Acute Pain Management

Richard Halliwell Westmead Hospital westmeadanaesthesia.org

“Pain is a more terrible lord of mankind than death itsel Albert Schweitzer

The importance of Pain Relief

Adverse effects of unrelieved pain

• 57% of patients considered pain to be their most important fear about surgery

Warfield, C. A. and C. H. Kahn (1995). “Acute pain management. Programs in U.S. hospitals and experiences and attitudes among U.S. adults.” Anesthesiology 83(5): 1090-4.

Is pain important to patients?

Verbal Pain score No Pain = 0; Worst pain imaginable = 10. With rest and movement.

Acute Pain: Scientific Evidence 4E 2015

Remember the Pain History...

Classes of Analgesic drugs

• Opioids

• Anti-inflammatory drugs - NSAIDs, Coxibs

• Other adjuvants - Paracetamol, Tramadol

• Anticonvulsants / Neuropathic agents • Ketamine, gabapentin, pregabalin,…

• Antidepressants – amitriptyline, duloxitene

Multimodal analgesia

• Combining drugs that act in different ways • Improves analgesia with a lower dose of each drug –

therefore limiting toxicity / side effects

Tips for Opioids Card

Tips for Opioids Card

• CNS • analgesia, sedation, euphoria, miosis • addiction is very rare (1:5000)

• Respiratory • ventilatory depression, hypercarbia, decreased cough, • airway obstruction (esp. OSA patients)

• GIT • ileus, constipation, nausea, vomiting, increased smooth muscle tone

• CVS • minimal - if normovolaemic (bradycardia, hypotension)

Effects of Opioids

Opioid Parenteral IM SC Oral Morphine 10mg 30mg Oxycodone 15mg 20mg Methadone* 10mg 20mg Codeine 130mg 200mg Hydromorphone 1.5mg 7.5mg Pethidine 100mg 300mg Fentanyl 100mcg NA

Equivalent Opioid doses

*Warning: Difficult to use. Note: single dose comparisons only

Opioids: High risk groups

• Elderly

• Obese

• Sleep Apnoea

• Respiratory disease

• Head Injury

• Renal or Hepatic impairment

Avoid, reduce dose or closer monitoring

Good use of Opioids • Wide dose variability between patients (10 x)

• The right dose is ‘enough’

• Reasons for inadequate pain relief • dose too small • dose too infrequent

• If still in pain but not sedated or resp depression then give more!

• Don’t use long term.

• Weight is a poor guide

• Patients on chronic opioids need more

• Omitting opioids in regular opioid users will lead to withdrawal syndrome

Opioid dose selection

Source:http://www.medicine.ox.ac.uk/bandolier/booth/painpag/acutrev/analgesics/leagtab.html

League table of percentage of patients achieving at least 50% pain relief over 4-6 hours in patients with moderate to severe pain, all oral analgesics except IM morphine.

Adding non-opioids: useful

Safety monitoring of Opioids

• Respiratory rate is not sensitive for opioid induced respiratory depression

• Sedation is much more sensitive!

• Significant risk in • Obstructive Sleep Apnoea • Obesity-related hypoventilation • Sleep disordered breathing

Specialised Opioids: for experienced prescribers only!!

•Hydromorphone (aka. Jurnista) •Fentanyl patches (aka. Durogesic) •Transmucosal Fentanyl (Actiq) •Methadone •Buprenorphine (Norspan) •Oxycodone SR +Naloxone (Targin)

Long acting Opioids

•Must not use in the acute situation!

• Examples • Oxycontin, MS Contin, Kapanol, Jurnista, Durogesic • Don’t confuse names

• Good for persistent or chronic pain

• If you give too much you are in trouble!

Macdonald and Macleod. Has the time come to phase out codeine?. CMAJ : Canadian Medical Association journal. October 14 (2010) on-line

Codeine: It’s a pro-drug! Now prescription only. Panadeine® removed from hospital use.

Analgesic window

Time

Rec

epto

r opi

oid

conc

entra

tion

Intermittent opioid dosing

Pain

Sedation, respiratory depression

Systemic opioids: Patient Controlled Analgesia

Allows the patient to self titrate their effective safe dose

Analgesic window

Time

Rec

epto

r opi

oid

conc

entra

tion

PCA - Dose titration in the individual

Opioids and discharging patients • If taking a big doses then

ask for advice • Need a de-prescibing plan • If complex pain then ask

for advice too • Communicate to GP on

Discharge Summary about a pain plan

• On going opioids in non-cancer pain is dangerous!!

