Anaesthesia Flashcards
During Anaesthesia what could be causing a decrease in HR and BP?
What are the side effects of Alpha 2 agonists?
- Heavy Sedation + Analgesia, muscle relaxation
- BradyCardia, AV block
- Hypertension–> Normotension / Hypotension (Xylazine only)
- Respiratory Depression
- Hypothermia
- Emetics
Under anaesthetic what Mean and Systolic Blood Pressure should we keep above?
- Mean BP >60
- Systolic >80
Normal BP
- Mean BP - 80-100
- Systolic - 100 - 140
Why do we use hemostats?
We use them to cause trauma to the blood vessels which sets of the intrinsic cascade.
Platlets, Coagulation Factors, Vessel Wall, assess before surgery
Why do we premedicate?
What kind of drug will kill an animal?
- Less drugs of induction
- Less Drugs for Maintenance
- Quiet Recovery
Anaesthetics will kill an animal.
Name the Neuroleptic drugs we use for sedation
- Acepromazine
- Azaperone (Pigs only)
- Droperidol
What are some of the Injectable Anaesthetic drugsused in Veterinary medicine
- Propofol
- Alfaxalone
- Ketamine
- Barbituates - Thiopentone
Why do we intubate animals during anaesthesia?
- Maintain a Patent Airway
- Protect against Aspiration
- Provide/Maintain Oxygenation
- Maintain Anaesthesia (Volatile)
- Controlled Ventilation (CO2)
- Minimise Envrionmental Contamination
How does Ketamine work?
It does not work on the GABA receptor, it causes a dissociative Anaesthesia via dissociating the Thalamus from the hemispheres of the brain. These work on the MDMA receptors, it blocks these receptors blocking the Calcium from entering the synapse
- What is this grip called?
- Why do we use it?
- Finger-tip grip
- Cuts with the belly of the blade, avoids choppy strokes, Firm, precise and long stroke.
- Free hand to put tension on the tissue.
Side Effects if Propofol?
- GABA receptor ON = Brain OFF
- Decreased Heart Contractility
- Vasodilation
- Respiratory Depression APNEA
Thiopentone
Administration
Onset
Duration
General
Thiopentone - Barbitunate
- Administration
- IV (Causes necrosis when Paravenous)
- Onset
- One Circulation Time
- Duration
- 10 mins
- General
- Arrousal due to redistubition
- Dont use in Greyhounds
- Reduce Seizure Activity
- Reduced ICP
- Powder - 2.5% solution
- five the first 1/3 quick Then the remainder titrate to effect
Acepromazine
- Administration
- Onset
- Duration
- General
- Administration -
- IV, IM, SC, PO
- Onset -
- 20-30 mins
- Duration -
- 6 hours
- General -
- Attention in MDR1 -/-
- Do not give to Boxers
When premedding Smallies/Horses what do you want in one and not in the other
Horses you do not want Muscle Relaxants
When using a doppler to measure Blood pressure, when the sound returns as we reduce the pressure in the cuff, what does this messure?
Systolic Blood Pressure
- When do we use a non-rebreathing system?
- What are the advantages to Non-rebreathing system?
- Animals <15kgs Body Weight
- Less Resistance (no soda lime, no valves)
- Less equipment dead space
How is the Heart rate / pulse rate assessed?
- Pulse Rate : Palpate pulse
- Heart Rate : Stethoscope
- Pulse Oximetry
- ECG
What are the volatile Anaesthetics used in Veterinary medicine?
- Isoflurane
- Sevoflurane
What is a Biomaterial?
A Biomaterial is any substance that has been engineered to interact with biological systems for an intended therapeutic or diagnostic purpose.
- May be placed inside or outside the body.
- May be temporary or intended to be permanent
- May be designed as reactive or unreactive
During ANaesthesia what can cause an increase in BP?
Difference between Tranquilisation and Sedation
- Sedation - Arousable
- Tranquilisation - Animal will respond eg calling the dog to follow you then it will go back to sleep. Stop stimulus and the animal is down again.
What are the 3 groups of Analgesia used in Veterinary medicine?
- Opioids
- NSAIDS
- Other Analgesics
When Anaestising a cat like this what do we need to take into account?
No Barbiturate due to the low body weight they will lose a lot of heat. Barbiturate lowers body temp
Benzodiazepine
- What is its mode of action?
- It has a binding site within the GABA receptor which when bound makes it easier for the GABA receptor to open and allows Chloride to inter the cell which causes hyperpolerasiation - the cell becomes less excitable therefore falling asleep
Buprenorphine
Administration
Onset
Duration
General
Buprenorphine - Partial Mu agonist
- Administration
- IV, IM
- Onset
- 1 - 3 mins (IV) - 15 mins (IM)
- Duration
- 2-4 hours
- General
- Scheduled Drug
- Analgesia slightly higher than morphine - Ceiling Effect
- Hyperthermia in Cats
High affinity for the receptor hard to kick off
What is the mechanism of action for a local anaesthetic?
