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375 Cards in this Set
- Front
- Back
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Which class of drug is the oldest injectable anesthetic?
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Barbituates
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Which barbituate is on of the few available today in vet med?
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Thiopental
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In solution, thiopental is highly alkaline, what effect does this have on tissues?
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Highly irritant if extravasated
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What is the mechanism of action of barbituates?
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Depresses the RAS in the brainstem responsible for wakefulness, interacts with GABA
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Which is the active portion of a barituate...the protein bound or unbound?
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The unbound is active
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Thiopental is up to 40% unionized in plasma, making it lipid soluble. In this form, what can the drug do?
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Cross the blood brain barrier
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What biochemical condition will increase the intensity of the barbituate effect?
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Acidosis
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Is recovery from a drug due to metabolism or redistribution?
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Redistribution
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In which breeds should Thiopental be avoided?
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Sight hounds (low body fat = lack of depot for the drug)
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How quickly does Thiopental take effect?
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One arm-brain time...unconsciousness in 30 seconds
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What effect does Thiopental have on intracranial pressure?
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Lowers it
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What are the CVS effects of Thiopental?
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Cardiovascular depression, vasodilation, drop in output. arrhythmogenic
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What respiratory effect is usually seen post induction?
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Apnea
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What caution must be taken with preparing Propofol?
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Contains no preservative, can grow bacterial
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What is the mechanism of action of Propofol?
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Enhances GABA activity, enhances NMDA activity
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What effect does Propofol have on intraocular pressure?
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Reduces it
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What are Propofol shakes?
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Some animals can develop muscle rigidity and spasm following induction. responds to Ketamine
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Does Propofol raise the seizure threshold?
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No, used as an anti-convulsant in dogs with refractory epilepsy
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What are the CVS effects of Propofol?
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CVS depression, vasodilation, decreased aterial blood pressure, stroke volume and cardiac output Little effect on heart rate
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What are the respiratory effects with Propofol?
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Respiratory depression
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How can the pain of injecting Propofol be reduced?
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Draw blood back into the syringe prior to injection, use a low dose of lidocaine
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Do pigs require higher or lower doses of Propofol?
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Higher
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What caution should be taken when using Propofol in cats?
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Prolonged recovery if used as CRI
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Which neuroreactive anesthetic agent is not yet licensed in the US?
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Alfaxalone
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What is the mechanism of action of Alfaxalone?
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Enhances inhibitory effects of GABA, acts on central glycine and nicotinic Ach receptors
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Alfaxalone has CVS effecst similar to what agent?
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Propofol
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In which species is Alfaxan not used?
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Dogs, histamine release
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Name the 2 common dissociative drugs used in vet med
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Ketamine, Tiletamine
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Ketamine is usually co-administered with what other class of drugs?
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Rarely given alone, usually given with BZ, ACP, A2 agonist
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What is the mechanism of action of Ketamine?
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Unclear. Believed to be a result from inhibition of excitatory neurotransmitters
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What is the name of the Ketamine metabolite formed in the liver?
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Nor-ketamine
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What is a disadvantage of Ketamine in terms of recovery?
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Usually an unpleasant recovery
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What are the CNS affects of Ketamine?
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-increased cerebral blood flow -increased cerebral O2 consumption -increased intracranial pressure -epileptogenic -good analgesic -increases muscle tone
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What ocular effects are seen with Ketamine?
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-eyelids remain open (use eye gel) -increases intra-ocular pressure -dilated, centrally fixed pupils
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What effect does Ketamine have on the CVS?
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Stimulates the CVS, indirect sympathomimetic action
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What are the respiratory effects of Ketamine?
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Minimal respiratory depression Pharyngeal/laryngeal reflexes maintained Apneustic breathing Hypersalivation
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What are some conditions that contra-indicate the use of Ketamine?
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-increased ICP -hepatic, renal disease w/ obstruction -risk of seizure -increased intra-ocular pressure
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How does Tiletamine compare to Ketamine?
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Similar in action, but more potent and a longer duration of action
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What are the common uses for Tiletamine?
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-aggressive dogs, feral cats -horses, pigs, exotics
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What is the advantage of using Etomidate?
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Has minimal CVS depressant effects, minimal effects on the sympathetic nervous system and barorecptors
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What is the effect of Etomidate on the adrenals?
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Temporary adrenal suppression
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What is TIVA?
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Using drugs in combination as a continuous IV infusion to maintain anesthesia when an inhalational agent is not desirable or possible
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What are the properties of the ideal drugs for TIVA?
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non cumulative -rapidly metabolized -non irritant -no undersirable properties from long administration
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What is an example TIVA technique used in equine medicine?
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Triple drip...Guaphenesin, ketamine and xylazine
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In which breeds do you avoid Thiopental?
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Sight hounds
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What issues are associated with brachycephalic dogs and inducing anesthesia?
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-stenotic nares
-elongated soft palate -braod, thick muscular tongue -narrow laryngeal opening, everted saccules |
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All of the physical issues with brachycephalic dogs place them at risk for what?
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Respiratory obstruction
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Which dog breeds are more sensitive to ACP?
