Download Cardiac Meds - hostedvoipinfo.net

Cardiac Meds
Cardiac Output
Stroke Volume
Afterload
PVR
Preload
Venous
Return
Viscosity
Aortic
Impedance
Ventricular
Compliance
X
Contractility
=
Heart Rate
Meds
Sympathetic
Stimulation
Preload
• Function of the volume of blood to the LV and
the compliance (ability of the ventricle to
stretch) of the ventricles at the end of diastole
(LVEDP)
• Factors affecting are: venous return, total
blood volume and atrial kick
• Hypovolemic patient has too little preload
• Heart failure patient has too much preload
Afterload
• Ventricular wall tension or stress during
systolic ejection
• Increase in afterload relates to an increase in
the work of the heart
• Increased afterload R/T:
– Aortic stenosis
– Vasoconstriction and SVR
– Blood volume and viscosity
• To decrease, use vasodilators, decrease
myocardial oxygen demand
Contractility
• Inotrophy or enhancing strength, can be
positive or negative
• Sympathetic medications increase contractility
• Ca++ is a medication that will increase
contractility by increasing actin and myosin
contractions
• Digoxin also works to increase Ca++ channels
by slowing the Na/Ca pump
Control of Heart Rate
• SNS- sympathetic nervous system
– Fight or flight
– Increase HR, BP, respirations, dilate pupils
• PNS- parasympathetic system
– Decreases contractility, rate
– Vagus nerves to the SA and AV nodes
• Baroreceptors- pressure sensors in carotids and aortic arches
• Chemoreceptors- pH levels in aortic arch
• ANF- atrial natriuretic factor- hormone secreted by the atria in
response to atrial pressure
– Causes Na and water to be excreted and also vasodilates
Control of Stroke Volume
• Preload
– Increase use:
• Fluid resusitation
– Decrease use:
• Diuretics and vasodilators
• Afterload
– Increase use:
• Vasopressors
• Volume expanders
• Afterload
– Decrease use:
• Vasodilators
• Diuretics
• Decrease sympathetic
stimulation
• Contractility
– Increase use:
• Sympathetic stimulants
– Decrease use:
• CCB’s
• Decrease sympathetics
Vasopressors
• Sympathomimetic-inotrophic
• Medications that mimic the sympathetic
system, work on alpha, beta and dopamineric
receptors
• Require continuous monitoring of BP and
heart rate
• Alpha: vasoconstricts peripheral arterioles
• Beta 1: Increased HR, contractility
• Beta 2: Bronchodilation
Vasopressor
• Dopamine
– Stimulates alpha and
beta receptors
– In small doses (2-5
mcg/kg/min) produces
renal vasodilation
– Larger doses (max 20
mcg/kg/min) alpha and
beta stimulation
– Increases HR and BP
• Precautions:
– Give IV only, can
sloughing of tissue with
extravasation, if it does
infiltrate, give
phentolamine IV to the
site
– Tachyarrhythmias,
palpations, hypotension
if not hydrated,
headache, dyspnea
Vasopressor
• Epinephrine
– Alpha-Adrenergic, beta 1
and beta 2 stimulant
– Produces
bronchodilation and
vasoconstriction
– Increases HR, BP and
bronchodilates
– Given IV, SQ and
inhalation
– Max is 20 mcg/min
• Precautions:
–
–
–
–
–
Tachyarrhythmias
Angina
Nervousness, tremors
Hypertension
Works almost
immediately IV
– Watch for chest pain and
HR >120, can cause
cardiac arrest with too
last a rate
Vasopressor
• Norepinephrine
– Stimulates alpha, beta
receptors
– Need to hydrate patient
– Lacks beta 2 effects
– Marked alpha
vasoconstriction
– Used in shock states
– Max is 16 mcg/min
• Precautions:
– Closely monitor HR and
BP, can elevate quickly
– Monitor for peripheral
vasoconstriction, in high
doses, can constrict all
extremities
– Can decrease the C.O. if
rate is too high
Vasopressor
• Dobutamine
– Synthetic
cathecholamine with
mainly beta effects
– Mild stimulation of beta
2
– Increases myocardial
contractility
– Useful with heart failure
patients
– Max is 20 mcg/kg/min
• Precautions:
– Monitor for increased
HR and BP
– PVC’s and angina
– Watch for shortness of
breath
– May be given over a long
infusion for heart failure
patients
VasopressorsPhosphodiesterase Inhibitors
• Cause increased levels of
AMP and Ca++
• Medications:
– Amrinone (Inocor)
– Milrinone (Primacor)
• Cause an increase in cardiac
output and some decreased
afterload
• Effective in heart failure
patients to increase C.O.
