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PAIN

Posted by SAMUEL ISABIRYE on February 18, 2013 at 8:15 AM

‘Pain is what the patient says hurts’

This is the most common symptom of disease. The nature, location and cause of pain differ in each case. Pain requires a holistic approach as it can be affected by spiritual, psychological, social and cultural factors which may need to be addressed after physical pain is controlled

Important categories of physical pain are: Nociceptive pain: the pain pathways are intact

- these pains respond to the analgesic ladder

Neuropathic pain: there is damage to nerves or the pathways

- these pains respond only partially to the analgesic ladder and need adjuvants of amitryptiline or phenytoin (see below)

Causes

Acute: postoperative, acute infection or trauma

Chronic pain:

-constant and usually increasing: cancer

-recurrent sickle-cell crisis, arthritis, HIV/AIDS

-drug side-effect or toxicity eg peripheral neuropathy due to isoniazid (anti-TB drug) or D4T (stavudine, antiretroviral drug)

Clinical features

Those of the underlying disease

Further therapeutic clues to the nature and management of pain may be elicited by:

Duration

Severity – can assess using the Numerical Rating Scale, where the patient grades his/her pain on a scale of 0= no pain to 5= worst pain ever experineced

Site and radiation

Nature (eg. stabbing, throbbing, crushing, cramp-like)

Periodicity (constant or intermittent)

Relieving or aggravating factors

Accompanying symptoms

Remember there may be more than one pain-ask the patient and get a detailed history as above for each pain

Management

Reasons for poor management of pain

Pain, especially if chronic, is often poorly managed for a number of reasons including:

Waiting for the patient to complain about pain rather than asking the patient about it

Failure to obtain details of pain from attending nurses and relatives who often know the patient better than the clinician

Prescribing the right drug in the wrong dose or with the wrong frequency or duration

Failure to prescribe an appropriate adjuvant drug, eg. antidepressant or anticonvulsant in neuropathic pain

Failure to make adequate use of strong opioids (eg. morphine) where indicated, because of misplaced fear of causing addiction, respiratory

depression or death

Failure to use other forms of therapy where appropriate, eg. radiotherapy, steroids, cytotoxic chemotherapy, antibiotics, muscle relaxants, etc

Failure to regularly review the patient’s condition and the drug regime prescribed

Lack of the right medicines

The aim of pain management is to:

Diagnose and treat the disease causing the pain

Achieve total pain relief with minimal side-effects and therefore enable the patient to live as normal a life as possible

Non-drug treatment may include:

Lifestyle adjustment

Patient counselling

Massage with aromatherapy oils – may be useful for neuropathic pain and muscular pain

Reflexology

Application of heat or cold packs

Relaxation

Distraction e.g. listening to radio

Non-pharmacological treatment of underlying cause e.g. surgery or radiotherapy of cancer

Important management points

Health professionals specially trained in palliative care should supervise management of chronic pain in advanced or incurable conditions (eg. cancer, AIDS)

Morphine is usually the drug of choice for severe pain

See also Pain and Symptom Control in the Cancer and/or AIDS patient in Uganda and other African Countries, 4th edition, HOSPICE AFRICA

UGANDA, 2006

In continuous pain, analgesics should be given:

-by the clock (i.e. according to a regular dose schedule)

-by the patient (i.e. self-administered)

-by the mouth (i.e. as oral dose forms)

Nociceptive or Somatic pain

Pain arising from any organ of the body with intact nerves:

-the commonest type of pain (may occur in any patient)

Medicines required depend on intensity of pain and are selected in steps according to the WHO analgesic ladder

Step 1: Non-opioids

paracetamol 1g every 4-6 hours (max: 4g daily) or aspirin 600mg every 4-6 hrs

- do not give aspirin in 3rd trimester of pregnancy or NSAIDS (give doses after food) eg. ibuprofen 1.2–1.8g daily in 3-4 divided doses

- max: 2.4g daily or indomethacin 50-200mg daily in divided doses or diclofenac 75-150mg daily in 2-3 divided doses

Child:

(ENDED HERE TO EDIT)f

paracetamol 10 – 15 mg/kg every 4-6 hours

or ibuprofen 20 mg/kg every 4-6 hours (give

after food)

 

-max 500 mg per day in children < 30 kg.

