Principles of Acute Pain
Management
29.9.10
Rik Kapila

What this talk isn’t….
 A pharmacology lecture
 A physiology lecture
 Comprehensive

What this talk is ( I hope!)….





An overview
Relevant
Enlightening
Interesting
An opportunity

What is pain?

“An unpleasant sensory and emotional experience arising from actual or potential tissue damage or described in terms of such damage”.
International Association for the Study of Pain

Perhaps more usefully…

“whatever the experiencing person says it is, existing whenever he says it does."
Margo McCaffrey 1968

Epictetus (55-135 A.D)

‘It is not death or pain that is to be dreaded but the fear of pain or death’

Lance Armstrong (1971- present)

‘pain is temporary – quitting lasts forever’

Saint Augustine of Hippo (354-430)

‘the greatest evil is physical pain’

Does pain matter?

Cardiovascular

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Tachycardia
Hypertension
Increased myocardial oxygen consumption
Myocardial ischaemia

Respiratory

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Decreased lung volume
Atelectasis
Decreased cough
Sputum retention
Infection
Hypoxia

Gastrointestinal

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
Decreased gastric motility
Decreased bowel motility
Ileus

Genitourinary
 Urinary retention

Metabolic


Increased catabolic hormones
–
–
–
Cortisol
Glucagon
Growth hormone
Reduced anabolic hormones
– Insulin
– Testosterone

Psychological

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Anxiety
Fear
Sleep disturbance
Depression
Distressing for patient, family and staff

Chronic Pain after Surgery
 Not fully understood
 Worse after some surgery than others
 Aggressive acute management may reduce incidence of chronic problems

But more of that later….

This is why pain matters



1975 endorphin enkephalin
 Dynorphin
 synthesised in pituitary


Receptors in the peri-aqueductal gray matter

Endogenous morphine


Responsible for “hedonistic tone”
Increase descending inhibition in spinal cord
 Increased release in:
–
–
–
–
– happiness touch / massage sex exercise hypnosis / relaxation
– placebo effect -anticipation of the above

Endogenous morphine
 Increased release in:
–
–
–
–
–
– happiness
Increase descending inhibition in spinal cord touch / massage sex exercise hypnosis / relaxation
– placebo effect -anticipation of the above


How does this link in with the anatomy?



On the way up…
A δ - fast - instant reaction
C - slow - throbbing after-pains / chronic pain


A β - non-pain but inhibit Aδ and C when stimulated
Rubbing / massage / TENS


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Local anaesthetics - block
NSAIDS and ketamine - modulate
Pain to cortex via spino-thalamic tract

How does this link in with the anatomy?

In the central processor…
 Augment the endorphin system
 placebo
 opioids
 Psychological
 Self-hypnosis / relaxation

How does this link in with the anatomy?

On the way down…
 Noradrenergic pathways - inhibitory
 adrenaline in spinals ?
 Serotonin pathways facilitate
 Block with ondansetron !



How can we manage pain?
 Multimodal
 Multi disciplinary

Analgesic ladder

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WHO
Simple analgesics first
Moderate opioids next
Strong opioids last

Paracetamol


Paracetamol

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Paracetamol in acute postoperative pain
Clinical bottom line
Paracetamol is an effective analgesic.
A single dose of 1000 mg paracetamol had an NNT of 3.8 (3.4-4.4) for at least 50% pain relief over 4-6 hours in patients with moderate or severe pain compared with placebo based on information from
2,759 patients.
Paracetamol is not associated with increased adverse effects in single dose administration.

NSAIDS
 Non-selective eg. Diclofenac, ibuprofen
 Selective eg. Parecoxib, celecoxib

NSAIDS
 Good
–
–
– Part of multimodal analgesia
Bone pain
Opioid sparing
 Bad
–
–
–
–
Gastric
Renal
Asthma
Bleeding
 GRAB

Codeine
 Oral codeine in acute postoperative pain
 Clinical bottom line:
 Codeine 60 mg orally is not an effective analgesic for postoperative pain.
 A 60 mg oral dose of codeine had an NNT of
16.7 (11-48) for at least 50% pain relief over
4 to 6 hours compared with placebo in pain of moderate to severe intensity.