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Boxers, giant breeds, setter
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What effect can opiois have on sled dogs?
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Dysphoria
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In older dogs (5-10 years), what pre-anesthesia lab work should you perform?
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Assessment of renal function
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When would you preform a complete biochem profile prior to anesthesia?
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Older animal, elective procedure of more than 30-40 minutes
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If a breed is associated with a coagulation problem, what test should you perform?
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BMBT
(Doberman, corgi) |
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In a diabetic animal, what level would you check just prior to anesthesia?
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Glucose
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Sedation can be thought of as what?
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Heavy pre-mediation
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Sedation is usually a combination of a tranquillizer and an opioid. This combination is called a what?
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Neurolepanalgesic
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What is the purpose of sedation vs anesthesia?
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Allows for relatively non-painful procedures or manipulation with the need for GA.
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What are the default drugs for sedation in a dog?
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ACP plus morphine
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In what cases would you reduce the amount of ACP given?
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-sensitive breed (Boxer)
-older animal -older, sensitive -when prolonged sedation is not wanted |
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When using the IV route instead of the IM route for sedation, by how much is the dose decreased?
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one-half
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When would ACP not be used?
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-hypovolemia, shock or hypotension
-skin testing -impaired liver function |
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When might the morphine dose be increased for sedation?
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-aggressive, boisterous temperament
-increased potential pain -if a lower dose of ACP is used |
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When would morphine not be used for sedation?
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-concerned about vomiting
-not a painful procedure -don't want prolonged sedation -skin testing (histamine release) -certain breeds can react (sled dogs) |
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What sedative would you used for an aggressive dog?
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Medetomidine
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By which route is it best to administer pre-med drugs?
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IV- allows accurate titration
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As a premed, Thiopental should be given in a concentration of 2.5% max. Why?
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To reduce the risk of arrhythmias or perivascular slough
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When would you not use Thiopental?
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-hypovolemic animals
-liver, kidney, heart dz |
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How is Propofol administered?
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Slow IV to effect
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Giving Propofol too quickly can induce what?
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Apnea
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During induction with Propofol, what side effect might you seen?
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Muscle twitching
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What other pre-med drug has similar effects to Propofol?
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Alphaxalone
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Why would you choose Etomidate as a pre-med?
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-preserves cardiac function
-minimal respiratory depression |
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What are the drawbacks to Etomidate?
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-pain on injection
-high incidence of nausea & vomiting |
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Which combination of pre-med drugs are very unpleasant and can cause dysphoric recoveries in dogs?
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Diazepam/Ketamine
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Diazepam/Ketamine should be avoided in which situations?
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Animals at risk of seizuring or with increased CSF pressure
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What is the last choice method for induction in dogs?
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IM- medetomidine-xylazine plus ketamine
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When would sevoflurane be the inhalational agent of choice in dogs?
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For mask induction
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Halothane should be avoided in dogs with what conditions?
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-CV dz
-cardiac arrhythmias -hepatic/renal dz -IICP |
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If using nitrous oxide, what must you monitor?
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Oxygenation- at least with pulse ox
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When do you extubate a dog?
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When he starts to swallow
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What are the default pre-meds given to cats?
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ACP plus morphine IM or SC
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For fractious cats, what drug could you add?
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Ketamine
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What adjustment would you make to the ACP dosage in older cats?
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Lower it
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When would you decrease the dose of morphine in cats?
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Old and quiet cats, cats with impaired liver function
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When should morphine not be used in cat anesthisia?
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When skin testing is the procedure
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What other opioid works well in cats?
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Buprenorphine
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Why do some vets give atropine to cats?
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To reduce salivation caused by ketamine
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When would you give a high dose of ketamine to a cat?
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-young, bouncy cat
-nasty/aggressive cat |
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As a last result, in dealing with an agressive cat, what pre-med drug could you give?
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Ketamine- PO
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When would you not use Ketamine in a cat?
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-older, quiet cat
-quesitonable liver/kidney function -urethral obstruction -risk of seizure |
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Compared to dogs, the induction dose of propofol needs to be higher or lower?
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Higher induction dose
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During intubation of a cat , how could you reduce the occurrence or laryngospasm?
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Apply lidocaine to the larynx
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What triad of signs should you watch for in cats?
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Hypotension
Bradycardia Hypothermia |
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What are inhalational anesthetic agents?
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Drugs that reach the circulation by the respiratory system
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How are these drugs absorbed into the bloodstream?
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Via the capillaries
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What is saturated vapor pressure?
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The equilibrium point for a vessel containing a volatile liquid, at a specific temp, where the number of molecules entering the gaseous phase equal the number of molecule leaving it
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What is a partition coefficient?
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The relative affinity that 2 tissues (or phases) that are in contact with each other have for the same substance.
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What does a partition coefficient greater than 1 mean?
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That the FIRST names tissue is going to hold more of the substance
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The ratio of the amount of anesthetic dissolved in blood and in gas is called what?
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Blood-gas solubility coefficient
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Does a soluble inhalational agent have a large of small blood-gas coefficient?
