Term
| What would an IDEAL anesthetic drug do? |
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Definition
- produce unconciousness with amnesia
- provide analgesia
- provide good muscele relaxation
- result in no adverse changes to CV, Resp, Endocrine, Gi, or any other body function
- Have a high therapeutic index and high margin of safety
- be efficatious in a wide variety of species
- be effective by several different routes (IM, IV, etc)
- have a short duration of action and not accumulate
- be readily metabolized and excreted,
- have a specific reversal agent,
- have a physiologic pH;
- Not irritating to tissues
- formulated in a non-toxic vehicle;
- be chemically stable;
- have a long shelf-life
- be inexpensive |
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Term
| Injectible anesthetics provide only? |
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Definition
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Term
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Definition
| unconciousness and some analgesia |
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Term
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Definition
| Total Intravenous Anesthesia |
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Term
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Definition
| Partial Intravenous Anesthesia |
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Term
| Why is there increase in use of injectible anesthetics? |
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Definition
- marked CV depression due to use of inhyalants
- exposure of personnel to waste gases |
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Term
| Clinically relevant inj. anesthetic agents: |
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Definition
Barbiturates (Thiopental)
Non-barbiturates ( Propofol, Dissociative agents - Ketamine, Tiletamine; Etomidate, Alfaxan). |
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Term
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Definition
Propofol (manufacturing), Thiopental (due to increase in demand);
-Currently veterinarians can obtain Propofol but not thiopental; |
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Term
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Definition
FDA drug (C-III)
Ultra short acting thiobarbiturate. |
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Term
| Physical properties and Clinical Consequences of Thiobarbiturates: |
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Definition
- prepared from alkaline solutions;
- pH OF tHIOPENTAL IS BW (10.5-11)
- Incompatible with acidic solutions;
- resistant to bacterial growth;
- Multidose vials can be used over several days;
- Be careful not to inject perivascularly (highly irritant and damaging)
- better and safer use if diluted with saline or lidocaine;
- should only be administered through an intravenous catheter; |
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Term
| What are two things on which degree of ionization of Thipental is dependent upon? |
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Definition
pH
Dissociation constant (pKa) |
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Term
| _______ form of Thiopental can penetrate cell membranes? |
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Definition
| Un-ionized, nonpolar (un-dissociated) |
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Term
| In an acidic environment more of _______ form of Thiopental exists, which leads to ________ cell penetration and ________ anesthetic effect. |
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Definition
| non-dissociated, greater, greater |
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Term
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Definition
- inmportant in effectiveness of Thiopental;
- Thiopental is highly protein bound, so if the p has low protein values, its effectiveness is higher; |
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Term
| Clinical uses of neuromuscular blocking drugs |
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Definition
- to produce eyeballs that are centrally located for ophthalmic procedures;
- to reduce the amt of primary anesthetic needed to produce adequate operating conditions (most useful in sick or geriatric patients)
- to assist in reduction of dislocated joints and displaced fractures;
- to relax skeletal muscles for easier sx access;
- to control ventilation when initiating IPPV, especially during thoracic sx
- to facilitate atraumatic ET intubation in cats;
- to prevent reflex movement in delicate sxs; |
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Term
| Classification of neuromuscular blockers? |
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Definition
- Depolarizing (non-competitive): succinylcholine and decamethonium
- Non-depolarizing (competitive): long acting (pancuronium), intermediate-acting (atracurium, vecuronium), short-acting (mivacurium). |
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Term
| Depolarizing neuromuscular blockers: |
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Definition
- physically resemble ACH
- Binds to ACH receptors and generates muscle action potential;
- not metabolized by Acetylcholinesterase;
- the persistance of this agent in synaptic cleft results in prolonged depolarization of the muscle end plate;
- the continuous end plate depolarization causes muscle relaxation |
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Term
| Mechanism of muscle relaxation? |
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Definition
- after initial excitation and opening, odium channels close;
- as long as depolarizer continues to bind ACH receptors, the sodium channels cannot reopen;
- once the channels close, the action potential disappears and the membrane downstream returns to its resting state, resulting in muscle relaxation; |
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Term
| Non-depolarizing neuromuscular blockers? |
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Definition
- bind to ACH receptors;
- do not induce conformational change necessary for ion channel opening
- since ACH is precluded from binding to its receptors, no end plate potential develops resulting in muscle relaxation; |
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Term
| Commonly used neuromuscular blocking agents at UF CVM? |
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Definition
Atracurium besylate (Tracrium)
Pancuronium bromide (Pavulon) |
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Term
| Sequence of muscle relaxation: |
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Definition
- muscle of the face, jaw, tail>
- neck muscles and those of the distal limbs
- proximal limb muscles
- muscles of the pharynx and larynx
- abdominal muscles
- intercostal muscles
- diaphragm |
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Term
| Requirements before using a neuromuscular blocker? |
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Definition
- available facility to administer IPPV
- animal must be adequately anesthesized; |
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Term
| Technique of relaxant anesthesia? |
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Definition
- Administer premedication ( allows for reduction of the total amt of anesthetic for induction and maintenance)
- anticholinergic (atropine or glycopyrrolate)
-induction and maintenance (use agents based on specific case)
- Muscle relaxant (just prior to surgery to best utilize the period of paresis, IPPV is applied as soon as relaxant takes effect) |
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Term
| In what sxs should a muscle relaxant be given as soon as intubation is completed and a IPPV be administered right after induction of anesthesia? |
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Definition
| in some Cardiothoracic sxs |
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Term
| What physical characteristics should you see in a patient under full neuromuscular blockade? |
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Definition
- no jaw tone
- no pedal withdrawal reflex
- no palpebral reflex
- eyeball central
- apnea |
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Term
| What are the signs of awakening under neuromuscular blockade? |
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Definition
- tachycardia
- lacrimation
- slight muscle movement of the face, tongue (curling of the tip of the tongue), or distal limbs in response to painful stimulation.
