Cardiovascular Agents Flashcards
1
Q
Inotropic agents
A
- Dobutamine
- Dopamine
- Epinephrine
- Vasopressin
2
Q
Dobutamine
A
- Fast-acting inotropic agent
- beta-adrenergic
- increases myocardial contractility and stroke vol.=increase CO
- decreases peripheral resistance
- used for heart failure and shock that has failed to respond to fluid therapy and use of pressor is contraindicated
- only injectable
- Rapid onset of action (within 2 min)
- Short duration (10 min) - CRI
- Drug interactions
- beta-blockers = antagonize inotropic effects
- insulin = increased need
- oxytocin drugs = severe hypertension
- Need constant BP monitoring
- Compatible with
- dextrose
- saline
- LRS
3
Q
Dopamine
A
- Weaker inotropic effect than Dobutamine
- At higher doses = pressor effects=vasoconstriction
- increased organ perfusion (at low dose)
- increased BP and CO (at high dose)
- Used in shock and cardiovascular collapse
- Low dose
- dilation of renal, mesenteries and coronary vascular beds (dopaminergic receptors)-limited in cats
- Mid-range dose
- peripheral vasoconstriction
- organ vascular perfusion preserved via beta-adrenergic effects
- High dose
- alpha-adrenergic effects causing vasoconstriction
- useful in decompensated shock states (vasodilation and low cardiac pre-load)
- renal blood flow can decrease as a result of increased vasoconstriction
- CRI
4
Q
Epinephrine
A
- alpha and B-adrenergic agonist
- Increases HR and contractility
- Low doses
- B-effects causes vasodilation and lower diastolic blood pressure
- High dose
- alpha-effects dominate
- pressor effects of vasoconstriction and increase peripheral resistance
- Excitatory effects
- causing ventricular fibrillation
- caution use in pre-fibrillatory rhythms
- Increased myocardial oxygen demands
- from inotropic and chronotropic effects
- *Global vasodilation and academia as a result of shock, sepsis, or prolonged cardiopulmonary arrest (CPA)
- cell membranes are less responsive to adrenergic vasoconstriction like epinephrine and dopamine
5
Q
Vasopressin
A
- non-adrenergic vasoconstrictor and inotrope
- Catecholamine-resistance shock
- cell membranes still responsive to vasopressin
- Increases
- MAP
- renal blood flow
- oxygen delivery to tissues
- cardiac output
- low doses
- CRI 0.01-0.04 U/min
- 0.5-1.0 mU/kg
- vasoconstriction to organs don’t occur
- high dose
- selective vasoconstriction
- renal and GI blood flow decreases
- only administer after fluid resuscitation has occurred
- or ischemia can result
- useful in asystole and CPA
0. 2-0.8 u/kg - can be used in conjunction with catecholamine pressor
- BP monitoring essential
6
Q
Antiarrhythmic drugs
A
- Lidocaine
* Procainamide
7
Q
Lidocaine
A
- Class IB antiarrhythmic
- used to Tx ventricular tachyarrhythmia
- Combines with fast sodium channels
- inhibits recovery after repolarisation
- Little effect on SA node automaticity, AV node conduction or Bundle of His-Purkinjie conduction
- Use with caution with patients with SA, AV or intraventricular heart block
- increases fibrillation threshold
- Controversial in cats
- increased sensitivity to CNS side effects
- increased monitoring and halved dose acceptable
- Dose:
- 2mg/kg IV bolus (repeated 3X until conversion to sinus rhythm)
- 50-80mcg/kg/min CRI
8
Q
Procainamide
A
- Class IB antiarrhythmic similar to lidocaine
- impairs contractility to a greater degree than lidocaine
- not first choice drug for CPR
- GI side effects (anorexia, vomiting and diarrhoea)
- Cardiac side effects (weakness, hypotension, negative inotropism, widening QRS complexes)
9
Q
Angiotensin converting enzyme (ACE) inhibitors
A
- Benazepril
- Enalapril
- Reduces blood pressure in hypertensive patients
- Reduces vascular resistance
- thus treating CHF
- Use with caution in renal patients
- lower renal perfusion pressures
10
Q
Calcium channel blocking agents
A
- Amlodipine
- tx of hypertension
- inhibits calcium influx across cell membranes
- peripheral arteriolar vasodilator = reduce afterload
- slow onset and PO only
- potential side effect = hypotension =monitor BP
- Diltiazem
- similar vasodilator
- slows AV node conduction and prolongs refractory times
- useful in supraventricular tachycardia (SVT)
- bradycardia as side effect
- avoid concurrent use with beta blockers
- cytoprotective - less oxygen free radical metabolites
- alternative tx for oliguric renal failure in cats
11
Q
Beta-adrenergic blocking agents
A
- Atenolol
- Propanolol
- can cause bronchoconstriction
- Sotalol
- Tx hypotension, hypertrophic cardiomyopathies and some tachyarrhythmias
- Negative inotrope
- cause hypotension
12
Q
Vasodilating agents
A
- *CHF needs rapid reduction in vascular resistance to reduce afterload and improving cardiac function
- Nitroglycerine
- skin paste
- transdermal
- wear gloves
- Nitroprusside
- rapid acting intravenous hypotensive agent
- can be used in conjunction with an inotrope such as Dobutamine for synergistic effect for CHF
- BP monitoring essential
- short acting duration
13
Q
Diuretics
A
- Loop diuretics
- Furosemide
- increases renal excretion of water, sodium, potassium, chloride, calcium and magnesium
- rapid onset - 5 mins
- serum half-life of 2 hours
- short duration of action
- must ensure water access at all times
- watch for hypotension
14
Q
Thiazide diuretics
A
- interferes with sodium ion transport
- enhance excretion of water, sodium, chloride, potassium, and magnesium
- used in tx of systemic hypertension and nephrogenic diabetes insipidus
- side effect: electrolyte imbalances
- do not use in: renal or hepatic impairment or diabetes mellitus
15
Q
Potassium sparing diuretics
A
- Spironolactone
- inhibits aldosterone at distal renal tubules
- enhance sodium, chloride, and water
- decrease potassium excretion
- weaker than furosemide
- useful in tx of edema when potassium loss is a concern and unable to supplement
- hyperkalemia (side effect)
