Acute pain management

Contents

Oral & rectal analgesia

Types of oral analgesia :

1. Opiates
2. Nonsteroidal Anti-inflammatory Drugs (NSAIDS)
3. Combination Drugs

Intravenous (IV) Opiates

Side effects of opiate administration
Predictors of drug dose

Adult doses (>50 kg)
Paediatric doses (<50 kg)
Infusion regimen

Protocols for delivery of opiate analgesia

Oral & rectal analgesia

Oral analgesia is the most common form of analgesia prescribed outside the hospital setting but often poorly prescribed and administered within the hospital. We encourage oral analgesia to be given when the patient is able to absorb fluids. Rectal analgesia is a useful route of administration particularly in patients suffering nausea or anorexia.

There are a number of advantages of oral analgesia :

patient comfort & familiarity
ease of administration
no chance of needlestick injury
inexpensive

When parenteral analgesia is no longer required, conversion to oral doses of analgesia is quite straightforward. The dose should be individualised for each patient and administered at regular intervals to maintain a plasma level within the analgesic corridor. Controlled release preparations are designed to produce slow, uniform absorption for eight or more hours.

N.B.

There is considerable literature that supports the use of NSAIDS and paracetamol to reduce opiate requirements. Prescribing a regimen that includes regular oral or rectal analgesia plus parenteral opiates is recommended.

N.B. The use of 'PRN' orders in hospital patients is discouraged as the drugs are usually administered at infrequent intervals and often only after a patient request. This usually produces inadequate analgesia.

A suggestion is to prescribe for a set time interval and a given number of doses or days, eg. Digesic 1- 2 tablets 4 - 6 hourly x 36 hours. The drugs should be regularly reviewed for efficacy and side effects.

Types of oral analgesia :

1. Opiates

Equianalgesic doses

OPIOID	TRADE NAME	I.M.(mg)	ORAL(mg)	DOSE PO
Morphine	Morph mix MS Contin	10	30 - 60	10-20 mg 4-6hrly 30 mg 12hrly
Physeptone	Methadone	10	20	5-10mg 6-8hrly
Codeine	Codeine Phos	130	200	10-60 mg 4-6hrly
Oxycodone	Endone Prolodone	15	30	5 mg 6hrly

Oxycodone conversion chart

Determine the parenteral dose of morphine or pethidine administered in the previous 24 hours to convert to the equivalent dose of oxycodone.

MORPHINE	PETHIDINE	OXYCODONE
10 - 20 mg / last 24 hours	75 - 150 mg / last 24 hours	5 mg 6 hourly
20 - 30 mg / last 24 hours	150 - 225 mg /last 24 hours	5 mg 4 hourly
30 - 40 mg / last 24 hours	225 - 300 mg / last 24 hours	10 mg 6 hourly
40 - 50 mg / last 24 hours	300 - 375 mg / last 24 hours	10 mg 4 hourly
> 50 mg / last 24 hours	> 375 mg / last 24 hours	continue current regime

2. Nonsteroidal anti-inflammatory drugs (NSAIDS)

NSAID	TRADE NAME	ROUTE	DOSE
Paracetamol	Panadol, Setamol Dymadon	PO PR	paed :15mg/kg 4hrly; max 100mg/kg/d 7-12yrs : 250mg 4-6hrly; max 1500mg/d adults : 0.5-1g 4-6hrly; max 5mg/d
Aspirin	Dispirin, Aspro	PO	adults : 300-900mg 4-6hrly, max 4g/d
Diclofenac	Voltaren,Fenac	PO,PR	adults : po 50mg 8hrly; pr 100-200mg/d
Indomethacin	Indocid	PO,PR	adults : po 25-50mg 8hrly; pr 100mg/d
Naproxen	Naprosyn	PO,PR	adults : po250mg 6-8hrly; pr 500mg/d
Piroxicam	Feldene	PO	adults : 10-20mg/d (once daily)
Many others exist

3. Combination drugs

DRUG	TRADE NAME	ROUTE	DOSE
Dextropropoxyphene + paracetamol	Digesic, Paradex Capadex	PO	1-2 tabs 4hrly
Paracetamol 500mg + Codeine 8mg	Panadeine Codalgin	PO	7-12yrs : 0.5-1 tab 4hrly adults : 2 tabs 4hrly
Paracetamol 500mg + Codeine 30mg	Panadeine Forte	PO	7-12yrs : 250mg 4-6hrly adults : 1-2 tabs 4-6hrly
Morphine 5mg + Aspirin 250mg	Morphalgin	PO	adults : 1-2 tabs 4-6hrly

Intravenous (IV) opiates

Opiates may be endogenous or exogenous, but they all act on opiate receptors throughout the body to reduce the transmission of pain signals to the brain. We are encouraging the use of IV opiates as this has proven to be a safe and efficacious method of obtaining rapid analgesia.

We strongly encourage the use of needle-free systems for the provision of pain relief in this era of life-threatening blood-borne infections.

Side effects of opiate administration

In equianalgesic doses the side effects are very similar regardless of the drug chosen. These effects are usually dose related so careful titration for the individual patient will reduce the likelihood of these occurring.

