Anaesthesia: Monitoring Small Animals and Equine Practicals Flashcards
How would you monitor anaesthesia in a 12 year old TBX mare with colic for exploratory laparotomy?
Systemically compromised individual- acid base disturbances, electrolyte imbalences, likely abnormal fluid balence
Unkown pathology
Unpredictable length of procedure
Basic techniques with- ECG, Capnography, Invasive arterial pressure monitoring, ideally with blood gas analysis
Can you name these devices?
How would you monitor anaesthesia in a 12 mo pony for routine castration at owners?
Basic monitoring techniques only
Should be a healthy animal undergoing a short, uncomplicated procedure of predictable duration
What are the advantages and disadvantages of invasive and non-invasive blood pressure monitoring?
Invasive:
Give real time, continuous readings
Require aterial cannulation
Only accurate for mean AP
Electronic expensive
Non invasive:
Variable acuracies
Doppler measures return of flow following occlusion
Require correct size and application of cuff
Intemittent readings
What information is given by invasive arterial blood pressure monitoring?
Gives diastolic pressure, systolic pressure and mean pressure
But because it gives a pressure time graph additional information can be gained:
- Myocardial contractility- how steep the upstroke is
- Systemic vascular resistance- how quickly the trace drops back down from max value
- Volume status- all the peaks are the same height
- Most will estimate HR
What are the normal values for systolic pressure, diastollic pressure and mean pressure with blood pressure monitoring?
Systolic- 80-130mmHg
Diastolic pressure- 40-60mmHg
Mean pressure- >60mmHg
What do you think of this invasive blood pressure reading?
Extremely hypotensive animal
Peaks of different heights suggest animal is hypovolaemic which will be contributing to this
Requires immediate attention
What is suspicious about the above reading and how could it be resolved?
The trace is typical of an arterial cannula being occluded by a thrombus or becoming kinked
Flushing and/or repositioning of the cannula should restore the trace and values to reflect the true situation.
What does capnography inform you about during anaesthesia?
Ventilation- end tidal CO2 is used as a surrogate, non-invasive mesurement of arterial CO2
Circulation- there needs to be efficient system to transport CO2 from cells to lungs. If end tidal CO2 drops it may indicate circular failure
Metabolism- sudden increases in ETCO2 may indicate a hypermetabolic state
Equipment faults- sudden absence of ETCO2 may be the first indicator of extubation or disconnection of endotracheal tube/capnography
What do the following capnograms tell you?X
A- rebreathing CO2- capnorgram doesn’t return to baseline between breaths, most likely causes are soda lime depletion or inadequate fresh gas flow
C- mild hypoventilation- ETCO2 is slightly high
E- Normal capnogram- shape WNL
What do the following capnograms tellyou?
B- Double respiratory pattern- typical of an animal being mechanically ventilated and taking spontaneous breaths in between
D- Progressive hypoventilation- slight rebreathing- starts normal but peaks gradually increase
F- Cardiogenic oscillations- intrathoracic pressure fluctuations caused by myocardial contractions can sometimes be detected as a jagged return of capnogram
What are the three components of the ECG and what happens during each?
P wave- atrial depolarisation
QRST complex- ventricular depolarisation
T- ventricular repolarisation
What could cause a 2nd degree AV block?
What treatmenr would you give if BP was normal or low?
Drugs- metomidine (opioids)
Increased vagal tone- anaesthetic agents
High resting vagaltone- fit animal
If BP normal- none
If BP was low- antagonise metomidine, give parasympatholytics
Didn’t finish monitoring of SA- cba- cheers future Patrick
Hope you’re feeling better