• Precautions:
– Given as a continuous IV
infusion
– Can cause PVC’s and V tach
because of increased
contraction
– Monitor for drops in BP R/T
decreased afterload
– Watch for thrombocytopenia
and abnormal liver function
Other Vasopressors
• Phenylephrine (neosynephrine)
– Stimulates alpha
receptors only
– Used by anesthesia
– Can increase myocardial
demand
– Works very quickly
• Vasopressin (antidiuretic
hormone)
– Nonadrenergic
peripheral
vasoconstrictor
– Used in VF and pulseless
VT, 40Units
– Used as an IV infusion in
sepsis with peripheral
vasodilation
Vasodilators- Direct Smooth Muscle
Relaxants
•
•
•
•
Decrease PVR
Arterial and venous dilation
Improves cardiac output
Medications:
– Nitroprusside (Nipride)
– Nitroglyceride
– Hydralazine (Apresoline)
• Precautions:
– Closely monitor BP, can drop
dramatically, especially
nipride
– Long term nitroprusside
therapy can lead to
thiocyanate toxicity
– NTG is used with unstable
angina (given 5-300 mcg/min
– Apresoline is not a
continuous infusion, major
side effect is tachycardia
Vasodilators- Ca++ Channel Blockers
• Arterial vasodilation
• Reduce the influx of
calcium and decrease
resistance
• Used mostly for
hypertension
• Also to slow rapid
rhythms, such as SVT,
and Atrial fib
• Medications:
–
–
–
–
Nicardipine (Cardene)
Nifedipine (Procardia)
Diltiazem (Cardizem)
Verapamil (Calan)
• Side effects:
– Hypotension,
bradycardia, nausea,
heart failure and
peripheral edema
Vasodilators-ACE inhibitors
• Vasodilate by blocking
the conversion of
angiotensin I to
angiotensin II, decreases
PVR
• May drop BP
dramatically if volume
depleted
• Stops Na and water
retention
• Medications:
– Captopril (Capoten)
– Enalapril (Vasotec)
• Precautions:
– Hypotension, chronic
cough, neutropenia and
elevated liver enzymes
Vasodilators- Alpha adrenergic blockers
• Block peripheral alpha
receptors in arteries and
veins
• Orthostatic changes may
result
• May lead to fluid
retention
• Medications:
– Labetalol (normadyne)
• Alpha & beta blocker
• Decreased BP without
increased HR
• Used in aortic dissections
– Phentolamine (Regitine)
• Peripheral alpha blocker,
decreases afterload
• Used with
pheochromocytomas
Vasodilators- DA-1 receptor agonists &
Synthetic BNP
• Dopamine DA-1 receptor
agonists, vasodilates
peripheral and renal
arteries
• Medication:
– Fenoldopam (Corlapam)
• Hypertensive
emergencies
• Watch for hypotension
and tachycardia
• Natrecor:
– Brain naturietic peptide
– Used for decompensated
HR with dyspnea
– Vasodilates pulmonary
bed, reduces SVR and
PVR
– Lowers BNP levels
– Infusion runs for 6-48
hours
Vaughn Williams Classification- Used for
Antiarrhythmics
• Class I agents interfere with the sodium (Na+)
channel.
• Class II agents are anti-sympathetic nervous
system agents. Most agents in this class are
beta blockers.
• Class III agents affect potassium (K+) efflux.
• Class IV agents affect calcium channels and
the AV node.
• Class V agents work by other or unknown
mechanisms.
