Week 6 - Pre-Anesthetics Flashcards by Christine Parascandola

Anesthesia is defined as a state of ______, _____ loss of _______ or ______
that is induced for medical purposes.

controlled, temporary, sensation, awareness

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In what situations is anesthesia used?

It is used daily in most veterinary practices to provide
* For diverse range of indications including
 Sedation
 Tranquilization
 Immobility (very important)
 Muscle relaxation
 Unconsciousness
 Pain control

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What indications is anesthesia used for?

 Surgery
 Dentistry
 Grooming
 Diagnostic imaging
 Wound care
 Capture/transport of wild animals

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What is difference between being
1. Fully conscious
2. Unconscious
3. Sedated
4. General Anesthesia

Fully conscious: patient is awake but under sedation (light, moderate, or deep).

Unconsciousness: general anesthesia –> light, moderate, deep, ___.

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Define local anesthesia. Provide examples.
Is the patient awake or asleep?

Local anesthesia: numbs a small section of the body. Examples: cataract
surgery, a dental procedure or skin biopsy.
Patient is awake during the procedure.

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Define regional anesthesia
Provide examples.
Is the patient awake or asleep?

Regional anesthesia: blocks pain in a larger part of the body. Examples:
an epidural, a spinal for hip or knee surgery, or an arm block for hand surgery. Patient can be conscious during the procedure, or have sedation

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Define general anesthesia
Provide examples.
Is the patient awake or asleep?

General anesthesia: makes you unconscious and insensitive to pain or any other stimuli. General anesthesia is used for more invasive surgical
procedures, or procedures of the head, chest, or abdomen.
Patient is not awake.

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Define sedation
Provide examples.
Is the patient awake or asleep?

Sedation: relaxes to the point where patient can be easily aroused or awakened. Much easier than anesthesia.

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Different anesthetic procedures for patients based on preexisting conditions:
Type of surgery
Age of the animal
Financial situation of the owner b/c it is expensive.

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Describe stage 1 of Anaesthesia.

Stage 1 of anesthesia is Analgesia. It is characterized by Disorientation in humans,
in pets – sometimes not obvious.
Analgesia without amnesia (loss of memory).

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Describe stage 2 of anesthesia.

Stage 2 is called excitement
The goal of stage 2 of anesthesia is to move through this stage as rapidly as possible. Nausea, vomiting, hyperactivity, and irregular respiration can occur in this stage.
Animals should fast before surgery. Vomiting –> chance of aspirating

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Describe stage 3 of anesthesia.

Stage 3 is called surgical anesthesia
The goal of this stage is muscle relaxation, complete loss of pain sensation. Characterized by sleep, normal respiration, and blood pressure.

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Describe stage 4 of anesthesia.

Stage 4 is called medullary depression.
If a patient is too deep at this is considered an anesthetic crisis.
During this stage vasomotor and respiratory centers are depressed –> can lead to coma and death. This stage is also called anesthetic crisis.

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An Anesthetic is a drug used to induce a loss of ______ with or without ______

sensation, unconsciousness

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Adjunct is a drug that is not a ____ anesthetic, but that is used during anesthesia to produce other desired effects such as ?

true, sedation, muscle relaxation, analgesia, reversal, neuromuscular blockade,
or parasympathetic blockade

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Explain the anesthetic drug policy.

Policy:
* The anesthetic protocol, dose, and route are chosen by the Veterinarian
* Many clinics have a routine protocol, but it is important to consider all aspects of the patient’s minimum database (clinical history, age, etc).

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When are pre-anesthetic medications used?

Used prior to the administration of an anesthetic agent to make anesthesia safe and
more agreeable to the patient.

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What are pre-anesthetic medications used for?

Used:
* For sedation, to reduce anxiety (benzos come in here) and apprehension
* To obtain an additive or synergistic effect so that induction could be smooth and rapid.
* To counteract certain adverse effects of anesthetic drug.
* To relieve from pain (analgesia).

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What are the routes of administration for pre-anesthetic medications?

Routes of administration:
* SC: slowest onset, longest duration
* IM: faster onset, shorter duration
* IV: fastest onset, shortest duration

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What are the effects of pre-anesthetic medications and adjuncts?

Calm and sedate excited animal
Minimize adverse drug effects
Reduce dose of concurrent drugs
Smoother anesthetic induction and recovery
Provide Analgesia
Muscle relaxation

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Opioids provide?

analgesia

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Tranquilizers provide?

provide pre-operative sedation and amnesia and help to prevent or counteract the CNS
stimulation caused by some anesthetics.

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Central muscle relaxants provide?

muscle relaxation during anesthesia

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Anticholinergic agents prevent?

profuse salivation and bradycardia

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Pre-anesthetic medications generally include combinations of drugs from multiple categories:

 Opioids (Morphine)  Phenothiazine tranquilizers (Acepromazine) pathway they travel down? Dopaminic  Benzodiazepines (Diazepam) pathway = GABA  α2-Agonists (Xylazine)  Anticholinergics (Atropine)  Muscle relaxants (Baclofen)

What pathway do tranquilizers travel down?

Dopaminic

What pathway do benzos travel down?

GABA

Most general anesthetics are not?

analgesics

True analgesics don’t provide ?

general anesthesia

Patient will feel pain after surgery if we don’t give?

anesthetics with analgesics

Opioids are commonly used for ________ and _________ analgesia

premedication, perioperative

Morphine is safe, effective analgesic for most small animal patients. * Effective for mild and severe pain * Added benefit of being a good sedative for dogs.

