Diuretics. Mannitol (Amboss and UW) Flashcards
Osmotic diuretics?
Mannitol
Mannitol mechanism of action? 2 mechanisms
Increase osmolality;
No saluresis
Mannitol increase osmolality. Of what?
- Serum osmolality and
2. Glomerular filtrate (aka tubular fluid osmolality)
Mannitol. Increased serum osmolality mechanism?
Serum: ↑ shift of water into the intravascular space → ↑ binding of water → ↓ intracranial and intraocular pressure
Mannitol. Increased glomerular filtrate osmolality mechanism?
↑ tubular fluid osmolarity → ↑ binding of water → ↑ urine production
Mannitol filtration and absorption?
The osmotic diuretics are filtered freely in the glomeruli and are not reabsorbed throughout the entire tubule.
What pressures decrease when used mannitol?
Decr. intracranial and intraocular pressure
What is saluresis?
Saluresis aka natriuresis.
Increased renal excretion of sodium. Natriuresis also results in an increase in urine output (diuresis) because of the osmotic effect of sodium.
Why osmotic diuretics are not useful for the saluretic treatment of edema?
Because osmotic diuretics (mannitol) does not cause saluresis.
Mannitol indications?
Elevated ICP (e.g., cerebral edema)
Acute glaucoma
Prevention of acute renal injury in cases of oliguria
Forced renal excretion of substances (e.g., drugs or toxins), DRUGS OVERDOSE
Mannitol contraindications?
Anuria
Progressive heart failure
Severe pulmonary edema
Severe dehydration
Why mannitol is contraindicated in anuria?
With ineffective glomerular filtration and/or anuria, osmotic diuretics can lead to severe volume overload with subsequent pulmonary edema.
Why mannitol is contraindicated in HF?
Osmotic diuretics initially increase circulating blood volume, causing cardiac strain.
Why mannitol is contraindicated in pulmonary edema?
Due to circulatory overload
Why mannitol is contraindicated in dehydratation?
Although extracellular fluid volume is increased, intracellular volume decreases.
Side effects of mannitol?
Dehydration
Initial cardiac volumetric strain (itampa)
Metabolic and electrolyte imbalances
What metabolic changes occur as complication of mannitol?
a. Effective glomerular filtration → hypernatremia (due to water decr in blood?)
b. Ineffective glomerular filtration or administration of very high doses → ↑ plasma osmolality → ↑ extracellular fluid volume → pulmonary edema, potassium fluctuations, hyponatremia or hypernatremia, and/or metabolic acidosis
How flow water in the presence of mannitol?
down to its concentration gradient from the intracellular space to plasma (intravascular compartment).
BBB and mannitol?
Mannitol does not cross BBB, therefore is used to treat elevated intracranial pressure (water from brain parenchyma goes to vasculature –> reduced intracranial volume and pressure).
Intraparenchymal hemorrhage and midline shift. what medication?
Mannitol
What is the origin of mannitol?
sugar alcohol
Administration of mannitol?
Parenteral - nes blogai reabsorbuojasi, bet jeigu duo p/o, tai sukeltu osmotic diarrhea.
how changes plasma Na concentration when mannitol effect ooccurs?
Na plasma concentration DECREASES because of water movement to intravascular compartment (DILUTIONAL HYPONATREMIA).
Bet tipo jeigu glomerular function is in tact, tai dahuja issifiltruoja vandes ir buna hypernatremia
how changes renal blood flow when mannitol effect ooccurs?
Due to plasma volume expansion renal blood flow INCREASES –> Increased glomerular filtration and renal tubular flow.!!!!!
