Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BVETMED3 > Anaesthesia > Flashcards

Anaesthesia Flashcards

1
Q

What is balanced anaesthesia

A

Practice of using smaller doses of many different kinds of medication rather than higher doses with fewer drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How long should animals be fasted before anaesthetic

A

> Dogs and cats - 6-8 hours
Ruminants - 24/48 hour
Horse - 8 hours ( even though cant vomit, full abdomen can decrease functional residual capacity
Rabbits and rodents cant vomit so doesnt matter
Ferret - 4 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are you looking for in a pre anaesthetic blood test

A

> Older animals testing renal and liver function
Detect any underlying diseases
Get baseline figures so can detect post op changes
PCV > 20% need transfusion
Testing for adequate albumin because its the primary serum binding protein. Therefore decreased albumin results increased free drug and a delayed recovery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the mortality risks of anaesthetic

A 
Dog - 1:1850
Cat - 1:900
rabbit 1:72
Horse - 1:100 ( worse in colic cases) 
Chinchilla and guinea pig - 1:33
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the ASA class classification

A

> ASA I - Normal healthy animal
ASA II - Mild systemic disturbance, no clinical signs (e.g mild diabetes or obese)
ASA III - Moderate systemic disturbances with mild clinical signs ( e.g anaemia, pyrexia or symptomatic heart disease)
ASA IV - Severe systemic disturbance that is a constant threat to life (e.g severe heart failure or sepsis)
ASA V - Not expected to survive 24 hours without intervention ( GDV or severe trauma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Whats the role of a pressure regulator on an anaesthetic machine

A

Reduce cyclinder pressure to a safer level ( Atomospeheric pressure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a circuit factor and how do you calculate minute volume

A

Circuit factor - Fresh gas flow needed to prevent rebreathing. Expressed as a multiple of the animals minute volume

MV = Tidal volume x Respiratory rate
*Tidal volume is estimated at 10-15ml/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why is an initial high flow rate required for a rebreathing system

A

Needed to flush air out of system so it doesnt dilute anaesthetic agent. Once a stable plane of anaesthesia is established can reduce flow rate to 50ml/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the common premedications

A
  1. Phenothiazine - Acepromazine
  2. Alpha 2 agonsit - Medetomidine/xylazine
  3. Benzodiazipines - midazolam and diazepam
    Commonly combined with opoids (morphine/methadone) as it enhances then sedative effected of the drugs and provides analgesia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe pros and cons and contraindications of Acepromazine

A 
Wait for 20minutes for effect
Pros:
> Inexpensive
> Anti arrythmic
> Antagonise CRTZ - no vomiting 
> Long acting tranquilzer ( 4-8 hours)

Cons:
> No analgesia
> Less reliable sedative in aggressive animals
> Vasodilation and hypotension

Contraindications:
> Decreases seizure threshold so avoid in these patiens
> HCM and left ventricular hypertension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the pros and cons and contraindications of medetomidine

A 
Commonly used for short procedures in healthy animals. Also used for aggressive animals
Pros:
> Provides good analgesia
> Reliable in a variety of species
> short acting ( 1-1.5 hours)
> Antagonizable
Cons: 
> Arrythmogenic
> Increases BP and urine production
> Cardio/respiratory depression
> more expensive
> Inhibits Beta cells in pancreas = hyperglycaemia

Contraindications:
> Diabetes patients
> Patients with cardio-respiratory disease
> ASA III or above

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the pros and cons of benzodiazapines (midazolam/diazapam)

A

Ideal for neonates, geriatrics, those at risk of seizures, cardiac impairment and when muscle relaxation is needed ie in fracture repairs.
Pros:
> Minimally effects CV & respiratory function
> Myorelaxation - excellent muscle relaxant
> Tranquilizer in neonates and geriatric patients
> Anti convulsivant (anti seizure)

Cons:
> Not a reliable sedative agent
> Possible paradoxic reaction - excitement ( give with opoids)
> Antagonists are expensive
> Myorelaxation may result in decreased respiratory function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What receptors do opoids bind to and what are the side effects

