Acute pain. Flashcards
What is nociceptive pain?
response to injury or pathology.
Are we best using one, or a number of drugs to manage acute main?
multi-modal of low does drugs from different categories is best.
What is an analgesic corridor?
Blood levels of drugs should be maintained within this.
When taking a pain history, apart from socrates what should we ask patients about?
impact on function, sleeping and eating.
effectiveness of analgesia
previous/current therapy.
Where do high pain patients e.g. post op start on the pain ladder?
At the top and work their way back.
What are rules for prescribing to pain in renal failure?
Best to avoid NSAIDS.
Some drugs have minimal active metabolites e.g paracetamol or fentanyl so wont accumulate.
Most other analgesics can be used but dosage needs to be reduced to allow for decreased clearance.
What are the two key issues we need to think about when prescribing pain meds to people with renal failure?
Further damage to renal function
Accumulation of active metabolites
What should we think when prescribing in vomiting?
probably not oral route.
How does paracetamol work?
Inhibits prostaglandin synthesis in the CNS
What prescribing factors must we remember with paracetamol?
Remember to reduce dose if weight <50kg
What do NSAIDs do?
inhibit the enzyme cyclo-oxygenase [cox]
What are the contraindications for NSAIDs?
Gastrointestinal bleeding [old or new] or active peptic ulceration
Coagulopathy
Renal impairment
Aspirin/NSAID allergy
What are the cautions for NSAIDs?
Elderly
Dehydration
Asthmatics [ask about sensitivity to NSAIDS]
Certain types of surgery, e.g. - plastic or eye surgery, some orthopaedic surgery
Cardiac failure
Pregnancy
Concurrent medication e.g. anticoagulants
How do you manage opioid resp depression?
Give oxygen
Adjust dose or stop delivery of opioid until situation satisfactory
If necessary give naloxone titrate to effect
Respiratory depression may be delayed after intrathecal or epidural opioids.
What are the strong opioids?
Morphine, Diamorphine, Oxycodone, Fentanyl, Methadone
What are the weak opioids?
Codeine, Tramadol
How is morphine metabolised and excreted?
Metabolised in the liver to M6G and M3G - these have longer half-lives than morphine and are excreted via the kidney
What is oxycodone?
Synthetic opioid
What is the onset of oxycodone?
Good oral bioavailability
Fast onset and short time to steady state
What is tramadol and where/how does it work?
Centrally acting synthetic analgesic: mu opioid receptor activity + inhibits the uptake of noradrenaline and serotonin
What are the advantages of tramadol?
said to be absence of tolerance, lower abuse potential, less respiratory depression, less constipation - nausea, vomiting and sedation may still occur
When should we avoid tramadol?
epileptics as reduces threshold.
What are contraindications to PCA?
Patient inability to comprehend the technique e.g. extremes of age
Patients inability to press the button e.g. severe rheumatoid
Patient rejection
Ward staff must be trained appropriately
If we need to give an IV top up for PCA pain control, what drugs should be used?
same drug as in the PCA.
What are the different N and V drugs we use, plus class?
Antihistamines e.g. Cyclizine
5HT3 antagonists e.g. Ondansetron
Antidopaminergic e.g. Prochlorperazine, Metoclopramide
Anticholinergic e.g. Hyoscine
When scoring pain, what do we need to ensure?
We add a movement component e.g. cough.
What pain scores need intervention?
2 and 3
How do we assess respiratory depression on opioids?
0= None (patient alert) 1= Mild (occasionally drowsy; easy to rouse) 2= Moderate (frequently drowsy; easy to rouse) 3= Severe (somnolent; difficult to rouse) S= Sleep (normal sleep; easy to rouse)
How do we chart N and V on opioids?
0= None 1= Mild (no treatment required) 2= Moderate (helped by treatment) 3= Severe (despite treatment)
How long do fentanyl patches take to kick in?
12 hours
What analgesics are good for renal impairment?
fentanyl
alfentanil
oxycodone
What type of drug is clonidine?
antihypertensive used as an analgesic in specialist settings
What does clonidine do?
reduces norepininephrine release and so inhibits sympathetic nervous synstem
What are the side effects of clonidine?
hypotension
bradycardia
sedation
What is a good treatment for limb ischaemia and why?
nerve block as causes vasodilation
When does pain become chronic?
after 3 months or after healing should have normally been completed.
What are the three main categories of pain?
nociceptive
neuropathic
cancer
(acute or chronic of any)