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Large
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As a general rule of thumb, what type of inhalational agent works faster?
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A more insoluble agent
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The extent to which any tissues take up an anesthetic agent depends on its what?
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Blood supply and size
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Based in perfusion and proportion of body mass, the body can be divided into what 4 basic groups?
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-vessel-rich
-muscle/skin -fat -vessel poor (connective tissue etc) |
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Of the four body groups of tissue, which one has the highest perfusion (as a % of cardiac output)?
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Vessel rich tissue
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The vessel-rich groups is composed of which tissues?
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-brain
-heart -liver -kidneys -endocrine glands -splanchnic bed |
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When will uptake of an inhalational agent stop in a particular tissue?
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When the tissue is saturated
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Which is the first tissue to saturate?
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Brain- small volume, high affinity, well perfused
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What is MAC?
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The minimum concentration of an anesthetic agent(measured at the alveolus) which will prevent purposeful movement in response to a supramaximal (painful) stimulus, in 50% of patients
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MAC is a way of comparing what, across agents?
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Potency
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Is a lower MAC more or less potent than a higher MAC?
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More potent
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How would you monitor the MAC during anesthesia?
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Expired, or end tidal, concentraions are a close approximation
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What factors can decrease a MAC?
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-narcotics, sedatives, tranq
-nitrous oxide -age (old animals & neonates) -hypothermia -pregnancy -severe hypoxia -sever hypercapnia -hypotentsion |
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What factors can increase MAC?
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-hyperthermia
-neurotransmitter release |
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What is the approximate MAC of
Halothane Iso Sevo Des? |
H = 0.8-0.9
I = 1.5 S = 2.4 D = 8 |
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How do you tell the amount of remaining nitrous oxide in a cylinder?
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Weigh it
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Under which conditions would you not use N2O as an anesthetic agent?
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Head trauma or cerebral edema
(raises cerebral blood flow of ICP) |
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Compared to other inhalational agetns, N2O is the only one that has what additional property?
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Analgesia
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What effects does N2O have on the CVS?
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-mild sympathetic stimulation (maintains BP, HR, CO)
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N2O has min respiratory effects. At 100% it is lethal, never use a flow greater than what?
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66%
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How is N2O eliminated?
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Through the lungs
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What is the difference between the use of N2O in animals compared to humans?
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N2O is only half as potent in animals
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What are the benefits of using N2O?
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-accelerates uptake of volatile anesthetics via second gas effect
-good analgesia -decreases amount of inhalation agent needed to maintain plane |
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What are the disadvantages of nitrous oxide?
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-low potency
-expensive -potential for human abuse -potential for hypoxia if wrong conc. given -potential for diffusion hypozia at end of anesthesia |
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N2O can reduce the MAC of other inhalational agents by how much?
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20-25%
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What is the danger is using N2O in terms of gas-filled spaces?
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N2O has low solubility and can diffuse into gas filled spaces such as the rumen, a GDV, pneumothorax and cause increased pressure
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At the end of anesthesia with N2O, how do you avoid diffusion hypoxia?
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Administer O2 for 5-10 mins following the cessation of N2O
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What is the special storage requirement for Halothane?
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Unstable in UV light- stored in a dark bottle
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Halothane has what added to it as a preservative?
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Thymol
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Why is Halothane the most dangerous inhalational agent to use in animals with head trauma or suspected brain tumors?
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Increases cerebral blood flow and decreases cerebral metabolic rate
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What are the CVS effects of Halothane?
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-dose-dependent CVS depression
-direct myocardial depression -decreases stroke vol, CO, BP -arrythmogenic |
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What are the respiratory effects of Halothane?
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Dose-related respiratory depression
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How does Halothane depress hepatic function in animals?
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Decreased hepatic perfusion associated with decreased cardiac output
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Halothane undergoes more metabolism in which organ than any other inhalational agent used in vet med?
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The liver
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What effects does Halothane have on the Gi system?
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-reduces GIT motility
-reduces splanchnic blood flow by up to 33% |
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What other effects does Halothane have?
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-profound relaxation of uterine muscles
-relatively poor skeletal muscle relaxation |
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Does Isoflurane require a preservative?
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No
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Should Isoflurane be used in the case of head trauma?
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Yes, increases cerebral blood flow less than Halothane
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Does Isoflurane cause CVS depression?
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Yes, but by a different mechanism than Halothane
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What kindof myocardial effect does Isoflurane have?
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No direct myocardial depression
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Isoflurane causes vasodilation which has what effect on blood pressure?
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Hypotension
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What are the respiratory effects of Isoflurane?
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-respiratory depression
-irritant to upper airway |
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What effects does Isoflurane have on hepatic and skeletal blood flow?
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hepatic- well maintained
skeletal- increased |
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What is compound A?
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Some degradation of Sevoflurane occurs when exposed to CO2 absorbent, poducing compound A which has been shown to be nephrotoxic in rats
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Sevoflurane has similar effects to Isoflurane. What are the CVS effects of Sevoflurane?
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-CVS depression due to vasodilation
-does not sensitize the myocardium to catecholamines |
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Desflurane requires what special equipment?
