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3 components of balances anaesthesia

unconsciousness, analgesia and adequate mm relaxation


Goals of anaesthetic monitoring - 4

- ensure all components of balanced anaesthesia are provided
- maintain homeostasis
- detect any adverse effects of anaesthesia and correct immediately


Other than the patient, what else should the anaesthetist also monitor? 3

(Patient first)
Anaesthetic machine
Breathing system (+/- ventilator)
IV fluids


When do most anaesthetic deaths occur?

within 3 hours of the end of the procedure


What determines the level of monitoring?

Physical condition (animal)
Surgical procedure planned (intense then use both invasive and non-invasive measures)


What is the anaesthetic record?
What should it include? 7

legal document
shows trends
reference for future anaesthetics

Should include:
Drugs (time, dose, route)
All intra-operative monitoring (blood tests, blood loss and urine output)
IV fluids (rate, type)
All procedures (intubation, invasive monitors)
Time of important events (induction, position, timing, extubation)
Unusual events/complications
Condition of animal at end of procedure.


What is the blood volume of dogs and cats?
Why is this important?

Dogs = 80ml/kg
Cats = 60ml/kg

(useful to calculate and note the values for blood loss equal to 10%, 15% and 20% of blood volume to help in decision making as to whether to give crystalloids, colloids or blood)


What should you do if an anaesthetic machine doesn't have low oxygen warning alarms fitted?

check cylinder (or pipeline) pressure and oxygen flowmeters constantly. If using NO2 on older machines without anti-hypoxic devices, it is also essential to check the O2:NO2 ratio regularly to ensure you aren't delivering a hypoxic mixture to the patient.


What other machine checks should be made?

- Vaporiser settings and level of volatile anaesthetic in vaporiser
- Breathing system (+/- mechanical ventilator) for operation adn disconnedtion
- Fluid administration (rate, contents)


What 2 readings need to be measured by equipment during anaesthesia?

Arterial BP
End-tidal CO2


What can you listen for when monitoring anaesthesia? 5

Ventilation sounds
Leaks (ETT or breathing system)
Low oxygen pressure warning alarms
Malfunctioning equipment


What can you look for when monitoring anaesthesia? 3

Eye position
Chest movements
Colour of MMs


What can you feel for when monitoring anaesthesia?

Pulses - quality, rate, rhythm
Jaw tone
Palpebral reflex
Relaxation - limbs and reflexes


What can you smell for when monitoring anaesthesia?

Detecting volatile anaesthetic agent which would indicate leaks or disconnections


What is the anaesthetist's first priority when anaesthesia is induced?

ABC assessment:
AIRWAY - placement of ETT, secured, cuff inflated
BREATHING - rapid, slow, regular/irregular
PULSE - strong, weak, thready, absent
Then once you are confident in the patient's condition, make a quick assessment of the patient's depth


How do you assess patient's depth under anaesthesia? 4

- Eye position, nystagmus (species and drug dependent) lacrimation, pupil size and response to light
- Palpebral reflex - absent/present, brisk/sluggish, other CN reflexes.
- Muscular relaxation - jaw tone etc.
- EEG changes


What physiological parameters need to be monitored during anaesthesia?

Pulse rate
RR, depth, quality


What can be used in small animals for physiological parameter monitoring?

oseophageal stethoscope - for heart and respiratory sounds.


What clinical observations should be monitored? 8

Depth of anaesthesia
Chest movements
Pupil size
Response to surgery
Blood loss
(Urine output)


What equipment observation should be monitored? 6

Respiratory gases
Pulse oximeter
Blood pressures
Blood gases


What does an ECG inform you of?

electrical activity of the heart


What does an ECG not inform you of?

mechanical activity of heart


T/F: after a patient has been euthanased under GA, a normal ECG trace may remain for several minutes



Why is ECG monitoring recommended under GA?

cardiac arrhythmias occur in over 80% anaesthetised patients, most not clinically significant. most familiar departure from normal is sinus arrhythmia (so common it cannot be considered an abnormality, CO should be unaffected). abnormal ECGs have more significance if they indicate atrial contraction isn't followed by ventricular contraction (2nd degree AV block) or ventricular activity is not preceded by atrial contraction (3rd degree AV block).


When might AV blocks be seen under GA? 2

- bradycardic patients
- if sedated with an alpha-2-agonist
= so long as arterial BP is satisfactory,it may not be significant


What might VPCs be a warning of? 5

underlying heart disease
others - surgery to remove splenic tumours


Why should VPCs be monitored closely?

worsening can progress to ventricular fibrillation (VF)


What is the most common cause of delayed recovery from anaesthesia?

Hypothermia - can also cause other problems (bradycardia, increased susceptibility to infection, risks increasing the anaesthetic depth inadvertantly). Smaller the patient, the greater the risk (increased surface area to mass ratio)


What is malignant hyperthermia (MH)?

very rare, genetic condition
triggered by used of older anaesthetics (halothane, suxamethonium)


What is core temp. most effectively measured by?

thermistor probe in oesophagus (slightly more reliable) or rectum (slightly less reliable)

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