Pain Flashcards
Definition of pain?
an unpleasant sensory or emotional experience associated with actual or potential tissue damage, or described in terms of such damage
What factors influence the perception of pain?
- psychological factors including previous experiences
- pre-existing pain (acute or chronic)
Which aspect of pain must the pharmacist respond to?
The patients perception of the pain
What are the three tpyes of pain?
- Nociceptive
- No apparent cause
- Neuropathic
What are the types of nociceptive pain? Types of neuropathic pain?
Acute and chronic
What are the types of acute nociceptive pain?
Immediate and delayed response
Difference between acute and chronic pain?
acute:
- usually obvious tissue damage
- pain resolves on healing
- serves a protective funciton
Chronic:
- 3-6 months +
- goes beyond expected period of healing
- no protective function
- degrates health and function
What can chronic pain be a result of?
Dysfunctional activation of pain pathways
How is acute pain protective?
Causes patient to seek medical help. Also reduce mobility so that the damage can heal
Importance of pain management to pharmacists?
OTC analegesics should no longer be prescribed
Around 35% of pharmacists speak to pain patients 2-5 times a day
Results suggest patients are given inconsistent advice about OTC analgesics
Examples of acute pain in community pharmacy?
Minor ailments
- Backache, earache, sprains and strains, headache
OTC
- menstrual pain, migraine, post procedural pain
Why is post procedural pain more common for community pharmacists to manage?
Patients being discharged on day case far more frequently
Which acronym should you use when asking about pain?
SOCRATES
Site
Onset - when, how quickly
Character - aching, stinging,stabbing, burning etc
Radiation
Associations - any other symptoms e.g. nausea, sweating
Time course - specific pattern throughout the day?
Exacerbating/relieving factors
Severity
What patient factors must be taken into consideration before treatment for acute pain is decided on?
Co-moribities and medications
- esp anything already tried by the patient for the pain
Balance between patient’s subjective pain analysis and other factors?
Since pain is a perception, must believe the patient on how they feel it. Balance with other monitoring parameters and clinical signs of pain level
High tech method of regional pain relief?
Epidural infusion - local anaesthetic with or without opioid
Low tech method of regional pain relief?
Nerve block - local anaesthetic with or without opioid
Steps of the stepwise strategy for mild-moderate pain?
- Paracetamol
- Sub paracetamol for ibuprofen
- Paracetamol + ibuprofen
- Substitute ibuprofen for stronger NSAID (naproxen usually). keep paracetamol
- weak opioid + paracetamol and/or NSAID
Important considerations for treating mild-moderate pain?
Treat underlying cause when possible
Use full therapeutic doses before switching agent
Use weak opioid at step 2 if C/I to NSAID
Consider PPI cover for NSAIDs
Avoid combination drugs as first line (they are useful for stabilised
Why avoid combined analgesics in acute pain?
Harder to change doses and step up/down. Can leave shorter periods between dosing
Analgesia choice in children for acute pain? (>3 months)
Paracetamol or ibuprofen alone first line
If no response - check adherence and dosing
Then switch
Red flags associated with arthritis pain that may usually be managed in the community?
- Deformity associated with pain
- Too painful to move / cannot bear weight;
- Severe swelling, discolouration, hot to the touch or bleeding;
- Persistent joint pain, tenderness or swelling;
- Prolonged or severe morning stiffness (more than 30 minutes duration);
- Feeling unwell or presence of fever;
- Tingling or numbness
Examples of acute pain in secondary care?
Trauma/burns Myocardial Infarction Kidney Stones Childbirth Post-operative pain Sickle cell crisis
What is importanct to determine when someone presents with back pain?
Neuropathic or nociceptive
Warning signs when a patient presents with back pain?
recent trauma or injury, pain down legs and below knees, loss of bladder/bowel control, weight loss
How is back pain treated?
According to the pain ladder. Short course of benxos may be used if spasms are present
patient must be advised that laying down for long periods will make it worse
How much paracetamol to give to a 3-6 month old?
2.5mL infant suspension
How much paracetamol to give to a 6-24 month old?
5mL infant suspension
How much paracetamol to give to a 2-4 year old?
7.5mL infant suspension
How much paracetamol to give to a 4-6 year old?
10mL infant suspension
How much paracetamol to give to a 6-8 year old?
5mL six plus suspension
How much paracetamol to give to a 8-10 year old?
7.5mL six plus suspension
How much paracetamol to give to a 10-12 year old?
10mL six plus suspension
Max daily doses of paracetamol by weight?