-not recommended for children under 1 year

old

 

Note on antipyretic effect

 

The above doses of aspirin, paracetamol and

ibuprofen may also be used for antipyretic therapy

 

Step 2: Weak opioids

 

ALWAYS GIVE WEAK OPIOIDS WITH A LAXATIVE

UNLESS SEVERE DIARRHOEA IS PRESENT

 

 

f

codeine phosphate 30-60mg every 4 hours

child 1–12 yrs: 3mg/kg daily in divided doses

or dihydrocodeine 30mg every 4-6 hours

child >4 yrs: 0.5-1mg/kg every 4-6 hours

 

f

+/-Step 1 drug

 

UCG 2010 408

 

 

 

18. Miscellaneous conditions

Step 3: Strong opioids

 

ALWAYS GIVE STRONG OPIOIDS WITH A LAXATIVE

UNLESS SEVERE DIARRHOEA IS PRESENT

 

 

Notes

 

z

Morphine 10mg parenteral is equivalent to 30mg

by mouth (i.e. multiply parenteral dose by 3 to

get oral equivalent).

 

z

Morphine 5mg by mouth is equivalent to 1.6mg

parenteral (i.e. divide oral dose by 3 to get the

parenteral equivalent).

 

z

Regular injections are not indicated in chronic

pain.

 

z

Chronic pain is more manageable when

controlled using small doses of oral morphine

titrated to control pain without causing

drowsiness. It is due to accumulation of

metabolites which are also active analgesics.

 

z

Respiratory depression has not been recorded

when morphine is given orally and titrated

against pain and drowsiness - however it has

occurred due to regular parenteral dosing.

 

f

morphine (as oral solution 1mg/ml): initially

2.5-5mg orally (see also note below) every 4

hours

 

-

then titrate the dose according to response

-

continued drowsiness indicates too much and

the dose should be titrated down slowly

-

oral morphine solution is absorbed from the

buccal mucosa and can be dripped into the

mouth in adults and children

or morphine (as slow-release tablets, eg

morfine SR).

-

start with 10mg orally or rectally every 12

hours

-

adjust the dose (but not the frequency) to

 

UCG 2010

409

 

 

 

18. Miscellaneous conditions

achieve satisfactory pain control

-

if the patient is changing from oral liquid to

slow-release tablet preparation, add the total

taken in 24 hours to control pain and divide

this by 2 to get the nearest equivalent dose

as morfine SR (10mg and 30 mg available

in Uganda)

f

Leave patient with a few extra doses of oral

morphine to take for breakthrough pain and

calculate needs at next visit. (Breakthrough pain

is a temporary exacerbation of pain after pain

has been controlled on a regular dose of oral

morphine.

f

The breakthrough dose is equivalent to the 4

hourly dose of oral liquid morphine being taken.

If the patient needs regular breakthrough doses,

then add the number of breakthrough doses

given in a day to the total daily dose, then divide

by six to get the new 4 hourly dose. For example,

a patient on 5mg oral morphine every 4 hours

(=30 mg in 24 hours) requiring 3 breakthrough

doses in a day (=3 x 5mg, total 15 mg) would

need a new total of 45 mg of oral morphine in a

 

day = 45/6 or 7.5 mg every 4 hours).

 

f

+/-Step 1 drug

 

Notes

 

Dose titration:

 

z

When titrating the dose upwards because pain is

not controlled, increase by 50-75% of the

previous dose

 

Pethidine:

 

z

Avoid this in treating chronic pain because:

-

it accumulates with severe side-effects on the

gut

-

it does not work well by mouth except in large

doses with resultant severe side-effects

 

UCG 2010

410

 

 

 

18. Miscellaneous conditions

z

Use for analgesia in labour: 50-150 mg orally

every 4 hours prn or 50-100mg SC repeated prn

after 1-3 hours

 

-max: 400mg/24 hrs

Child >6 mths: 0.5-2mg/kg/dose

-

only use as one off-dose for acute severe pain if

morphine not available

 

Respiratory depression:

 

z

This side-effect of opioids does not occur when

oral small doses are used initially, and gradually

titrated according to response

 

z

If mistakenly given in large doses by injection,

respiratory depression can be reversed by

 

naloxone

 

Nausea and vomiting:

 

z

Rarely occurs in Africans, commoner in

Caucasians

z

Occurs only in the first five days (it is self-

limiting)

 

z

Control with an oral antiemetic (for 5 days only),

eg.

haloperidol 1mg every 12 hours

or metoclopramide 10mg every 12 hours

 

z

Vomiting later on is usually due to another cause

in the illness

 

Use of morphine in dyspnoea and severe diarrhoea:

 

z

Use in small oral doses to relieve dyspnoea in

respiratory diseases such as lung cancer, pleural

effusion, COAD, heart failure and pneumonia

-

it increases relaxation and oxygenation

-

start with 2.5mg orally every 4 hours or add

 

2.5mg every 4 hours to present analgesic dose

z

Use similar small doses for severe diarrhoea in

HIV/AIDS patients

 

UCG 2010

411

 

 

 

18. Miscellaneous conditions

Cautions on use of opioids

 

z

Contraindicated in respiratory depression and

head injury

 

z

Use with care in the following conditions

-

advanced liver disease (but can be used in

hepatocellular carcinoma [HCC] when titrated

as above)

-

acute asthma

-

acute abdomen (can use while awaiting

diagnostic tests - never leave the patient in

pain)

-

hypothyroidism

-

renal failure (reduce starting dose and/or

reduce dose frequency)

-

elderly or severely wasted patient (reduce

starting dose and/or reduce dose frequency)

 

z

Use with extreme care (i.e. start with small doses

and use small incremental increases) in:

-

hypovolaemic shock: start with 10mg IV (as

absorption is slow due to hypovolaemia)

-

recurrent or concurrent intake of alcohol or

other CNS depressants

 

18.4.2. Neuropathic pain

Occurs as a result of damage to nerve tissue. There

 

are two clinical kinds of pain:

 

z

Stabbing-type pain in a nerve distribution with

minimal pain in between (eg. trigeminal

neuralgia) but can occur with any nerve

 

-responds to phenytoin

z

Paraesthesia, dysaesthesiae or burning-type pain

eg. post-herpetic neuralgia

 

- responds well to small doses of amitriptyline

z

Both elements may be combined

a) Trigeminal neuralgia or stabbing-type pain

 

Acute phase:

f

phenytoin 200-400mg daily in 1-2 divided doses

 

UCG 2010

412

 

 

 

18. Miscellaneous conditions

-

drug of choice because has minimal side-effects

 

and does not need monitoring

-

may need up to 600mg daily

-

avoid if patient is on antiretroviral therapy due

 

to interactions (Nevirapine and Protease

inhibitors)

or carbamazepine initially 100mg 1–2 times

daily

 

-

increase gradually according to response

-

causes white cell depression

-

needs monitoring

-

more expensive than phenytoin

-

usual dose: 200mg 3-4 times daily (up to 1.6g

 

daily may be needed)

 

-

avoid if patient is on antiretroviral therapy due

to interactions (Nevirapine and Protease

inhibitors)

 

f

±

amitriptyline 12.5-25mg at night or every 12

hours depending on response

 

b) Post-herpetic neuralgia

 

Acute phase:

f

amitriptyline 12.5-25mg at night or every 12

hours depending on response

 

If stabbing element to pain:

 

f

add phenytoin (doses as above)

 

18.4.3. Back or bone pain

z

Pain in the lumbar region of the spine

 

- is a symptom not a disease entity

z

Bone pain anywhere

Causes

 

z

Disc degeneration (often has a neuropathic

element because of pressure on sciatic or other

nerve)

 

z

Osteoporosis (if collapse of vertebrae or fracture)

 

z

Infection, eg. TB, brucellosis

 

z

Metastatic disease, eg. breast or prostate cancer

 

UCG 2010

413

 

 

 

18. Miscellaneous conditions

z

Cervical cancer

z

Strain

z

Congenital abnormalities

z

Spondylolisthesis (forward shirt of one vertebra

 

upon another, due to defect of the joints which

 

normally bind them together)

z

Renal disease

z

Pelvic infection

z

Retroperitoneal infection

 

Clinical features

 

z

Depend on the cause

z

In infections: pain is throbbing and constant

z

Sciatica -if sciatic nerve roots involved

 

Differential diagnosis

 

z

See distant causes above

 

Investigations

 

¾

As far as possible try to establish the cause and

type of pain (nociceptive or neuropathic)

¾

X-ray: spine and pelvis

-

if available, is affordable and will aid

management

 

Management

f

analgesics (see management of somatic pain)

-

give a Step 1 drug for 7 days or as long as

required according to patient

-

NSAIDs are the Step 1 drug of choice in bone

pain

-

may have to add a Step 2 or 3 drug especially

in metastatic disease

 

For acute back pain:

 

f

Rest the back on a firm but not hard surface

 

For neuropathic element:

 

f

Manage as for neuropathic pain above

 

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