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The means the loss of sensation
This refers to the reversible state of unconsciousness, immobility, muscle relaxation and loss of sensation throughout entire body
This refers to the specific stage of general anesthesia that allow procedures to be performed without pain or movement
surgical anesthesia (stage 3 plane 2)
This refers to a drug-induced CNS depression and drowsiness with mild analgesia
This refers to a drug induced state of calm and unconcern without analgesia
This refers to the stage of anesthesia where the patient is awake by may react unpredictably
pre-narcosis : stage 1
This refers to the stage of anesthesia where the patient loses consciousness but still has all reflexes
narcosis : stage 2
Which stage of anesthesia is a bite likely to occur?
narcosis : stage 2
This refers to the stage of anesthesia where the swallowing reflex is abolished and intubation can take place
Unconsciouness : stage 3 plane 1
This refers to the stage of anesthesia where most reflexes are abolished and surgical intervention can take place
surgical : stage 3 plane 2
This is a sub stage of unconsciousness where respirations fall below 12/min, blood press is less than 79 mmHg, capillary refill time > 2 second and under the tongue is gray with lowered oxygenation
Stage 3 plane 3
This is a sub stage of unconsciousness where cardiac and respiratory arrests begin, eyes fully dilate and remain fixed
Stage 3 plane 4
This refers to the stage of anesthesia where complete cessation of respiration and total circulatory collapse occur
Death : stage 4
An artificially induced sleep with marked analgesia although there is some visceral pain
This refers to the loss of sensation in a small area of the body produced by injection of anesthetic agent in proximity of the area of interest
This type of anesthesia is the loss of sensation in a limited area produce by an agent injected in close to nerves supplying that area
2 types of regional anesthesia
This is involuntary state of rigidity with analgesia, amnesia and immobility caused by CNS stimulation rather than depression often associated with cyclohexamines
This refers to a type of anesthesia produced by combining a tranquilizer and an opioid
neuroleptanalgesic - Innovar-vet
What to drugs make up Innovar-Vet
- droperidol (tranq)
- fentanyl (Duragesic patch) (opioid)
This type of anesthesia refers to the use of a combination of drugs in smaller quantities that maximized benefits, minimizes adverse affects and produces the appropriate degree of anesthesia to the patient and procedure
How must the anesthetist approach each and every anesthetic procedure?
They must take a genuine interest in the well-being of the patient by taking personal responsibility
These life phases are the most critical for all surgery patients
This refers to a patient that has reached 75% of its life expectancy for that breed
This means to give a drug until the desired level of effect is attained rather than the entire recommended dosage
dose to effect
With the exception of mitral valve insufficiency patients what is generally advocated for geriatric patients?
Due to geriatric reduced tolerance to hypotension and ability to concentrate urine what is usually advocated until the time of anesthesia?
Give access to water
This means less than 2 weeks old
This means between 2-8 weeks old
At what ages do veterinarian commonly consider neonatal and pediatric?
- neonatal: less than 3 months
- pediatric: before the animal reaches puberty
Considerations to aid the anesthetist
- 1. Availability of equipment and facilities
- 2. Familiarity with anesthetic agent
- 3. Knowledge of procedure required
- 4. Individual Patient Problems
- 5. Cost of procedure
- 6. Speed of surgeon
What are the 3 general areas of breed considerations?
- 1. Anatomical differences
- 2. Variable responses regarding barbiturates
- 3. Propensity of heat loss/gain
Generally which dog breeds experience heat loss?
Generally which dog breeds experience heat gain?
large fatty breeds
What condition can arise regarding body temperature and the administration of sevo/isoflurane?
Why is pre-operative fasting not recommended for neonatal patients?
Hypoglycemia and dehydration are highly likely to occur
Which crystalloid may be used instead of LRS in a neonatal patient?
Dextrose 5% in water
Why is it important especially with neonates to get an accurate weight before surgery?
To calculate anesthetic doses correctly since the have a very narrow margin of error
Why should injectable pre-anesthetics like acetylpromazine, xylazine or barbiturates be avoided in neonatal patients?
