Anaesthetics Flashcards
3 components of anaesthesia?
- Analgesia
- Sedation/Hypnosis
- Muscle relaxation
3 different states of hypnosis?
- Awake
- Sedated
- Asleep
Define Anaesthesia
Pharmacologically induced, reversible state of sleep characterised by lack of pain, awareness of surroundings and memory of events
3 main risks to a patient undergoing surgery?
- Surgery itself - damage to structures, blood loss, complications
- Effects of anaesthesia
- Pre-existing disease
List 3 potential intra-operative problems
- Fluid balance
- Hypoxia
- Hypothermia
- Pain
- Anaphylaxis
- PE
- Death
What type of post-operative drugs may be written up for a patient?
- Analgesia, e.g. paracetamol, codeine, tramadol
2. Anti-emetic, e.g. ondansetron
Anaesthesia. What are the three broad classes of anaesthesia?
- Local (regional or neuraxial)
- Sedation
- General
Anaesthesia. Which type of anaesthetic goes into the CSF?
Spinal (type of local)
Anaesthesia. Which type of anaesthetic goes into the space between the ligamentum flavum and the dura?
Epidural (type of local)
Anaesthesia. Which has a faster onset; Spinal or Epidural?
Spinal
How do local anaesthetics act?
- Reversibly block sodium channels
2. Inhibit generation of action potentials within nerve cells
Local Anaesthetics. Which type of nerve fibres are blocked first?
Small diameter and unmyelinated
B
C and Ad
Ab
Aa and Ag
Local Anaesthetics. What is the effect of blocking B fibres?
Vasodilation
Which fibres are responsible for pain and temperature?
C and A-delta
Which fibres are responsible for light touch and pressure?
A-beta
Which fibres are responsible for motor and proprioception?
A-alpha and A-gamma
Give 2 reasons why adrenaline is often given with local anaesthetics
Adrenaline causes vasoconstriction, resulting in:
- Reduced blleding
- Prolonged LA effect through reduced reabsorption from tissues
Could you use adrenaline with a local anaesthetic in end arteries, e.g. the fingers?
No - causes vasoconstriction
2 key local anaesthetic agents?
- Lidocaine
2. Bupivacaine
How long does Lidocaine take to work? How long does it last?
Immediate onset
Lasts 15 mins
How long does Bupivacaine take to work? How long does it last?
10 mins to onset
Anaesthesia lasts 2 hours; analgesia lasts 12-24 hrs
Sedation. Give 3 key effects of drugs given for sedation
- Reduce anxiety
- Reduce consciousness
- Reduce irritability of the airway
- Induce amnesia
Sedation. What type of sedation is IV Midazolam used for?
Short-term; i.e. endoscopy, regional anaesthesia
Sedation. What drug may be given for long-term sedation?
IV Propofol +/- alfentanil