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A heated vaporizer
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Is the MAC of Desflurane higher or lower than other agents?
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Higher- but with high SVP and BP, easy to achieve
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What do muscle relaxant drugs do?
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Act to modify the activity of the post-synaptic muscle membrane and thus produce muscle relaxation
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What level of sedation and analgesia do muscle relaxants provide?
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None
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When are NMBD's used?
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-intra-ocular surgery
-reduces surgical traction and post op discomfort -may facilitate intubation and IPPV -predictable total relaxation -non-depolarizing drugs can be antagonized |
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Which surgical procedure is it often truly necessary to use NMBDs?
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ocular surgery
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Neuromuscilar blockade may alos be used on high risk cases such as....
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-thoracotomy
-diaphragmatic hernia repair -laparotomy -othro sx -ear sx |
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What are some disadvantages to using NMBDs?
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-controlled ventilation is essential
-difficult to monitor anesthesia & analgesia -no motor response to stim- can cut a nerve -monitoring neuro blockade is complex -recurarisation |
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What are the 3 essential prerequisites of using NMBD's?
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-ensure unconsciousness
-ensure adequate analgesia -ensure ventilation support |
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What are the absolute contraindications of using NMDB's in animals?
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-inability to ventilate the animal
-inability to provide adequate anesthesia and analgesia |
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Muscle paralysis follows what pattern?
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From periphery to centrally- face and tail first, diaphragm last
return of function is opposite |
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After paralysis with an NMBD, what autonomic response should you look for?
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-mydriasis
-lacrimation -salivation -tachycardia -hypertension -arrhythmia -paradoxical jaw tone -paradoxical jaw twitching |
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What is the preferred method for monitoring the use of a NMBD?
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Peripheral nerve stimulator
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if monitoring the effects of a NMDB by clinical signs, what do you look for?
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-head lift
-cough -squeeze -inspiratory force |
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Name the 3 centrally acting muscle relaxant drugs
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-Guaifenesin
-Benzodiazepines -A2 agonists |
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Guaifenesin is usually mixed with other anesthetic agents for which species?
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Horses
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Where is the effect of Guaifenesin?
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Block transmission of nerve impuleses at the internuncial neurons of the spinal cord, brainstem and subcortical areas
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What effect does Guaifenesin produce?
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Tranquillization, ataxia and recumebency, no analgesia
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When is Guaifenesin used?
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Induction of anesthesia in horses and cattle
TIVA (w/ Ketamine and Xylazine) triple drip |
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When has Guaifenesin been used in dogs?
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To treat tetanus
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Cattle are sensitive to a risk of hemolysis, what concentration of Guaifenesin is used?
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Never more than 5%
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What GGE should be used in horses?
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Never more than 10%
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Along with the centrally acting NMBD, name the 2 other types used?
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Depolarizing
Non-depolarizing |
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How are the depolarizing drugs (suxamehtonium) broken down?
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By pseudocholinesterases
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The non-depolarizing agents include which drugs?
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-Vecuronium
-Rocuronium -Atracurium |
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The non-depolarizing NMDB are structuarlly related to what drug?
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ACh
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How do the non-depolarizing NMDB's work?
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By competitive block, compete with ACh the the nicotinic ACh receptors
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How is a neuromuscular blockade with a non-depolarizing drug reversed?
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With anticholinesterases
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What is the onset of action in a dog given Vecuronium?
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3 minutes
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In terms of cardiac effects, why is Vercuronium a good choice for a NMBD?
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Excellent Cv stability, wide spearation between vagal and neuromuscular blocking doses
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Rocuronium has a duration of action of how long?
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30 minutes
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Which NMBD is used in dogs, cats and horses?
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Atracurium
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Atracurium is the NMBD of choice in which type of patient?
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Critically ill..has rapid recovery and used in patients with renal and hepatic disease/failure
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Which category of NMDB's are reversible?
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Non-depolarizing
Vecuronium, atracurium |
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What is the timing for giving a reversal agent?
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Only when there are clinical signs or evoked signs of spontaneous recovery
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In dogs and cats, what drugs are given to reverse NMDBs?
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Anticholinesterases and an antimuscarinc (to protect against the muscaric effects of the build up of ACh)
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When reversing an NMDB in a horse, is atropine also given?
|
No
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Name the 2 anthicholinesterase drugs.
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-Neostimine
-Edrophonium |
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How do anticholinesterases work?
|
Stop the breakdown of ACh in the region of the muscle plate, the increase in ACh can then compete for the receptors and replace the NMBD
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In the absence of a peripheral nerve stimulator, how do you know that the reversal of a NMDB is complete?
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Good jaw tone
Brisk palberal reflex |
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What is the "fish eye" sign?
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Animal is still not completely reversed
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When using a nerve stimulator, what is the most popular stimulation pattern used to check for nerve response?
|
Train of Four
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What is the amount of nerve blockage as demonstarted by a train of four pattern that shows 1 twitch?
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90% block
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What is a common method of performing surgery on a ruminant?
|
Standing
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A caudal epidural is used in a cow for what purpose?
