Pain and management Flashcards by Sara assadi

why is morphine not recommended in those with pancreatitis?

causes sphincter of oddi to contract which can actually increase pressure and thus pain.

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what is entanox and when should it be avoided?

oxygen and nitrous oxide

avoided in pneumothorax.

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what is pain?

An unpleasant sensory and emotional experience associated with actual or potential tissue damage. can be acute or chronic

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Explain the difference between acute and chronic pain.

acute pain: has rapid onset, limited duration <3 months, identifiable cause

chronic pain: lasts beyond healing time >3 months, no identifiable cause.

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outline the physiology behind pain?

nociceptors at tissue surfaces that can detect damage
This results in activation of Ad (sharp) and C fibres (dull pain) to the spinal cord and up to the brain.

within the spinal cord there is an area called the substantia gelatinosa which allows descending inhibitory neurons to modify the amount of transmission of ascending pain fibres.

Thus pain is influenced by descending inputs (emotion)

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what scoring systems can be used for pain?

APACHE II: score from 0-71 based on age, health and many other factors

ask patient to score 1-10
ask patient to describe pain

in children harder so may have to score based on HR, Resp rate, facial expression, skin colour and crying

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what are the non-pharamacological ways of controlling pain?

hypnosis, music, exercise, CBT, mediation
anything changing emotion - e.g. increase socialisation

fix the original problem e.g. gastritis - give omeprazole

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Describe the WHO analgesic ladder

non-opiods: NSAIDs, paracetamol, aspirin
weak opioids: codeine, tramadol
strong opioids: morphine, fentanyl and pethidine

can also used adjuvants such as ketamine, Entonox and midazolam

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how does the management of acute and chronic pain differ with regards to the WHO analgesic ladder?

acute: start high and reduce (come down ladder)
chronic: start at bottom and work way up.

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why is it important to manage pain?

pain increases sympathetic NS and leads to vasoconstriction which reduces tissue perfusion and healing.

also reduces mobilisation and thus increases likelihood of VTE and pneumonia

also reduces depth of breathing and coughing - therefore more likely to get pneumonia/ atelectasis

reduces muscle wasting from lack of movement
reduces risk of chronic pain developing

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what are the adverse effects of pain?

tachycardia, increased BP and increased myocardial demand for O2
Increased resp rate but reduced tidal volume,
N&V, ileus

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name 3 NSAIDs

Ibuprofen
Diclofenac
naproxen

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what are the indications of NSAIDs?

what additional indications does aspirin have?

anti-inflammatory
analgesia
anti-pyrexial

good for MSK pain

Aspirin:

thromboprophylaxis
prevention of DVT, Stroke, MI, pre-eclampsia

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How do NSAIDs work?

inhibition of COX enzymes
reduces production of prostaglandins which are involved in pain (activate nociceptors)
also prostaglandins in brain cause pyrexia.

NSAIDS reversible inhibit COX enzymes

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how does aspirin work?

irreversibly inhibit COX enzyme

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what are the contraindications to NSAIDs/ asprin?

contraindications in renal impairment, gastric ulceration, asthma (bronchoconstriction), allergies, coagulation defects

aspirin should not be given to people with Gout - can precipitate it.

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what are the ADRs of asprin/ NSAIDs?

gastric ulceration
bronchoconstriction 
bleeding 
skin reactions
drop in GFR

aspirin can precipitate gout

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what serious complication is aspirin associated with in children/

reyes syndrome (swelling of liver and brain) 
can occur in children who are treated with aspirin for a viral infection.

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what are the indications of paracetamol?

analgesia

anti-pyretic

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what are the side effects of paracetamol?

very minimal

but can be hepatotoxic in overdose

when should the dose of paracetamol be reduced?

in those <50kg

hepatic impairment or alcoholics

what dose of paracetamol is safe?