> 50kg: 4g
41-49kg: 3g
<41kg: 2g
First line NSAID therapy for acute pain?
Ibuprofen 400mg tds
Second line NSAID therapy for acute pain?
Naproxen 250-500mg twice daily
Available OTC but only for menstrual pain
(second line regional pain relief consider topical NSAID)
When to consider a topical NSAID for acute pain?
For single regional pain relief (especially wrists, hands, knees, elbows, or feet)
Cautions/contraindications for NSAIDs?
Elderly – renal function/co-morbidities
Asthmatics, previous GI ulcer and/or bleed, renal impairment (incl AKI), cardiovascular disease (CI in failure)
What must be considered for long term NSAID therapy?
Gastric protection
What NSAID type drug can be used in very severe acute pain?
Paracoxib (COX-2 inhibitor) I.V.
- good for after surgery when patients NBM, only injectible coxib
What is important about the WHO stepwise ladder for severe pain? Why?
Start at the top and work down
When patients are in severe pain working up the ladder takes too long and leaves them very uncomfortable until sufficient pain relief is found
Step 1 of the WHO stepwise ladder for pain?
For mild pain
No opioid
with/without simple analgesic
Step 2 of the WHO stepwise ladder for pain?
For moderate pain
Opioid for mild to moderate pain
plus non-opioid
with/without adjuvant analgesic
Step 3 of the WHO stepwise ladder for pain?
For severe pain
Opioid for moderate to severe pain
plus non-opioid
with/without adjuvant analgesic
What are the commonly used opioids for acute pain and their forms?
Codeine (oral or iv) , tramadol (oral, iv, im), morphine (oral, pr, iv, im), oxycodone (oral, iv), fentanyl (iv, buccal, sublingual, nasal)
Oral morphine equivalent of 60mg oral codeine?
3-9mg (divide by 10ish)
Oral morphine equivalent of 100mg oral tramadol?
10mg (divide by 10)
Oral morphine equivalent of 10mg iv morphine?
20mg (x2)
Oral morphine equivalent of 100mcg iv fentanyl?
10mg (x100)
Which opioid is especially good for children in severe pain and why?
Fentanyl - lozenges/sublingual available so easy to give without need for tablets or needles
Three main principles for using opioids safely?
- carefully titrate the dose against the desired effect
- check previous exposure to opioids (higher tolerance)
- consider patient age, size, renal function, co-morbidities etc
What needs to be monitored carefully in patients given opioids for acute pain?
drowsiness, respiratory depression - as long as these aren’t occurring can step up pain relief further if required
How do acute pain protocols differ from regular dosing info?
Allow smaller amounts of opioid to be given at shorter intervals to sustain pain relief. can start with a small dose then add in more after an hour etc if needed
What is a PCA?
Patient controlled anaethesia
Patient delivers a small IV bolus at button press
usually morphine, fentanyl or oxycodone (f & o safer in renal impairment)
Benefits of a PCA?
- has lockout period so patient cannot overdose themselves
- allows a dose of analgesia that is sufficient but also not too much, just as required
- higher patient satisfaction as don’t need to wait for someone to give pain relief
- can monitor amount of pain relief used over time period
Important for HCPs to know about PCAs?
- if dexterity/understanding is an issue, PCA not suitable
- only the patient should press the pump, not nurses or relatives
How does PCA use reduce risk of sedation and respiratory depression?
as soon as the patient gets drowsy from the opioid, they sleep a bit and stop pressing the pump until concentrations fall and they wear off
Place of simple analegsics and NSAIDs in severe pain management?
Can reduce amount of opioid needed so safer for patient
How to step down from PCA?
- Usually onto oral opioid such as morphine or oxycodone (or weak opioid if use has been low)
- Starting dose needs to take into consideration previous PCA use over the last 24 hours
e. g. 30mg IV PCA Morphine – convert to 60mg oral Morphine in divided doses - Dose may still need to be titrated to effect – prescribed as required and continue to monitor and score pain.
- Adjuncts should be also used where appropriate (opioid sparing effects)
Uses of epidural anaesthesia?
CHildbirth, infusion after major surgery
What is epidural anaesthesia?
Form of regional anaesthesia with drugs delivered via a catheter directly into the epidural space:
Use a combination of local anaesthetic and strong opioid (typically levobupivicaine 0.125% with fentanyl 2mcg/ml)
Infusion rate dependant on position of epidural, pain score balanced with clinical observations.
Patients able to mobilise with infusion in-situ post operatively
Monitoring requirements for epidural patients?
