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)
What are the side effects of Ketamine?
- Dissociative Anaesthetic, NMDA receptor blocker = Good Analgesic
- Increase’s Heart Rate
- Increases Blood Pressure (Secondary to Increased Heart Rate)
- Mild Respiratory Depression
What is Cryptic Implant Infection
Where an implant has been placed, and bacteria has caused the biofilm and infection. You treat with antibiotics and infectino clears however once AB’s are stopped the bacteria in the biofilm elvolve slightly and then start to replicate again, which again produces another infection. This keeps happening until the implant is removed. (TPLO)
Explain the concept of Biocompatibility
How does this differ from biomaterial?
- Biocompatability determins the interaction between biomaterial and tissue
- Biomaterial Acts as a foreign body when implanted
Methadone
Administration
Onset
Duration
General
Methadone - Pure Mu Agonist
- Administration
- IV, IM
- Onset
- 1-3mins (IV), 15mins (IM)
- Duration
- 2-4hours
- General
- Scheduled Drug
- Analgesia comparable with Morphine
What happens at induction?
- Injection of IV Anaesthetic
- Patient losses consciousness
- Intubation
Xylazine
Administration
Onset
Duration
General
- Administration
- IV, IM
- Onset
- 1-3mins IV, 30mins IM
- Duration
- 30-45mins
- General
- Strong emetic in cats
- Increases mortality in small animals anaesthesia - Hypertension followed by hypotension
- Used in large animals
Whats the difference between Opioids and NSAID as an analgisic?
Opioids - Symptom Pain
NSAID - Cause of Pain
In regards to Local Anaesthetics what effects do they have on
- The Brain
- The Cardiovascular System
- The Circulation
- The Respiration
- Temperature
- Vomit Centre
What methods are there to measure blood pressure?
- Non-Invasive
- Doppler
- Oscilliometric
- Invasive
- Arterial Catheter
List the 4 sympathetic receptors and what does activation of these cause?
- Alpha 1 - Skin vasoconstriction
- Alpha 2 - GI
- Beta 1 - Heart Rate increase
- Beta 2 - Respiratory Broncho Dilation and vasodilation
When using an Endo Tracheal Tube what size do we use for
- Cat
- Dog <10kg
- Dog 10-30kg
- Dog >30kg
- Cat
- 3-5mm ID (inner Diameter)
- Dog <10kg
- 5-8mm ID
- Dog 10-30kg
- 8-12mm ID
- Dog >30kg
- >12mm ID
What is the MAC for
- Isoflurane
- Sevoflurane
- Isoflurane 1.3 - 1.6%
- Sevoflurane 2.3 - 2.6%
Describe the tissue response continuum
- The Biomaterial:tissue interface is important
- Implantation results in a tissue response continuum:
- Injury - during implantaion
- Blood-Biomaterial Interaction - Vroman effect
- Inflammation and propagation of wound healing
- foreign body reaction and fibrous encapsulation
Side effects of Barbituates
- GABA receptor (extra binding site) Increases the effect
- Heart Contractility Decrease, Arrhythmogenic (bigerminus)
- Vasodilation
What side effect do Benzodiazepines have?
- Anxiolytic, mild sedation, central muscle relaxation, paradoxic reaction in young and healthy animals. NO Analgesia
- No other effects
What are the three groups of drugs used for sedation?
- Neuroleptics
- Benzodiazepenes
- Alpha-2
Alfaxalone
Administration
Onset
Duration
General
Alfaxalone - Injectable Anaesthetic
- Administration
- IV, IM, SC
- Onset
- One Circulation Time, 10mins (IM)
- Duration
- 10 mins
- General
- Give to effect. Dose depends on premedication
- Excitations during recovery
- Use vial within 24hours “better” than propofol
Why do we withold food and water before surgery?
As it increases the risk of reguration and aspiration
Of the two Volitile Anaesthetics we use which one has a quicker onset and recovery?
Why is this?
Sevoflurane is less soluable (need less molecules in the blood to be at equlibrium) therefore has quicker onset and recovery
What are some Co-Induction Agents?
- Opioids
- Fentanyl
- Remifentanil
- Central Muscle Relaxants
- Benzodiazepines
- Guaifenesin
What are the side effects of Volatile Anaesthetics?
- Unconciousness - Anaesthetised
- Decreased Heart Contractility
- Vasodilation –> Hypotension (Dose dependant)
- Respirator Depression
- Indirect Hypothermic due to Vasodilation
How long do we withold Food and Water from the following animals before anaesthesia
- Dog and Cat
- Horse
- Cow
- Heavy Bulls
- Sheep and Goats
- Pig
- Which of the 2 volitile Anaesthetics is more lipophillic?
- What does having a higher lipophilicity mean?
- Isoflurane is more lipophillic (loves to be in the brain)
- Lipophilicity determines necessary does therefore
- Higher Lipophilicity = Lower MAC
What are the side effects of Neuroleptics?
