Pain

Question 1

Effect of pain on CVS + RS

Answer 1

CVS: tachycardia, HTN, increased O2 demand

RS: reduced VC + FRC, basal atelectasis

Question 2

Describe the 3 neuron pathway of pain

Answer 2

1st: Site of injury - dorsal root ganglion to spinal cord
2nd: spinal cord to thalamus
3rd: thalamus to somatosensory area

Question 3

Types of nociceptors + what they respond to

Answer 3

Mechanoreceptors = pinprick + pinch

Silent receptors = inflammation

Polymodal = pressure, heat + allogens

Question 4

What are allogens?

Answer 4

Bradykinin, histamine, serotonin, H, K + prostaglandins

Question 5

What happens when there is an injury?

Answer 5

Histamine + bradykinin released

Phospholipase A2 activated

Converts phospholipids to prostaglandins

Question 6

Action of paracetamol

Answer 6

Inhibits prostaglandin production

COX 3

Question 7

Action of NSAIDs

Answer 7

COX inhibitors

Blocks prostaglandin + thromboxane production

Question 8

COX1 vs COX2 inhibitors, names + SE

Answer 8

1 = Ibuprofen, diclofenac

SE = bronchospasm, GI effects, renal + platelet

2 = parecoxib, celecoxib

Less SE

Question 9

Action of tramadol

Answer 9

MU receptor agonist

Increases inhibitory descending activity (serotonin + noradrenaline)

Question 10

What is the RAT system?

Answer 10

Recognise Assess Treat

Question 11

Methods of assessing pain

Answer 11

Verbal rating

Visual analogue scale (VAS)

Faces pain scale (FPS)

Question 12

Treatments that act on peripheral system

Answer 12

Non-drug: rest, ice, compression, elevation

Anti-inflammatory meds

Question 13

Treatments that act on spinal cord

Answer 13

Non drug = acupuncture, massage

Opioids, ketamine, local anaesthetics

Question 14

Drug treatments that act on brain

Answer 14

Paracetamol Opioids Amitryptiline Clonidine

Question 15

3 layers of spinal cord

Answer 15

Pia mater Arachnoid mater Dura mater

Question 16

Where is the CSF?

Answer 16

Between pia + arachnoid aka subarachnoid space

Question 17

Where does a spinal block go?

Answer 17

Subarachnoid space

Question 18

Where does spinal cord + subarachnoid space end?

Answer 18

Spinal cord = L1

SA space = S1

Question 19

Where does epidural space end?

Answer 19

Sacrococcygeal hiatus

Question 20

Where can you do a spinal block?

Answer 20

L4/5, L3/4, L2/3

L3/4 is ideal

Question 21

Where can you do an epidural block?

Answer 21

Risk of damage above L1

For labour - done at same level as spinal block

Question 22

What layers does the needle pass through for an epidural + spinal?

Answer 22

Skin S

C fat

Supraspinous ligament

Interspinous ligament

Ligamentum flavum

EPIDURAL

Dura + arachnoid mata

SPINAL

Question 23

What is a spinal block?

Answer 23

Single shot injection of anaesthesia into CSF

Rapid onset, anaesthesia for 2-3 hrs

Small 24G needle

Question 24

What is an epidural?

Answer 24

LA +- opioid via catheter

Slower onset

Less motor block than spinal T

itratable analgesia for up to 72 hrs

Large 14G needle

Question 25

A vs C nerve pain

Answer 25

A = sharp pain

C = chronic pain

Question 26

What is the dose of paracetamol for IV + PO?

Answer 26

15mg/ kg (for >12 y/o + >50kg) every 4 hrs

1g every 4 hrs

Question 27

Doses of codeine + max dose

Answer 27

8mg 15mg 30mg 60mg

Max 240mg in 24hrs

Question 28

What to co-prescribe with an opioid?

Answer 28

Nalaxone (opioid receptor antagonist)

Question 29

Codeine in breastfeeding

Answer 29

Goes into milk so give dihydrocodeine instead

Question 30

SE of tramadol in elderly

Answer 30

Hallucinations

Question 31

What is the reverse analgesic ladder?

Answer 31

Start with strong opiates and titrate downwards in severe acute pain

Question 32

Use of magnesium

Answer 32

Good pain relief intra-operatively

Bronchodilation

Question 33

How does ketamine work?

Answer 33

NMDA antagonist (used in Alzheimers)

Question 34

How do neuropathic analgesics work?

Answer 34

Work by neuromodulation