Pain management

Question 1

Physiology of pain

Answer 1

Nociceptor –> electrical activity
Conducted by C and A delta nerve fibres of the peripheral nerves to the dorsal root ganglion in the spinal cord
Various neuropeptides modulate the transmission of these signals in the spinal cord
Thalamus and then to cortex

Pain –> sympathetic stimulation –> myocardial ischaemia and reduced blood flow
Restricts mobility
Atelectasis
Can’t cough and clear
Hormonal, metabolic and immune systems are affected

Question 2

Acute pain

Answer 2

3 causes
Ischaemia, bleeding, anastomotic leak, compartment syndrome

ABCD

SOCRATES

Question 3

NSAID

Answer 3

Prostaglandin inhibition

Role in renal regulation, gastric protection, platelet function

COX-2 inhibitors have minimal systemic side effects

Question 4

Opioids

Answer 4

N+V, constipation, itching, bladder retention, drowsiness, respiratory depression, opioids

PCA

Give laxatives

Always think about O2 when on PCA

Pain, sedation and nausea score

Question 5

Epidural

Answer 5

Also blocks sympathetic

LA+opioids

Damage to nerve roots
Dural puncture
Haematoma
Infection

Not within 12 hours of clean, and removal not within 4 hours of

Bromage score
1 knees
2 feet
3 neither

Can mask other causes of hypotension

Question 6

LA toxicity

Answer 6

Metallic taste
Tingling
Agitation
Decreased consciousness
Hypotension
Convulsions
Apnoea
Cardiac arrhythmia 
Arrest

ABCDE