Analgesia Flashcards
how pain is transmitted?
peripheral pain receptors or nociceptors sending message via afferent nerve fibres
to spinal cord: activates the spinothalamic tracts
to the brain: autonomic response (brainstem - HR, RR, pupillary etc)
conscious pain perception (cerebral)
emotional response (limbic)
and descending pain pathway
Chemical mediators of pain (tissue damage, inflammation and ischemia)
Prostaglandin
substance P
cytokines
Non-opioid analgesics
Corticosteroids
Paracetamol
Aspirin
NSAIDs
Pharmacodynamics of Paracetamol
Inhibits prostaglandins (COX1,2 and 3) to reduce pain and fever
Endocannabinoid reauptake inhibitor
Adverse effects of Paracetamol
Well tolerated (no anti-inflammatory benefits, no thromboxane and not GIT irritant
However, highly toxic when overdose
Pharmacodynamics of NSAIDs
Inhibits COX 1(enzyme maintaining stomach lining) and COX 2 (enzyme that triggers pain) which synthesise prostaglandins causing inflammation and pain
NSAID drugs
ibuprofen
naproxen
diclofenac
celecoxib
Adverse effects of NSAIDs
GI upset (N&V, diarrhoea, abdominal pain)
HTN
Kidney problem (NSAIDs are nephrotoxic)
Blood clots (stroke)
NSAIDs, Beta blockers and aspirin can cause bronchospasm for pts with?
Asthma
Nursing cosiderations for taking NSAIDs
Educate pt to:
take it with food to decrease stomach irritation
do not take it with empty stomach
For acid reflux:
administer Omeprazole
Selective COX 2 inhibitor meds
Celecoxib
Etoricoxib
Meloxicam
Salicylates pharmacodynamics
Analgesic - inhibits prostaglandins
Antipyretic - decrease body temp
Anti-inflammatory - inhibits COX 1&2
Anticoagulant - prolongs bleeding times and inhibits platelets aggregation (Aspirin)
Salicylates meds
Aspirin
Antidote for Aspirin overdose
Sodium Bicarbonate
Antidote for salicylate poisoning
activated charcoal
Nursing considerations for taking salicylates
Cease taking salicylates 1 week before major surgery (risk for bleeding)
Monitor GI bleeding
Pharmacodynamics for Nonsalicylates
Analgesic and antipyretic (do not have anti-inflammatory or antiplatelet effects)
Nonsalicylate meds
Acetaminophen (Tylenol) - for mild to moderate pain, substitute for Aspirin allergies and bleeding tendencies
Adverse effects of Nonsalicylates (chornic use or higher dosage)
Hives
Hemolytic anemia
Pancytopenia (low levels of blood cells - RBC, WBC and platelets)
Hypoglycaemia
Hepatoxicity, Hepatic failure and jaundice (yellow skin)
Contradictions to Acetaminophen
Liver dysfunction (alcoholism)
Nursing considerations for pt taking Acetaminophen
Assess alcohol use
Malnourished pts with chronic alcohol use can have increased risk of liver damage
Limit drug dosage below 2g a day
Antidote for Nonsalicylates toxicity
Acetylcysteine (protects liver cells and destroys acetaminophen metabolism)
Categorise weak and strong opiates
Strong opiates:
Morphine, fentanyl, oxycodone, methadone, heroin
Weak opiates:
Codeine, tramadol (has SNRI agents)
Pharmacodynamics of opioids (opioid agonists)
Generally: Binds to opioid receptors in the brain causing an analgesic sedative and euphoric effect (addictive)
Pain signals sent to brain - Inhibits action potentials (causing hyper polarisation) and release of neurotransmitters in spinal cord
Decrease pain perception: activates descending inhibitory controls in the midbrain
Decrease anxiety (euphoric effect)
Long term and short term adverse effects of Opioid analgesics
Long term:
Constipation (client doesn’t build tolerance)
Short term:
Miosis (constricted pupils)
Orthostatic hypotension
Respiratory depression
Pain suppression
Itch and rash (histamine release)
N&V
Euphoria
Sedation
Opioid tolerance means
the need to increase dosage to maintain a therapeutic effect
Opioid dependence means
biological adaptation whereby a dose reduction of cessation will result in withdrawal symptoms
Opioid addiction means
behavioural response in which a person seeks and develops compulsive behaviour in obtaining and consuming the substance despite of its adverse effects.
symptoms of opioid tolerance and intolerance
tolerance: N&V, sedation, euphoria and respiratory depression
intolerance: constipation and miosis
Opioid meds
Morphine
Codeine
Oxycodone
Methadone
Fentanyl
Opioids do NOT produce _______ and ___________ benefits as it is not used for fever, gout/ rheumatoid arthritis.
antipyretic and anti-inflammatory
Nursing considerations for pts taking opioids
Constipation:
adm laxatives, encourage fluids, fiber and fruits, encourage to defecate when they the feel the urge
Respiration:
breathing exercise to increase RR
adm naloxone if overdosed or RR dropped < 12
Falls:
encourage to rise slowly and assist with ambulatory acitivities
Opioid meds:
TAKE IT WITH FOOD to avoid GI upset
DO NOT drink alcohol
Pharmacodynamics of Fentanyl
lipophilic (fat soluble) - can cross membranes easily
Less histamine release
weak opioid agonist with SNRI properties
Tramadol
Adverse effects of Tramadol
increased risk of N&V and neurological effects such as hallucinations and seizures
risk of serotonin syndrome
Pharmacodynamics of Naloxone (opioid antagonist)
Antidote for opioid overdose (causing respiratory depression)
Strong affinity for opioid receptors
Short half life (monitor pt)
Rapid reversal (after adm naloxone) of opiate toxicity can cause:
recurring pain
seizure
hypertension
pulmonary oedema
severe agitation