Itching Nausea and vomiting Drowsiness Respiratory depression Urinary retention Hypotension Bradycardia Headache (dural puncture) Motor Block - Essam (arms) and Bromage (lower limb) scores
Don’t want to block any motor nerves so any tingling/loss of sensation or function/changes in bladder and bowel function are dangerous
What others types of pain relief can be used for severe acute pain?
- Local Anaesthetic Infusions – acute post-op pain or trauma
- Transversus Abdominis Plane (TAP) block- newer technique in abdominal surgery
- Ketamine infusions - difficult pain cases. Carefully controlled and monitored as hypnotic and amnesic (good for trauma)
- Entonox (Nitrous oxide “Gas and Air”) – childbirth, wound dressings, joint manipulations
Things to consider when advising on analgesia?
What should you consider when advising on analgesia? Type and severity of pain Efficacy of agents for type of pain Route available and mode of delivery - Enteral (oral, rectal, feeding tubes) - Topical (but not patches) - I.V. incl P.C.A. - subcutaneous - Epidural or spinal
Contra-indications (Incl: allergy status)
Co-morbidities
Other medication
Which patients are more difficult to manage pain well?
babies and children, elderly respiratory disease renal failure head injury addiction acute pain on top of chronic
Role of the pharmacist in acute pain management?
choice of agent, interactions, route, dosage, side effects, patient counselling, communication with MDT
Stage 1 of anaesthesia?
- induction/analgesia
- reduced response to pain
- conscious but drowsy
- varies with the agent (ether>halothane)
Stage 2 of anaesthesia?
- !important to limit this as dangerous
- choking, gagging, vomiting, moving
- excitement
- loss of response to non-painful stimuli
- gag reflex and coughing increased
- response to pain preserved
Stage 3 of anaesthesia?
- the desired phase for surgery
- progressive shallowing of breathing
- regular respiration
- possibly some reflexes and muscle tone preserved
- movement ceases
Stage 4 of anaesthesia?
Death
- overdose
- medullary paralysis
- respiration and vasomotor control ceases
Pharmacokinetics desired for general anaesthesia?
- we would like rapid induction and rapid recovery
- avoid stage 2 and 4
- avoid side effects
What combinations of drugs are used for anaesthesia?
analgesics, muscle relaxants, axiolytics, different anaesthetics
these make the stages of anaesthesia less apparent
Components of modern general anaesthesia?
- rapid induction of unconsciousness e.g. iv propofol
- maintenance of unconsciousness and production of aneasthesia e.g. inhales N20 / halothane
- supplementary analgesic e.g. iv morphine
- neuromuscular blocker e.g. atracurium
4 types of anaesthetics?
inhalational, intravenous, neurolept, dissociative
Advantages of inhaled anaesthetics?
- easy to maintain degree of anaesthesia (fast air:blood equilibrium)
- rapid emergence
Disadvantages of inhaled anaesthetics?
- cumbersome and expensive apparatus
- administered via a mask- psychological effects
- atmospheric pollution
Toxicity of inhaled anaesthetics?
toxic metabolites
- fluranes generate fluoride which is renally toxic
- Halothane converted to bromide and trifluoroacetic acid, hepatotoxic
- metabolism is unimportant for elimination as exhaled, but metabolites aren’t good
What is MAC in anaesthetics?
Minimum alveolar concentration - concentration required to produce anaesthesia in 50% of patients
measure of potency of the anaesthetic
What is the blood-gas partition coefficient
- A measure of how well the drug dissolves in blood
- Determines rate of induction and recovery
the lower the more potent
What is the oil-gas partition coeffient and what is the significance of a high value clinically?
A measure of how well the drug dissolves in fat
- high value means high potency
- distributed in fat which is poorly vascularised so leaves body much slower - hangover effect (worst in fat patients)
Most common inhaled anaesthetics?
N2O and isoflurane
desflurane and sevoflurane becoming more popular (cheap)
Place of ether in anaesthetic use?
Explosive, causes nausea but cheap so still used in third world countries (not listed in BNF)
General points about isoflurane?
- widely used but being replaced
- no metabolism, little toxicity, not proconvulsive
- hypotension as decreases vascular resistance
- ## coronary vasodilator
General points about sevoflurane?
- ‘anaesthetic of choice’
- very rapid induction
- v expensive
- some concerns regarding neurodegeneration
- recovery so rapid that post op pain relief is needed
General points about N2O?
- nitrous oxide, entenox
- Low blood gas partition coefficient
- analgesic effect at concentrations lower than those that cause unconsciousness
