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69 Cards in this Set
- Front
- Back
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What are the 4 classes of cardiovascular drugs used for support in anesthesia?
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1) Anticholinergic drugs
2) Sympathomimetic drugs 3) Vasoactive drugs 4) Anti-arrhythmic drugs |
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What are 2 classes of respiratory drugs used for support during anesthesia?
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1) Sympathomimetic drugs
2) analeptic drugs |
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What are 2 types of peripheral muscle relaxants used for support during anesthesia?
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1) Depolarizing
2) Non-depolarizing |
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What do we measure as an indicator of CO?
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HR & BP
-may be flawed but the best we have |
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Organ perfusion is dependent on maintaining adequate ____.
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CO
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***What is the most common complication during general anesthesia?
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Hypotension
-many anesthetics depress cardiac function, produce vasodilation |
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**Hypotension is when the MAP < _____ or SAP < ______.
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MAP< 60 mmHg
SAP <90 mmHg |
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**Our goal during anesthesia is to maintain a MAP > ____ mmHg or SAP > ____mmHg.
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MAP > 70 mmHg
SAP > 90 mmHg |
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What type of anesthetics are the worst about causing vasodilation?
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inhalants
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What are the 4 steps in treating hypotension?
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1) Stabilize rate/rhythm
2) Fluids 3) Anesthetic depth 4) Inotropic support |
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Arterial pressure = ____ x_____
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CO X PVR
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What i the distribution of blood throughout the body amongst venous system, arterial system, capillaries and heart, lungs?
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Venous system: 70%
Arterial system: 10% Heart, lungs: 15% Capillaries: 5% |
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Where is the majority of resistance in circulation?
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Small arterial capillary beds (capillaries)
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What are 2 cardiac factors that affect cardiac output?
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1) Heart rate
2) Contractility |
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How does vagus nerve affect the heart?
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Slows heart rate
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What changes resistance in the tissues to try to match flow w/ need of individual tissues?
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Local modulators
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You give a horse dobutamine (loading up sympathetic) then heart rate is still low, should you give an anticholinergic?
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No, bc heart will go from 25 beats/min to 225 beats /min
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How is norepinephine synthesized at sympathetic nerve terminals?
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Tyrosine--> dopamine---> vesicles and dopamine is converted to Nepi --> vesicles released--> circulation + reuptake
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____ innervation of the adrenal gland causes release of norepinephrine and epinephrine.
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Sympathetic
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What is the predominate effect of alpha1 receptors?
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Vasoconstriction in peripheral vasculature
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What is the predominant effect of Beta1 receptors?
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Positive inotropy, chronotropy in the heart
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What is the predominant effect of beta2 receptors?
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Bronchodilation
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We use cardiovascular drugs in anesthesia to treat what 3 conditions?
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1) Hypo/hypertension
2) brady/tachycardia 3) Arrhythmias |
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True or false. Hypotension may resolve with treatment of bradyarrhythmias.
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True
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What are 6 causes of bradyarrhythmias?
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1) Drugs
2) Vagal stimulation 3) Excessive anesthetic depth 4) Fluid overload 5) Hyperkalemia 6) Hypothermia |
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________ is a major cause of bradyarrhythmias and doesn't respond to pharmacological intervention.
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Hypothermia
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When an animal has bradycardia, what other parameter should you check?
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BP
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What are 6 options to consider for treatment of bradycardia when an animal is under anesthesia?
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1) Reverse drug effects (?)
2) Warm patient 3) Decrease fluids -if overloaded 4) Stop stimulation (vagal) 5) Correct electrolyte abnormalities 6) Specific therapy -atropine -glycopyrrolate |
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What are 8 drugs that can be used for inotropic support (increased contractility) in a bradycardic patient?
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1) *Dopamine
2) *Dobutamine 3) Phenylephrine 4) Ephedrine 5) Epinephrine 6) Norepinephrine 7) Isoproterenol 8) Vasopressin |
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What receptors does dopamine work on?
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alpha1
beta1 beta2 dopamine |
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What receptors does dobutamine work on?