Class Ia
• Medications:
– Quinidine
– Procainamide
– Disopyramide
• Type:
– Na+ channel block
intermediate
• Use:
• Ventricular arrhythmias
• Prevents recurrent atrial
fib, triggered by
overactive vagal
stimulation (WolffParkinson-White
syndrome)
Class Ib
• Medication:
– Lidocaine
– Phenytoin
– Mexiletine
• Type:
– Na+ channel block fast
• Use:
– Ventricular tachycardia
– Atrial fib
– Prevention during and
immediately after an MI,
but it is now discouraged
R/T increased risk of
asystole
Class Ic
• Medications:
– Flecainide
– Propafenone
– Moricizine
• Type:
– Na+ channel block slow
• Use:
– Prevents paroxysmal
atrial fib
– Treats recurrent
tachyarrhythmias of
abnormal conduction
system
Class II
• Medications:
–
–
–
–
–
Propranolol
Esmolol
Timolol
Metoprolol
Atenolol
• Type:
– Beta Blocker
• Use:
– Decrease myocardial
infarction mortality, used
post MI
– Prevent recurrence of
tachyarrhythmias
– Decrease Beta 1 and 2
stimulation, decrease HR
and BP
– Side effects of
bradycardia, fatigue, wt.
gain, impotence,
depression
Class III
• Medications:
–
–
–
–
Amiodarone
Sotalol (also a Beta)
Ibutilide
Dofetilide
• Type:
– K+ channel blocker
• Use:
– Ventricular tachyarrhythmias
– Atrial flutter and atrial fib
– Wolff-Parkinson-White
syndrome
• Side effects:
– SOB, bronchospasm, renal or
hepatic insufficiency
– Photosensitive, use
sunscreen and sunglasses,
may cause bluing of periphery
Class IV
• Medications:
– Verapamil
– Diltiazem
• Type:
– Ca++ channel blocker
• Use:
– Prevent recurrence of
paroxysmal SVT
– Reduce ventricular rate in
patients with atrial fib
– Decrease the contraction of
muscle tissue, prevents slide
of actin and myosin
– Avoid grapefruit juice it can
increase serum levels, as do
high fat meals
– Monitor thyroid function
Class V
 Medications:
Adenosine
Digoxin
 Use:
 Supraventricular arrhythmias
 Contraindicated in ventricular
arrhythmias
 Side effects:
 Type:
Work by other methods,
direct nodal inhibition
Na/Ca pump
 Digoxin- bradycardia, anorexia,
nausea & vomiting,
yellow/green halos, heart
blocks, arrhythmias, causes
hypocalcemia and hypokalemia
Aspirin
• Acts to reduce inflammation by inhibiting the
production of prostaglandins
• Decreases platelet aggregation, decreases the
incidence of TIA’s and MI
• Dosage of 81 mg maintenance, not enteric
coated in MI
• Monitor for GI bleeding, exfoliative dermatitis,
Stevens-Johnson syndrome, tinnitus
Other Emergency Medications
• Atropine:
– Parasympathicolytic, enhances
the SA node and AV node
conduction
– Used for bradycardia and
asystole
– Side effects:
• Tachycardia, urinary
retention, blurred vision,
bowel obstruction, not for
Complete heart block
• Calcium Cl:
– Enhances myocardial
contractility for pts with
elevated K, Mg and low
Ca and CCB toxicity
– Side effects:
• Coronary and cerebral
vasospasm, ventricular
irritability, cautious if on
Digoxin
Other Emergency Medications
• Magnesium
– Reduces post infarction
arrhythmias and pump failure
– Hypomagnesemia can cause
refractory V fib and sudden
cardiac death
– Side effects:
• Flushing, sweating,
hypotension, sensation of
heat, flaccid paralysis,
circulatory collapse
• Diprivan (Propofol)
– Short acting sedative,
used for sedation with
patients who have
airway and ventilatory
support
– Side effects:
• Hypotension, rebound
tachycardia and increased
ICP when wean off,
hepatotoxicity
Other Emergency Medications
• Lorazepam (Ativan)
– Benzodiazepine sedative
– Effects last 6-8 hours
– If given intraarterial can cause
gangrene and limb loss
– CNS depression is prominent if
over 50
– Contraindicated if glaucoma
– Watch for airway depression
• Midazolam (Versed)
– Benzodiazepine sedative
– Effects last 1.5-2 hours
– Depresses respiratory rate,
apnea, can cause hypotension
– Hiccups, headache, nausea,
amnesia, confusion
– Can be reserved with romazicon
(flumazenil)
Other Emergency Medications
• Succinylcholine
– Neuromuscular blocking agent
– Rapid acting agent for intubation
– Side effects:
• Hypotention, tachycardia,
hyperkalemia, severe in
neurologic patients
myoglobinuria, malignant
hyperthemia
• Rocuronium or
vecuronium
– Neuromuscular blocking agent
– Lasts 20-60 minutes
– Can cause tachycardia,
hypotension and bronchospasm
in some patients, prolonged
weakness if renal involvement