Week 4 - Pain Flashcards
What is the name of the receptors that receive pain stimulation?
Nociceptors.
Nociceptors are specialized sensory receptors that respond to potentially damaging stimuli by sending signals to the brain, leading to the sensation of pain.
How do nociceptors work?
Damage leads to chemical mediators (Substance P) that lower the depolarisation threshold of the neuron.
This process involves the release of certain chemicals that sensitize the nociceptors, making them more responsive to pain stimuli.
Name the two types of nerve fibres that transmit pain.
C-fibres and A delta fibres.
C-fibres are smaller and unmyelinated, while A delta fibres are larger and myelinated.
Describe how C-fibres and A delta fibres differ from each other.
C-fibres: smaller, unmyelinated, located in deep tissue. A delta fibres: larger, myelinated, faster transmission, located in superficial tissue.
This difference affects the speed and type of pain sensation each fibre transmits.
Why do visceral organs such as the heart have a dull heavy ache associated with them?
They are served by C-fibre nociceptors.
The dull ache is due to the slower transmission of pain signals from C-fibres.
What are the five steps associated with a combined approach to pain relief?
- Reassurance
- Distraction
- Positioning
- Splinting
- Analgesia
These steps aim to manage pain through both psychological and physical strategies.
List four pharmacodynamic effects of morphine.
- Analgesia
- Decreased GI motility
- Respiratory depression
- Sedation
- Nausea and vomiting
- Miosis
These effects highlight the multifaceted impact of morphine on the body.
Explain why fentanyl is faster acting than morphine.
Fentanyl is more lipophilic and passes through cell membranes faster.
This property allows fentanyl to reach its site of action more quickly than morphine.
Why does morphine cause hypotension, while fentanyl is less likely to do so?
Morphine causes more histamine release, leading to more vasodilation.
Histamine release can cause blood vessels to widen, resulting in lower blood pressure.
How does lignocaine work as an analgesic?
It inhibits sodium channels at peripheral nerves, preventing sodium influx, depolarisation, and action potentials.
This mechanism blocks pain transmission along the nerve.
What are the indications for Ondansetron?
Clinically significant nausea and/or vomiting.
Ondansetron is typically used to prevent nausea and vomiting, especially in post-operative or chemotherapy patients.
Should ondansetron be given prophylactically when an opiate is administered?
Not generally.
Prophylactic use of ondansetron is not standard practice with opioid administration.
Is naloxone an opiate receptor agonist or antagonist?
Antagonist.
Naloxone is used to counteract the effects of opioid overdose.
What is the maximum dose of naloxone per administration for IV and IM routes?
- IV: 0.4mg
- IM: 0.8mg
These dosages are critical for effectively reversing opioid overdose.
Describe how to draw up fentanyl
Draw up 100mcg/2ml of fentanyl into a 10ml syringe. Draw up 8ml of 0.9% NaCl to make a concentration of 100mcg/10ml – 10mcg/1ml.
This method ensures a proper dilution for safe administration.
Describe how to draw up and administer IV Ketamine for an 80kg patient.
Draw up 100mg of Ketamine in a 100ml Glucose bag to create a 1mg/1ml solution. Maximum dose: 20mg (0.25mg x 80). Administer 2mg/2ml every 1-2 minutes as needed, up to 20mg within 15 minutes.
Proper dosing is essential for effective sedation and pain management.
