC blocks, and intercostal blocks

53
Q

What are the S/Sx of Pneumothorax?

A

-Decreased breath sounds
-Decreased HR and BP
-Decreased O2 sat -> cyanosis
-Increased HR, RR, JVD
-SOB w/retractions and nasal flaring
-Pain in chest/epigastric area that worsens with cough or deep breath (sudden onset, sharp)
-Tracheal shift away from PTX (late sign)
-Progressively expanding chest wall

54
Q

How do you perform US assessment of a PTX?

A

-Use a linear or phase array probe
-Air rises to the highest area. Place them supine and look at the anterior chest, mid-clav line between the 2nd-4th rib
-Looking for pleural sliding during respiration, acoustic artifacts seen when pleural layers are touching, and for lung edge (where lung stops touching chest d/t air pocket)

55
Q

What is pleural sliding?

A

Respiration causes visceral and parietal pleura to slide over each other
-US can see this sliding motion
-Air between pleural layers disrupts US beam
-No pleural sliding = Air present = Pneumothorax
-Can see “shimmering effect” In 2D mode
-In M Mode, normal lungs are “Sea Shore” and PTX causes Stratosphere or Barcode pattern. PTX does not have motion because there’s no lung there.

56
Q

What are B-Lines?

A

-Present in normal lung
-Artifact due to acoustic differences of air/water in lung tissue
-If absent = PTX

57
Q

What are Comet tails?

A

-Present in normal lung
-Artifact due to US waves bouncing off interface of the pleural layers
-Move synchronously with respiration
-If absent = PTX

58
Q

If even 1 of either B-lines or Comet tails is present, what does that mean?

A

There is NO Pneumothorax

59
Q

What are A-Lines?

A

-Present in PTX
-Horizontal lines equally spaced, emanating from the pleural line
-Echo into a hollow chamber. No lung tissue there. Means PTX.

60
Q

What is the Lung Point Assessment?

A

-The location on the chest where the lung stops touching the chest wall.
-Most specific sign for PTX
-Most difficult to find (even for experienced operators)
-By finding edges of air pocket on the chest, a calculation can be made to estimate Pneumo size
-Finds dividing line of PTX and normal lung

61
Q

What is the treatment for PTX?

A

-Admission to the hospital
-Monitor closely
-Supportive therapy
-Chest Tube possible
-May resolve spontaneously over time

62
Q

Most nerve deficits associated with RA are _____.

A

Transient
-Transient paresthesias are reported in up to 10%
-Can last days - weeks
-Permanent injuries are very rare (localized numbness -> paralysis)

63
Q

What increases risk of Nerve Injury?

A

-Needle mvmt around partially anesthetized nerves (use of a blunt needle decreases risk)
-Increased risk with proximal blocks
-Pre-existing pathologies (DM, PVD, atherosclerosis)

64
Q

What are the different mechanisms of nerve injury?

A

-Mechanical
-Stretch
-Pressure/Compression (hematoma, neural edema, intraneural or intrafascicular injection
-Chemical (LA, Epi. All LA are toxic, Ropivicaine is least)
-Vascular (prolonged disruption of blood flow to nerve. Lidocaine inhibits neural blood flow, seen even after Lido wash out).

65
Q

What is Intraneural injection?

A

-Needle is inside nerve and injection of LA inside the nerve
-Pressure increases inside nerve, decreasing blood flow, creating injury
-Epineurium (outer layer) is very tough and fibrous, does not swell up)

66
Q

What is intrafascicular injection?

A

Injection of LA into the bundles of nerves surrounded by tough, fibrous perineurium
-Where the axons are running
-Blunt needle is less likely to pierce!
-Not easily distended to compensate
-Higher injection pressure = increased fascicular pressure
-Perineurium and supporting connective tissues have blood vessels.

67
Q

What is the difference between proximal vs distal regarding Intrafascicular Injection?

A

Injection risk increases with proximal and decreases with distal.
Proximal:
-Few large fascicles
-Inc fascicle density
-Tightly bound by sheath
-Easy to needle

Distal:
-Many small fascicles
-Low Fascicle:Epineural density
-No sheath
-Difficult for needle to enter fascicle.

68
Q

Describe the vasculature associated with an Intrafascicular injection.

A

-Ischemia leads to injury
-Intrinsic: within epineurium
-Extrinsic plexus around nerve, anastomosis with inner
-Microvascular blood flow issues may be why some patients are at increased risk
-LA decreases blood flow, possibly contributing to injury

69
Q

How do you manage post-op Neuropathy?

A

-Tell patient what S/Sx to report
-Assess reversible causes: cast too tight? compartment syndrome? Hematoma?
-Ask Surgeon - possible procedural contribution?
-Consult neuro asap, especially if motor is involved
-EP testing

Motor involvement is very bad sign. Resolution of sensory symptoms usually occurs within 4-6 weeks, and can take up to 1 year.

Principles 2 (45 decks)

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