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Surgery of the tail, anus, vagina and perineum. Prevents rectal straining during calving
Replacement of prolapsed uterus |
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What is the effect of a caudal epidural on the uterine motility and locomotor function of the hindlimbs on a cow?
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Unaffected
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Where should the approach for a caudal epidural be made?
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Between Cd 2 and Cd3
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What drugs can be used for the caudal epidural?
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Lidocaine
Xylazine |
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What local anesthetic technique can be used during flank surgery- c-section, abomasal surgery?
|
Inverted L-block
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Where is the anesthetic agent injected for an inverted L block?
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Below transverse process of lumbar vertebrae
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What other type of flank procedure anesthesia can be used?
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Paraverterbral anesthesia
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The nerves for a paravertebral block are located where?
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T13, L1, L2
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What are the 2 approaches to a paravertebral block?
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Dorsal
Lateral |
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What are the signs of a successful lateral paravertebral block?
|
-Anesthesia of the skin, peritoneum & musculature of the flank, increased skin temp and scolisos towards the desensitized side
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Whay arent line blocks recommended for C-section?
|
-distortion of normal tissue architecture
-incomplete anesthesia -incomplete muscle relaxation of dep players of abd muscle wall -formation of hematomas along site -increased cost- large doses |
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What anesthetic technique is used for digital surgical procedures in large ruminants?
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Intravenous regional analgesia
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In cattle and sheep, dehorning is achieved using what kind of anesthetic procedure?
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Cornual nerve block
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Which approach to horn nerve block is taken?
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Cornual branch of the lacrimal nerve
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In goats, which additional nerve needs to be blocked for dehorning?
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Medial cornual branch of the infratrochlear nerve
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In goats and large ruminants what other block should be done?
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Ring block around the horn base
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What is a good sign of a successful zygomaticotemporal nerve block?
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Eye blink during administration
Drooping of upper lid after |
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Which nerve, in a ruminant, is blocked to paralyze the eyelid (without analgesia)?
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Auriculopalpebral nerve
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Why would you block the Auriculopalpebral nerve?
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Removal of FB (in combo with local anesthetic
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What 2 neve blocks are used for procedures on the eye?
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Retrobulbar
Peterson's block |
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Which solution strength of Xylazine should be used in cattle?
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2%- extremely sensitive
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A higher dose of Xylazine increases the risk of what?
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Recumbency
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In which situation should Xylazine not be used in cattle?
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Last trimester of pregnancy
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For diffcult ruminants, what drug can be used?
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ACP
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What drug can be given with Xylazine or ACP if you don't want the cow to go down?
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Morphine
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What type of regurgitation can occur in a cow during induction?
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Active regurgitation
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During surgery what type of regurgitation can occur?
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Passive
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During ruminant surgery, what can cause bloat?
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Accumulation of CO2 and methane in the rumen, not able to eructate
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What effects will increasing abdominal pressure have?
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Impair repsiration and venous blood return to the heart
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When will the ability to eructate return?
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When the animal is in sternal recumbency and in an advanced stage of recovery
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What complication can occur during ruminant anesthesia in regards to saliva?
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Ruminants produce a huge amount of saliva, during anesthesia the swallowing response is suppressed, saliva accumulates- can cause upper airway obstruction
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Hypoventilation during anesthesia can occur due to....
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-central depression
-V/Q inequalities due to recumbency -low chest wall, lungs difficult to expand -more impedence due to diaphragm position -expanding rumen puts pressure n diaphragm |
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How are complication minimized during ruminant anesthesia?
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-starvation 12-18 hrs prior
-with hold water 12 hours -keep head elevated intubate asap -adequate depth |
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How can the possibility of bloat be lowered?
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With hold highly fermentable food for 24 hrs
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Should atropine be give in cattle to reduce saliva production?
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No, just makes saliva more viscous
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What premeds are used in cattle?
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none
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IV access is best given where?
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Auricular vein
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What drugs for induction should be the first choices?
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Ketamine/diazepam
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What drugs comprise the triple drip?
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GGE-Ketamine-Xylazine
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What percentage of GGE should be mixed with Ketamine for triple drip?
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5%
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Why should you provide supplemental O2 when using triple drip in a cow?
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associated with marked hypoxemia and respiratory depression
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Entubation of an adult cow is performed how?
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Blindly
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Maintenance of anesthesia of a cow is achieved by using which inhalant?
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Iso or Halothane
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What is the position of the eyes during deep anesthesia of a cow?
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Central
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What are sings of a lighter plane of anesthesia?
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Chewing and swallowing
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In which position should the cow be placed for recovery?
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Sternal recumbency and supported
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To which class of drugs are goats extremely sensitive?
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A2 agonists
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Even at very low doses, what side effect can xylazine cause in sheep?
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Pulmonary edema
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How can the risk of pulmonary edema in sheep be reduced?
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Give IM
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Whcih drug, unlicensed in sheep and goat, can give a moderate to deep sedation?
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Medetomidine
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ACP given at what level of dose can provide sedation?