Due to immature liver they are inefficient in metabolizing these drugs
What is the preferred method of anesthetizing neonatal patients?
Use of a mask to "gas down" the patient with inhalant anesthetics like sevo/isoflurane
This term describes an animal that is 1/2 again over their optimal weight
Patient Preparation steps:
- 1. Preliminary General Examination
- 2. Efforts made to correct any concurrent illness several days ahead
- 3. Fast patient for 8-12 hours (water ok until anesthesia induction)
- 4. Check all anesthesia and surgery equipment
- 5. Ensure indwelling catheter is in place, patent and fluids are flowing
- 1. Fluid administration during surgery
- 2. Rapid administration of emergency drugs
- 3. Multiple syringe drug administration
- 4. Protects against perivascular irritation from highly alkaline drugs
- 5. Prolonged administration of antibiotics/analgesic
This type of catheter is primarily used in equine medicine that involves administering fluids through the jugular vein.
Through the needle
This type of catheter uses a long thin needle to insert it into the vein more commonly used with small animal practices.
Over the needle
This is the term for the long thin needle in a catheter
Maintenance fluid rate for canines over 20lbs
Maintenance fluid rate for canines 20lbs and under and felines
Surgery fluid rate
Shock fluid rate for canines
Shock fluid rate for felines
Rapid rehydration rate for canines
20mL/# for the 1st hour then lower to maintenance rate
Rapid rehydration rate for felines
10mL/# for the 1st hour then lower to maintenance rate
This type of fluid is commonly used during a state of acidosis (95% of shock patients)
Lactated Ringers Solution
This type of fluid is primarily used with vomiting and diarrhea cases
0.9% Normal Saline
note: replaces Na+(diarrhea) and CL-(vomiting) that is lost
This type of fluid is primarily used in equine medicine during a state of alkalosis
Ringers solution (is acidic)
This is a blood substitute made from bovine hemoglobin that does not require blood typing
Classes of drugs commonly used as pre-anesthetics
- 1. Alpha-2 agonists
- 2. Cyclohexamines
- 3. Opioids
- 4. Anticholinergics
- 5. Tranquilizers
Reasons for Pre-anesthetic use:
- 1. Reduce the amount of general anesthetic required to induce anesthesia
- 2. Calm or sedate excited/vicious animal
- 3. Reduce side effects from general anesthetic use
- 4. Decrease post operative pain/discomfort
List Anticholinergic drugs:
- Diethyl ether - no longer used
- Glycopyrrolate (Robinul)
These causes of vagal bradycardia are the reason why anticholinergics are given
- Manipulation of the eye
- Traction of deep visceral organs
- Direct vagal stimulation
- Endotracheal intubation
Effects of Atropine
- 1. Increased heart rate
- 2. Decreased saliva/respiratory secretions and intestinal motility
- 3. Bronchodilation
- 4. Mydriasis
Manufacturers of atropine sulfate
- Atoject - Vetus Animal Health
- Atropine - Butler Company
What is Atropine derived from?
Atropine specific mode of action
Competitive antagonist of muscarinic cholinergic receptors
Species Atropine is approved for:
Advantages of Glycopyrrolate over Atropine
- 1. No CNS effect/Does not cross blood-brain barrier
- 2. Longer vagal blocking activity
- 3. More pronounce antisialagoue
- 4. Less tachycardia/arrythmias
- 5. Longer half life
This refers to the time it takes for the concentration of a drug in the blood to decrease by one-half.
Glycopyrrolate dose strength
0.005 - 0.010 mg/kg IV
What is the disadvantage of glycopyrrolate
- Dog/Cat/Horse: 0.01-0.02mg/kg IV
- Cattle: 0.02-0.04mg/kg IV
Manufacturers of Glycopyrrolate
Robinul - Baxter Healthcare Corp.
Species Glycopyrrolate is approved for:
Glycopyrrolate is what type of compound?
Quaternary Ammonia Compound
Specific method of action of Glycopyrrolate
Muscarinic receptor antagonist
What is the anticholinergic of choice for lagomorphs?
