Diuretics Flashcards
Forces Favoring Filtration
Glomerular hydrostatic pressure 60
Bowman’s capsule colloid osmotic pressure 0
Forces Opposing Filtration
Bowman’s capsule hydrostatic pressure 18
Glomerular capillary colloid osmotic pressure 32
GFR is normally preserved by
maintaining a constant RBF over a range of systemic blood pressures with MAP 50 to 150 mmHg
these patients have a higher GFR when RBF is constant
hypertensive
describe the Myogenic Autoregulation of RBF and GFR
↑ arterial pressure stretches afferent arteriolar wall then a reflex constriction occurs
↓ Arterial pressure causes arteriolar dilation
describe Tubuloglomerular Autoregulation of RBF and GFR
↓ RBF = ↓ GFR which results in afferent arteriolar dilation which increase GFR and RBF and restore filtration
Renin released = angiotensin II = ↑ GFR
what is urine made of?
electorlytes
waste products
metabolites
Urine excretion is equal to
Filtration rate – reabsorption rate + secretion rate
Diuretic Uses 6
Reduce HTN (decrease intravascular fld vol.)
Treat pulmonary and peripheral edema
Electrolyte and pH corrections (hyperkalemia)
Reduce ICP, brain bulk
Prevent ARF due to ischemic insult
Drug clearance
how are diuretics classified?
Site of action on renal tubules
How they excrete solute
Main classifications diuretics?
Thiazide diuretics Loop diuretics Osmotic diuretics Potassium-sparing diuretics Carbonic anhydrase inhibitors
4 Loop Diuretics
Furosemide (Lasix)
Torsemide (Demadex)
Bumetanide (Bumex)
Ethacrynic Acid (Edecrin) no longer avail.
moa loop diuretics
Inhibit reabsorption of NaCl in
ascending loop
Most effective diuretic class
Loop Diuretics
what are Loop Diuretics used for?
Used more to decrease intravascular fluid volume and for rapid excretion of drugs
Do loop diuretics increase GFR?
nope
loop diuretics Stimulates production of prostaglandins which produces
Vasodilation
Increased RBF
Loop Diuretics (Lasix) indications 5
Rapid intravascular fluid removal Hyperkalemia treatment Acute pulmonary edema Kidney stone extraction, lithotripsy Reduce intracranial pressure
what can be used in combination with mannitol and why?
Systemic diuresis and ↓ CSF production to reduce ICP
hypokalemia is Loop Diuretics Concern, which causes
Shown to deplete myocardial K+ stores
Potential digitalis toxicity
Enhanced NMB effects
what does lasix do in large doses 1-4 mg/kg in regards to NMB
inhibits phosphodiesterase, increasing cAMP (same as azathioprine, Imuran) – makes patients resistant to NMB
what does lasix <1mg/kg do in regards to NMB with small doses?
decreased cAMP production – makes patients sensitive to NMB.
big concern of loop diuretics we have known since nursing school
ototoxic
loop diuretics cause many imbalances, what should you be ready for?
Potassium replacement may be indicated Cardiac dysrhythmias can occur Fluid volume replacement may be indicated Orthostatic hypotension Hemoconcentration, (increased Hct, BUN) Mild hyperglycemia