Regional anesthesia Flashcards

1
Q

What is RA?

A

Reversible abolition of pain and sensation in a part of the body without loss of consciousness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the categories of RA?

A

1.Neuraxial anesthesia (Spinal anesthesia and Epidural)
2.Peripheral nerve blockades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the MOA of LA?

A

LA produce anesthesia by inhibiting excitation of nerve endings or by blocking conduction in peripheral nerves.
Anesthetics reversibly bind to and inactivate sodium channels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens when autonomic fibers are blocked?

A

Vasodilation and hypotension occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the advantages of spinal anesthesia?

A

1.Avoids hazards of GA
2.Rapid action
3.consciousness is preserved
4.Alternative to GA for certain poor risk patients
5.Lesser post op confusion
6.Safe and cheaper alternative
prolonged post op analgesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where does the spinal cord end in adults and Children?

A

Adults -L1
Children-L3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the anatomical landmark of the spine?

A

-1st palpable spinous process-C2
-Most prominent spinous process-C7
-Inferior angle of the scapula-T7
-Illac crest -L4/5
-Posterior Superior Iliac Spine-S2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the importance of the palpable spinous processes?

A

Help define midline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the name of the line joining the top of the illiac crests at L4/5?

A

Tuffiers line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the skin anatomy from posterior to anterior?

A

Skin
Subcutaneous fat
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural Space
Dura matter
Subdural space
Arachnoid matter
Subarachnoid space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do dermatomes help with?

A

To know level of spinal anesthesia.

Sympathetic block higher than sensory which is higher than motor block.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the dermatomal levels?

A

T10-Umbilicus
T6-Xiphoid
T4-nipples
T12,L1-Inguinal ligament,Crest of ilium
S2-S4-perineum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the cardiac accelerator fibers and what is their effect when blocked?

A

Cardiac accelerator fibre: T1-T4(Bradycardia & ↓ contractility)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the vasomotor fibres and what are their effects when block?

A

Vasomotor fibre : T5-L1( Determine vasomotor tone)(vasodilation on blockade)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the indications for Spinal anesthesia?

A

1.Operations below lower half of body -include surgery on the lower limb, pelvis, genitals, and perineum, and most urological procedures, obstetric procedures e.g ceasarean section

2.Patients with systemic disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the absolute contraindications for Spinal anesthesia?(5)

A

Inadequate drug/ equipment
Severe hypovolemia
Increased ICP
Patient refusal
Infection at puncture site

17
Q

What are the relative contraindications for Spinal anesthesia?(5)

A

Sepsis
Coagulopathy
Uncooperative patient
Spinal deformity
Preexisting neurological deficit

18
Q

Hod does spinal anesthesia differ in pregnancy and why?

A

A decreased dose is required .
Mechanical factor- Compression of IVC causes shunting of blood to the venous plexus in the vertebral canal-decreased vertebral canal space and CSF volume.

Hormonal factors- higher progesterone levels increase the sensitivity of neuronal membranes to LA

19
Q

What are the immediate complications of spinal anesthesia?(5)

A

Hypotension
Bradycardia
high and total spinal block
Epidural hematoma
Bleeding

20
Q

What are the late complications of spinal anesthesia?(3)

A

Post dura puncture Headaches,
infections
urinary retention

21
Q

What is the difference between a high and total spinal block?

A

High spinal involves a spread of LA affecting spinal nerves above T4.

Total spinal, there is an intracranial spread of LA resulting in loss of consciousness.

Effects are of variable severity depending on maximum level that is involved but can include cardiovascular or respiratory compromise

22
Q

What is the management of hypotension?

A

oxygen therapy
vasoconstrictor drugs
↑rate of I.V
treat bradycardia

23
Q

How do you manage a high/total spinal anesthesia?

