Lecture 24: CV Support Drugs & Basic CPR (Exam 3)

Question 1

What should MAP & SAP be to prompt recognition & tx will ensure perfusion of vital organs

Answer 1

• MAP > 60 - 70 mmHg
• SAP > 80 - 90 mmHg

Question 2

What are the common causes of CV depression during ax

Answer 2

• Drugs
• Equipment malfunction/misuse
• Shock/sepsis
• Hypovolemia
• Mechanical ventilation
• Surgical procedure
• pre existing CV dx
• Metabolic dx

Question 3

What is the key to CV depression during ax

Answer 3

Treat the underlying cause of hypotension

Question 4

What is the equation for CO

Answer 4

HR x SV

Question 5

What is the equation for MAP

Answer 5

CO x SVR

Question 6

List management options for CV depression

Answer 6

• Adjustment to current ax manangement
• Fluids
• Anticholinergics
• Vasopressors
• Positive ionotrops

Question 7

What are sympathomimetics that support CV

Answer 7

• Positive ionotropes
• Vasopressors

Question 8

Describe sympathomimetics

Answer 8

• Includes endogenous catecholamines, synthetic catecholamines, & synthetic non catecholamines
• Have relative selectivity of sympathomimetics for various adrenergic receptors depends on the chemical structure of the drug
• Act on alpha & beta adrenergic or dopaminergic receptors directly or indirectly & these receptors are coupled to G proteins
• The density of alpha & beta adrenergic receptors in tissue determines the response of the drug

Question 9

Fill out the following:

Answer 9

Question 10

Describe dobutamine

Answer 10

• Mostly beta 1 (+) ionotropic effects
• Has dose dep beta 2 & alpha 1 agonist effects
• Increase in myocardial contractility, stroke vol, & cardiac output
• For px w/ dilated cardiomyopathy, heart failure, show, & low CO
• CRI dose used for tx of hypotension in small animals

Question 11

Describe dopamine

Answer 11

• Endogenous catecholamines
• Precursor to NE
• Acts directly & indirectly on both a & B 1 receptors
• Has dopaminergic (D1 & D2) effects
• Increases CO, HR, BP, & SVR

Question 12

What does dopamine tx? What about a low & high doses?

Answer 12

• tx of acute heart failure & severe hypotension/shock
• low dose d1 & d2 affects - dilation of renal, mesenteric, coronary, intracerebral vasular beds (can indirectly increase the production of urine in px w/ acute renal failure)
• At higher doses of dopamine - increase SPR due to a1 receptor effect

Question 13

Describe ephedrine

Answer 13

• Mixed inotropic pressor agonist @ a1, a2, B1, & B2 receptors
• Used for the management of hypotension during ax in horses
• Can be used in dogs but effects may be short lived
• Dose is species dep

Question 14

Why is ephedrine used in horse to manage hypotension during gen ax

Answer 14

B/c it can be given as a bolus instead of a CRI due to its longer duration of action compared to other CV support drugs

Question 15

Describe noreepinephrine

Answer 15

• Agonist @ a1, a2, & B1 receptors
• Has (=) potency to epinephrine for stimulation of B1 but has little effect on B2
• Is a potent a-agonist that produces intense arterial & venous vasoconstriction in all vascular beds
• Tends to decrease CO & may cause metabolic acidosis
• Can cause necrosis

Question 16

What is the main use of norepinephrine

Answer 16

Used as a CRI for the tx of refractory hypotension due to vasodilation from inhalant ax or sepsis b/c the effects are mostly on the a1 receptor @ the clinically used dose rate

Question 17

Describe epinephrine

Answer 17

• Has both vasopressor & inotropic effects by directly stimulating a1, B1, & B2 receptors
• Most potent activator of a-adrenergic receptors
• Reserved for use as a bolus during CPR
• Can be given as a CRI as a last resort for tx of severe hypotension due to endotoxemia

