w/c 27-Jan-14 Flashcards
What are the three components of general anaesthesia?
1) unconsciousness -narcosis = lack of awareness
2) Analgesia (pain is a conscious perception) - antinocieption
3) Muscle relaxation
What is ‘balanced anaesthesia’
A movement away from using a single drug to do all three components we want from a GA.
It is a combination of drugs which reduces the side effects; allows ‘lightening up’
Which breed is said to be sensitive to acepromazine (ACP)?
Boxers are said to be susceptible to ACP
ACP is a sedative and an antiemetic
How many hours should be waited till GA in induced in dogs and cats?
Withhold food for 6 hours
According to statistics, which species is more likely to die under anaesthetic; cat or dog?
Healthy Cat: 1 in 895 die
Healthy Dog: 1 in 1849 die
Guinea Pig: 1 in 26 die
In the context of anaesthesia, what is the ASA score?
ASA score is a measure of the animals physical status
Dangers of nitrous oxide
More dangerous and can inhibit DNA synthesis and cause CNS damage.
What is the recommended maximum concentrations of anaesthetic gases?
Nitrous oxide:100ppm
Sevoflurane: 60ppm
Isoflurane: 50ppm
Halothane: 10ppm
A blue cylinder probably contains what gas?
What is important about this gas?
Nitrous oxide
Stored in a liquid phase with gas on the top. As long as some liquid is left, will always have a +ve pressure gauge. HAVE TO WEIGHT to determine amount left.
Significance of the Bodok seal
Must be placed between cylinder and anaesthetic machine to make a gas-tight join.
VERY LOAD NOISE if missing when cylinder turned on
Why does the vaporizer need to be kept upright?
Otherwise the bypass channel may flood with anaesthetic and dramatically increase output = DANGEROUS
Why do you need to be careful using emergency oxygen flush?
Oxygen is given at a pressure of 400kPa directly from the cylinder.(40 litres/minute)
Higher pressure= careful LUNG DAMAGE
What is a ‘low-resistant’ or ‘draw-over’ vaporizer?
Patients respiratory effort determines amount of anaesthetic agent breathed in.
Vaporiser is positioned WITHIN the anaesthetic circuit.
Anaesthesia too light = increased respiratory effort = sleep!
Advantage/Disadvantage of rebreathing system
ADVANTAGE: exothermic reaction when CO2 react.
Low volatile agent consumption
Most economical in large animal
DISADVANTAGE: Exact composition of gas is not known
Expensive
Slow to change depth of anaesthesia
Advantage/Disadvantage of non- rebreathing system
ADVANTAGE: Simple/cheap, inspired air composition is known, low resistance to breathing
DISADVANTAGE: High gas flow requirements
Expired heat loss
Breathing/Non-Rebreathing system can change depth of anaesthesia more quickly
Non rebreathing systems can change depth of anaesthesia more quickly
Which type of breathing system allows for heat to be retained?
Exothermic reaction between carbon dioxide and soda lime = REBREATHING SYSTEMS can RETAIN HEAT.
Most economic in large animals
Which set is best as IPPV?
IPPV: Intermittent Positive Pressure Ventilation
How are non-rebreathing sets classified?
Rebreathing of carbon dioxide is prevented by having enough fresh gas flow (FGF) into the circuit to wash away exhaled gas from previous exhalation.
Classified depending on FGF (Classification from A to F)
Which is the best sets for IPPV?
MAGILL and LACKS (not good for IPPV, as Mapleson classification A, need to increase FGF)
AYRE’ST PIECE/ BAIN (better for IPPV) as don’t need to increase FGF
IPPV: INTERMITTENT POSITIVE PRESSURE VENTILATION
Which set would be given for animals <10kg?
Ayre’ T-piece.
Good choice for IPPV (as already high FGF)
Low resistance to breathing.
When is the breathing set Humphrey ADE used?
Versatile system, by means of a lever switch system can be conversed from a Mapleson A to a Mapleson D or E.
i.e. A: good for spontaneous respiration
D/E good for controlled respiration
Why can circle rebreathing systems only be used in animals >10kg?
Gas can only move in one direction (i.e. a circle!)
Two way valves are present. Resistance to breathing is higher
What breathing set would you use for a 6kg Jack Russel?
Tpiece
minimal resistance
How do you calculate FGF?
FGF: Respiratory Rate x Tidal Volume x Circuit Factor
During a laporotomy the monitor shows
A falling blood pressure and rising pulse would be indicitive of what?
Hypovolemia
e.g. haemorrage?
When is the wet/dry/warm/cold quadrant used? What do the terms relate to?
In the absence of best evidence i.e. less common cardiac diseases.
Warm: output/circulatory signs
Wet: Congestive signs.
In the absence of best evidence, which drugs would be given for a COLD DRY patient? (CVS)
Cold: Poor circulation
Dry: No congestion
Afterload reduction, anti-arrythmics, inotropes
What is the main evidence of excessive a) preload
b) afterload
Excessive Preload: Congestion i.e. Pulmonary oedema
Excessive Afterload: Pale/Cold patients (increased resistance to ejection)
How do calcium channel blockers help improve diastolic function?
Calcium channel blockers hasten relaxtion (I.E. calcium antagonist- Amlodipine)
Also can use beta-blockers to slow heart rate.
Can reduce fibrosis by using ACEI
Amlodipine is also used to treat hypertension
Spironolactone is an example of a
Diuretic that works by blocking aldosterone receptors
What is the main problem associated with diuretics?
Kidney is very good at developing a new equilibrium (i.e. absorbing sodium in the distal tubule more)
Furosamide is a LOOP diuretic that blocks sodium reabsorption.
If not altered/ checked kidney can become refractory to diuretics
Function of Pimobendan
Pimbobendan (Vetmedin) is a phosphodiesterase inhibitor and calcium sensitiser
i.e. arterio/veno dilator and positive inotrope to enhance systolic function
Example of a venodilator
Nitroprusside (Nitrates act as endogenous nitric oxide to relax smooth muscle)
or glyceryl trinitrate (acts in same mechanism)
What is the function of Amlodipine?
Enhances diastolic rythem by allowing for ventricular filling. Hastens relaxtion
Is a calcium blocker i.e. calcium antagonist
Three main types of acquired cardiovascular disease in order of frequency
- Degenerative mitral valve disease: SMALL DOGS
- Dilated cardiomyopathy
- Pericardial effusion
A Cavalier King Charles Spaniel presents with a LEFT APICAL SYSTOLIC MURMER. What is the highly suggestive of?
DMVD: Degenerative Mitral Valve Disease