The routine use of glycopyrrolate in horses can produce which conditions
Ileus and colic
Of the many reasons of choosing glycopyrrolate over atropine, these two are considered primary:
- 1. longer acting
- 2. safer on to use in animals with preexisting heart condition d/t less tendency towards cardiac arrhythmias/tachycardia
This class of drugs produce a calm and unconcerned state but do not provide analgesia
What is the primary disadvantage to tranquilizers?
Phenothiazine traquilizer effects:
- Lengthens the effect of general anesthetics and reduces the amount necessary
- Alpha 2 antagonist
- Prolongs and ensure mild recovery when used with sedatives and hypnotics
Onset of effect for Acetylpromazine
- IM: 10-15 minutes
- Oral: 1 hour
Duration of Acetylpromazine
- Generally 4-8 hrs
- Geriatrics/hepatic dysfunction: up to 48 hrs
- Cattle: 82 hrs
Manufacturers of Acetylpromazine maleate
- PromAce: Ft. Dodge
- Aceproject: Vetus Animal Health
Species Acetylpromazine approved:
- Horses - not intended for food
Adverse affects of Acetylpromazine
- Peripheral Vasodilation (hypotension)
- Reduces seizure threshold
- Splenic engorgement by sequestration of RBCs (drops HCT by 50%)
- Priapism in stallions (penile prolapse)
- Can inhibit temperature regulation
The main difference between a sedative and a tranquilizer:
Sedatives provide analgesia
Thiazine Derivatives/Alpha-2 agonists:
General Sedative side effects:
- Repiratory Depression
- Bradycardia and hypotensive heart block
- Rumenal Tympany
- Hepato and Nephrotoxic
Xylazine side effects:
- Vomiting in cats (90%) and dogs (50%)
- Reduces secretion of insulin causing transient hyperglycemia
- Decreases minimum alveolar concentration & other requirements for other anesthetics
Alpha-2 agonist method of action:
Stimulate Alpha 2 adrenergic receptors of the brain and spinal cord to decrease the level of nor-epinephrine resulting in sedation/analgesia/muscle relaxation
This drug is considered the prototypical Alpha-2 agonist
In 1962 Xylazine was first synthesized for what purpose?
Anti-hypertensive in humans
What species of animal was Xylazine first used in Europe?
Manufacturers of Xylazine
- Sedazine - Ft Dodge
- Rompun - Bayer
- AnaSed - Lloyd Inc.
- gen. Xylazine - Butler
- X-ject E & SA - Vetus Animal Health
Reversal agent for Xylazine
Xylazine dose strengths
- 20mg/mL (sm. animal/Cattle)
- 100mg/mL (horses)
0.25mL/20lb IV canine only
Advantage of detomidine over xylazine
2x the half life
Detomidine should not be given to horses with which conditions?
- 1. Renal disease
- 2. Respiratory disease
- 3. Colic pain
- 4. Endotoxic shock
This thiazine derivative has a higher than normal degree of selectivity for Alpha-2 binding sites
Dexmedetomidine (DexDormitor) - Pfizer
Dexmedetomidine onset times:
- IV - 5 minutes
- IM - 10 to 15 minutes
Reversal Agent for Dexmedetomidine
Atipamazole (Antisedan) - Pfizer
Drugs in the Benzodiazepine class:
- Diazepam (Valium) - human C-IV
- Zolazepam (only with Tiletamine in Telazol) C-III
- Midazolam (Versed) - human C-IV
- Lorazepam (Ativan) - human
Benzodiazepine method of action
Stimulates the release of gamma-aminobutyric acid (GABA) mainly but also some glycine to inhibit neurotransmission in the brain and spinal cord
Diazepam common uses:
- 1. Antianxiety - calming
- 2. Skeletal muscle relaxation
- 3. Anticonvulsant
- 4. Relatively safe with patients with cardiac/respiratory issues
Why is diazepam not drawn up ahead of time nor mixed with most drugs?
It will absorb into plastic and is physically incompatible with most drugs because if its water insolubility
What other considerations are there when handling/using diazepam?
- 1. It is light sensitive
- 2. Will cause cardiac arrhythmia if given rapidly
What is the only benzodiazepine approved for cats and dogs?