A

Following an algorithm
1.Call for help
2.Stop the epidural infusion being given
Give 100% oxygen
Put the patient in reverse trendelenburg position
Reassure the family/friends
3.ABCD approach
4.If there is A/B compromise: Maternal collapse call
Intubate and ventilate the patient
-RSI ,cricoid pressure
-Induction agent but lower dose
-Maintain sedation/ventilation till block wears off
5.If the baby is compromised -Lower segment C/S .If not liaise with senior obstetrician.
6.if there is circulation compromise:
-Lateral tilt the patient
-Ensure large bore IV cannula
-Bradycardia-Atropine
500mcg(repeat if needed)
-Hypotension-Rapid Iv Fluid bolus
-Vasopressors
-if the hypotension is severe or
there is a poor response then -
give adrenaline(5o-100mcg)

24
Q

What is a post dural puncture headache?

A

Due to leak of CSF from dural defect leads to traction in supporting structure especially in dura and tentorium & vasodilatation of cerebral blood vessels.

25
Q

After how long does it post puncture does the headache occur?

A

12-72hrs

26
Q

What are the features of a post dural headache?

A

Usually bifrontal and or occipital, usually worse in upright , coughing , straining
Causes nausea, photophobia, tinnitus, diplopia[6th nerve], cranial nerve palsy

27
Q

How do you manage a post dural headache?

A

Place patient in supine position
Give adequate hydration
NSAIDS
If this does not resolve in 12-24hr then Epidural blood patch of 20ml

28
Q

List 6 factors that may increase incidence of post -spinal puncture headache?

A

Age -Younger than older
Gender-Female than males
Needle size-Large bore than small bore

Needle bevel-Less when bevel is placed in the long axis of the neuraxis
Number of dural punctures-Increases with the number of punctures

29
Q

Describe how you position the patient for administration of RA?

A

Sitting
With Legs hanging over side of bed
Put Feet up on a Stool (no wheels)
Assistant MUST keep the patient from Swaying
Curve her back like a “C”,

Lateral Decubitus
Needs to be Parallel to the Edge of the Bed
Legs Flexed up to Abdomen
Forehead Flexed down towards Knees

30
Q

What factors affect block height?

A

Baricity of anesthetic solution

Position of the patient

Drug Dosage (mg)

Concentration times volume

Addition of Opioids

Site of Injection

31
Q

What is baricity and describe the different forms of baricity?

A

Density of solution in relation to density of CSF

Hypobaric solutions-rise against gravity.

Hyperbaric solutions-tend to follow gravity.

Isobaric solutions-tend to remain in the same height where they are injected.

32
Q

What adjuvants can be used with LA in Spinal and Epidural anesthesia?

A

1.Opiods -improves analgesic
2.Epinephrine- 0.2mg decreases blood flow and prolongs block by decreasing the rate of LA reabsorption
3.Clonidine- 15-45mcg Prolongs duration of sensory analgesia
4.Neostigmine- 5-100mcg inhibits breakdown of acteylcholine.

33
Q

What examples of Opiods used as adjuvants?

A

fentanyl-12.5mcg
sufentanyl-2.5-5mcg
Diamorphine -0.3mg
morphine- 0.1-0.2mg

34
Q

What is a peripheral nerve blockade?

A

Injection of LA agents around nerves in the peripheral nervous system to achieve reversible numbing of pain conduction in the corresponding innervated tissue

35
Q

Examples of PNB?

A

1.Interscalene
2,AXillary
3.Femoral
4.Sciatic
5.Popliteal
6.Lumbar plexus
7Brachial plexus

36
Q

List 4 complications of PNB?

A

Intravascular injection

Local anaesthetic toxicity

Nerve damage

INFECTION

37
Q

How do you prepare for an PNB?

A

Consent, infection control

Equipment: drugs, syringes, needle, USS machine, nerve stimulator

Assistance

38
Q

Give examples of LA drugs ?What adjuvant can they be given with?

A

Amine
Lignocaine 3mg/kg
7mg/kg with adrenaline

Bupivacaine 2mg/kg
2mg/kg with adrenaline

Ropivacaine 3mg/kg
3mg/kg with adrenaline

Esters
Procaine

Cocaine

39
Q

How do the ensure that the anesthetic drug has reached the desired destination or is working?

A

1.Ultrasound guide
2.Nerve Stimulation
3.Paresthesia