Anaesthesia 4 Flashcards
CLASSIFICATION OF ANAESTHETIC CIRCUITS (OPEN)
Lint/gauze placed on the nose
and volatile anaesthetic agent dropped onto the material
CLASSIFICATION OF ANAESTHETIC CIRCUITS (Semi-open)
gauze placed inside a mask attached to oxygen
CLASSIFICATION OF ANAESTHETIC CIRCUITS (Semi-closed)
Non rebreathing circuit
CLASSIFICATION OF ANAESTHETIC CIRCUITS (closed)
rebreathing circuit
Mapleson
Non-Rebreathing Systems
A, (B, C no longer
used), D E F
Howto remember Mapleson classification
A= APL near patient
D = Distant APL valve
E = Everything absent (APL & bag)
F= Free flow (APL valve absent)
semi-closed circuits require high gas flow to prevent?
Re-breathing the carbon dioxide rich expired gas
Adjustable Pressure Limiting Valve AKA
APL valve
Pop off
Heidbrink
How to choose the correct Reservoir Bag
3 - 6 x the tidal volume.
Non-rebreathing Circuits Advantages
Low resistance (ideal for
small animals)
Changes in the settings are
almost immediate
Can use- Nitrous Oxide & Carbon Dioxide
Non rebreathing circuits disadvantages
High gas flow rates required.
High volatile agent consumption rate.
Expired moisture and heat loss
Ayres T-piece (E) & Jackson Rees
Modification (F) circuit factor advantages
2.5-3
animals <10kg
Minimal resistance
Jackson Rees ideal for IPPV
Modified Bain
(structure, animal weight?, circuit factor, main benefits)
- Coaxial
- Fresh gas (inner tube)
Expired gas (outer tube) - animals 10 - 25 kg
Circuit factor 2.5-3
-Parallel bain
less drag
Bag nearest machine
Ideal for IPPV
Magill
(weight of animals?, Circuit factor, main disadvantage)
animals 10 - 35 kg
Circuit factor = 1 - 1.5
Not good for IPPV
Lack
Outer tube(fresh gas) inner tube (expired gases)
- Animals 8 - 40 kg
Long tubing =drag
Mini Lack - <10kg
Suitable for IPPV
Rebreathing Systems general advantages
Flow rates are very low
animals 10-80kg
Low pollution
Preserves moisture and heat
What is Soda Lime made up of?
- Calcium Hydroxide - 90% (lime)
- Sodium Hydroxide - 5% (soda)
- Potassium hydroxide with Silicates - 1%
- Water – 4%
- pH indicators
Soda lime colour changes
- Pink to white
- White to purple
is soda lime acidic or alkaline
Alkaline
Circle System
- Higher gas flow rate (10 - 15 min) then decrease the gas flow
- Circuit factor = 0.3 X minute volume
F Circuit
coaxial
Patient attached at coaxial end/ diverges-machine attached to outer tubing.
Less drag- one length tubing
thermally efficient
Humphrey ADE System
Combination of Mapleson A: (Magill and Lack), Mapleson D: (Bain) and Mapleson E: (T-Piece)
Exhaust Valve
central spindle of the
valve
Soda Lime Canister
Contains 500 grams of soda lime Last 8-12 hours
What parts requires annual maintenance on the Humphrey ADE?
- The brass cylinder inside the main body
- The exhaust valve
- The soda lime canister
IPPV basic principles
close APL valve
give breath
watch chest
What’s a Darvall ZDS
a mask
Types of ET Tube
Armoured or guarded
Murphy eye
ET tubes low volume, high pressure
Red rubber & Sillacone
ET tubes high volume, low pressure
PVC
Supraglottic Airway Devices
Used for rabbits and cats mainly
Tidal volumes calculations normal
(TV ml = BW kg x 10-15ml/kg)
DOG = 10 ml/kg
CATS AND SMALL DOGS = 15 ml/kg
DEEP CHESTED DOGS = 12 – 15 ml/kg
Minute Volume calculations
MV ml/min = TV ml x RR bpm
Flow Rate calculations
FLOW RATE L/min = TV ml x RRbpm x CF÷1000
Name the PHENOTHIAZINES
ACP
Name the ALPHA-2 ADRENORECEPTOR AGONISTS
- Medetomidine
- Dexmedetomidine
Name the BENZODIAZEPINES
- Diazepam
- Midazolam
Name ANTICHOLINERGICS and PARASYMPATHOLYTICS
- Atropine
- Glycopyrrolate
Opioids
MU-Agonists
- Morphine
- Methadone
- Fentanyl
- Pethidine
- Alfentanil
Opioids * PARTIAL MU-AGONIST
- Buprenorphine
Opioids KAPPA-AGONIST
Butorphanol
Opioids Antagonist
Naloxone
How does Phenothiazines (ACP) work
Blocks dopamine receptors in the CNS.
Phenothiazines (ACP) Advantages
✓ Sedation/tranquillisation
✓ Anti-arrhythmic
✓ Anti-emetic
✓ Antihistamine
Phenothiazines (ACP) Disadvantages
x Hypotension
x Contraindicated in epilepsy
x Hypothermia
x Not appropriate for Boxers
How do Benzodiazepines work
Bind to receptors in the CNS
Benzodiazepines Advantages
✓ Minimal CVS and respiratory effects
✓ synergistic with ketamine
✓ Muscle relaxation/Anticonvulsant
✓ Can be reversed by Flumazenil
Benzodiazepines
disadvantages
x Causes excitement
x Thrombophlebitis
x Used immediately
x Painful I/M
How do Alpha 2 Agonists work?
Bind alpha-2 adrenergic receptors
Advantages of Alpha 2 Agonists
✓ Potent sedation and hypnosis
✓ Analgesic effect
✓ synergistic with ketamine
✓ Can be reversed by Atipamezole
Disadvantages of Alpha 2 Agonists
x Effects CV/respiratory
x Vomiting
x Increased urine production
x Hyperglycaemia
what do Antimuscarinics do
Suppress the parasympathetic nervous system
Advantages of Antimuscarinics?
(Atropine and glycopyrrolate)
✓ Reduces saliva and bronchial
secretions
✓ Blocks vagus nerve
✓ Prevents bradycardia
✓ Promotes bronchodilation
Antimuscarinics disadvantages
x Cardiac arrhythmias
How do Opioids work?
Bind to specific opioid receptors located in the CNS
Opioids Advantages
✓ Sedation
✓ analgesia
✓ Minimal CV effects
✓ Synergistic
✓ Can be reversed by naloxone
Opioids disadvantages
x Dysphoria
x CNS effects
x Respiratory depression
x Nausea and vomiting
x Bradycardia and hypotension
x Antitussive
x Urinary retention
Why we do Pre anaesthetic blood test
- Haematology?
Checks for anaemia and coagulation disorders
why we do Pre anaesthetic blood test
-Biochemistry?
checks for metabolic disorders
why we do X-rays prior to surgery
Chest - for RTA’s and patients with neoplasm
Why we ultrasound prior surgery
Cardiac function
ECG AKA
Electrocardiography
ECG checks for
detect any abnormalities in the
pulse rhythm