Recommendations... • Titrate the right dose of

morphine or oxycodone

• Add a co-analgesic (paracetamol, NSAID: if safe)

• If pain persists consider a new cause or complcation

• Need help? - call for help page 9288 APS reg.

NSAIDs & COX 2 Inhibitors...

Basic Pharmacology of NSAIDs

• NSAIDs reduce opioid dose requirements and reduce nausea, vomiting, sedation

• Paracetamol reduces opioid dose requirements (not side effects)

• Non-selective NSAIDs can increase the risk of bleeding

• NSAID + Paracetamol is better than paracetamol alone

• With care, NSAID induced renal impairment is low

NSAIDs....

Suggested NSAIDs....

•Celecoxib 100 to 200 mg BD

• Lower GI risk, no anti-platelet effect, still has renal risks

•Diclofenac 50 mg TDS

• Caution if cardiac risk, bleeding, renal impairment, PUD, asthma, but safe with breast feeding

•Ibuprofen 400mg to 800 mg Q6h

•If unsure ask!

•Use for shortest duration! eg 3 or 5 days

Paracetamol

• Usually safe – use correct dose and duration

• But, a leading cause of acute liver failure (via NAPQI)

• Risk factors for Hepatic injury • Dose > 4 g/day • Dose too much for body size • Co-existing liver injury • Malnutrition

Paracetamol

Epidural and Intrathecal Analgesia

Intrathecal opioids

• Very small doses of morphine lasts for up to 24 hours e.g. 0.2 mg

• Delayed onset of respiratory depression • Ask for advice if adding a systemic opioid

• Examples: • Caesarian section • Hip or knee replacement • Laparotomy, bowel resection etc

Acute Pain Services: formally organised care 24/7

•Manages advanced forms of pain relief

•Call if usual analgesia not working •Improve safety, education •Help with palliative care

Page 9928 (24/7)

Mini feedback from the homework

• Oxycontin® 30mg po bd OR

•Immediate release oxycodone

S8 Prescriptions A separate script is required for each S8

medication. The strength of the intended dosage form

(e.g. 5mg tablet, 1mg/mL liquid) needs to be specified

Quantity must be specified in words AND numerals.

It is a legal requirement, not a hospital policy

OXYCONTIN® = Oxycodone (Controlled Release)

10mg 15mg 20mg

30mg 40mg 80mg

Non-formulary brand of modified release Oxycodone - Sandoz®

(available as 5mg, 10mg , 20mg, 40 80 )

Oxycodone Immediate Release

Oxynorm® 5mg 10mg 20mg 1mg/mL

liquid

Endone® 5mg

Other formulations include: • Suppository (Proladone®)

30mg • Solution for injection or

infusion (OxyNorm®) 10mg/mL or 20mg/2mL

Dose • Never prescribe dose in mL alone:

oMay be multiple strengths available, hence always specify strength of medication (mg/mL)

oA 10mg/mL solution can result in a 10 times overdose if 10mL is prescribed but 10mg intended

• Never place a decimal point and zero after a whole number

e.g. 2.0mg (could be seen as 20mg) oShould be 2mg

• Never leave a decimal point ‘naked’ e.g. .5mL

oShould be 0.5mL (could lead to 10x overdose)

What’s wrong with this?

and Naloxone

(Controlled Release) Oxycodone 5mg + Oxycodone 10mg + Oxycodone 20mg +

Naloxone 2.5mg Naloxone 5mg Naloxone 10mg

Oxycodone 40mg + Naloxone 20mg

Prescribe both in generic and brand

and Naloxone

(Controlled Release) • Oral naloxone has high first-pass metabolism; low oral

bioavailability • Block opioid receptors in the gut only

• Reduced constipation compared with Oxycontin®

• Most benefit in patients who have developed opioid induced constipation. And those who have not benefited from laxatives.