Zolazepam in Telazol
Why is Telazol painful upon injection?
low pH (2.2-2.8)
- Dogs/cats - 0.1-0.2mg/kg IV
- Horses - 0.01-0.03mg/kg IV
Why must the corneas be protected from light and lubricated when Telazol is given?
The cyclohexamine tiletamine will cause the eyes to remain open
Advantages of midazolam over diazepam
- 1. water soluble - can be mixed with other pre-anesthetics
- 2. less tissue irritation
- 3. quick onset - 3 min
Drugs in the Opioid Class:
- Morphine sulfate
- Meperidine HCL (Demerol)
- Pentazocine (Talwin)
- Oxymorphone (Numorphan)
- Hydromorphone (Dilaudid)
- Butorphanol (Torbutrol,Torbugesic)
- Fentanyl (Duragesic)
Name the 5 opioid receptors:
- 1. CNS receptors are stimulated (pure agonist) or blocked (mixed/antagonist)
- 2. superior analgesia
- 3. Do not cross blood-brain barrier
- 4. Reversible
The three most common opioid analgesics in veterinary medicine:
Opioid Adverse effects:
- 1. Profound respiratory depression
- 2. Bradycardia
- 3. Increased intestinal peristalsis followed by stasis
- 4. Physical dependence
Which opioid is primarily a human drug but useful in cats at low dosages?
Meperidine HCL (Demerol)
Which opioid was replaced by Banamine for colic in horses?
This opioid is no longer available in the US.
This opioid replaced Oxymorphone
Which form of butorphanol is used in dogs as an antitussive?
Which form f butorphanol is used in primarily in large animals?
This refers to the combination of an opioid and a tranquilizer
Name a commercially available neuroleptanalgesic and its constituents
- droperidol - tranquilizer
- fentanyl - opioid
Nickname for Malignant Hyperthermia
Porcine Stress Syndrome
As a result of Malignant Hyperthermia control of which mineral regulation is lost at the level of the skeletal sarcoplasic reticulum?
What breed of dog does Malignant Hyperthermia occur in mostly?
What breed of horse does Malignant Hyperthermia occur in mostly?
This is the muscle relaxant used to pretreat animals to prevent Malignant Hyperthermia
Dantrolene sodium (Dantrim)
What type of gene is associated with Malignant Hyperthermia?
This refers to the process by which an animal loses consciousness and enters surgical anesthesia
What is the main goal of anesthetic induction?
To take the patient from consciousness to Stage 3, plane 2 smoothly and rapidly in order to place an endo-tracheal tube
List the injectable anesthetic by class (or drug if no class exists):
List the inhalant anesthetics
- Diethyl ether
- Nitrous Oxide
Outline the phases of General Anesthesia
- 1. Pre-anesthetic Phase
- a. Minimum Patient Database
- b. Fasted 8-12 hours
- c. Administer Pre-anesthetic drugs
- d. Administer Basal Anesthetic
- 2. Induction Phase (Stg 3, pln 2)
- 3. Maintenance Phase (maint of Stg3, pln 2 not motion)
- 4. Recovery Phase (RVT solely responsible for patient's life)
Steps for General Anesthesia Safety
- 1. Know your drugs before administration
- a. how is drug eliminated
- b. which cross blood-brain barrier
- c. reversal agents available
- 2. Preanesthetics to:
- a. reduce secretions and prevent bradycardia
- b. reduce amount of gen. anesthesia to speed induction/recovery
- 3. Double check dosages with DrY/Denise/Kathleen
- 4. Give basal to effect
Pupil size in terms of anesthetic depth (not on anticholinergics)
- Stage 1 - normal
- Stage 2 - smaller diameter
- Stage 3 - smaller still
- plane 1 - Same as stage 3
- plane 2 - same as stage 1
- plane 3 - Pupils start dilation
- plane 4 - Dilation continues
- Stage 4 - complete dilation and fixed
Procedure that constitute "no pain" requiring only moderate sedation with small analgesia
- Physical examination
- Suture removal
- Bandage change
- Cast application
- Nail trim
What is considered a minor pain level?