Question 18

What are the effects of epinephrine on a1 receptors

Answer 18

Intense vasoconstriction

Question 19

What are the effects of epinephrine on B1 receptors

Answer 19

Increases SAP, HR, & CO

Question 20

What are the effects of epinephrine on B2 receptors

Answer 20

Modest decrease in DAP due to vasodilation in skeletal m & bronchodilation

Question 21

What are the net effects of epinephrine

Answer 21

• Increase in pulse pressure
• Min change in MAP
• Preferential distribution of CO to skeletal m
• Decreased SVR
• Renal blood flow decreases
• Coronary blood flow increases
• Secretion of renin b/c of B stimulation in the kidneys

Question 22

Describe phenylephrine

Answer 22

• Increased peripheral vascular resistance by agonist effect on the a1 receptors
• Can be used in px w/ severe vasodilation
• Used in dogs/cats to increase BP
• Generally recommended to avoid use in preg px

Question 23

Why is phenylephrine not recommended to use w/ preg px

Answer 23

It decreases blood flow to the uterus & therefore impairs oxygen delivery to the fetus

Question 24

Describe vasopressin

Answer 24

• Works through stimulation of the V1 receptor located on vascular SM
• Has no inotropic or chronotropic effects
• Indicated for vasodilatory hypotension due to sepsis, prolonged hemorrhagic shock, or cardiac arrest

Question 25

How is a infusion of dompaine or dobutamine made

Answer 25

* Dobutamine must be diluted to a concentration of < 5 mg/mL * Dobutamine & dopamine are physically compaticle w/ DSw, 0.9% NaCl, dextrose-saline, & LRS * Desired infusion concentration can be made in a syringe & delivered by syringe pump if ava or can be place in a bag of IV fluids & del by calculated drops per second or an accurate fluid pump * Dobamine & dobutamine are stable for about 24 H @ room temp so it should not be made up in advance of anticipated use

Question 26

Answer the following case

Answer 26

Question 27

Answer the following case

Answer 27

Question 28

What are the key take aways of CPR

Answer 28

* Cats are almost 5x more likely to survive to hospital discharge than dogs * Anesthetic related CPA events are almost 15x more likely to be discharged compared to other groups

Question 29

What are the goals of recover guidelines

Answer 29

* Review of literature * Dev consensus on CPR guidelines * Provide education & training for vet medical care teams

Question 30

What is the "chain of survival"

Answer 30

* Prevention/early recognition * Basic life support (BLS) * Advanced life support (ALS) * Post resuscitation care (post cardiac arrest care)

Question 31

What are the signs of cardiopulmonary arrest

Answer 31

* Not responsive * Not breathing * No pulse detected

Question 32

What are the steps of basic life support

Answer 32

1. Shake & shout (provide stimulation) 2. If not breathing/responsive immediately start chest compressions @ 100 - 120 per min & depth of 1/3 to 1/2 chest width (don't stop to check the pulse for 2 mins) 3. Est airway & ventilate @ 10 bpm (give breath every 6 secs)

Question 33

Describe how chest compressions are given

Answer 33

* px position: lateral recumbency * compressor position: stand behind the px (along the spine) * Hand position: hand over hand w/ interlaced fingers * Compressors stance: shoulders over elbows/hands, lock the elbows, & bend @ the waste * put the px on the floor or get on the table/stool if need be

Question 34

What are the different patient chest types

Answer 34

* Large round chest (A) * Large keel chest (B) * Wide chest - bulldogs, dorsal recumbency, compress to 25% depth (C) * Cats & small dogs - circumferential, one handed palm, or one handed thumb to fingers (D)

Question 35

How many breath per min should be delivered? what is the wanted tidal vol, inspiratory time, & peak pressure

Answer 35

* 10 bpm * TV = 10 ml/kg * Inspiratory time = 1 sec * Peak pressure < 40 cmH2O

Question 36

Describe airway & ventilation during CPR

Answer 36

* Ideally intubated w/ appropriately sized ETT w/ the cuff inflated & the tube secured in place * Can use a tight fitting mask & self inflating bag to deliver breath (ambu bag) * Use of 100% O2 is reasonable * If not able to intubate do mouth to snout using a ratio of 30 compression to 2 ventilation tech

