Flashcards in L46 + 47 + SG 1 Deck (27)
What cannot pass the barrier between the intravasc and interstitial spaces?
No permeable to proteins
Ex: albumin is the main protein that prevents movement of fluid into interstitium
What cannot pass the barrier between the interstitial and intracellular spaces?
No permeable to electrolytes b/c of the cell membrane
Goal to keep cells the same - maintain fxn
Explain changes to Starling forces during heart failure leading to peripheral edema.
Heart = ineffective pump
Blood packs up into venous system
Increase hydrostatic pressure intravasc -> fluid forced into interstitium = EDEMA
Define osmolality - inlcude units.
+ particles in 1 L water = mmol/L
Aka [ ] by number
Plasma osmolality = [electrolytes] + [nonelectrolytes]
What are the 2 ways that the extracellular space can epand if extra volume is present?
1. Edema - duh, into interstitium (also look at lungs)
2. HTN if expand intravasc
Describe scenarios in which there is volume overload (expand interstitium) but intravasc depletion
Lose oncotic pressure
Total body Na increased
- Cirrohsis w/ ascites
- Nephrotic syndrome
- Burns (lose protein via skin)
What is step 1 of dx approach for hypo-osmolar states?
Posm: hypo, pseudo or hyper osmotic?
What is step 2 of dx approach for hypo-osmolar states?
ECF assessment - hypo, eu, or hypervolemic
4 causes on differential for euvolemic hypotonic hyponatremia
Pysch pt downing H2O
Equation to calculate Posm?
Posm = 2[Na] + (BUN/2.8) + (glucose/18)
4 causes on differential for hypervol hypotonic hyponatremia
= pt really volume overloaded by intravasc depletion
Oliguric renal failure
What are 5 key symptoms for dx of nephrotic syndrome?
1. Proteinuria = > 3.5gm/24 hrs
2. Hyperlipidemia - liver sees low ECV and throws fat to try to compensate
5. Edema (hypervol)
What is the U Na cut off for renal vs non-renal causes of hypovol hyponatremia?
Renal: U Na > 20 = kidney is wasting Na even though you should be saving it
Non-renal: U Na
3 causes on the differential for non renal hypovol hypotonic hyponatremia
1. GI losses: vomiting, diarrhea, fistula
2. Skin losses (burns)
3. Remote diuretic use
4 causes on differential for renal hypovol hypotonic hypoNa
1. Acute diuretics
2. Salt wasting nephropathy
3. Adrenal insuff (Addison's disease)
4. Osmotic diuretics
4 factors necessary in nephron to excrete free water
1. Normal GFR
2. Distal delivery of Na past prox loop of Henle
3. Intact ascending loop
4. Suppress ADH
What Uosm > x denotes a failure to suppress ADH?
Uosm > 100
What happens to the 4 steps in the kidney during hypovol?
↑Prox tubule Na reabsorption - first step to fixing the prob fast but...
↓s Distal Na delivery
↓ Loop Na reabsorption
↓ Ability to suppress ADH
What happens to the 4 steps in the kidney during euvolemia?
Only ↓ability to suppress ADH (think SIADH)
What happens to the 4 steps in the kidney during hypervolemia?
Same as hypovol b/c intravasc hypervol!
Symptoms of hyponatremia
Signs of hyponatremia
Depressed deep tendon reflexes
Treat hypovol hypoNa
Treat euvol hypoNa
2ary: V2 receptor antag
Treat hypervol hypoNa
Maybe V2 antag and/or diuretics (for edema)
What are you worried about if you correct hypoNa too fast?
Esp if chronic hypoNa