Heavy sedation with analgesia or short anesthesia
What procedures constitute minor pain?
- Urinary catheterization
- Dental cleaning
- Ear treatment
- Abscess lancing
- Cutaneous growth removal
What is considered a moderate pain level?
- Needs pre-anesthetics
- General Anesthesia
- Possible post-op pain management
What procedures are considered moderate pain level?
- Dental Extraction
- Cutaneous Mass
What is considered a severe pain level?
- Analgesic premedication
- General Anesthesia
- Post-op pain management essential
What procedures constitute severe pain level?
- Fracture repair
- cruciate ligament repair
- Ear canal ablation
List drugs in Cyclohexamine class:
- Phencyclidine (C-I) "Angel Dust, PCP"
- Ketamine (Ketaset, Vetalar, Vetamine, Ketaject)
- Tiletamine - only as a component of Telazol
- Good somatic analgesia but not visceral
- Induces catalepsy but is temporary
- Lowers seizure threshold
- Can be given orally to fractious animals
Cyclohexamine recovery times:
- Horses IV: 20-30 min
- Dogs IV: 2-24 hours
- Cats IM: 3-6 hours
Two reasons why barbiturates are still used today.
- 1. easy to administer
- 2. inexpensive
What are the 2 major drawbacks of barbiturates?
- 1. Highly alkaline - will cause tissue necrosis down to the bone
- 2. Short period of apnea
How do barbiturates cause apnea and what drug was developed because of it?
- 1. Causes a decreased response of the CO2 receptors in the Aortic arch and Carotid sinus
- 2. Doxapram was developed to make the receptors more sensitive to CO2
This is the term given to drugs like Doxapram that make receptors in the aortic arch and carotid sinus more sensitive to CO2
Two ways in which barbiturates are classified
- 1. By the length of their action
- 2. By their side chain
List the barbiturates according to their length of action.
- Ultra short acting: 10 minutes
- Thiamylal sodium (Biothal)
- Thiopental sodium (Pentothal)
- Methohexital (Brevane)
- Short acting: 45 min - 1hr
- Long acting: 6-7 hrs to 24 hrs
List the barbiturates according to their side chain
- Oxybarbiturates (oxygen)
- Thiobarbiturates (sulfur)
- Thiamylal sodium (Biothal)
- Thiopental sodium (Pentothal)
- Methohexital (Brevane)
This term refers to a drug that has been around so long that it no longer has a proprietary name
All opioids are reversible by these two drugs:
- Naloxone (Narcan)
- Nalorphine (partial antagonist)
This opioid is used exclusively by zoos and wildlife parks and is considered the most concentrated of the opioids
Advantages of propofol
- Ideal for short procedures without gas
- Easy induction and transition to gas
- Safe for sighthounds and geriatrics
- Minimal effect on cardio and respiratory systems
- Full standing recovery in 20 minutes
- Repeat doses will not increase recovery time
Disadvantages of propofol
- Rapid administration can cause cardiopulmonary depression
- Because it is an emulsion, vials are single use to prevent bacterial contamination
- Injections need to be titrated to patient's response
- May induce myoclonus
Manufacturers of Propofol
- PropoFlo - Abbott Laboratories
- Propofol - Baxter
- Rapinovet - Schering-Plough
Species approved for Propofol
This is a brief involuntary twitching of a muscle or muscle group often seen with propofol use.
This is a condition in cats repeatedly dosed with propofol.
Heinz bodies - hemoglobin precipitates out of the red blood cell
These two chemicals are produced by the body that stimulate the opioid receptors.
These 4 drugs stimulate all 4 opioid receptors
- Morphine sulfate
- Meperidine (Demerol)
- Fentanyl (Duragesic)
- Hydromorphone (Dilaudid)
This opioid is considered a pure antagonist thus the reversal agent that acts on all opioid receptors
This opioid receptor is more known for producing euphoria and hallucinations (dysphoria) when stimulated
These two opioid receptors both produce sedation, analgesia and respiratory depression when stimulated.
This opioid receptor is more known for producing motor dysfunction as well as analgesia.