1g every 4 hours

max 4g/day

describe the biochemistry behind paracetamol overdose?

paracetamol is normally conjugated with glucuronide in phase 2 metabolism
however a small % undergoes phase 1 metabolism to produce NAPQI which is toxic

in overdose phase 2 metabolism becomes saturated and more NAPQI is produced.

how is paracetamol overdose managed?

if within 4 hours: activated charcoal orally

otherwise 0-36 hours: IV N-acetylcysteine
OR methionine by mouth (if no IV access)

how is codeine given? what do we need to be aware about its metabolism?

orally | variable - some people cant metabolise it, some people more so.

what is the action of tramadol?

opioid receptor agonist | but also inhibits NA and 5HT3 reuptake inhibitor - so improves emotional state and hence pain from another aspect

what are the problems with using tramadol?

ADR like other opiods + lowers seizure threshold - so not good in epilepsy - can also interfere with SSRIs - may lead to serotonin syndrome

when is fentanyl used?

often used as a patch in chronic pain - it is a longer lasting analgesic can also be used as spinal/epidural anaesthesia

what is used to treat opioid overdose?

naloxone - | opioid receptor antagonist

when are opioids contraindicated?

acute resp depression at risk of paralytic ileus head injury be aware in those with dementia as can worsen confusion (but so can pain)

how do opioids work?

bind to endogenous opioid receptors result in hyperpolarisation of cells to reduce excitability and pain transmission inhibit release of substance P within spinal cord

What are the general ADRs of opioids?

``` respiratory depression constipation - so should be accompanied with laxative if using >3days N&V Miosis euphoria confusion ```

how long can a fentanyl patch last and what are the benefits of this delivery? how often do you change buprenorphine patches?

72 hours less issues with compliance absorbed directly into blood, no first pass effect buprenorphine -change every 7 days

why should codeine not be given to children?

unpredictable metabolism and because only small could overdose

what is oromorph?

liquid morphine

what should you do If there is an opioid allergy?

ensure it is an allergy and not sensitivity/ side effect e.g. N&V is a side effect and can be managed with anti-emetic sensitivities can be managed by lowering opioid dose and giving anti-histamine/emetic if allergy then use local and regional anaesthetic techniques instead, paracetamol/NSAIDS, entanox

what is a peripheral nerve block?

local anaesthetic is injected around a peripheral nerve. done using ultrasound and electrical current to ensure it is injected into the right place

what is patient controlled analgesia? what is the advantage of this?

this is an IV pump whereby a bolus of analgesic agent is given when patient presses the button. Advantage of this is that analgesia is tailored to patients needs. safe- risk of overdose is minimal can measure how much is given minimises time patient is in pain - quick feedback

what should be monitored if a patient is on PCA?

``` infusion should be checked hourly resp rate level of pain sedation heart rate vomiting document all of these ```

when is PCA not appropriate?

low GCS | poor manual dexterity

how is spinal analgesia administered?

inject below level of L1 to avoid spinal cord | inject around spinal nerves i.e. past the arachnoid membrane and into the dural space

what drugs can be used in a spinal/epidural analgesia?

levobupivacaine and can add fentanyl

how is an epidural prepared?

A catheter is first inserted into the correct place - between 2 vertebrae and then through ligamentum flavum and stop just before arachnoid layer i.e into epidural space

what observations should be made before and throughout an epidural?

resp rate, HR, BP sedation score, pain score, vomit score temperature, pulse oximetry every hour also check sensory and motor functions to ensure it has worked.

at what level should an epidural be administed for abdominal surgery ? for labour?

abdominal: thoracic level - T6/7 lumbar level for labour - L1/2

List some side effects of an epidural | and how can each be solved?

``` hypotension - due to sympathetic nerve block - solved by fluids and IV phenylephrine epidural abscess/ haematoma - treat asap to avoid neuro problems standard opioid side effects itching nose - anti-histamine infection urine retention - catheter nerve damage - recovers in a few months paralysis - very rare ```

how is bone pain treated?

bisphosphonates

how is pain from muscle spasms treated?

diazepam

give the 4 steps for managing nerve pain.

step 1 = TCA - amitriptyline step 2 = anticonvulsants - gabapentin step 3 = ketamine step 4 = spinal analgesia