A 
Opoids bind to u receptors (providing analgesia) and k receptors (cause dysphoria).
Side effects;
> sedation
> respiratory depression
> vomitting
> dysphoria
> myosis (constriction) in dogs and mydriasis (vasodilation) in cats
> bradycardia
> urinary retention
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the common opoids used in practice

A

> Morphine - Potent u receptor agonist. cheap and not licenced

> Methadone - u agonist. Onset time is 10 minutes, lasting 2-4 hours. Blocks CRTZ preventing vomiting, licenced in dogs

> Butorphanol - k & u agonist = Mild sedative and poor analgesic. used in combination with other sedatives

> Buprenorphine - Licenced in small animals

> Fentanyl - Potent u agonist. Short acting and often infused during surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the most common inducing agent and what are its possible side effectis

A

Propofol
> Rapid onset and rapid metabolism
> Can cause tremors due to imbalance between parasympathetic and sympathetic nervous system
> Metabolism slower in cats - deficiency in several conjugation pathways
> When used with a alpha 2 agonist causes bradycardia, resulting in longer onset

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is alfaxalone

A

Induction & maintenance agent that can be given IM or IV. Rapid onset of action with short duration. Poorly soluble so marketed with cyclodextrin. Less cardio pulmonary depression that propofol. Excitement on recovery if not adequately sedated.

17
Q

What is ketamine

A

A dissociative anaesthetic - Also analgesic action at sub anaesthetic doses. Given IM (stings)or IV.
If given alone causes rigidity and excitation. always combined with another sedative.
> Used in horses after profound alpha 2 agonist sedation in combination with benzodiazepine ( counter act muscle rigidity).
> Intubation difficult as cranial reflexes preserved therefore gag reflex present.
> Stimulates sympathetic system causing increase in BP and Hr ( good for geriatrics)

18
Q

What is the ‘triple combination’

A 
Ketamine + medetomidine + opoids
> Used for aggressive cats and dogs
> IM and onset in 3-5 mins
> Suitable for short duration procedure
> 3-5mg/kg
19
Q

Why is thiopental no longer licenced

A

Was an induction agent. No longer licenced because if given extravacularly causes necrosis.

20
Q

What is etomidate

A

Induction agent which is minimally depresses the Cv and respiratory system. Good for sick and compromised patients. Depresses cortisol production for 6 hours.

21
Q

between sevoflurane and isoflurane which has the higher partition coefficient and what does this mean clinically

A

Sevolflurane has a lower partition coefficient. This means that patient is induced quicker and recovers quicker.

22
Q

What is MAC and what effects it

A

Minimum alveolar concentration is the concentration of vapour in lungs required to prevent movement (due to surgical pain) in 50% of population.
*Isoflurane has a lower MAC than sevo

Influenced by:
> dose of sedative/premed
> severe anaemia
> Severe hypotention
> Pregnancy
> Hypo/hyperthermia
> Age = a decrease in age causes an increase in MAC
23
Q

What is the Bispectral index

A

Monitors the patients electroencephalograms (electrical activity in brain). Provides a single number ranging from 0-99, 0= dead and 100= fully awake. Between 40-60 is a good level of anaesthesia

24
Q

How can blood pressure be monitored and what are normal values

A

Non invasive - doppler flow detection
> Probe tapped to metatarsal or tail where pulse can be felt
> Cuff placed proximal to dopple probe and attached to manometer
> Cuff inflated untill pulse no longer audible, cuff gently released and reading taken
> can have automatically inflated cuff (oscillometric)

Invasive - Arterial catheterisation
> Catheter placed in peripheral artery & attached to manometer or electronically transduced.

  • Dog - Systolic=140 diastolic=75 mean=100
    Cat - Systolic=180 Diastolic=100 mean=135
    Horse - Systolic=110 Diastolic=70 mean=90
25
Q

What is capnography

A

Measures end tidal carbon dioxide. normal range between 35-45mmHg.
Limitations:
> tachypnoea causes incomplete exhalation of alveolar gas
> High fresh gas flow rate will wash out end tidal gases
> Hypoventilation

26
Q

Cushings reflex

A

In response to increased intracranial pressure, leading to increased blood pressure, Bradycardia and irregular breathing and many indicate imminent cerebellar herniation which leads to death.

