Introduction to Anaesthesia Flashcards
What is General Anaesthesia?
It is the controlled reversible production of unconsciousness through pharmacological means.
What is the aim of General Anaesthesia?
Controlled depression of the CNS to produce lack of awareness of painful inputs (nociception).
Where do we want minimal depression during anaesthesia?
Of the hind brain region - cardiovascular centres.
Where do we want to depress during GA and why?
Front brain so that the patient is not aware.
Name 5 methods to introduce local anaesthesia into the body?
- Topical
- Infiltrative
- Conductive
- Epidural
- Subarachnoid
Name 3 reasons we anaesthetise our patients?
- Unconsciousness- pain free
- Restraint - immobilisation (patient and practitioner safety)
- Relaxation - surgical access (this will improve the access)
When were barbiturates developed?
1920s
What is the triad of anaesthesia?
Hyponosis, Anti-nociception (analgesia), muscle relaxation
What do we mean by hypnosis?
Artificially induced sleep - cannot wake up therefore different wave form of sleep.
What are the 4 areas involved with anti-nociception?
- Perception (cerebral cortex)
- Modulation
- Transmission (sensory nerves)
- Transduction (sensory nerve endings, nociceptors)
What can block transduction?
NSAIDs
What can block perception?
Opioids.
Give an example of a muscle relaxant?
Diazepam or a specific neuromuscular junction blocking agent e.g. curare (plant extract)
Why is it important to use muscle relaxants?
It is very difficult intubating patients that have not recieved muscle relaxants.
What are the outdated 4 stages of anaesthesia?
- Induction
- Excitement
- Operative
- Danger
What are the signs of the induction stage?
- pupil normal size
- reaction to light
- irregular pulse
- normal resp.
- normal BP
What are the signs of the excitement stage?
- normal pupils
- exaggerated response to light
- Increased resp rate
- pulse irregular and fast
- BP high
What are the signs of the operative stage?
- Small pupils
- No reaction to light
- steady resp rate
- steady, slow pulse
- normal BP
What are the signs of danger stage?
- dilated pupils
- No response to light
- no resp rate
- weak to thready pulse
- low BP
What are the modern three classes to monitor anaesthesia?
- Conscious
- Unconscious
- Dead