Pain Flashcards
What are the Different Types of Pain?
- Nociceptive (damage to the tissues)
- Non-cancer acute
- Chronic
- Neuropathic pain (damage to the nerves)
- Cancer related pain
What is Pain?
Unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
What is nociception?
Nociception is the neural process by which body detects noxious stimuli
What is the process of Pain?
- Detection – nociceptors detect noxious stimulus
- Transmission – after detection done by calcium channels, there’s an influx of calcium ions through calcium channels which release vesicles containing new stimulatory receptors
- Central perception – emotionally will respond differently
What is the Assessment of Pain?
- Vocalisation: whimpering, crying
- Facial expression: looking tense, frowning, look frightened
- Behavioural change: increased confusion, refusing to eat, rocking, look withdrawn
- Physiological change: Temperature, pulse or BP, flushing or pallor
What is Acute Pain?
- Positive biological function – protective role
- Short duration (<12 weeks)
What are the Goals of Treatment of Acute Pain?
- Relieve pain with minimal side effects
- Optimise function
- Prevent progression to chronic pain
Is there specific treatment for acute pain?
- Specific treatment for the underlying condition and symptomatic management of pain which usually resolves with healing of the underlying illness or injury
What is the Approach to Acute Pain Management?
If analgesics are required?
- Non-pharmacological approaches may be adequate in patients with mild pain
- If analgesics are required
- Use a stepwise approach starting at a step that corresponds to the severity of the patient’s pain
- Pick the analgesic based on the pain that is being reported
What are the 5 Guiding Principles Pain Management of Analgesics?
- ‘By Mouth’: Oral forms preferred where possible
- ‘By the Clock’: Given at regular intervals rather than on demand
- ‘By the Ladder’: Adhere to principles of ladder
- ‘For the Individual’: Individualise therapy based on the level of the patient’s reported pain
- ‘Attention to Detail’: Monitor patient’s pain closely
What is Chronic Pain?
- Pain which has been present daily for 3 months
- Persists after healing is complete or due to chronic disease
Chronic pain may be precipitated by:
- Acute pain following surgery or injury
- Acute pain associated with illnesses such as HIV, herpes zoster
- Stroke resulting in central post-stroke pain syndromes
- Spinal cord injury resulting in radicular ‘at level’ pain, distal neuropathic pain and various musculoskeletal pain syndromes
- Therapy with antineoplastic drugs
What are the Risk Factors for Transition from Acute to Chronic Pain?
- Disease that doesn’t abate
- Significance of the pain
- Inadequate pain relief
- Neuropathic nature of pain
- Patient factors (poor understanding of cause of pain and uncertainty about its significant)
- Inappropriate non-drug treatment (e.g. prolonged immobility)
What are the General Principles for Managing Chronic Pain?
- Perform a comprehensive clinical assessment
- Focus on appropriate combinations of physical, psychological and pharmacological therapies
- Consider non-pharmacological therapies first if no need for immediate drug therapy
- Consider drug therapy if non-pharmacological therapies are unsuccessful or inappropriate
- If drug therapy is used, give each drug in an appropriate dose for required effects before adding other drugs
- Regularly review patients to check their pain control, function and quality of life and their need for ongoing or change of therapy
- Provide long-term support
What are Pharmacological Management Strategies for Chronic Pain?
- If drug therapy is used, give each drug in an appropriate dose for required effects before adding other drugs
- Use regular medications and minimise PRNs (unlike cancer pain where we ‘maximise prns’)
- Avoid parenteral routes
- Avoid pethidine, benzodiazepines and long-term NSAIDs
- Optimise adjuvant/non-opioid analgesics
What are Non-Pharmacological Modalities?
- Physical techniques
- Mind-body techniques
- Mind-based techniques
- Use of aids/orthotics and OT
- Social/environmental interventions
- Combination of any or all of the above
In chronic pain, what should be taken into consideration before starting opioids?
- Explore all other treatment options, both physical and psychological
- Discuss the adverse effects and possible harms and benefits of long-term opioid therapy
- Obtain acceptance from patient about the expected outcome of therapy
- Explain that the opioid is being used as a trial and treatment will cease if there hasn’t been significant progress towards achieving treatment goals over 4 weeks
- Assess the potential for opioid abuse or misuse
- Obtain agreement about monitoring, treatment adherence and the consequences of non-adherence
When changing from one opioid to another opioid, what should be taken into consideration?
