T1 L22: Analgesia, Sedation, and local anaesthetic Flashcards
What is analgesia?
Medication that relieves pain
What is the gate theory of pain?
It suggests that the spinal cord contains a neurological “gate” that either blocks pain signals or allows them to continue on to the brain
Physiology: C fibres let pain through but Ab fibres stimulate inhibitory neurones. the descending pathways prevent central passage
What are some methods of scoring pain?
Linear (1-10)
Smiley/sad faces
Mild, moderate, severe, or excruciating
What is the WHO analgesic ladder?
It starts with aspirin and NSAIDS if pain unrelieved. Then you can add some local anaesthetic and weak opioids and the final step is strong opioids
What is the WFSA analgesic ladder?
The World Federation of Societies of Anaesthesiologists (WFSA) Analgesic Ladder has been developed to treat acute pain
First you would give strong opioids by injection or some local anaesthetic and then you would move downwards into opioids by mouth as pain decreases and finally onto aspirin and NSAID’s
What is the drug Naloxone used for?
Causes acute drug withdrawal. It acts on opioid receptors and antagonises them
It’s an opioid
Why does Naloxone often need to be re-administered?
Because it has a really short half-life
What are some methods of administration of analgesic agents?
Intravenous patient control analgesia Infusion Intramuscular Oral Intra nasal/aerosol Epidural/spinal
Where are opioid receptors found in the body?
Pons and mid brain Periaqueductal grey matter Nucleus raphe magnus Spinal cord posterior horn 1 and 2 Peripheral tissue GI tract
Why are there so many opioid receptors around the body?
Because the body produced its own endorphins
Which opioid subtypes cause nausea?
Kappa OP2
Which opioid subtype causes respiratory depression?
Delta OP1
What are some side effects of using morphine?
Respiratory depression
Nausea and vomiting
Constipation
Miosis (shrinking of pupils)
Which receptors does Ketamine act on?
NMDA
Kappa and delta
Not GABBA
What is the triad of ketamine action?
Local/general analgesic
Anaesthesia
Sedative
Which analgesic drug can be used for its antisuicidal effects with depression?
Ketamine
What is the physiology behind the action of NSAID’s?
Inhibit COX 1 and 2
What is the triad of NSAID action?
Analgesic, Antipyretic, inti inflammatory
What does antipyretic mean?
Reduces fever
What are some side effects of NSAID’s?
Gastric irritation
Bronchospasm
Renal impairment
Platelet function (aspirin)
Why is aspirin not used for children?
Because of Reyes syndrome
- A rare but serious condition that causes swelling in the liver and brain. It mostly affects children and teenagers recovering from a viral infection, most commonly the flu or chickenpox
What happens during a paracetamol overdose?
Hepatotoxicity and Glutathione depletion
Give examples of some antiemetic drugs
Hyocine Metaclopromide Steroids Prochlorperazine Cannabinoids Propofol
Describe the Ramsay Sedation scale
Patient anxious cooperative responds only to commands Brisk response to Glabellar tap/shout Sluggish response No response
What is a Glabellar tap?
A tap on the head between the eyes to see if the person blinks
What is the main drug used for sedation?
Benzodiazepines
How do Benzodiazepines work?
They work on GABBA A and B (inhibitory neurotransmitter)
What are some side effects of benzodiazepines?
Over sedation
Loss of airways
Respiratory depression
ABC
What happens in the body during a local anaesthetic overdose?
Vasoconstriction
Ventricular fibrillation
How is an overdose of local anaesthetic treated?
ABC
Oxygen
Lipid 20% (lipid rescue)
How can local anaesthetics be given?
Spinal epidural caudal
Skin
Aerosol/ Nebulised
