Week 3- PCA, epidural Flashcards
3 types of pain
2 classifications
- Nociceptive (somatic) – injury to body tissue
- Visceral – pain that comes from the visceral organs (ie. GI, heart, etc.)
- Neuropathic – central and/or peripheral nerve pain
Acute – subsides with healing; under 6 months
Chronic – persistent, can be debilitating, often associated with a long term illness
pain pathway
- transduction (release of sensitizing chemicals)
activate nociceptors and lead to generation of an action potential - transmission
- injury, sc, brain, thalamus, cortex for processing - perception (conscious experience of pain)
- modulation (neurons originating in the brain stem descend to the spinal cord and release substances
meds that impact transduction
CLAN
NSAIDs
Local anaesthetics
Antiseizure drugs
corticosteroids
Mechanism of action
NSAIDs
Local anaesthetic
antiseizure drugs
corticosteroids
block prostaglandin production
block AP initiation, inhibit cyclo-oxygenase action
block AP initiation
block AP initiation
pain drugs affecting transmission
opioids
cannabinoids
opioids
cannabinoids
MOA
- block release of substance P, decrease conscious experience of pain
- inhibit mast cell degranulation and response of nociceptive neuron
pain meds impacting perception
noa
NSAIDs
Opioids
adjuvants (relaxation, imagery, muscle relaxant)
adjuvants (relaxation, imagery, muscle relaxant)
MOA
dependent on specific adjuvant
modulation pain meds
tricyclic antidepressants (eg. amitriptyline)
tricyclic antidepressants MOA
interfere with reuptake of serotonin and norepinephrine
Pain can lead to physiological changes, such as
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increase Heart rate Respirations Blood pressure
Immune function
Healing
what is a PCA
method of pain management via infusion that permits patients to self-administer small amounts of pain relieving medications via a specially designed pump.
routes of PCA
3
- IV
- subcutaneous or intraspinal delivery (Patient Controlled Epidural Anaesthesia- PCEA) of medication to reduce pain (usually opioids)
benefits of PCA
- report better analgesia and lower pain scores than those only receiving nurse administered opioids
- Fewer post operative complications may arise because earlier and easier ambulation occurs as a result of effective pain relief
Benefits of using a PCA compared to nurse administered opioids
Overall patient satisfaction is much higher (lower pain scores)
Patient has sense of control over their pain control and healing
Improved patient outcomes/fewer post op complications because earlier ambulation occurs as a result of effective pain management
Pharmacokinetic control much more stable
pt spends more time in ____ when having a PCA
therapeutic range
criteria to get a PCA
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- Patient must be cognitively capable of understanding the concept
- Able to physically press the button
- Willing to control their own pain this method
- Not sedated from other medications
safety/risks of PCA
- Medication errors
- Use of narcotic drugs including their risks
- Close nurse monitoring of side effects
- System locked and accessed by staff only
- Patient understanding
IV morphine
onset
duration
half-life
- considered
- metabolites excreted by
17 mins
4-5 hours
2 hours
considered gold standard for pain relief. metabolites are excreted by the kidneys (90%) in first 24 hours
Hydromorphone IV
onset
duration
half life
comments
10 times more lipophilic than morphine. effective analgesia effects in 15 mins
4-5 hours
2-3 hours
5-7 times more potent than morphine
fentnyl
onset
duration
half life
- more potent than
- metabolized by
- watch for
- does not
effective analgesic in 4-5 min
can last longer then elimination half life if longer infusion times/obese pt
initial redistribution in 13 min
elimination half life 3-4 hours
80-100 times more potent than morphine. need to watch for delayed res depression
metabolized by the liver, does not produce histamine release.
PCA side effects depends on
drug being administered
some PCA side effects
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- increase risk of respiratory depression
- sedation
- N/V
- urinary retention
- pruritis
- reduced gastric motility
NV occurs in ___% of pts
who’s at higher risk
20-30%
female
non-smokers
use of intra-operative opioids
history of PONV
duration of surgery (increases by 60% for each 30 mins of surgery)