Butorphanol: partial agonist (μ), +++ (k) * Keep analgesia, reversal of sedation and respiratory depression

Pre-anesthetic * agonists, partial agonists, or mix agonist-antagonists * May be used alone or in combination with - Tranquilizers - Anticholinergics

What is the purpose of administering pre-Anesthetic Tranquilizers

Reduce anxiety, produce calming, enhance CNS depressant and analgesic effects of other anesthetic drugs

Phenothiazine: Acepromazine (ACE) is an ____ sedative admnistered before?

oral, stressful events (such as thunderstorms)

What is Phenothiazine/ACE used to treat?

motion sickness and nausea associated with car or plain rides

ACE * Pre-anesthetic sedation * Decrease dose of general anesthetic * Not a pain reliever (that is why it is used in combination with opioids) * May be used with opioids for minor procedures * Approved for horses, dogs, and cats * Administered IV or IM * Easy induction and recovery * No reversal agent * Metabolized by liver * Will slowly cross the placenta * FDA approved

Acepromazine has an Increased potency and long duration (10-20 times more potent than chlorpromazine) Caution: geriatrics, neonates, debilitated animals.

What breed considerations should be taken into account when administering ACE?

Breed considerations : may have increased risk of side effects Australian shepherds (MDR1 mutation - glycoprotein that is important for drug transport, metabolism, excretion, dristribution, etc - mutation --> drug toxicity.) (less dose) Giant breeds, boxers, greyhounds, bulldogs (less dose). Terriers and cats (may require more dose of ACE)

If you administer too much ACE (overdose), what reversing agent can be used?

Norepinephrine

Describe the effects on the CNS when ACE has been administered

* Calming, reluctant to move, decreased interest to surroundings * Sedation less pronounced in cats * Not an analgesic

Describe the effects on the cardiovascular system when ACE has been administered

Peripheral vasodilation that leads to hypotension, decreased heart rate (bradycardia), and hypothermia * Protects against arrhythmias

Describe the effects on the respiratory system when ACE has been administered

Without significant respiratory depression

Describe the effects on the GI system when ACE has been administered

Antiemetic

Describe the adverse effects of ACE on the CNS?

Adverse Effects: * CNS: reduced seizures threshold may produce aggression or excitemen

Describe the adverse effects of ACE on the Cardiovascular system?

hypotension (dose-dependent)

Describe the adverse effects of ACE on the the penis?

Penile prolapse seen in horses and other large animals may lead to permanent injury

What can happen to an animal's PCV after ACE has been administered?

Decreased packed cell volume (PCV) up to 30% ( anemia )

Pre-Anesthetic Benzodiazepines (BDZs) produce?

Produce anxiolytic, anticonvulsant, and muscle relaxant effects, potentiate general anesthetics

Name the Pre-Anesthetic Benzodiazepines (BDZs)

* Diazepam (Valium R ) * Zolazepam * Midazolam * Clonazepam

Describe the pharmacological effects of BDZ's on the CNS.

* Calming and antianxiety (old or ill patients) * Not an effective sedative or analgesic * Anticonvulsant * Appetite stimulation (cats and ruminants)

Describe the pharmacological effects of BDZ's on the cardiovascular system.

* Minimal effect with a high margin of safety THIS IS VERY IMPORTANT

Describe the pharmacological effects of BDZ's on the respiratory system.

* Skeletal muscle relaxation Benzodiazepines (BDZs)

Diazepam (Valium) * Not ______ _____ * Don’t mix with _____-___ drugs and don’t store in ____ * Store in ____ * Commonly use with ketamine (in general can be used in combination) to induce anesthesia in small animals and horses (not as much now) * Slow IV administration

water soluble, water-soluble, plastic, dark

What are the adverse effects of Diazepam (Valium)?

* Disorientation and excitement: young, healthy dogs (paradox) * Dysphoria (dissatisfaction with life) and aggression: cats * Muscle fasciculations (eyelid twitch or leg spasm): horses * Ataxia and recumbence: any large animal b/c damages cerebellum and spinal chord. * Diazepam must be given slowly (IV) * Oral diazepam in cats can cause liver damage

You have given this horse Diazepam...what has happened?

Ataxia and recumbence: any large animal b/c damages cerebellum and spinal chord.

Midozalam * Water soluble * Administration: IM or SC * Excellent sedative for swine, rabbits, and birds * Used in combination with ketamine to induce anesthesia in dogs, small mammals, and birds

Zolazepam * Available only as a component of Telazol R * A powdered product reconstituted with sterile water * Used in cats

Neuroleptanalgesia is defined as?

A profound state of analgesia and sedation induced by simultaneous administration of an opioid and a tranquilizer. Great sedation, does not care, no pain.

Which opiods cause neuroleptanalgesia?

Morphine has an affinity for mu receptors, binds to kappa Hydro is 5x more potent than morphine so it can be used in smaller doses. - = no affinity + = affinity

Which tranquilizers cause neuroleptanalgesia?

Which drug combination is the best in achieving neuroleptanalgesia?

Hydromorphone + Dexmedetomidine: the best!

What is neuroleptanalgesia mainly used for?

when you don’t want to do General Anesthesia (GA). Examples: Sedation for minor procedures * Induction of general anesthesia: in dogs (not used often)

Opiods such as Morphine and Butorphanol provide?

Analgesia

Tranquilizers such as ACE and Diazepam provide?

provide pre-operative sedation and amnesia and help to prevent or counteract the CNS stimulation caused by some anesthetics. Do not provide analgesia.

Neuroleptanalgesia:

analgesic + tranquilizer