analgesia in oral surgery Flashcards
pain control
post op pain Vs during operative procedure
In dental practice pain control is an important aspect of pt management
- During
- After/post-op
Local anaesthetics are used everyday to control pain, BUT we also need to consider the use of systemic analgesic drugs to control post-operative pain
5 analgesia considerations
- ‘think’ postoperative analgesia
- Start systemic analgesics before the LA wears off – tell the pt to start 4 hours after if LA wears of 6 hours after
- ‘sell’ the prescription to obtain optimal response
- Use LA more
- Watch for risk groups
6 analgesia in dental practitioners formularly
- Aspirin (NSAID)
- Ibuprofen (NSAID)
- Diclofenac (NSAID)
- Paracetamol
- Dihydrocodeine (opioid)
- Carbamazepine
key facts of analgesia to know (5 topics)
- Mechanism of action
- Doses
- Side effects
- Interaction
- Groups pt to avoid
aspirin
use
- In the past aspirin was one of the more commonly used NSAIDs
- Effective for dental and TMJ pain
- Superior anti-inflammatory properties to paracetamol
- Less commonly used in dentistry now (iburprofen more)
- Can be bought over the counter as well as prescribed
Blood thinning uses
aspirin a.k.a
Acetylsalicylic Acid
5 properties of aspirin
- Analgesic
- Antipyretic
- Anti-inflammatory
- Anti-platelet
- metabolic
what is the common reason why pts are on aspirin
antiplatelet
- low dose 75mg (prevent strokes, heart attacks in past) on long term
- common in elderly pt
pain
Unpleasant sensation conveyed to the brain by sensory neurons, the discomfort signals actual or potential injury to the body
pain causes
production of prostaglandins
- trauma and infection lead to the breakdown of membrane phospholipids producing arachidonic acid
- arachidonic acid can be broken down to form prostaglandins
- prostaglandins sensitise the tissues to other inflammatory products which results in pain
how do drugs moderate pain
Prostaglandins do not cause pain directly BUT they sensitise the tissues to other inflammatory products such as leukotrienes
- so if prostaglandin production decreases this will moderate the pain
- How drugs work – minimise prostaglandin*
sequence of trauma to prostaglandin production (pain)
aspirin mechanism of action
- aspirin reduces production of prostaglandins
- it inhibits cyclo-oxygenases (COX-1 & 2)
- more effective at inhibiting COX-1
- COX-1 inhibition reduces platelet aggregation and predisposes to damage of the gastric mucosa
- Gastric mucosa – watch pt groups to avoid
can you develop a tolerance or dependence to aspirin
no
analgesic properties of aspirin
- Good for mild to moderate pain
- Mainly a peripherally acting agent
- Analgesic action of NSAIDs is exerted both peripherally and centrally
- Peripheral action predominate
- The analgesic action results from inhibition of prostaglandin synthesis in inflamed tissues (Cylclo-oxygenase inhibition)
- Analgesic action of NSAIDs is exerted both peripherally and centrally
antipyretic properties of aspirin
- Aspirin prevents the temperatures raising effects of interleukin-1 and the rise in brain prostaglandin levels
- So reduces elevated temperature in fever
Doesn’t reduce normal temperature
anti-inflammatory properties of aspirin
- Prostaglandins are vasodilators and as such also affect capillary permeability
- Aspirin is a good anti-inflammatory and will reduce redness and swelling as well as pain at site of the injury
metabolic effects of aspirin (4)
- Increase
- BMR
- Platelets
- Prothrombin
- Decrease
- Blood sugar
problems with aspirin use
- Adverse/side effects
- Groups to avoid
- Caution when prescribing
Not tend to prescribe for analgesia now
4 main adverse affects of aspirin
- GIT problems
- Hypersensitivity
- Overdose
- Aspirin burns
GIT problems associated with aspirin
- Mostly on mucosal lining of stomach
- Prostaglandins (PGE2 and PGI2)
- Inhibit gastric acid secretion
- Increase blood flow through the gastric mucosa
- Help production of mucin by cells in stomach lining (cytoprotective action)
- Care must be taken in patients with GIT problems
- Ulcers
- Gastro-oesophageal reflux
- Most pts taking aspirin will suffer some blood loss from GIT
- Not detectable macroscopically and asymptomatic
- Not effect day to day life – blood loss
- Not detectable macroscopically and asymptomatic
hypersensitivity problems with aspirin use
- Reactions include
- Acute bronchospasm/asthma type attacks
- Minor skin rashes
- Other allergies
- NSAID allergy inc aspirin
overdose of aspirin affects
- Hyperventilation
- Tinnitus, deafness
- Vasodilation and sweating
- Metabolic acidosis (can be life threatening)
- Coma (uncommon)
mucosal burns due to aspirin use
- Direct effect of salicylic acid
- Aspirin applied locally to oral mucosa results in chemical burns
- Aspirin has no topical effect
- Ensure aspirin is taken with water
- Can be large and significant
groups of people to have caution/avoid giving aspirin
- Peptic ulceration
- Epigastric pain
- Bleeding abnormalities
- Anticoagulants
- Pregnancy/breast feeding
- Patients on steroids
- Renal/hepatic impairment
- Children and adolescents under 16 years
- Asthma
- Hypersensitivity to other NSAIDs
- Aspirin is an NSAID
- Taking other NSAIDs
- Elderly
- Generally careful in elderly with all medications
- G6PD-deficiency
why avoid aspirin if
peptic ulceration
gastric or duodenal bleeding could result in perforations
