Anaesthetic equipment Flashcards
Which 5 pieces of equipment are needed for anaesthesia?
- Anaesthetic machine
- Anaesthetic breathing systems
- Endotracheal tubes
- Scavenger
- Calculator
What is the general aim of anaesthesia?
To ensure your patient is in a state of controlled unconsciousness
with associated analgesia and muscle relaxation
What are the 5 stages of anaesthesia?
- Pre-operative assessment
- Premedication
- Induction of anaesthesia
- Maintenance of anaesthesia
- Recovery from anaesthesia
What are the aims of premedication?
- Reduce anxiety
- Ease handling of the patient
- Smooth induction
- Smooth maintenance
- Smooth recovery
- Reduce the dose of anaesthetic drugs required
- Provide pre-emptive analgesia
Following premedication, anaesthesia of patients in veterinary practice generally involves the use of which two different agents?
- Injectable e.g. propofol
- Inhalation e.g. isoflurane
Which period is associated with the greatest risk of morbidity and mortality in anaesthesia?
Recovery period
What are the 3 functions of breathing systems?
- Deliver anaesthetic vapour
- Deliver oxygen
- Remove carbon dioxide
What are the two major types of breathing systems?
Rebreathing systems
Non-rebreathing systems
Describe a rebreathing system
- Allow the patient to rebreathe expired gas
- CO2 must be extracted before the patient rebreathes this gas
- Economical
- High resistance
- Suitable for patients over 15Kg
Describe a non-rebreathing system
- Don’t allow the patient to rebreathe expired gas
- Utilise a high fresh gas flow rate
- Suitable for patients less than 25Kg
What are the 5 principle components of a breathing system?
- Adaptor to connect to an ET tube
- Expiratory valve
- Reservoir bag
- Fresh gas tubing
- Expired gas tubing
What is the function of the expiratory valve?
Allows expired gas to exit the breathing system once the pressure in the system exceeds a certain level and prevents the animal rebreathing expired air.
What is the function of the reservoir bag?
Allows us to undertake intermittent positive pressure ventilation (IPPV) should the patient stop breathing
What should the capacity of the reservoir bag be?
Twice the normal tidal volume of the patient
What is present in the canister to react with expired CO2?
Soda lime
What are the 5 principle components of the anaesthetic machine?
- Fresh gas supply
- Flowmeter with bypass valve
- Vaporiser
- Breathing system with pressure relief valve
- Scavenging system
How is the anaesthetic machine designed to ensure that the correct gases enter the correct piping of the machine?
Gas cylinders are connected to the machine using a connector - these are designed so only one type of cylinder can connect to it
What is controlled by the flow meter?
The flow of gas (oxygen and anaesthetic gas) to the patient
What is the function of the vapouriser?
Mixes an appropriate level of inhalational agent with O2 in order to maintain anaesthesia
The amount of inhalational agent delivered by the vaporiser is measured as what?
A percentage so turning the dial on the vaporiser to 1 means the fresh gas delivered to the patient will be 1% inhalational agent and 99% O2
What is a scavenger system?
Removes exhaled gases from the vet’s environment
What is found within a scavenger canister?
Activated charcoal which removes organic gases
The scavenger has limited capacity so how can the efficacy be ensured?
By weighing daily
The Magill system consists of which 4 principle components of breathing systems?
- Connector to an ET tube
- Expiratory valve
- Reservoir bag
- Single tubing: expired and fresh are in the same tube
In what size of patient can the Magill system be used?
More than 10Kg
What is the Mapleson classification of the Magill system?
A
When is a Magill system not very effective?
- Surgery close to the head
- When giving intermittent positive pressure ventilation (valve and reservoir bag far apart)
Which system consists of all 5 components of a breathing system?
Mapleson D
The Mapleson D system is used in patients of what body weight?
Less than 10Kg
Why is the Mapleson D system less efficient than the Magill system?
Requires a higher fresh gas flow rate in order to ensure that expired gas is cleared from the reservoir bag prior to the next inspiration
What is classified as a Mapleson E?
Ayre’s T-piece
Which 3 principle components of a breathing system are involved in a Mapleson E system?
The connector to an ET tube
Green fresh gas tubing
Expired gas tubing
The Mapleson E system is used in patients of what BW?
Less than 10Kg
Why can IPPV not be performed in the Mapleson E system?
No reservoir bag
The Jackson-Rees modification is classified as a?
Mapleson F
Which components are present in the Mapleson F breathing system?
- Ayre’s T-piece
- Connector to an ET tube
- Reservoir bag with a connector
- Green fresh gas tubing
- Expired gas tubing
The Mapleson F system is used in Patients of what BW?
Less than 10Kg
Which breathing systems are the least effective and why?
Mapleson E and F
- high fresh gas flows are required in order to flush expired gas from the system
How is a Mapleson E system modified into a Mapleson F system?
Jackson-Rees modification of T piece - addition of a reservoir bag
What is the parallel lack system classified as?
Mapleson A
What does the parallel lack system consist of?
- Connector to an ET tube
- Expiratory valve
- Reservoir bag
- Fresh gas and expired gas tubing connected by a Y connector
The parallel lack system is used in patients of what size?
More than 7Kg
Why is the parallel lack system not suitable for prolonged IPPV?
Allows for build-up of CO2 in the system
Mapleson A systems have a circuit factor of?
1
What is the Co-axial Bain system classified as?
Mapleson D
What does a co-axial Bain system consist of?
- Connector to an ET tube
- Expiratory valve
- Reservoir bag
- Green fresh gas tubing which sits
within white expired gas tubing
The co-axial Bain system is used in patients of what BW?
Over 10Kg
Name the common rebreathing system
The circle system
What components make up the circle system?
- Soda lime canister
- Tubing
- Expiratory valve
- Connector housing one way valves
A circle system is used in patients of what BW?
More than 15Kg
What are the advantages of rebreathing (circle) systems?
- Conservation of heat and moisture in respired gases
- Efficient due to low fresh gas flow rates required
- Ability to perform IPPV
Which 2 aspects need to be considered to calculate the flow rate required for non-rebreathing systems?
- The patient’s minute volume
2. The breathing system being used
The minute
volume of our patients is approximately?
200ml/kg/min
What is the flow rate required when using rebreathing systems?
10-50ml/Kg/min
