Introduction Flashcards
What are the 4 main objectives of anaesthesia?
- To work with zero morbidity and mortality
- Make patient unaware of surgery and recover pain free
- Make some surgery posisble and all surgery as easy as possible
- To support psychological function and counter adverse effects of surgery
What are 7 differences between sleep and anaesthesia?
- Respond to pain in sleep, not in anaesthesia
- Move around in sleep vs. no movement in anaesthesia
- Can dream in sleep but not anaesthesia
- Maintain your airway in sleep (snoring/apnoea if not fully maintained), but lose this in anaesthesia
- Normal breathing in sleep, depressed ventilation and altered CO2 response in anaesthsia
- Can swallow in sleep, reduced swallowing under anaesthesia (pharyngeal secretions sometimes build up)
- Sleep EEG and anaesthesia EEG are very different
What are the 3 components of general anaesthesia?
- Hypnosis - ‘sleep’, lack of awareness
- Muscular relaxation - preventing movement in response to surgery
- Analgesia - obtund painful stimuli (note - can’t be in pain if anaesthetised but can respond - use analgesics to block response)
What is meant by a ‘balanced anaesthesia’?
Traditional name fo the combination of drugs: anaesthetic, aanlgesic and a if needed a muscle relaxant (this combo is given in addition to the large dose of IV or inhalational anaesthetic)
What are the 2 key things needed to achieve the components of anaesthesia?
- Sufficiently large dose of intravenous or inhalational anaesthetic
- Using a combination of drugs:
- anaesthetic at much lower dose
- analgesic
- muscle relaxant if needed
What are 2 broad approaches to anaesthesia?
- Single agent anaesthesia
- Balanced technique
What is the advantage of single-agent anaesthesia?
Very simple, only one delivery system needed
What is the key disadvantage of single-agent anaesthesia?
As such a large amount of one drug is needed, it can lead to respiratory and cardiac depression - “not taking the drug well” e.g. chloroform and ether in the past, can lead to death due to profound respiratory and cardiovascular depression
In modern times, what is single-agent anaesthesia used for?
Now used for short procedures only, e.g. resetting a wrist fracture: single shot of IV agent, IV agent infusion or inhaled in oxygen
What are 2 benefits of the balanced technique of anaesthesia?
- Each component contributes its effects
- Side effects are reduced
What is a key disadvantage of the balanced technique of anaesthesia? Give 3 examples.
Requires attention to detail
- Too little anaesthetic agent = awareness
- Too little analgesia = excess reponse to noxious stimuli
- Too little relaxant = unwanted movement, or unwanted muscle tone - e.g. makes abdominal surgery different
What are 2 steps to general anaesthesia and how can they each be achieved?
- Induction: can be induced by intravenous or inhalational agents
- Maintenance: can be maintained by intravenous or inhalational agents
What are 2 ways that general anaesthetics can be combined with other drugs?
- Can be combined with analgesics and muscle relaxants as in balanced anaesthesia
- Combined with local or regional anaesthesia
What are 2 states of patient care that general anaesthesia can be administered in?
- Patient breathing spontaneously OR
- ventilation provided artificially
What is sedation?
Form of semi-hyponosis in which the patient is rousable, can talk, but may have no memory of events (e.g. midazolam especially good at blocking memory)
Why is it important that a sedated patient is able to talk?
Means you must be able to maintain your airway
Where does sedation turn into anaesthesia and why is it important?
Some deep sedation may be like anaesthesia, need to think about maintenance of airway in these patients
What are the 2 types of local anaesthesia?
- Topical e.g. cream
- Infiltration e.g. before putting in venflon, dentist
What are 5 types of regional anaesthesia?
- Peripheral nerve block
- Ganglion/ plexus block
- Epidural
- Spinal
- Intravenous regional
What 2 types of anaesthesia are being increasingly combined?
General and regional anaesthesia
How does general anaesthesia act on the body’s response to pain?
Prevents pain that is generated from being interpreted as pain by the central nervous system; doesn’t stop transmission of painful stimuli from the source of pain
How do local and regional anaesthesia act with regards to pain?
Prevent transmission of a painful stimulus reaching the central nervous system
Why might local anaesthesia be combined with general anaesthesia or sedation on some occasions?
- When combined with general anaesthesia, local anaesthesia used as the analgesic part of balanced anaesthesia
- When combined with sedation, can take advantage of the benefits of both approaches
What is the chemical structure of most local anaesthetics?
- Most have a lipid soluble, hydrophobic aromatic group and a charged, hydrophili amide group and a charged, hydrophilic amide group.
- There is an amide or ester bond between groups