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alpha1
beta1 beta2 |
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what receptors does phenylephrine work on?
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alpha1
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What receptors does ephedrine act on?
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alpha1
beta1 beta2 |
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What receptors does epinephrine act on?
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Alpha1
beta1 beta2 |
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What receptors does norepinephrine work on?
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alpha1
beta1 beta2 |
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What receptors does isoproterenol act on?
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Beta1
Beta2 |
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What receptors does vasopressin act on?
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V1 receptors on vascular smooth muscle
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Dobutamine primarily has ___ receptor activity.
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Beta1
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What are the 2 positive effects of dobutamine?
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Inotrope
Chronotrope |
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What is a possible adverse effect of dobutamine?
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Arrhythmias possible (not common)
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How is dobutamine administered?
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CRI bc t1/2 is minutes
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***What is the first line inotrope in large animals?
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Dobutamine
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What is one way to tell that you have reached a high dose of dobutamine and don't need to give anymore?
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When HR increases, because positive chronotrope effect only occurs at high doses
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Explain the dose dependency of dopamine.
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At lower doses has dopaminergic effect (renal vasodilation) then as increases has beta1 affects then at high doses has alpha1 effect
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What are the therapeutic effects of dopamine?
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Positive inotrope
Positive chronotrope (high doses) |
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How is dopamine administered?
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Must be given CRI
T1/2= minutes |
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***What is the first line inotrope in small animal medicine?
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Dopamine
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Why is it really important to monitor blood pressure with regards to dopamine and dobutamine administration?
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Direct correlation b/w increasing doses and increasing cardiac index, but not with dobutamine and BP, so just bc improving cardiac index doesn't mean BP is increasing
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Ephedrine has mixed ___ and ___ receptor activity.
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alpha and beta
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What is the indirect action of ephedrine?
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Release of endogenous Nepi
-efficacy not as dependable |
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What are the effects of ephedrine?
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Positive inotrope, chronotrope, vasoconstriction
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How can ephedrine be administered?
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Intermittent bolus bc duration of action ~30-45 minutes
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What is the pro and con of ephedrine's half life?
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Longer so can give intermittent bolus, but have less control
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What are the effects of phenylephrine?
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Vasoconstriction
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Phenylephrine is an alpha1 agonist, so it has counter effects with what premedication?
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Acepromazine- alpha1 antagonist
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How is phenylephrine administered?
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-Systemically and topically
-Duration ~ 15 minutes IV -Can give intermittent bolus -Titrate to effect |
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What are the effects of vasopressin (ADH)?
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Stimulates V1 receptors---> INTENSE vasoconstriction
-V2 receptors--enhance water resorption **Extremely potent!!!!! |
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What are 2 possible side effects of vasopressin?
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Reflex bradycardia is common
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What are the effects of calcium administration?
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Positive inotropic effects
-more effective in patients w/ hypocalcemia |
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What forms of calcium are administered for the positive inotropic effect in hypocalcemic patients?
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Calcium chloride (3x more potent)
Calcium gluconate |
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What side effects can occur with high doses of calcium?
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Bradycardia
Arrhythmias |
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How should calcium be administered?
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Infuse slowly (15-30 minutes)
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True or false. Hypertension is commonly a primary disease.
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False, primary hypertension relatively uncommon so treat the cause
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What are 2 causes of hypertension?
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***Pain
Pheochromocytoma |
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What can you give a patient with hypertension from a pheochromocytoma?
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Esmolol
-short acting beta blocker |
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How should you treat tachycardia? (3)
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1) Treat the cause
-pain -hypoxia -hypercarbia -hypotension (reflex response) -pheochromocytoma 2) Fentanyl 3) Esmolol is an option |
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When an animal has a ventricular arrhytmia it is important to differentiate premature ventricular contractions from _______.
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Ventricular escape beats
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When do you know you need to treat ventricular arrhythmias?
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> 15-20 PVCS/min or runs of 5 or more or when multifocal
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What is the drug of choice in anesthesia to treat arrhythmias? How is it administered?
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Lidocaine
-bolus CRI (caution in CATS!!!!) |