The drug diffuses over the cell membrane (into the neuro fibre) and then when the Na+ channel opens at depolarisation it binds on the inside and blocks the channel.
It must be activated before local can have an effect. This is acheived for example pulling on the ovary and the stretch receptors go off, HR increases, splash on Local and it has immidiate effect.
Benzodiazepines
- Administration
- Onset
- Duration
- General
Diazepam/Midazolam
- Administration
- IM, IV, SC, PO or rectal
- Onset
- 1-3min IV, 30min PO
- Duration
- 45min - 3 hours
- General
- Diazepam always IV
- Midazolam: Water soluable = IM, SC or CRI
Azaperone
- Administration
- Onset
- Duration
- General
Azaperone - Neuroleptic
- Administration
- IM
- Onset
- 10mins
- Duration
- 2-4hours
- General
- Used only in pigs
What animals have a higher mortanility rate?
- Horse
- Dogs <5kg
- Cats <2kg
- Rabbit (1:72)
- Guinea Pig, Hamster (1:25)
Extremes in animals, eg Fat, Skinny, Brachiocephalic
What are the 9 points to consider when you need to anaesthetising an animal?
- Patient factors / Signament
- History
- Physical Examination
- Preanaesthetic considerations
- Anaesthetic protocol
- Premedication
- Induction
- Maintenance
- Recovery / Post operative Analgesia
- When do we ventilate an animal
- How do we monitor Ventaliation?
- When is it hypoventalating
- Monitoring the CO2 levels
Morphine
- Administration
- Onset
- Duration
- General
Morphine - Pure Mu Agonist
- Administration
- IV, IM
- Onset
- 1-3mins (IV), 15mins (IM)
- Duration
- 2hours
- General
- Emetic
- IV: Causes histamine release
- Scheduled Drug
- Gold Standard Analgisic
- EMETIC
Butorphonal
Administration
Onset
Duration
General
Butorphonal - Kappa agonist, MU antagonist
- Administration
- IV, IM, SC
- Onset
- 3 min (IV), - 15 Min (IM)
- Duration
- 1-2 hours
- 45mins only in cats
- General
- No Scheduled Drug
- Analgesia slightly higher than morphine - Ceiling Effect
- Antitussive / Antiemetic
What does Anaesthesia mean?
Lack of sensation
What are the two groups of Anaesthics?
- Injectable - Alfaxan, Propofol
- Volitile - Isoflurane,
Robivacaine 0.75%
- How is it administrated?
- What is the Onset time?
- What is the duration?
- What happens if given IV?
- What should you always do before injection?
- Local Block only NEVER IV
- Onset - 20mins
- Duration 4-6 hours
- Cardiovascular toxicity when given IV –> less cardiotoxic than bupivacaine, Seziures when given IV
- Always aspirate before injection
Your animal’s mucous membranes are pale, what does this tell you?
- The animal is either in pain or cold (Vasoconstriction)
or
- Amaemia or Blood Loss
List the types of cutting you can do with scissors
- Sharp Dissection (only ends of blades)
- Push Cutting (form of sharp dissection, Long inscision or thin, delicate tissue)
- Blunt Dissection
Dexmedetomidine
Administration
Onset
Duration
General
Dexmedetomidine - Alpha 2 agonist
- Administration
- IV, IM
- Onset
- 2mins (IV), 10mins (IM)
- Duration
- 30mins - 2 hours dose dependent
- General
- Less side effects than medetomidine but potent analgesic
- Hypertension followed by normotension
- Not licensed in Horses
When performing ligatures on an Artery and a seperate vein explain how you would place your ligatures
- First circlarge ligature will always be on the Blood flow side to slow down the blood.
- Second another circlarge will be on the distal side of where you will cut to stop blood flowing back after the cut and making a mess. This isolates your section.
- Third is a transfixing and will always be on the side closest to the cut but on the side that is remaining with the animal.
Ketamine
Administration
Onset
Duration
General
Ketamine - Dissacoative Anaesthetic
- Administration
- IV, IM, SC, PO
- Onset
- 3min (IV), 10min (IV)
- Duration
- 1 hour Dose dependent
- General
- Reflex’s are maintained
- Cataleptic state (must be combined with a muscle relaxant)
- Abuse
- Increases ICP (High Dose)
What are some consequences of Hypothermia during and after surgery?
- CNS Depression : Increased sensitiviy to drugs
- Prolonged Recovery (decreased drug metabolism)
- Increased Haemorrhage
- Hypotension : Bradycardia/vasodilation
- Decreased Immunity and increased infection
- Shivering (in recovery) and increased oxygen comsumption
What is the critical time of surgery that increases risk of wound infection?
90mins
What do we need to pay attention to when giving cats Opioids (especially Buprenorphine)
Causes Hyperthermia (Do not give antibiotics!! its a normal side effect)