Pain and analgesia Flashcards
Pain pathways
- perception is mediated by ? ? ? - nociceptors
- ?-? fibres give rise to perception of ? ? pain
- ? fibres = ? onset, ? pain
- sensory impulses enter the cord via the ? ? and then ? in the dorsal ? column or the ? tract
- ? pathways to and from the ? then mediate the ? components of pain
free nerve endings A-delta - immediate sharp C-fibres - slower, prolonged dorsal root ascend posterior spinothalamic thalamic cortex emotional
Pain has multiple ? effects.
Also lead to ? release, with resultant ? leading to increased ? work and delayed ?
psych catecholamine vasoconstriction cardiac healing
WHO pain ladder
1 - ? +/- adjuvant - eg paracetamol +/- ?
2 weak ? +/- ? +/- adjuvant eg codeine/? +/- paracetamol +/- ?
3 strong ? +/- ? +/- adjuvant eg morphine/? +/- paracetamol +/- ?
non-opioid nsaid opioid non-opioid tramadol nsaid opioid non-opioid fentanyl nsaid
Paracetamol
indicated in ?-? pain and ?
weak anti-? properties
oral doses achieve peak plasma conc within ?
SE are uncommon
dose - ? PO/IV ?ds up to ?/day
dose is reduced in patients under what weight?
dose of ?/day is recommended if RFs for ? eg ? age, poor nutrition, or ?
mild-mod, pyrexia inflam 1hr 1g, qds, 4g 50kg 3g, hepatotoxicity old alcoholism
NSAIDS
some ? effect, best for ? pain.
work by inhibited prod of ? enzymes - which normally promote prod of ? and ?
inhibition of ? enzyme relate to benefit from nsaids, with inhibition of ? enzyme leading to SE
antipyretic inflamm COX PG + Thromboxanes cox2 cox1
Nsaids
cox 1 - expressed in ? tissues, with the PGs produced involved in tissue ? eg -> platelet ?, ? blood flow autoregulation and ?? protection
cox 2 - induced in ? ? cells by ? and ?
- sensitises ? to inflam mediators such as ? peripherally
- sensitises ? pain fibres in the ? ? centrally
most homeostasis aggregation renal GI
active inflam IL-1, TNF a nociceptors bradykinin afferent dorsal horn
Nsaids Absolute contraindications? 2 SE - ? and gastric ? - ? (in aspirin sensitive asthmatics)) - ? insufficiency - ?toxicity - decreased ? count - ? reactions
severe HF
Hx of GI bleeds/ulceration
dyspepsia, ulceration bronchospasm renal cardio platelet skin
Nsaids
? 20mg od should always be co-prescribed with NSAIDS
Caution in ?, the ?, ?pathies or ?/?/? impairment
- ? CId with high ?? risk, ? best for these patients
? nsaid ? and ? can also be given - safe/effective for arthritis analgesia, esp ?
omeprazole asthma elderly coagulopathies cardiac/renal/hepatic diclofenac CV naproxen topical creams gels OA