RESPIRATORY: respiratory depression (NB. SEDATION = RESPIRATORY DEPRESSION until proven otherwise)
CNS: sedation, euphoria, miosis, nausea & vomiting, muscle rigidity
CVS: vasodilatation, occasional bradycardia (vagal), decreased myocardial O2 demand
GU: urinary retention
GIT: delayed gastric emptying, constipation, sphincter of Oddi spasm
OTHER: itch (often relieved by 0.1mg IV/SC Naloxone)

Predictors of drug dose

There is very little correlation between the patients weight & opiate requirements. Many of these drugs have wide interpatient dose variability.

Doses should be assessed on:

previous drug history & concurrent medications
degree of tissue damage expected/present
underlying medical diseases especially liver & renal dysfunction
age ie. lower requirements in the elderly & neonates

N.B. All opiate prescriptions must have the duration or a maximum dose prescribed.This is a legal requirement

A bolus doses of opiate is given to establish analgesic blood levels ie. acts as a loading dose. Further analgesia is then maintained by opiate infusion, intravenous opiate PCA (patient controlled analgesia) or SC (subcutaneous) morphine + oral analgesia.

Adult doses (>50 kg)

Bolus dose : pain management protocol (PMP)

Prescribe one of the following drugs as 'opiate as per PMP' in the variable drug dose section of the medication chart.

In the further instruction box state the number of times the protocol may be repeated ie. 'x 2 or 3'.

Drugs:

Morphine 1mg/ml: ie 10mg will be diluted in 10mls
Pethidine 10mg/ml: ie 100mg will be diluted in 10mls

PMP allows the prescribed drug to be made up to 10ml with normal saline then administration of 2 x 2.5ml aliquots of the drug followed by 1ml aliquots to a total dose of 10mls for a single administration of the protocol. The time interval between each aliquot is 3 minutes.

Infusion regimen Drug Concentration for a syringe pump: Morphine 1mg/ml range : 1 - 4ml/hr
Pethidine 10mg/ml range : 1 - 4ml/hr Drug Concentration for an infusion pump: Morphine 1mg/10ml range : 10 - 40ml/hr
Pethidine 1mg/ml range : 10 - 40ml/hr

Paediatric doses (<50 kg)

Bolus dose : pain management protocol (PMP)

Prescribe one of the following drugs as 'opiate as per paediatric 'PMP' in the variable drug dose section of the medication chart.

In the further instruction box state the number of times the protocol is to be administered ie. 'x 2-3'.

Drug doses are found in the accompanying tables.

Paediatric Pain Protocol : IV Morphine

WEIGHT
(kgs) mg/ml Morphine in
the syringe
Normal Saline

1 ml bolus
dose equals

12 - 18 kg 2 mg morphine = 0.2 mls 9.8 mls 0.2 mg

18 - 24 kg 3 mg morphine = 0.3 mls 9.7 mls 0.3 mg

24 - 30 kg 4 mg morphine = 0.4 mls 9.6 mls 0.4 mg

30 - 36 kg 5 mg morphine = 0.5 mls 9.5 mls 0.5 mg

36 - 42 kg 6 mg morphine = 0.6 mls 9.4 mls 0.6 mg

42 - 48 kg 7 mg morphine = 0.7 mls 9.3 mls 0.7 mg

48 - 54 kg 8 mg morphine = 0.8 mls 9.2 mls 0.8 mg

54 - 60 kg 9 mg morphine = 0.9 mls 9.1 mls 0.9 mg

> 60 kg adult dose

WEIGHT mg/ml Pethidine in Normal 1 ml bolus

(kg) the syringe Saline dose equals

12 - 18 kg 20 mg pethidine = 0.4 mls 9.6 mls 2 mg

18 - 24 kg 30 mg pethidine = 0.6 mls 9.4 mls 2 mg

24 - 30 kg 40 mg pethidine = 0.8 mls 9.2 mls 4 mg

30 - 36 kg 50 mg pethidine = 1.0 mls 9.0 mls 5 mg

36 - 42 kg 60 mg pethidine = 1.2 mls 8.8 mls 6 mg

42 - 48 kg 70 mg pethidine = 1.4 mls 8.6 mls 7 mg

48 - 54 kg 80 mg pethidine = 1.6 mls 8.4 mls 8 mg

54 - 60 kg 90 mg pethidine = 1.8 mls 8.2 mls 9 mg

> 60 kg Adult dose

Infusion regimen

Specific prescription and administration record forms for paediatric opioid infusion have been produced to enable safe and efficacious administration of opioids in the paediatric population. These forms are available through stores at Lismore Base Hospital.

Protocols for delivery of opiate analgesia

IV accredited registered nurses may administer opiates as per the protocol, located in the Acute Pain Service Manual on every ward
A patient receiving PMP opiates must receive individual nursing care until the protocol is ceased and the pain adequately controlled
No syringe containing opiate must be left unattended
Supplemental O2 should ideally be administered to all patients receiving opiates. Opiates cause periodic episodes of hypoxia especially while patients are sleeping

For further information, contact Sr Jenni Prince, Acute Pain Service co-ordinator, Lismore Base Hospital, or the department of anaesthesia, Clover House, ph (02) 6622 1285. (Director of anaesthesia, Dr Chris Lowry. Anaesthetists, Dr Melissa Goldberg and Dr David Scott.)
Email :

amprak@nor.com.au

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