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Low levels
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Which class of drugs has less CV depression than A2 agonists in sheep and goats?
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Diazepam
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A combination of Xylazine, Buprenorphine and what else can be used as cattle induction.
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Ketamine and diazepam
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Are llamas ruminants?
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No strictly...have a 3 compartment stomach
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Where is the best place to start an IV in a llama?
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Right jugular, high up
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Why might it be difficult to place a venous catheter?
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Veins have valves
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What length of ET tube is needed for llamas?
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35-40 cm
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What is a good alternative to orotracheal entubation?
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nasotracheal
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What premed is used for llamas?
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Xylazine
Opioids for analgesia or sedation |
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What induction drugs can be used?
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Xylazine
Telazol Propofol |
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How should the llama be maintained under anesthesia?
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Small camelids are sensitive to inhalants, use ketamine to reduce the need
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What is CPCR?
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Cardiopulmonary Cerebral Resuscitation
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The classic features of arrest include what signs?
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-absence of ventilation/cyanosis
-absence of palpable pulse -absence of heart sounds -dilated pupils |
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At what pressure does femoral pulse disappear?
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systolic < 60mm Hg
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At what pressure do heart sounds disappear?
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Systolic < 50mm Hg
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In contrast to humans. cardiac arrest in animals is usually the result of what?
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A non-cardiac condition
-anesthetic overdose -primary cardiac disease that affects other organs -dz of respiratory system -systemic dz |
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Being prepared to handle arrest means identifying high risk patients. which includes what conditions?
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-vagally mediate cardiac arrest
-anesthetic overdose -trauma -systemic/metabolic disease -hypothemria -respriatory dz -cardiac dz -acid-base abnormalities |
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In which species can vasovagal response primarily occur?
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Brachycephalic
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Boxers have enhanced parasympathetic tone combined with withdrawal of sympathetic tone...this usually manifests as bradycardia. What drug should you give?
|
Atropine..NOT adrenaline
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What are the warning signs of a possible impending cardiorespiratory arrest?
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-changes in resp rate, depth, pattern
-weak, irregular pulse, bradycardia -hypotension -unexplained change in depth of anes -cyanosis -hypothermia |
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CPCR consists of what 3 major components?
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-Basic life support (chest compression and artificial vent)
-Advanced life support (+ drugs) -Post -resuscitation care |
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Extended hypoxia can lead to brain damage which usually manifests how, in a dog?
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Blindness
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What is the first step you take during an arrest?
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Call for assistance
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What are the ABC's of treating an arrest?
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Airway
Breathing Circulatory support |
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Advanced life support includes what steps...D-E-F?
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Diagnosis and drugs
ECG Fabrillation |
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G-H-I of prolonged life support means what?
|
Gauging response
Hopeful measures for brain Intensive care |
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How many people are needed to competently perform CPR?
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4
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CPR will rarely be successful if there i no response after how much time?
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15 mins
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After turning off the inhalant, how many breaths do you give per minute?
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10-15
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Which acupuncture point may help reverse respiratory arrest?
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Jen Chung GV26
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If femoral pulse is low or weak, systolic must be what?
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< 80 mm Hg
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What are the 2 choices for chest resuscitation?
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Closed compression
Open massage |
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In which position is the patient for closed chest compression?
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Left lateral or dorsal recumbency
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How many compression per minute should be given?
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100-120
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In cats and small dogs., where do you compress?
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Directly over the heart
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Where do you perform compressions on a large dog?
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Widest part of thorax
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Lateral recumbency for chest compression is used on animals of what size?
|
Over 7kg
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Cardiac compressions should be interspersed with what other compressions?
|
Abdominal
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Through what 2 mechanisms does closed chest compressions produce flow?
|
-direct cardiac pressure (cardiac pump)
-pressure gradient (thoracic pump) |
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|
Closed chest compression achieves a cardiac output of how much?
|
20%
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To perform open cardiac massage a thoracotomy is performed where?
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Left lateral thorax between 4-6 ICS
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What is the advantage of open massage?
|
Does not raise atrial pressure, provides better cerebral and coronary perfusion
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Monitoring during CPR is essential and should include what?
|
-MM, CRT, cranial nerve reflex
-CNS -peripheral and central pulses -capnography -pulse ox -ECG |
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|
If needed, Doppler could be performed where to assess bloodflow?
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On the cornea....with copious amounts of gel
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What are the 4 cardiac rhythms that can cause a pulseless cardiac arrest?
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Asystole
Pulseless electrical activity Ventricular tachycardia Ventricular fibrillation |
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Which is the most common arrest rhythm in dogs and cats?
|
Asystole
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What is meant by pulseless electrical activity (EMD)
|
Despite normal heart rate and rhythm on ECG, no contractility in the myocardium
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What is the cause of ventricular tachycardia?
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Repetitive firing of ectopic focus or foci in ventricular myocardium or Purkinje system
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What is the only treat for ventricular fibrillation?
|
To de-fibrillate
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What is the number one drug in CPR?