why avoid aspirin if
epigastric pain
history of epigastric pain/discomfort or gastro-oesphageal reflux but no ulcer diagnosed
why avoid aspirin if
bleeding abnormalities
have known bleeding problems e.g. haemophilia
- high risk of bleeding - don’t want to exacerbate
why avoid aspirin if
anticoagulant medication
- Aspirin enhances warfarin and other coumarin anticoagulants
- Displaces warfarin from binding sites on plasma proteins
- Increases free warfarin
- The majority of warfarin is bound (inactive), if more is released this will become active increasing bleeding tendency
why avoid aspirin if
pregnant/lactation
- Especially 3rd trimester
- This is nearer delivery and may cause impairment of platelet function (Aspirin has antiplatelet property)
- Increased risk of haemorrhage
- Increased risk of jaundice in baby
- Can prolong/delay labour (unsure why)
- This is nearer delivery and may cause impairment of platelet function (Aspirin has antiplatelet property)
- Contraindicated in breastfeeding -> Reye’s syndrome
why avoid aspirin if
renal/hepatic impairment
- Aspirin metabolism is in liver and excretion mainly in kidney
- If renal impairment = excretion may be reduced/delayed
- Not a complete contraindication but administer with care/reduce dose and avoid if renal or hepatic impairment severe
Always caution renal and hepatic – most Mx metabolised in liver and excreted by kidney – like aspirin
nephrotoxicity and NSAID use
Prostaglandins PGE2 and PGI2 are powerful vasodilators synthesised in the renal medulla and glomeruli respectively,
- are involved in the control of renal blood flow and excretion of salt and water
inhibition of renal prostaglandin synthesis may result in:
- sodium retention
- reduced renal blood flow
- renal failure
NSAID may cause interstitial nephritis and hyperkalaemia
- Prolonged analgesic abuse over a period of years is associated with papillary necrosis and chronic renal failure
- Severe derangement of pt urea and electrolytes
inhibition of renal prostaglandin synthesis may result in (3)
- sodium retention
- reduced renal blood flow
- renal failure
why avoid aspirin in
children and adolescents under 16 years (inc breastfeeding)
Reye’s syndrome
- Rare
- Under 20s affected mainly
- Very serious, up to 50% mortality
- Related to brain damage due to encephalopathy
- Fatty degenerative process in liver (and lesser extent kidney)
- Profound swelling in brain
- Clinically
- Initially nausea, vomiting, lethargy
- Later seizures and coma
Contraindicated if under 16 years or breastfeeding
Avoid during fever or viral infection in adolescents
why avoid aspirin in
asthma pts
- NSAID not completely contraindicated as some asthmatics have no problems with them
- ask if used before and if any problems
- any shadow of doubt avoid NSAIDs
- ask if used before and if any problems
why avoid aspirin in
hypersensitivity to NSAIDs
- contraindicated in pts with a history of hypersensitivity to Aspirin or any other NSAIDs
- this includes those in whom attacks of asthma, angioedema, urticaria or rhinitis have been precipitated by aspirin or any other NSAID
why avoid aspirin
if taking other NSAIDs
- combination of NSAIDs will increase risk of side effects
- e.g. the combination of an NSAID and low dose aspirin may increase the risk of GIT side effects; and should be used if absolutely necessary and the pt monitored closely
why avoid aspirin in
elderly
- more susceptible to drug induced side effects in general
- they are often smaller/smaller circulating blood volume
- on other medications
- Higher risk interactions when polypharmacy
- Have other medical problems
G6PD - deficiency
glucose 6-phosphate dehydrogenase deficiency
Rare
Prevalent In individuals from:
- Most parts Africa,
- Most parts Asia
- Oceania
- Southern Europe
Inborn error of metabolism, predisposes RBC breaking down
why avoid aspirin in
G6PD-deficiency
Inborn error of metabolism, predisposes RBC breaking down
Susceptible to develop acute haemolytic anaemia on taking a number of common drugs
- Aspirin – possible risk of haemolysis in some G6PD-deficient individuals (acceptable up to a dose of at least 1g daily in most G6pD-deficient individuals)
absolute contraindication groups for aspirin use (4)
- Children and adolescents under 16 years; breast feeding (Reye’s syndrome)
- Previous or active peptic ulceration
- Haemophilia
- Hypersensitivity to aspirin or any other NSAID
thrombotic prophylaxis
- Thrombotic cerebrovascular/cardiovascular disease (HA, stroke)
- A single dose of aspirin (150-)300mg given as soon as possible after ischaemic event, provided no contraindications
- Maintenance treatment: 75mg daily
how to prevent aspirin damage to gastric lining
prescribe with PPI to protect (lansoprazole capsules, 15mg; gastro-resistant omeprazole capsules, 20mg)
- 5 day regime usually
iburpofen
use
Used more commonly than aspirin in dentistry
- Long term use recently associated with increased risk of cardiac events
NSAID
Available over the counter
Popular as post-operative analgesia following oral suragery
Paediatric suspension available
- Safely given to children
ibuprofen Vs aspirin
Similar but not identical effect as aspirin
Less effect on platelets
Not used therapeutically for this - Not used for MI or stroke
Irritant to gastric mucous – but lower risk than aspirin
May cause bronchospasm (care in asthmatics but not completely contraindicated)