- Sedation without ataxia (Priapism and no analgesia)
- Hypotension (a1 - receptor blocker - direct vasodilation)
- Hypothermia
- Antiemitic
Medetomidine
Administration
Onset
Duration
General
Medetomidine - Alpha2 agonist
- Administration
- IV, IM, PO in aggressive cat
- Onset
- 2min (IV), 10min (IM)
- Duration
- 30mins - 2 hours Dose dependent
- General
- Most potent sedative for small animals
- Hypertension followed by normotension
- Not licensed for Horses
What is the difference between Sedation and Anaethisitised?
Sedated = Arrousable
Under the Opioids group of Analgesics what drugs are
- Pure Mu Agonists
- Partial Mu agonists
- Kappa agonists / Mu Antagonists (Mixed)
- Pure antagonists
- Pure Mu Agonists
- Morphine
- Methadone
- Fentanyl
- Pethidine
- Partial Mu agonists
- Buprenorphine
- Kappa agonist /Mu antagonists (mixed agonists)
- Butorphanol
- Pure Antagonists
- Naloxon
If Mucous membranes are bright red what could this mean?
If they are blue?
- Sepsis or Hypercapnia (Vasodilation)
- Hypoxaemia
Mepivacaine 2%
- 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?
- What animal do we use Mepivacaine in and why?
- Local Block only NEVER IV
- Onset - 10mins
- Duration 3 hours
- Cardiovascular toxicity when given IV, Seziures when given IV
- Always aspirate before injection
- Horses - Less tissue swelling
What do you need when aiming for a balanced Anaesthesia?
Cause Unconsiousness, Analgesia, Muscle Relaxation
- What does MAC stand for regarding Volitile Anaesthetics?
- Explain what MAC is
- What does MAC refer to?
- Minimum Alveolar Concentration
- MAC = Minimum alveolar concentration or MAC is the concentration of a vapour in the lungs that is needed to prevent movement in 50% of subjects in response to surgical (Painful) stimulus.
- Refers to the inhalant only, no premed, no induction agent, no analgesia
What is the mode of action for Opioids?
When opioids bind to their binding site they reduce the secomd messanger cAMP which inturn closes the Calcium (influx) channel and opens the Potassium (efflux) channel causing the neuron to becom hyperpolarized and less likely to fire an action potential
What do we see if we use Ketamine on its own?
What do we use it with ?
- Muscle Rigidity
- Use with Diazapam or Medalazam
Why can we not use Opioids for longer than 24hours in horses?
Opioids cause GastroIntestinal Motility reduction.
What is the Onset and Duration of the following local anaesthetics
- Lignocaine (Local)
- Bupivacaine
- Ropivacaine
- Mepivacaine
How can you control Haemorrage? (Extrinsic Hemostasis)
- Pressure (Small Blled Points, Sponge applied directly vertical force)
- Haemostatic Forceps (Appropriate size, use tips, tips down then flip over so suture material can be passed under)
- Large Pedicle use three Rochestor Carmauld Haemostats
- Radiosurgery (Incision, Coagulation, Desiccation, Flugaration)
What is the normal heart rate for :-
- Cat
- Small Dog
- Medium-Large Dog
- Horse
- Cat - 150-180
- Small Dog - 80-120
- Medium-Large Dog - 60-100
- Horse - 30-40
Lidocaine 2%
- Can be used as an ? to treat?
- What routes of administration can be used?
- What is the onset?
- What is the duration?
- Where is it metabolised?
- When given IV what do you need to beware of?
- Local Anaesthetic, IV analgesic, IV Prokenitic, IV Toxin Scavenger. And used to treat a GDV
- Local of IV
- Local 10-15mins
- IV - 2 mins
- Local - 2 hours
- IV 20 min (CRI)
- 100% metabolised in the liver
- It drops blood pressure so do not give if animal is hypotensive.
Pethidine
Administration
Onset
Duration
General
Pethidine - Pure Mu Agonist
- Administration
- IM (NEVER IV - Histamine release)
- Onset
- 10-15min
- Duration
- 2 hours
- General
- Scheduled Drug
- Analgesia below morphine, but good sedation
- Spasmolitic - GIT & PSS (great for Foreign Body as gut does not cramp around the FB)
What is the antagonist for Benzodiazepines?
How does it work?
Administration
Onset
Duration
General
- Flumazenil
- Kicks the Benzodiazepines off the GABA receptor
- Administration
- IV
- Onset
- 2-5mins
- Duration
- 1 hour
- General
- Specific Antagonist on benzodiazepine receptor,
- Very Expensive
What does Anticholinergic drugs do?