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Oxygen
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Which is the first vein of choice for drug access?
|
Jugular
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Which injection route is the last resort?
|
Cardiac injection
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How would you administer intratracheal meds?
|
Use a cat urinary catheter to access respiratory bronchioles
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Why should you be careful in giving fluids?
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could produce elevated pre-load/CVP, and reduce coronary perfusion, increase ICP and pulmonary edema
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|
Name the 5 primary drugs used in CPR
|
-epinephrine
-atropine -lidocaine -vasopressin -reversal agent: naloxone, atipamezole, flumazenil |
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|
What are the contraindications for using epi during an arrest?
|
-ventricular tachycardia
-ventricular fibrillation -presence of drugs that increase adrenergic effects incr v fib |
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|
What effects does epinephrine have?
|
-arterial vasoconstriction
-increase myocardial contractility -bronchodilation |
|
|
What is the duration of action of epi?
|
Short 3-5 mins
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When is atropine given?
|
To treat bradycardia
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What effect does atropine have?
|
antimuscarinic
increases heart rate and systemic vascular resistance |
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|
Why is vasopressin given?
|
Massive selective vasoconstriction, maintains blood supply to the cerebral and renal vasculature
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|
|
what type of drugs are Lidocaine and Amiodarone?
|
Anti-arrhythmic
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|
|
The role of lidocaine in CPR is changing, when is it now indicated?
|
For ventricular arrhythmias following resuscitation
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|
|
Name the 3 anesthesia reversal drugs
|
-Naloxone
-Atipamazole -Flumazenil |
|
|
Electrical defib is the only treatment for what cardiac rhythm?
|
Ventricular fibrillation
|
|
|
What is involved in post resuscitation support?
|
-artificial ventilation
-inotropic support -sometimes pressor support -monitor urine and CVP -anticipate SIRS, renal failure, DIC -keep warm |
|
|
Local anesthetics are also referred to as what?
|
Local analgesics
|
|
|
What benefits are there to adding Local anesthetics to GA protocols?
|
-minimal equipment
-minimal systemic effects when given peripherally -reduce inhalational/IV anest reqs -reduce sympathetic response to surgery -improves post op analgesia |
|
|
What benefits does a local anesthetics given systemically have?
|
-central analgesic effect (Na channel blockade)
-prokinetic activity in GIT -antioxidant and inflammatory modulator |
|
|
LA's are classified into what 2 categories?
|
Esters and Amides
|
|
|
Which classification of LA's are used in vet med?
|
Amides
lidocaine bupivacaine mepivicaine |
|
|
How are amides metabolized?
|
Are very stable, metabolized by hepatic microsomes
|
|
|
How are esters degraded?
|
Degraded in plasma by pseudocholinesterases
|
|
|
Lipid solubility is responsible for which property of LA'a?
|
Anesthetic potency
|
|
|
In general potency of a LS increases with what?
|
Increase lipid solubility
|
|
|
What is the relationship between lipid solubility and speed of onset?
|
More lipid soluble the faster the speed of onset
|
|
|
Which property of LA's is responsible for the duration of action?
|
Protein binding
|
|
|
pKa determines what property of a LA?
|
Speed of onset
|
|
|
Onset of action is faster if the drug's pKa is what?
|
Close to physiologic pH
|
|
|
Which form of a drug crosses the cell membranes?
|
Un-ionized
|
|
|
What effect does dropping pH have on the un-ionized form of the drug?
|
With dropping pH non-ionized form decreases
|
|
|
What type of tissues have low pH, renedering a LA less effective?
|
Infected
|
|
|
How can you increase the portion of the drug into a non-ionized lipid soluble state to make it more effective?
|
Add sodium bicarb to alkalinize it
(also decreases pain on injection) |
|
|
LA's act on which part of the cell to prevent propagation of AP in all nerve?
|
Cell membrane
|
|
|
Which nerve requires a higher concentration of a LA to be effective?
|
Motor nerves
|
|
|
LAs can also effect the impulse transition in excitable tissue such as what?
|
heart, muscle and brain
|
|
|
What is the principle action of LAs on nerve cells?
|
Blocking sodium channels in the closed configuration
|
|
|
Which nerves are blocked first....smaller or larger?
|
Smaller
|
|
|
Generally in which order are nerves blocked?
|
-autonomic, pregang sympath
-slow pain post gang -fast pain temp -motor- muscle spindle, proprio -sensory- touch, pressure -motor- skeletal |
|
|
Esters are metabolized by what?
|
Para-amino benzoic acid (PABA)
|
|
|
Amides are metabolized where?
|
Liver with renal excretion
|
|
|
What is the half life of esters?
