Principles and Pharmacology Flashcards
1
Q
What are the different types of anaesthesia?
A
- general
- insensibility to whole body
- unconciousness
- regional
- insensibility to area/region of body
- applied to nerves suppling the area
- local
- insensibilty to only the relevant part of the body
- applied directly to the tissue
2
Q
What is the triad of anaesthetics?
A
- analegesia
- opiates
- local anaesthetics
- hypnosis
- opiates
- general anaesthetic agents
- relaxation
- muscle relaxants
- local anaesthetics
- general anaesthetic agents
3
Q
What are common problems with anaethesia?
A
- polypharmacy
- inc chance of drug reaction + allergy
- muscle relaxation
- requires artificial ventilation
- means of airway control
- serparation of relaxation + hypnosis
- not experiencing pain, but awake + paralysed
- traumatising patient
4
Q
What are the features of general anaesthetics?
A
- complexes processes lost first
- most primitive processes lost last
- reflexes relatively spared
- usually give IV induction, maintained by inhalation
- provide different gas to reverse effects of initially inhaled gas
5
Q
What is the mode of action of general anaesthetic?
A
- inhalation
- agents disolve in membranes -> have a direct physical effect
- enter + exit via lungs
- slow induction
- arterial conc equates ~ alveolar partial pressure
- MAC = min conc of a drug required in alveoli to provide anaesthesia
- halogenated hydrocarbons
- IV
- do allosteric binding to GABA receptors -> open Cl channels
- rapid effect, rapid recovery
- can cross BBB
- thiopentone, propofol
6
Q
What are the different phases of gas induction?
A
- anaelgesia/sedation
- excitation
- light-deep anaesthesia
- overdose
7
Q
What are the effects of general anaesthetics on normal physiology?
A
- centrally
- affects CVS via the hypothalamus
- directly
- on blood vessels
- ∴ vasodilation -> dec MAP -> dec CO
- resp
- inc RR
- dec tidal volume
8
Q
How are local and regional anaesthetics administered?
A
- US guidance
- brachial plexus block
- IV injection
9
Q
What are the effects of local and regional anaesthetics on normal physiology?
A
- similar effects on CNS as general anaestheic
- proportional to size of anaesthic area
- relatively sparin gon resp system
10
Q
How do local + regional anaethetics cause toxicity?
A
- high plasma level of LA, in well perfused area
- level will exceed rates of removal (clearance + metabolism)
- depends on;
- dose used
- rate of absorbtion
- patient weight
- drug used
11
Q
What are the symptoms of toxicity?
A
- circumoral + lingual paraesthesia
- light head
- tinnitus, visual disturbances
- muscle twitching
- drowsiness
- coma
- convulsions
- CVS depression
- cardiorespiratory arrest
12
Q
What is meant by differential blockade?
A
- different nerve fibre types have different physical attributes
- motor fibres are harder to block than pain fibres
- so analgesia can block pain without blocking movement
13
Q
What are the indications for muscle relaxants?
A
- when ventilation + intubation required
- when immobility essential
- microscopic surgery, neurosurgery
- access for body cavity surgeries
14
Q
What are the problems with muscles relaxants?
A
- awareness
- separation of unconciousness from hypnosis
- could lead to mismatch of doses
- incomplete reversal
- could lead to airway obstruction + ventilation insufficiency (in immediate post-op period)
- apnoea
- deoendance on airway + ventilation support
15
Q
What are the methods of airway maintainance?
A
- head tilt -> chin lift -> draw thrust
- ALWAYS
- face mask
- oropharyngeal airway (+ nasopharyngeal)
- must be fully unconcious + anaesthesed
- can cause vomiting + laryngospasm
- laryngeal mask airway
- maintains but does not protect airway
- endotracheal intubation
- cuffed tube in trachea
- *- maintain + protect airway**