27
Q

Why is small animal anaesthesia challeneging

A 
> Difficult IV access
> Intubation
> Thermoregulation - Increased surface area to volume ratio causes increased loss of heat = hypothermia
> difficult to access pain
> Post anaesthetic ileus common
> Small haemorrhage is significant
28
Q

When would you use gaseous induction and what are possible disadvantages

A

Gives a rapid induction/recovery & good for hepatic or renal compromised patients. Sevo is less irritant but not
licenced in small animals. Premed still used e.g opoid + midazolam or hyponorm (only licenced sedative in rabbits or rodents, use lower dosage than required)

Cons: 
> May hold breath to point of deatg
> Stress on induction
> No algesia
> Dose dependent cardiopulmonary depression
29
Q

How would you induce a small mammal by IM

A

Alpha 2 agonist + ketamine + opoid.
Deep sedation + good analgesia and easily reversed. However causes respiratory depression and bradycardia.not advised for sick patients.

30
Q

How can you intubate a small animal (3ways)

A

Pre-oxygenate first and dont attempt more than 3x will cause damage to the larynx.

  1. Blind - Pre-oxygenate check mouth for debris/food, nose to ceiling and introduce tube listening to sound.
  2. Visual (otoscope) - Use otoscope, displacing soft palate & visualize larynx. Thread urinary catheter through then ET tube.
  3. Laryngeal Mask - Sits over the larynx, easy to displace, so not ideal when you need to move patient.
  • Palatial ostium ( fusion of soft palate and base of tongue) limits visibility, therefore intubation not common in rodents
31
Q

Why are benzodiazapines not used in horses

A

Cause muscle relaxation, so cant be used with a standing sedation
Also not allowed to use in ruminants

32
Q

Why is acepromazine used in horses and is the rare side effect

A

Often combined with a opoid as it increases sedation. When used as a premed, halves the risk of an anaesthetic complication.

Risk of priapism ( active erection that doesnt go). Must be treated immediately or will cause permanent damage.

33
Q

When are alpha 2 agonists used in horse and what are the side effects

A

Infused for prolonged period of sedation. examples include xylazine, detomodine (IM), Romifidine (long acting and has least ataxia)
Side effects:
> Bradycardia
> Inc urine output
> Hypergylcaemia (can cause an incorrect DM diagnosis)
> gut stasis

34
Q

When is butorphanol used in horses

A

Used to increase the depth of sedation with acepromazine and alpha 2 agonist. Remove sensation of touch but doesnt have analgesic action. Analgesia provided by local blocks.

35
Q

what are the methods of IV induction in the horse

A
  1. Ketamin based - Alpha 2 agonist given first then ketamine. This prevents the side effects of ket (excitement and rigidity).
  2. hypotonic based - Alpha 2 agonist + ACP + thiopental (very irritant extravascularly). Guaifenesin also used (muscle relaxant giving good surgical conditions)
36
Q

In terms of positioning, what is important when a horse is under anaesthetic

A

> under front leg is positioned forward to prevent block of venous return
Head titled up to avoid nasal congestion
Dont extend hind leg. Stifle lock for more than 20 minutes will result in myopathy/neuropathy

37
Q

What inhalant agent is used in horses

A

Isoflurane is the only licenced agent in horses. Onset and recovery very fast, especially if ket used. Can almost be too quick resulting in a poor recovery

38
Q

What analgesia is used in horse intra operatively and post op

A

Ket is used as its most effective and improves cv status.

NSAID provide post op analgesia

39
Q

What are the possible anaesthetic problems encountered with horses

A

> Hypotension - expected decrease for first 30 minutes. give fluids and decrease volatile agent. can give inotrope (dobutamine)

> Hypercapnia - An increase co2 increases sympathetic tone and increases CO. can reduce by IPPV.

> Hypoxaemia - Worst in large horses in dorsal recumbancy. cause hyperventilation and a decrease in CO.

BVETMED3 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions