Post-operative Pain management

Question 1

Causes of Post operative pain

Answer 1

Somatic, visceral and neuropathic

Question 2

Negative effects of pain

Answer 2

Emotional and physical suffering, sleep disturbance
Hypertension and tachycardia, increased O2 use and decreased bowel movements
Delays mobilization leading to DVT

Question 3

Positive effects of pain

Answer 3

Warning of tissue damage

Immobilization to aid wound healing

Question 4

Anatomy of pain

Answer 4

Skin nocioceptors to C fibres up the spinothalamic tract to the thalamus and the limbic system

Question 5

Why do we need analgesia?

Answer 5

Comfort
Mobility (reduces risk of DVT, pressure sores & stiffness)
Respiration and prevents pneumonia in thoracic or upper abdominal surgery

Question 6

Reasons analgesia may be inadequate

Answer 6

Pain is subjective
Hard to predict severity
Inadequate knowledge of staff
Fear of side effects

Question 7

What effects the severity of pain?

Answer 7

Site and extent of wound, Age (goes both ways)
psychological & personal factors (anxiety, experience), coexisting medical problems and Drug tolerance
Pre-operative patient education

Question 8

Measurement of pain

Answer 8

Graded on subjective 1-10 or visual scales

pretty poor really

Question 9

Surgical Pain ladder

Answer 9

Increasing pain relief depending on operation performed
Start with NSAIDs/paracetamol, then wound infiltration with LA, then peripheral nerve block, then systemic opioids then PCA or epidural

Question 10

Minor surgery

Answer 10

Inguinal hernia, varicose veins, Gynae Laparotomy

Use paracetamol/NSAIDs + wound infiltration with LA and/or peripheral nerve block

Question 11

Moderate Surgery

Answer 11

Hip replacements, hysterectomy or maxiliofacial

Use paracetamol/NSAIDs + wound infiltration with LA and/or peripheral nerve block or PCA

Question 12

Major surgery

Answer 12

Thoracotomy, upper abdominal or knee surgery

Use paracetamol/NSAIDs + epidural/LA opioids or PCA

Question 13

Management of Pain

Answer 13

Combinations of drugs are best

Usually try to use the best combination of LAs, Opioids and NSAIDs/Cox-2 inhibitors

Question 14

Opioids

Answer 14

Morphine is gold standard - also diamorphine, papaveretum, fentanyl, codeine, tramadol

Question 15

Indications for using opioids

Answer 15

Moderate to severe pain
Prescribe on age not weight
Choose route: PO, SC, IV, IM, sub-lingual

Question 16

Effects of Opioids (6,4,3,3)

Answer 16

CNS: analgesia, sedation, euphoria, coma, tolerance/addiction, pupil constriction
GI: N&V, constipation, biliary spasm, slow gastric emptying
Resp: resp depression, apnoea, cough reflex suppression,
CVS: bradycardia, hypotension + urinary retention
SEs are worse in elderly & in combination with other drugs

Question 17

Analgesic corridor

Answer 17

The dose range where pain is adequately controlled by side effects are minimised

Question 18

Sedation score

Answer 18

Awake and alert (0)
Mild sedation (1)
Sleepy but rousable (2)
Unrousable (3)

Question 19

Methods of administering opioids (4)

Answer 19

IM PRN
IV PRN
Continuous IV infusion
IV PCA

Question 20

Mangement of opioid overdose

Answer 20

ABC to stabilise

Naloxone 0.4-0.8mg but may need an infusion or to be on ITU/HDU

Question 21

PCA for opioids

Answer 21

Pros –> titrate to needs, safe, smaller peaks, placebo
Cons –> Needs more monitoring, risk of SEs or OD, N&V
1-2mg bolus with 5-15mins lockout

Question 22

Oral opioids

Answer 22

Usually codeine with paracetamol (min 3mg/kg/day)

Codeine is metabolised into morphine - similar SEs (sedation and constipation)

Question 23

Tramadol

Answer 23

IV, IM or oral 50-100mg 8hrly, 100mg = 5-15mg morphine

Reduces 5HT and NAdr reuptake and is a weak opioid agonist - risk of serotonin syndrome if used with SSRIs

Question 24

Antiemetics

Answer 24

Metoclopramide (benzamide?) - SE - agitation
Cyclizine (antihistamine+anticholinergic) - painful IM or IV
Ondansetron (5-HT3 antagonist) +Dex (unclear mechanism)
Domperidol (butyrophenone) (Prochlorperazine (DA agonist)

Question 25

Laxatives

Answer 25

Osmotic (lactulose) 15-30ml BD regularly

Stimulant (Senna) 2-4 tabs nocte - short term effect

Question 26

Oral mild opioid preparations

Answer 26

Codydramol: Dihydrocodeine 6-10mg + paracetamol 500mg

Cocodcamol Codeine 30mg + paracetamol 500mg 1-2 tabs 4-6hrly

Question 27

NSAIDs

Answer 27

15-60% effect of opioids –> inhibit the production of PGs

Eg Aspirin, ibuprofen, diclofenac

Question 28

Side effects of NSAIDS

Answer 28

GI–>Gastric irritation, ulceration and bleeding
Resp–>Bronchospasm
Renal–> oliguria, renal failure, elderly at special risk
Skin rashes and antiplatelet effect
Increased risk of MI?

Question 29

Cox-2 inhibitors

Answer 29

Selectively inhibit Cox-2 enzyme so should be GI sparing
Paracoxib 40mg IV or Celecoxib 200mg OP
Concern over CVS SEs –> may be increased MI risk

Question 30

Paracetamol

Answer 30

Good SE profile, possible works on cannibinoid or COX-3

1g 4hrly max 4g/24hrs

Question 31

IM morphine Doses

Answer 31

20-39yrs     7.5-12.5mg
40-59yrs     5-10mg
60-69yrs     5-7.5mg
70-89yrs      2.5-5mg
>89yrs         2-3mg

Question 32

Opioids verses opiates

Answer 32

Opiates are naturally occuring substances similar to morphine - opioids are chemicals with an effect on the opioid receptor (Mew1/2, Kappa & delta)

Question 33

Aims of post-operative management

Answer 33

Reduce suffering and so improve clinical outcomes by increasing patients ability to move, cough, ADLs etc