Question 37

What should be done during the 2 min cycle of compressions & ventilations

Answer 37

* Hook up ECG leads * Place capnograph (ETCO2) @ the end o the ETT * Gain IV access (IO would be 2nd choice & some drugs can go IT if no other access ava) * Admin reversal agents if indicated (no cardiac sticks)

Question 38

How long should you take to stop compression long enough to feel for a femoral pulse & assess the ECG hook ups

Answer 38

No more than 10 secs

Question 39

If there is a pulse what should be done

Answer 39

ROSC

Question 40

If there is no pulse when checked what should be done

Answer 40

* Eval ECG to determine if there is a shockable or non shockable rhythm * Eval ETCO2 - if < 18 mmHg evaluate the quality of compressions

Question 41

What does this capnography wave form show

Answer 41

Cardiac arrest

Question 42

What does the capnography wave form show

Answer 42

Return of spontaneous circulation

Question 43

Which arrests rhythms are non shockable

Answer 43

* Asystole * Pulseless electrical activity (PEA)

Question 44

Which arrest rhythms are shockable (rate > 200)

Answer 44

* Pulseless ventricular tachycardia * Ventricular fibrillation

Question 45

Which arrest rhythm is this

Answer 45

Asystole

Question 46

Which arrest rhythm is this

Answer 46

PEA

Question 47

Which arrest rhythm is this

Answer 47

Pulseless ventricular tachycardia

Question 48

Which arrest rhythm is this

Answer 48

Ventricular fibrillation

Question 49

What are the emergency drugs for non shockable rhythms

Answer 49

* Vasopressors * Anticholinergics

Question 50

Describe vasopressors as a emergency drug

Answer 50

* Epinephrine & vasopressin * 0.01 mg/kg every other cycle

Question 51

Describe anticholinergics as an emergency drug

Answer 51

* Atropine & glycopyrrolate * Use one as early as possible & don't reduce * Glycopyrrolate onset is too slow for CPR use

Question 52

What does the ratio expression of strength mean for epinephrine

Answer 52

This is the formulation used for life threatening anaphylaxis, CPR, & sometimes for extremely low blood pressure under ax

Question 53

What is the reversal agent for opioids

Answer 53

Naloxone

Question 54

What is the reversal agent for benzodiazepines

Answer 54

Flumazenil

Question 55

What is the reversal agent for Alpha 2 agonist

Answer 55

Atipamezole

Question 56

What is the reversal agent for local anesthetic toxicity

Answer 56

Lipid emulsion infusion + supportive care

Question 57

What drug is considered for use in prolonged CPR ( > 15 min & pH < 7)

Answer 57

Sodium bicarb @ 1 mEq/kg

Question 58

Describe defibrillation

Answer 58

* 1st ling of tx for ventricular fibrillation or pulseless ventricular tachycardia * Immed after electrical defibrillation restart chest compression to replenish energy substrates & increase the chance of success before eval the ECG

Question 59

Describe the use of defibrillators

Answer 59

* Biphasic defibrillator dose: 2 J/kg * Double the dose for subsequent shocks (4 J/kg) * Use conductive electrode gel * Use of biphasic is recommended over monophasic b/c of less risk of myocardial damage & it is more effective w/ lower joules

Question 60

T/F: RECOVER recommends the use of IV fluid boluses in euvolemic dogs & cats during CPR

Answer 60

False; recommends against the use

Question 61

What is the use of IV fluids if a px is hypovolemic or in distributive shock

Answer 61

* use isotonic crystalloid during CPR * Hypertonic saline may be neuroprotective * Avoid synthetic colloids but blood products may be needed for significant hemorrhage * Manage electrolyte imbalance as needed

Question 62

What are some final takeaways that will help lead to a positive px outcome

Answer 62

* A well prepared/trained team * Effective closed loop communication * Ability to meet afterwards to discuss what went well & what to work on for next time * Stocked & ready to go crash cart * Perform compressions & ventilations effectively