Amides? |
Esters = few minutes
Amides = few hours |
|
|
Why is regional nerve blockade preferred over local infiltration of tissues with LAs?
|
LA's can produce local tissue irritation and are neurotoxic
|
|
|
LA's can also be systemically toxic, the degree of systemic toxicity is based in what?
|
-dose
-route -rate of absorption -acid-base status (acidosis incr tox) -rate of metabolism -presence of epi |
|
|
What is the toxic IV dose of Lidocaine?
|
10 mg/kg
never give more than 6-8mgkg dog/cat |
|
|
What is the toxic IV dose of
Bupivacaine |
4 mg kg
never give more than 2 |
|
|
What are the toxic doses of Ropivacine and Mepivicaine?
|
Ropivacaine 4-9 mgkg
Mepivicaine 25 mgkg |
|
|
How do you calculate toxicity levels if a combination of LA's are used?
|
Toxicity is additive
|
|
|
These toxic doses produce what type of effects?
|
CNS signs (convulsions)
|
|
|
In the case of a LA overdose, which signs are seen first...CNS or CVS?
|
CNS
|
|
|
what are the CNS signs of a LA toxicity?
|
-initial transient CNS depression & resp depression
-agitation, muscle twitching, convulsion |
|
|
What are the CVS effects of a LA overdose?
|
-direct myocardial depression--bradycardia and decr CO
-hypotension (vasodilation) |
|
|
Which LA toxicity is more difficult to treat?
|
Bupivaciane- high binding affinity for cardiac myocytes
|
|
|
How are seizures from a LA overdose treated?
|
IV Diazepam/midazolam plus O2
|
|
|
What CV support is needed in an LA overdose?
|
symptomatic support: fluids, O2, inotropes, antimuscarinics if bradycardic
|
|
|
What are the preventive measures to be take when using LA's?
|
-dose according to lean bodyweight
-use caution in small pts -weigh small pts -dilute LA to safe working volumes -check to ensure no accidental IV injection |
|
|
Which LA in particular has vasodilator properties?
|
All do but esp Lidocaine
|
|
|
Why is Epinephrine sometimes added to LAs?
|
Delays absorption, prolongs action and improves intensity
|
|
|
Why would you NOT add epi with LAs for ring blocks, local anesthesia of distal extremities?
|
Potential local tissue ischemia
|
|
|
What effect would adding an opioid to a LA have?
|
-increase efficacy, extend duration of block
-may also mediate local analgesia |
|
|
Which A2 agonists have been added to LAs?
|
Medetomidine, dexmedetomidine
|
|
|
When is a topical anesthetic used on the skin?
|
EMLA cream for catheter placement, bx
|
|
|
What is a splash block?
|
Direct application of a LA to a site of interest, most commonly the body wall on closure of the abdomen, peritoneum intra-op, ovarian ligaments, on wounds
|
|
|
When closing small lacerations of excising small masses, what type of LA application would you use?
|
Incisional and infiltrative
|
|
|
When is intrapleuarl LA used?
|
Can be instill thru a chest drain to facilitate movement of the animal, pain control
|
|
|
When might intraperitenal anesthesia be used?
|
Following laparoscopy or hysterectomy (Bupivacaine)
|
|
|
What is a soaker catheter?
|
A fenestrated tube place deep into a surgical site to allow continuous or intermittent application of LA
|
|
|
What procedure can be performed using infiltration/field block of LA?
|
-small skin masses
-ring block for teat surgery -disbudding -inverted L for standing lap/c-section -equine castration |
|
|
Where is the LA injected for equine castration?
|
Spermatic cord or testis
|
|
|
Intravenous regional anesthesia is also called what?
|
Bier block
|
|
|
When is intravenous regional anesthesia used?
|
Ruminant digital amputation/surgery
|
|
|
The procedure for a Bier block is to inject a LA into a local vein and isolate it from general circulation by what?
|
Applying a tourniquet
|
|
|
What is regional anesthesia?
|
Injecting LA around the specific nerve or nerves that innervate a surgical site
|
|
|
Regional anesthesia given where is used for standing laps and c-section?
|
Proximal and distal paravertebral
|
|
|
A brachial plexus block provides anesthesia at what level?
|
Below the elbow
|
|
|
What type of nerve block is used for de-horning?
|
Cornual nerve block
|
|
|
Which nerve block prevents eyelid closure during surgery?
|
Auriculopalpebral
|
|
|
Where do you inject a LA to have it be in the CSF?
|
SAS
|
|
|
What are the primary site for performing an epidural injection of LA?
|
Caudal epidural, Lumbosacral epidural
|
|
|
Caudal epidurl analgesia provides analgesia to what region?
|
Pelvis viscera and genitalia
also abd and hind limbs if vol is large |
|
|
Which spinal anesthesia is used most in dogs and cats?
|
Lumbosacral epidural
|
|
|
When performing an epidural on a cat, what must you be sure of in your location?
|
That your are far enough distal to avoid the a spinal injection
|
|
|
What is the most popular combination of drugs for epidural injection?
|
Morphine w/ Lido or Bupi
|
|
|
If CSF is seen on an epidural, it is possible to continue the injection but reduce the dose by how much?
|
50%
|
|
|
What is an absolute contraindication for administering extradural anesthesia?
|
Never in a pt with coagulopathy or skin infection over injection site
|
|
|
Full doses of LA admimistered ito the CSF can produce what?
|
Total spinal block
|
|
|
What other side effects can LA's have?
|
-hypotension
-bradycardia -coat abnormalities -pruritus -respiratory depression or arrest |
|
|
When are epidural catheters used?
|
For prolonged analgesia
|
