Anaesthesia Flashcards

1
Q

Preparation for anaesthesia

A

Starvation - controversial but feed night before and then not in the morning

Remove shoes/bandage feet

Clean mouth

IV canular

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2
Q

Equine pre-med

A

ACP IM (or IV) - cardioprotective, 45 mins before IV sedation

Alpha-2 agonist - gives good sedation prior to induction

Opiate - butorphanol if non-painful, morphine if painful

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3
Q

Equine induction agents

A

Ketamine IV (horse will fall down, very rigid) with Midazolam IV (muscle relaxant)

Propofol IV (can use in foals but not common)

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4
Q

Methods of anaesthesia in a horse

A

Free fall (if too dangerous to assist)

Assisted (one person, field or very small horse, hold head up so fall back)

Assisted (multiple people, knock down box)

Assisted (crush door, knock down box)

‘Flop’ techniqe with foals

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5
Q

Field maintenance of anaesthesia

A

Ketamine +/- alpha-2 top ups
- up to 1/3 induction dose every 10 mins

Triple dip - guaifenesin (muscle relaxant) + ketamine + alpha 2 agonist
- can’t give for more than 90 mins due to accumulation of guaifenesin -> very ataxic recoveries

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6
Q

Hospital meintenance of anaesthesia

A

Intubation

Circle breathing system with inhalant oxygen +/- air

Isoflurane

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7
Q

FIeld monitoring of anaesthesia

A

Manual HR and RR

Increased muscle tone - light

Increased resp rate with pain - light

Delayed action of ketamine so make sure to do top ups at least every 10 mins

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8
Q

Hosptial monitoring of anaesthesia

A

Same as SA

Blood gases useful, especially in colic

With foals monitor blood glucose and temperature

Nystagmus with inhalational = very light

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9
Q

Main physiological changes under anaesthesia

A

Hypoventilation (on inhalational not ketamine)

Decreased cardiac output

Hypotension (reduced CO and vasodilation)

Atelectasis and resulting V/Q missmatch (dependent lung lobe can collapse)

Hypoxaemia (supply oxygen, ventilate if hypoventilation is contributing)

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10
Q

Field recovery from anaesthesia

A

Kneel on neck until fighting to get up, holding nose towards you

Then stand well back with long rope on head collar

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11
Q

Hospital recovery from anaesthesia

A

Kneel on neck until they swallow - pull ET tube out

Intranasal oxygen

Pull lower leg forward

Empty bladder (catheter)

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12
Q

Two main methods of hospital recovery from anaesthesia

A

Free recovery - shut door and let horse stand by itself

Ropes - attached to head collar and tail, pull when horse stands up, can be risky

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13
Q

How long should a horse take to get up after anaesthesia

A

Approx 20 mins + 20mins per hour of anaesthesia

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14
Q

Complications of equine anaesthesia

A

Myopathy
Fractures
Neuropathies
Spinal cord malacia
Respiratory issues during anaesthesia
Respiratory obstruction during recovery
Post operative impactions

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15
Q

Myopathy in equine anaesthesia

A

Due to muscle compression and under perfusion

Keep blood pressure above mean of 70mmHg to reduce risk

Soft theatre bed

Commonly affects gluteal muscles in dorsal recumbency, and triceps in lateral

Mild to severe lameness on recovery

Swollen hot muscles

Manage with sedation, pain relief, steroids, IV fluids, support

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16
Q

Fractures in equine anaesthesia

A

Reducing myopathy will reduce risk

Higher risk in racehorses

Peri-parturient mares higher risk

17
Q

Neuropathies in equine anaesthesia

A

Due to pressure over nerves e.g. head collar buckles (facial nerve)

Pull lower leg forward during recovery (radial nerve)

Will see loss of motor function

Milder damage can be locally painful

18
Q

Spinal cord malacia in equine anaesthesia

A

Typically heavy breed horses

Result of pressure on or reduced blood flow to spinal cord - put slightly on side

On recovery will dog sit

Grave prognosis

19
Q

Respiratory issues in equine anaesthesia

A

Will breathe better in lateral

Blood gas monitoring to monitor arteral +/- venous oxygen and CO2

May need to ventilate

Try not to have neck overextended - can damaeg recurrent laryngeal nerve

20
Q

Respiratory obstruction during recovery in equine anaesthesia

A

Horses are obligate nasal breathers

Leave ET tube in until they can swallow

Nasal oedema or upper airway obstruction

Use nasal tubes or phenylephrine up nostrils

21
Q

Post operative impactions in equine anaesthesia

A

If caecal can rupture and die - may need surgical treatment

Probably multifactorial (pain, stress, reduced feeding, anaesthetic drugs, opiates)

Monitor faecal output post anaesthetic

22
Q

How to minimise anaesthetic complications

A

Shortest GA possible

Keep horse calm

ACP in pre med

Invasive blood pressure monitoring, should be >70mmHg

Partial IV anaesthesia

Best analgesia possible

Padded bed with care over pressure points

Out of hours surgery only if emergency