Tramadol



Oral tramadol in postoperative pain
Clinical bottom line: Tramadol is an effective analgesic in postoperative pain. A single 100 mg oral dose of tramadol is equivalent to 1000 mg paracetamol. A dose of 100 mg had an
NNT of 4.6 (3.6-6.4) for at least 50% pain relief over 4-6 hours in patients with moderate to severe pain compared with placebo.
At doses of 50 and 100 mg incidence of adverse effects
(headache, nausea, vomiting, dizziness, somnolence) was similar to comparator drugs. In dental trials there was increased incidence of vomiting, nausea, dizziness and somnolence.

Morphine

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The standard against which others are measured
Effective
May have side effects
Cheap

Oxycodone
 Synthetic opioid
 Developed in 1916 in Germany

Why use oxycodone?
 Subjectively
–
–
Better tolerated
Feel less ‘weird’
 Objectively
– Less hallucinations

Lets use it all the time!
 Expensive
–
–
MST 20mg
Oxycontin 10mg
 Better but not perfect
18p
47p
 Still have side effects
 Second line to morphine in cancer pain
– Br J Cancer 84(5);587-593

Morphine – Oxycodone relationship
 MST (regular)  Oxycodone MR (reg)
– Oxycontin
 Oral morphine solution
(prn)
 Oxycodone IR (prn)
– Oxynorm
 20mg orally
 10mg orally

How do regular and PRN work together
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Regular Px?
Having lots of prn?
Is the prn dose enough?
Increase the regular dose

Opioid problems
 Respiratory depression
 Sedation
 Constipation
 Nausea and vomiting
 Ileus


Urinary retention
Etc, etc, etc…..

Nausea and vomiting
 All of them can cause it
 Morphine is especially good at it
 Changing analgesic may help
 If someone is vomiting give the antiemetics intravenously!

Itching
 Opioids can cause itching
 Especially with neuraxial administration
 Difficult to treat
 Ondansetron can help
 Low dose naloxone can help
 Chlorpheniramine less so

Oramorph
 City Campus
–
–
–
– Single nurse administration
Used lots and lots
Predictable
Oral opioid of choice
 Queens Campus
–
–
–
–
2 nurses needed
Used much less
Alternatives used instead
Sevredol, tramadol, DHC

Why?
 I have absolutely no idea!

Abuse and addiction

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Its is a potential problem
Don’t let that stop you treating pain

Routes of administration
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Oral
Subcut
Intramuscular
Intravenous
Transdermal
Epidural
Intrathecal

Local Anaesthetics
 Lots of uses
 But you may see them cropping up in the following places:

Epidurals


Used in surgical patients
The significance of the little girl?

Spinals
 Intra and post op analgesia
 Can have opiate added to them


Need to watch for respiratory depression
Should have PCA obs even if they don’t have a PCA

But it still hurts…..

Take a critical look at the drug card
 What have they got?
 Regular or PRN?
 How much?
 How often?
 Are they actually taking it?
 Is the route appropriate?

Pain Team
 Help on many levels if you have a pain challenge:
– IVDU
– Acute on chronic pain
– Pregnancy
– Neuropathic pain
 Call for advice

How can we do it better?

Identify



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Regular assessment
At rest is not enough
Can they cough?
Can they deep breathe?
 It is easy to be comfortable lying still!

Respond

‘An hour of pain is as long as a day of pleasure’
Anon
 Be careful not to be prejudiced
– Acad Emerg Med 2006;13:140-146

Educate
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Patients
Nurses
Surgeons
Anaesthetists

Kiss-it-Better Hospital

Don’t forget the psychological side

Don’t forget that time and some physical contact can make a huge difference
 Acknowledge the problem and support the patient

And finally….
“Pain makes man think.
Thought makes man wise
Wisdom makes life endurable .”
(John Patrick 1905-1995)

Pumps and Stuff

PCA - City
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Omnifuse
Clinician code 66643
Just imagine you were texting OMNIFUSE!

PCA - QMC

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Graseby
No code
Need a key
Can’t do clinician bolus
 But Omnifuse should be coming at some point this year

Epidurals (non-obstetric)
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Gemstar
Yellow livery
Code 6546

Paravertebrals
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Gemstar
Grey livery
Code 1970
Think of Mr Catton!

Wound infusions

Nerve infusion analgesia

The End