- Always consider the dose potency (in relation to oral morphine) before swapping opioids
- When changing from one opioid to another, commence with 50%-75% of the calculated ‘equianalgesic’ dose and then titrate to response
What is Neuropathic Pain?
- Dysfunction or damage to the nerves, spinal cord or brain
- Constant burning, episodic shooting or electric pain in a region where there’s a disturbance of sensory and/or motor function, particularly to pinprick and thermal (warm and cold) sensibility
What are the 3 types of Neuropathic Pain?
- Hyperalgesia: increased responsiveness to normally painful stimuli
- Allodynia: painful response to normally non-painful stimuli
- Hyperpathia: abnormally painful reaction to a repetitive stimulus
What is considered an appropriate positive clinically relevant end point in neuropathic pain?
- 50% reduction in the level of pain is considered an appropriate positive clinically relevant end point, although 30% is sometimes accepted
If patient isn’t making progress in neuropathic pain, what referral should be made?
- If patient isn’t making progress, referral to a multidisciplinary pain management clinic may become necessary
Neuropathic Pain is usually refractory to what?
- Usually refractory to simple analgesics including paracetamol, NSAIDs and opioids
What is Trigeminal Neuralgia?
What is it treated with?
- Painful condition affecting nerves on the face
- Pain one side of the face, can be like an electric shock
- Treated with carbamazepine
What is Acute Herpes Zoster Pain?
How is it treated?
- Reactivation of varicella zoster virus
- Virus lies dormant in the DRG but causes an inflammatory response when reactivated
- Treatment
- If the rash has been present < 72 hrs, antiviral treatment reduces acute pain, duration of the rash, viral shedding and ophthalmic complications
- Valaciclovir, Famciclovir, Aciclovir
- Pain may occur before, with or following rash
- Pain persisting > 4 weeks after crusting of vesicles is considered Post Herpetic Neuralgia (PHN)
- Mild Pain – Paracetamol
- Severe Pain – Add Prednisolone to antiviral
- Alternatives for severe pain: TCA or opioid
- Topical: lignocaine ointment or lignocaine + prilocaine cream
- Advise patients not to apply on broken skin
- If the rash has been present < 72 hrs, antiviral treatment reduces acute pain, duration of the rash, viral shedding and ophthalmic complications
What is the Treatment of Post Herpetic Neuralgia?
- Start with simple analgesics: paracetamol (or ice massage)
- If simple analgesia inadequate: consider adjuvant analgesics: TCA, gabapentin or pregabalin
What are the General management principles of cancer pain?
- Follow WHO step-ladder approach
AND/OR
- Pick the analgesic based on the pain that’s being reported e.g. nociceptive or neuropathic or other
What is the Therapeutic Strategy in Cancer Pain?
- Analgesia should include:
- Background/preventative component
- Take regularly, irrespective of pain status
- Breakthrough/as needed component
- To be taken when pain ‘breaks through’ background analgesia
- Background/preventative component
How is Neuropathic Pain in cancer treated?
- Gabapentin has the best evidence
- Other AEDs, tramadol and TCAs also used
- Opioids usually use in combination with the medications used above
How is Breakthrough Pain Treated?
- Initially 1/6 to 1/10 of the background analgesia
- Ideally analgesics will have fast onset and short duration
- Give as needed with no strict minimum between doses
Breakthrough Pain Treatment: What are the Options?
- Morphine elixir/IR tablets, oxycodone IR tablets/elixir
- Onset in 30 mins and duration 4-6 hrs
- Transmucosal fentanyl, intranasal opioids and sub-cutaneous injections
Discuss Constipation due to Opioid use
- Dose related, tolerance doesn’t develop
- Prophylactic use in all patients
- 1st line treatment: docusate and senna
- Additional options include:
- Additional docusate
- Lactulose/Sorbitol
- Movicol
- Benefibre
- Suppositories/enemas
- Additional options include:
When should IR preparations be used?
- IR preparations: Breakthrough pain, works within 30 mins, take when pain starts
- Take prn medications as soon as they are required – pain better controlled
When should SR preparations be used?
Background pain, take on regular basis
What should you make patients aware of when starting opioids?
- May notice sedation, ‘fuzzy’/difficulty thinking or nausea
- Tends to be transient (7-10days)
- Caution with machinery driving
Discuss Changing between opioids/routes in Cancer Pain and Chronic Pain
- Cancer pain: change to 50-100% of equianalgesic dose
- Chronic pain: change to 50-75% of equianalgesic dose
