Acute Pain Management - Richard Halliwell Westmead Hospital westmeadanaesthesia.org - WSLHD

Acute Pain Management

Richard Halliwell
Westmead Hospital
westmeadanaesthesia.org

The importance of
             Pain Relief

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

Adverse effects of
 unrelieved pain

Is pain important to patients?
• 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.

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

Remember the Pain History...

Acute Pain: Scientific Evidence 4E 2015

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

Effects of Opioids
• 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)

Equivalent Opioid doses
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
      *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.

Opioid dose selection

• Weight is a poor guide
• Patients on chronic opioids need more
• Omitting opioids in regular opioid users will
  lead to withdrawal syndrome

Adding non-opioids: useful

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.

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

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!

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

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

Intermittent opioid dosing
                                     Sedation, respiratory depression
Receptor opioid concentration

                                    Analgesic window

                                                    Pain

                                  Time

Systemic opioids:
           Patient Controlled Analgesia

Allows the patient to self titrate their effective safe dose

Receptor opioid concentration   PCA - Dose titration in the individual

                                          Analgesic window

                                        Time

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....
•   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

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

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

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           Page 9928 (24/7)

•Help with palliative care

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,

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                   Tick if
                                                         Slow
                                                        Release
                                • Check suitability of dosage
                                      form for the route of
                                  administration. SR dosage
                                   forms cannot be crushed
                                  as they lose the sustained
                                     release characteristics
  This box must be ticked if a     leading to a drug dump
  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              X6 doses
   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

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

 Expect patients to have good pain relief.
        Your patients will thank you.

Therapeutic Guidelines:
 Highly recommended