vasovagal response (pallor of mucous membranes, reduction of perceived pulse quality due to bradycardia, hypotension, peripheral vasodilation)
- increased metabolism manifested as increase in end-tidal CO2 |
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Term
| What steps to deepen anesthesia should be taken? |
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Definition
- administer increments of IV anesthetic (Thiopental, Propofol, Ketamine)
- Increase setting of the vaporizer
- Administer additional dose of analgesic. |
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Term
| What are the 3 sites for stimulation of the nerve in monitoring neuromuscular blockade? |
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Definition
1) Ulnar (located superficially on the medial aspect of the elbow).
2) Peroneal (palpate across the shaft of the fibula, located just distal to the head of the fibula)
3) Facial ( ventral to the eye) |
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Term
| Describe a four step technique of peripheral nerve stimulation in monitoring of neuromuscular blockade? |
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Definition
1. Place two electrodes along the peripheral nerve
2) Turn on the nerve stimulator
3) Train-of-Four
4) Tetanus (nerve is simulataneously stimulated for 5 seconds at about 50 Hz) |
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Term
| What is subjective evaluation of muscle tone? |
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Definition
| The presense of spontaneous ventilation is not necessarily indicate that the animal fully recovered from neuromuscular blockade. |
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Term
| Drugs used to reverse neuromuscular blockade? |
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Definition
1- Neostigmine
2- Pyridostigmine
3- Edrophonium |
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Term
| What are some signs of anticholinesterase (neostigmine and others)? |
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Definition
these are related to muscarinic effect of the drugs:
- bradycardia
- salivation
- urination
- defecation |
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Term
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Definition
- antigen and IgE antibodies;
- previous sensitization to an antigen is required |
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Term
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Definition
- Reaction mediated by histamine;
- previous sensitization to an antigen is not required and can happen even with the first exposure to a substance |
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Term
| Name agents that can cause irritation if injected perivascularly? |
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Definition
- Thiopental
- Thiamylal
- 20-50% glucose
- Sodium bicarbonate |
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Term
| Mnagement and TX of perivascular irritation? |
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Definition
- infiltrate tissues with saline until moderately distended;
- If thiopental or Thiamylal are given perivascularly, infiltrate the area with Lidocain (w/o Epinephrine) up to 2 mg/kg;
- Apply hot pack frequently;
Can apply DMSO gel topically, twice a day for up to 3 days. No tissue sloghing will result. |
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Term
| What agents can trigger anaphylaxis or anaphylactoid reactions? |
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Definition
- anesthetic drugs (thiopental, thiamylal, atropine, morphine, meperedine, cremaphor EL, tubocurarine, procaine hydrochloride, xylazine, ketamine)
- antibiotics (penicillin)
- dextran, plasma or blood
- iodinated contrast material |
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Term
| How to help prevent anaphylactic reactions? |
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Definition
1) good history
2) administer IV meds (esp antibiotics) slowly;
3) if suspicious of possible reaction, administer a test dose first;
4) Cross-match (if blood transfusion is needed)
5) avoid blood or blood product transfusions if possible;
6) if it is known that the p will receive an agent with reaction potential, corticosteroid and an H1 antagonist can be given prophylactically. |
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Term
| What are names and doses of agents administer to prevent possible anaphylactic reaction? |
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Definition
- Dexamethasone (1-4 mg.kg IV);
- Prednisolone Sodium Succinate (10-25 mg/kg IV);
- Diphenhydramine (0.5-1.0 mg/kg IV, IM) |
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Term
| Cardiovascular signs of anaphylactic reaction: |
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Definition
- hypotension - may be only sign if p is anesthesized!!!
- Cardiac arrest or cardiovascular collapse;
- Tachycardia;
- Arrhythmias |
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Term
| Respiratory signs of an anaphylactic reaction: |
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Definition
- Cyanosis or hypoxemia;
- Labored breathing;
- Bronchospasm;
- Laryngeal edema; |
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Term
| Cutaneous signs of an anaphylactic reaction: |
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Definition
- Utricarial rash
- Hyperemia of the skin;
- thickening of lips, eyelids and skin folds |
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Term
| What are differentials for anaphylactic reaction? |
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Definition
anesthetic overdose (occurs more frequently than anaphylaxis)
pulmonary edema
hypotension from other causes
fat embolism
venous air embolism;
aspiration of gastric contents;
pneumothorax;
bronchospasm;
vasovagal reaction;
septic shock; |
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