Pain and Analgesia

Question 1

Precautions with Nitrous Oxide:

Answer 1

GAS FILLED SPACES
- PTx
- Bowel obstruction
- Bullae
- Decompression
- Head injury

PREGNANCY
- Not until labour (teratogen, miscarr)

NEED FOR > 50% FiO2

*Diffusion Hypoxia (Fink effect) in minutes after cessation- wean via 100% O2

Question 2

Topical anaesthesia options:

Answer 2

EMLA/ Angel
—> (MethHb risk with EMLA prilo)
Lignocaine/ cophenylcaine spray
Lignocaine gel
Laceraine (ligno/tetra/adrenaline)
Oxybupricaine/tetracaine (cornea)
Benzocaine (intraoral, non-soluble)

Question 3

NSAID precautions:

Answer 3

GI
- Dyspepsia most common (antacid, food)
- PUD incl bleed, perf. Usually long term but CAN occcur anytime, partic in >60/steroid use/anticoag (PPI/misoprostol if long term, or a COXIB- less risk)

RENAL
- Fluid retention, AKI
- Partic if ACE/ CKD/ reduced renal perfusion (eg. CCF), or ACE/diuretic (triple whammy)
- Can use, but 3-5 days only

BLEEDING
- Platelet dysfunction
- Avoid in thrombocytopaenia, active bleed, bleed risk, anticoagulated.

CARDIOVASCULAR
- ACS, sudden death, stroke
- Diclofenac ++

BRONCHOSPASM
- At risk: asthma, NASAL POLYPS
- Rare, but can be severe/fatal

PREGNANCY
- T1- miscarriage
- T3- closure of DA (RHF, hydrops, death in utero)
Fine for breastfeeding

Question 4

Use of Naloxone:

Answer 4

Opioids, BZD, Clonidine.

IV: 100-200 microg. Repeat 30-60secs
IM/SC: 400

Only reverses sedation/resps.

• DO NOT FULLY REVERSE IF OPIOID DEPENDENT (withdrawal)
  —> Aim airway and adequate resps.

Effect lasts 20-90mins.
WATCH FOR RESEDATION
Repeat dose/ infusion

Infusion at 2/3 of initial effective dose, per hour.

After using Naloxone: monitor for resedation, withdrawal.

Question 5

Signs of toxicity vs adverse effects with opioids.

Answer 5

TOX:
- Coma
- Resp depression
- Miosis

ADVERSE:
- Resp depression
- Hypotension- vasodil (fentanyl less)
- Sedation

• Histamine: rash, urticaria, bronchospasm. NOT ALLERGY (not fentanyl)
• Rigidity (fentanyl. SLOW push)
• Constipation
• Urinary retention (BPD)
• Adrenal insufficiency (chronic use)

Addiction, dependence, tolerance.

Question 6

Tramadon’t:

Answer 6

‘Dirty’: mostly actually an SNRI. Only an opioid after metabolism- and an extremely weak one.

Metabolism very variable (like codeine), P450. Effect unpredictable/ may be none.

Multiple adverse:
- Serotonin syndrome (with other drugs)
- Seizures
- Hypoglyc
- Tachycardia
- Delirium
- Drug interactions (P450)

… whyyyy

Question 7

List 10 adjunctive/ mechanistic analgesics:

Answer 7

ANTICONVULSANT
Pregabalin, gabapentin, carbamazepine

ANTID
Amitriptyline/ nortriptyline
SSRI (eg. Venlafaxine)

RELAXANTS
BZD, Baclofen, cyclobenzaprine

OTHER
Capsaicin
Local/topical anaesthetics
Ketamine
Chlorpromazine/ stemetil
Buscopan

Question 8

Structure for chronic pain presenter in ED:

Answer 8

Always consider new, acute pathology
Consider drug-seeking: check register
Validate and empathise

If acute pain element : opioids appropriate.
If actually sustained acute pain (eg. malignancy): opioids appropriate
—> Use conversion/ equianalgesic doses (reduced by 25% for cross-sensitivity)

If exacerbation of chronic pain: not for opioids. PPS and adjunct uptitration.

ISSUES: non-noxious, true hyperalgesia, drug dependence vs addiction, tolerance, opioid cross-sensitivity, multimodal/disciplinary

Question 9

Analgesia in renal failure:

Answer 9

Paracetamol- YES
NSAIDS- 3-5 days only
Opioids- Fentanyl preferred. Dose reduce others (active + neurotoxic metabolites accumulate).

If on dialysis: whatever! *Note fentanyl NOT dialysable

Question 10

Analgesia in liver failure:

Answer 10

Paracetamol: safe in reduced dose <2-3G/day for mod CLD/ cirrhosis
NOT IN ACUTE FAILURE

NSAIDS: avoid. Risk hepatorenal Sx, bleed. Ibuprofen okay if short term and mild CLD.

Opioids: fentanyl preferred. Reduce dose and lengthen intervals.
*constipation —> encephalopathy. Coprescribe LAXATIVE.

Question 11

Dose IN fentanyl in paeds?

Answer 11

1.5microg/kg

Repeat half or same in 10mins

Question 12

Paediatric procedural analgesia:

Answer 12

-Okay to talk about procedure/ see equipment etc.
-Parent present and actively involved
- Positive demeanour
—> avoid false reassurance, bargaining, apology
- Analgesia (utilise topical)
- PLAY THERAPY

Question 13

Paediatric pain scales

Answer 13

VISUAL ANALOGUE
eg.Wong-Baker Faces
—> Age 3+

NUMERICAL
eg. 1-10
—> 6+
—> Need numerical concept/ abstract thinking

BEHAVIOURAL and BEHAV/PHYSIOL
Eg. FLACC
—> Good for cognitive impairment, very young

__________

Use language child gets (“hurt” or “ouch”)
Ask carer
Check frequently, recheck after interventions