Therapeutics - Approach to Treatment Flashcards
key steps
1) Correct identification of the underlying disease process
2) Staging of the severity of disease
3) Applying “evidence based medicine”
4) In the absence of “best-evidence” making an informed and rational decision on the basis of the type of signs being shown and the type of therapy that would be most effective.
“wet” patient - define
showing congestive signs
“cold” patient - define
poor output signs
wet to dry - drugs
diuretics
preload reduction
cold to warm - drugs
improve output
inotropes
afterload reduction
anti-arrythmics
Heart failure characteristics
Increased preload Increased afterload Impaired inotropy Impaired lusitropy (ability of the heart to relax) Abnormalities of rate and rhythm
classes of diuretic
loop diuretic
thiazides
potassium sparing diuretics
Site of action of diuretics - carbonic anhydrase (CA) inhibitors
posterior convoluted tubule
Site of action of diuretics - furosemide
loop of henle
Site of action of diuretics - thiazides
distal convoluted tubule
Site of action of diuretics - potassium sparing
Collecting ducts
risks of diuretics
Hypovolaemia
Hypotension
Electrolyte disturbances
Stimulation of RAAS
preload reduction
signs of congestion
diuretics
venodilation - decr pressure
afterload reduction
patient can become hypotensive
arteriodilators
pateint appears cold
improve systolic function - when + what to use
dilated cardiomyopathy + mitral valve disease
inotropic agents improve output signs
improve diastolic function - drug types
ca channel blockers - hasten relaxation
beta blockers - decr heart rate
ACEI - decr fibrosis
optimise cardiac rate + rhythm
arrhythmias
change SV, HR + CO
benefits of afterload reduction
Increased stroke volume Increased cardiac output Decreased mitral regurgitation decr systolic wall tension decrs cardiac work Decreased myocardial oxygen demand Improved oxygenation of myocardium
risks of afterload reduction
hypotension
Decr blood pressure may compromise perfusion of essential vascular beds
afterload reduction - drugs
Balanced vasodilators
ACE inhibitors
Pimobendan
Calcium channel blockers
problems with inotropes
Increased myocardial work May be associated with incr rate of myocardial deterioration Incr myocardial oxygen demand Exacerbate ischaemia/hypoxia May lead to rhythm disturbances Digoxin exception due to other effects Reduced heart rate Decreased sympathetic tone
