Analgesia sedation - Local anaesthetics Flashcards
What is the gate theory
- Melzack and Wall
- C fibres lets pain through
- Ab Fibres stimulate inhibitory neurones
- Descending Pathways prevent central passage
Fibres involved in pain modification
- Nociceptor C, A delta fibres
- Central Interpretation
- Not just Drugs!
Pain score systems
- Linear
- Smiley/Sad Faces
- Mild Moderate Severe Excrutiating
Pain ladder 1
- NSAIDS/Paracetamol
- Weak Opiates/ Local Anaesthetics
- Strong Opiates
Pain ladder 2
- Strong opioids by injection, local anaesthesia
- Opioids by mouth(as pain decreases)
- Aspirin and NSAIDs
What are opioid receptors antagonised by
- Naloxone
Examples of naturally occurring opioids
- Morphine
- Codeine
Example of a semi synthetic opioid
- Diamorphine
Example of a synthetic opioid
Fentanyl
Example of a weaker opioid
Codeine
Methods of opioid administration
- Intravenous pca/infusion
- Intramuscular
- Oral
- Intra nasal/aerosol
- Epidural/spinal
Locations of opioid receptors
- Pons and Mid brain
- Periaqueductal Grey Matter
- Nucleus Raphe Magnus
- Spinal Cord Posterior Horn 1 and 2
- G I T
- Peripheral Tissues
Subtypes of opioid receptors
- MU 1 and 2 OP3
- Delta OP1
- Kappa OP2
Side effects of morphine
- Respiratory Depression/Airway Loss
- Nausea and Vomiting
- Constipation/Pruritis
- Miosis
Features of ketamine
- NMDA Receptors
- Kappa and delta receptors
- Not GABA
- Analgesic local/general
- Anaesthetic
- Sedative
Side effect of ketamine
- Emergence phenomena
Features of NSAIDS
- Act by inhibiting Cyclooxygenase 1and 2
- Analgesic, Antipyretic, Anti inflammatory
Features of aspirin
- Acetylsalycilic acid
- Oxidative phosphorylation
- Air Hunger
- Reyes Syndrome
Features of paracetamol
- Mechanism of Action ? Central prostaglandin effect/unknown
- Side effects
- OVERDOSE Hepatotoxicity/glutathione depletion
- N acetylcysteine
Other analgesia
- Anxiolysis
- Local anaesthetics
- Antidepressants,antiepileptics,Tramadol
- Guanethadine, ketamine, clonidine
- Acupuncture
- Inhalational Nitrous oxide
- Penthrox (methoxyflurane)
- Magnesium
Features of antiemetics
- Avoidance of emetics N2O Sevoflurane
- Use propofol
- Cyclizine
- Ondansetron
- Hyoscine 1944
- Metoclopromide
- Steroids
- Prochlorperazine
- cannabinoids
- People remember!
Ramsay sedation scale
1 - Patient Anxious 2 - Cooperative 3 - Responds only to commands 4 - Brisk response to Glabellar Tap/Shout 5 - Sluggish Response 6 - No response
Examples of benzodiazepines
- Midazolam, Diazepam, Lorazepam
Physiology of benzodiazepines
- Gabba- aminobutyric Acid
- Inhibitory Neurotransmittor
- Receptors A and B
Side effects of benzodiazepines
- Over Sedation
- Loss of Airway
- Respiratory Depression
- ABC
- Flumazanyl with caution
- Myth of safety ,Light Anaesthesia
Other sedatives
- Low Dose Vapours
- Ketamine
- Hyoscine
- Propofol Low dose
- Major Tranquillisers
- Alpha 2 agonists
Classification of local anaesthetics
- Amides -NH.CO-
- Lignocaine,Prilocaine,Bupivacaine
- Esters –CO.O-
- Cocaine , Amethocaine
Mechanism of local anaesthetic action
· Na Channel Blockade
· Un- ionized Drug Through Membrane into axoplasm
· Protonated
· Blocks Channel thus blocking action potential
Where to put local anaesthetics
· Anatomy Local Blocks /Ultrasound · Spinal Epidural Caudal · Skin · Aerosol/Nebulised · Combination with GA Part of Triad
Side effects of local anaesthetics
· Skin/Subcutaneous · Brachial Plexus · Epidural · Caudal · Intercostal · VESSELS AND NERVES FOLLOW EACH OTHER
Toxicity -
· CARDIOVASCULAR · Dysrythmias,Cardiac Depression · CENTRAL NERVOUS SYSTEM · Fitting/Anxiety/Lossof Consciousness · Circumoral numbness · Ref Paper Mask 1990
Side effects of NSAIDS
Side Effects
- Gastric Irritation
- Bronchospasm
- Renal Impairment
- Platelet function ASPIRIN