• Less benefit in those who have not developed constipation • Can still be abused by chewing/crushing and swallowing - just like

Oxycontin®

• Do not use in moderate or severe hepatic impairment • Doses above Oxycodone 40mg/Naloxone 20mg po bd are not

recommended as there are no studies to support its use at high doses

Modified Release Medication

• Check suitability of dosage form for the route of

administration. SR dosage forms cannot be crushed

as they lose the sustained release characteristics leading to a drug dump

Tick if Slow

Release

This box must be ticked if a sustained or modified release

form of an oral drug is required (eg. XR, SR, CD, MR,

EC, CR, ER, XL)

These medications cannot be crushed for an NG/PEG tube –

use an alternative

PRN section Transcribe allergies from the front of

the chart Must have indication

Must have a frequency Must have max dose/24hours

Watch for duplication on regular chart e.g. Paracetamol (including

Panadeine/Forte®), metoclopramide

S8s must have finite number of doses

e.g. ‘6 doses’ written

X6 doses

Poor pain control • Patient may be given extra breakthrough doses and it

is most important to return and review the patient’s pain control

oBreakthrough doses are usually one-sixth of the total daily dose. The range maybe hourly to every 4

hourly with an immediate release preparation oMake sure your calculation for is correct!

• Alternatively, it may be necessary to re-titrate the patient by converting to immediate release

preparations, either as the original medication or converted to morphine.

Conversion for titration • Calculate the daily requirements for oxycodone

oOxycontin 30mg po bd oTotal daily dose is: 60mg

Make sure you are VERY CLEAR which MEDICATION and DOSAGE

FORM you are converting to!!!! Be VERY CAREFUL - the dose requirements may decrease when

switching to other opioids, especially if your patient was constipated!!!!!! There is often not a cross tolerance to opioids so when converting from

one opioid to another doses should be commenced at around a 50% lower equianalgesic dose with the prescribed option to use PRN doses if

needed.

Tools to assist you with Dose Conversions

Conversion for titration • Convert from oxycodone to morphine: oOxycodone is more potent than morphine

10mg of ORAL oxycodone = approximately 15mg of ORAL morphine Therefore,

60mg of oral oxycodone = 60 x 1.5 = 90mg of oral morphine OR

60mg of oral oxycodone = y . 10mg of oral oxycodone 15mg of oral morphine

y = 60 x 15 ÷ 10 y = 90mg of oral morphine per DAY

As a 4 hourly dose of oral morphine, Dose = 90mg ÷ 6 = 15mg po q4h (immediate release)

Conversion for titration • Convert from oral morphine to parenteral morphine:

oThere is often not 100% bioavailability (i.e. Absorption) when medications are given orally. NEVER PRESCRIBE “po/subcut” (PRESCRIBE ONE ROUTE ONLY)! o15mg of oral morphine = approximately 5mg of subcutaneous morphine

Therefore, 90mg of oral morphine = 90 x 0.333 = 30mg of subcutaneous morphine

OR 90mg of oral morphine = z .

15mg of oral morphine 5mg of subcutaneous morphine z = 90 x 5 ÷ 15

z = 30mg of subcutaneous morphine As a 4 hourly dose of morphine,

Dose = 30mg ÷ 6 = 5mg subcut q4h

Case scenarios to discuss.

Jack has pain...

Jack has pain...

• 24 yrs male

• Motor bike crash • Fractured femoral shaft

• What can you do first?

Jack has pain... • Assess pain

• Oral route not appropriate

• Morphine IV 5mg Q5min PRN • May initially need 15 to 20 mg in total

• Monitor: sedation, pulse oximetry, resp rate

• Splint and immobilise

• Adjuvants • Paracetamol IV

• ?nerve block - femoral

Tony has pain...

Tony has pain...

• Nurses call you at 10 pm

• Not your patient

• 34 year old man • Day 2 postop open colectomy for ulcerative colitits • What can you do first?

Tony has pain...

• Assess pain and history • Severity, site, nature, onset • Prior opioid use (long term, dose)

• Exclude complications • Check wound and observations

• Check current analgesics and doses

Tony has pain...

• Optimise current analgesia • Drug, dose, route frequency

• Add adjuvants - • NSAID’s if safe, paracetamol, tramadol

• Maybe discuss with APS registrar • PCA? Others…

What’s wrong with this?.

What’s better??

Better..

You can treat pain well

Your patients will thank you.

Expect patients to have good pain relief.

Therapeutic Guidelines: Highly recommended