Decreases Parasympathetic drive - eg decreases vagal tone, therefore increases heart rate
Naloxone
Administration
Onset
Duration
General
Naloxone - Mu & Kappa Antagonist
- Administration
- IV - Emergency
- Onset
- 2 min
- Duration
- 1 hour
- General
- Specific Antagonist
- Also Antagonises endorphines
Side effects for Alfaxalone
- GABA receptor on = Brain Off (unconscious)
- Decreased Heart Contractility, Increased Heart Rate
- Vasodilation
- Mild Respiratory Depression
What are the two categories of Local Anaesthetics?
Amides
Esters
What are some commonly used biomaterials used in veterinary medicine?
- Surgical staples and vascular clips
- Tubular implants - Silicone rubber (catheters)
- Surgical Mesh
- Pacemakers
- 316 & 316L steel
- Cobalt-chromium alloys (hip replacement)
- Titanium (Plates and screws)
- Monofilament Nylon (Joint Stabalisation)
During Anaesthesia we have a decrease in Blood Pressure and a marked incread in Heart Rate, what could be causing this?
When monitoring anaesthesia what are we monitoring?
- Depth of Anaesthesia
- Oxygen delivery to tissues
- Function of the cardiovascular system
- Function of the pulmonary system
- Body Temperature
What is a Biofilm?
How is it formed?
- A biofilm is made from bacteria adhearing to biomaterial placed inside the body
- Biofilm = interface layer + Bacterial glycocalyx layer
- Biofilm Formation
- Reversible attachment
- Irreversible attachment
- Differentiation
- Detatchment
What is TIVA
PIVA
Total intravenous Anaesthesics
Partial Intravenous Anaesthesics
What are the side effects of Opioids?
- Sedation (Smallies), Box Walking (Horses)
- Bradycardia (increases Vagal Tone)
- Respiratory Depression
- Hyperthermia in cats (especially Buprenorphine)
- Emetic (Morphine), No Effect (Methadone), Antiemetic (Butorphanol)
List the important properties of biomaterial that determins its biocompatibility.
- Aim for biological inertness
- Testing for biocompatibility and against effects of
- Tissue sensitization
- Local and Systemic toxicity
- Genotoxicity, carcinogenicity and teratogenicity
- Biodegradation effect
- What drug should you not give Boxers?
- What drug should you not give to Greyhounds
- Acepromazine
- Thiopentone
What is the mode of action for Anaesthetics?
They have a binding site within the GABA receptor which when bound enhances the GABA receptor itself
When on the timeline classification would we use Opioids?
- Premedication
- Induction
- Maintenance
- Recovery
Propofol
Administration
Onset
Duration
General
Propofol - Injectable Anaesthic
- Administration
- IV
- Onset
- One Circulation time
- Duration
- 10Mins
- General
- No Analgesia
- Open Vial must be used within 24hours
- Muscle twitches
- Sedation Effect varies with dose
Define General Anaesthesia
a reversable unconciousness caused by anaesthetics
What are the Alpha 2 agonists we use in veterinary medicine?
Alpha 2 Agonists
- Xylazine - Large Animals
- Medetomidine
- Dexmedetomidine
- Detomidine
- Romifidine
ALpha 2 Antagonist
- Atipamezol
Fentanyl
Administration
Onset
Duration
General
Fentanyl - Pure Mu agonist
- Administration
- IV, IM
- Onset
- 1 min
- Duration
- 20 mins (CRI)
- General
- Scheduled Drug
- Analgesia 100 times morphine
Why does Acepromazine cause hypotension?
It acts on the Alpha 1 receptors blocking them, This turns off the Vasoconstriction of Alpha 1 causing vasodilation decreasing blood pressure.
Bupivacaine 0.5%
- 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 - 20 Mins
- Duration - 4-6 hours
- When given IV you have Cardiovascular Toxicity and Seziures
- Aspirate ALWAYS
What is Dead Space?
- Potential Space between tissues
- Fills with Blood/Serum
- Medium for Bacterial Growth
- Seperates Tissues
- Delays tissue healing
What is Arterial Blood Pressure?
Arterial Blood Pressure = Cardiac Output x systemic vascular resistance
What is the mode of action for Neuroleptics?
What is a limitation of giving a Neuroleptic?
Dopamine receptor Blocker
Must be given before the animal is agitated. Eg give it before fireworks not after the dog is agitated from them going off.
What do we monitor to ascertain Cardiac Output and Tissue perfusion
- Mucous Membrane colour
- Capillary Refill Time
- Heart Rate and Pulse Rate
- Blood Pressure
When would you use a stab inscision and with what blade?
- Into a hallow viscious
- WIth an 11 blade
What does Alpha 2 agonists drugs do to the body?
- They cause vasoconstriction in the GI (and mildly in the skin) increasing the blood pressure, increasing Afterload.
- A Reflex bradycardia (secondary)
Name the Benzodiazepines used in Veterinary Medicine for sedation
Diazepam
Midazolam