Lecture 24: CV Support Drugs & Basic CPR (Exam 3) Flashcards
What should MAP & SAP be to prompt recognition & tx will ensure perfusion of vital organs
- MAP > 60 - 70 mmHg
- SAP > 80 - 90 mmHg
What are the common causes of CV depression during ax
- Drugs
- Equipment malfunction/misuse
- Shock/sepsis
- Hypovolemia
- Mechanical ventilation
- Surgical procedure
- pre existing CV dx
- Metabolic dx
What is the key to CV depression during ax
Treat the underlying cause of hypotension
What is the equation for CO
HR x SV
What is the equation for MAP
CO x SVR
List management options for CV depression
- Adjustment to current ax manangement
- Fluids
- Anticholinergics
- Vasopressors
- Positive ionotrops
What are sympathomimetics that support CV
- Positive ionotropes
- Vasopressors
Describe sympathomimetics
- 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
Fill out the following:
Describe dobutamine
- 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
Describe dopamine
- Endogenous catecholamines
- Precursor to NE
- Acts directly & indirectly on both a & B 1 receptors
- Has dopaminergic (D1 & D2) effects
- Increases CO, HR, BP, & SVR
What does dopamine tx? What about a low & high doses?
- 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
Describe ephedrine
- 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
Why is ephedrine used in horse to manage hypotension during gen ax
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
Describe noreepinephrine
- 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
What is the main use of norepinephrine
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
Describe epinephrine
- 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
What are the effects of epinephrine on a1 receptors
Intense vasoconstriction
What are the effects of epinephrine on B1 receptors
Increases SAP, HR, & CO
What are the effects of epinephrine on B2 receptors
Modest decrease in DAP due to vasodilation in skeletal m & bronchodilation
What are the net effects of epinephrine
- 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
Describe phenylephrine
- 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
Why is phenylephrine not recommended to use w/ preg px
It decreases blood flow to the uterus & therefore impairs oxygen delivery to the fetus
Describe vasopressin
- 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
How is a infusion of dompaine or dobutamine made
- 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
Answer the following case
Answer the following case
What are the key take aways of CPR
- 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
What are the goals of recover guidelines
- Review of literature
- Dev consensus on CPR guidelines
- Provide education & training for vet medical care teams
What is the “chain of survival”
- Prevention/early recognition
- Basic life support (BLS)
- Advanced life support (ALS)
- Post resuscitation care (post cardiac arrest care)
What are the signs of cardiopulmonary arrest
- Not responsive
- Not breathing
- No pulse detected
What are the steps of basic life support
- Shake & shout (provide stimulation)
- 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)
- Est airway & ventilate @ 10 bpm (give breath every 6 secs)
Describe how chest compressions are given
- 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
What are the different patient chest types
- 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)
How many breath per min should be delivered? what is the wanted tidal vol, inspiratory time, & peak pressure
- 10 bpm
- TV = 10 ml/kg
- Inspiratory time = 1 sec
- Peak pressure < 40 cmH2O
Describe airway & ventilation during CPR
- 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
What should be done during the 2 min cycle of compressions & ventilations
- 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)
How long should you take to stop compression long enough to feel for a femoral pulse & assess the ECG hook ups
No more than 10 secs
If there is a pulse what should be done
ROSC
If there is no pulse when checked what should be done
- Eval ECG to determine if there is a shockable or non shockable rhythm
- Eval ETCO2 - if < 18 mmHg evaluate the quality of compressions
What does this capnography wave form show
Cardiac arrest
What does the capnography wave form show
Return of spontaneous circulation
Which arrests rhythms are non shockable
- Asystole
- Pulseless electrical activity (PEA)
Which arrest rhythms are shockable (rate > 200)
- Pulseless ventricular tachycardia
- Ventricular fibrillation
Which arrest rhythm is this
Asystole
Which arrest rhythm is this
PEA
Which arrest rhythm is this
Pulseless ventricular tachycardia
Which arrest rhythm is this
Ventricular fibrillation
What are the emergency drugs for non shockable rhythms
- Vasopressors
- Anticholinergics
Describe vasopressors as a emergency drug
- Epinephrine & vasopressin
- 0.01 mg/kg every other cycle
Describe anticholinergics as an emergency drug
- Atropine & glycopyrrolate
- Use one as early as possible & don’t reduce
- Glycopyrrolate onset is too slow for CPR use
What does the ratio expression of strength mean for epinephrine
This is the formulation used for life threatening anaphylaxis, CPR, & sometimes for extremely low blood pressure under ax
What is the reversal agent for opioids
Naloxone
What is the reversal agent for benzodiazepines
Flumazenil
What is the reversal agent for Alpha 2 agonist
Atipamezole
What is the reversal agent for local anesthetic toxicity
Lipid emulsion infusion + supportive care
What drug is considered for use in prolonged CPR ( > 15 min & pH < 7)
Sodium bicarb @ 1 mEq/kg
Describe defibrillation
- 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
Describe the use of defibrillators
- 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
T/F: RECOVER recommends the use of IV fluid boluses in euvolemic dogs & cats during CPR
False; recommends against the use
What is the use of IV fluids if a px is hypovolemic or in distributive shock
- 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
What are some final takeaways that will help lead to a positive px outcome
- 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
