Term
| Define: hypernatremia/hyperosmolality; hyponatremia/hypoosmolality |
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Definition
1) water deficit (concentrated sodium)
2) water excess (diluted sodium) |
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Term
| What is the principle mediator of volume status? |
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Definition
| 1) sodium content; tightly regulated |
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Term
| What are major indicators that could lead to a diagnosis of hypovolemia? hypervolemia? |
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Definition
1) hypotension, tachycardia, orthostatic hypotension; reduced skin tugor; dry mucous membranes; reduced fractional excretion of sodium and urine Na; elevated BUN, creatinine, HCT; reduced urine output
2) edema; pulmonary edema; elevated JVP; hepatic fullness; hypertension; elevated brain natriuretic peptide (BNP) |
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Term
| What is the fractional excretion of sodium? |
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Definition
| 1) FENa+ = urinary sodium excretion rate divided by filtered load (GFR*P_Na) = 0.79% |
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Term
| What is the greatest clinical utility for FENa+? |
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Definition
| 1) setting of liguria where the clinician is trying to differentiate between acute kidney injury and decreased effective circulating volume as the cause |
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Term
| What solute primarily determines ECF volume? |
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Definition
1) Na
2) Na Loss = ECF volume contraction; retention = ECF volume expansion |
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Term
| What are the major components to the appropriate kidney response to volume depletion? |
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Definition
1) urinary Na < 20mEq/L = aldosterone effect
2) FENa <1% = aldosterone effect
3) FENa>1% = kidney source of volume loss |
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Term
| What are sources of volume loss in the kidney with FENa>1%? |
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Definition
1) diruetics, osmotic diuresis (mannitol)
2) salt losing nephropathy
3) hypoaldosteronism
4) post obstructive diuresis
5) kidney damage such that the ability to reabsorb Na is affected |
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Term
| What is the treatment for volume depletion? |
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Definition
| 1) sodium (volume) replacement |
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Term
| Define: edema. what are two major factors? |
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Definition
- palpable swelling due to expansion of interstitial fluid
1) starling forces
2) Na retention by the kidney |
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Term
| What is the cascade that leads to the edematous state (HF, cirrhosis, nephrotic syndrome) |
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Definition
1) distubred starling forces causing movement of fluid into interstitium
2) transient contraction of plasma volume
3) sodium retentive mechanisms
4) re-expansion of ECF with "normalization" of plasma volume
5) restoration of tissue perfusion |
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Term
| What are the major problems that may lead to edema formation? |
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Definition
1) increased capillary pressure (inc. venous volume; venous obstruction)
2) decreased plasma oncotic pressure
3) increased capillary permeability |
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Term
| What is the equation to calculate the net filtration pressure? |
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Definition
| 1) NFP = Lp*S*[(Pcap - Pis) - sigma(PiCap - Piis)] |
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Term
| What are mechanisms that help protect the body from edema formation? At what increase in net filtration pressure will the body begin developing edema? |
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Definition
1) increased lymphatic flow; increased filtration to decreased deltaPi; increased filtration decreased deltaP
2) increases greater than 15mmHg |
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Term
| Where is edema located with left heart failure? right heart failure? |
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Definition
1) pulmonary edema
2) peripheral edema; ascites |
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Term
| What is the forward hypothesis of edema in heart failure? |
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Definition
| 1) primary event is reduced cardiac output leading to under-perfusion of kidneys and Na retention (stim SNS and RAAS precedes edema) |
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Term
| What is the sequence of events leading to edema in HF? |
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Definition
| 1) cardiac dysfunction; decreased cardiac output; kidney Na and water retention leading to increased blood volume; increased venous pressure; increased capillary hydrostatic pressure; increased transcapillary gradient; movement of fluid from plasma to interstitium; peripheral edema; increased left ventricular filling; mnormalization of cardiac output; compensated state |
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Term
| What are hte treatments of chronic heart failure induced edema? |
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Definition
1) Tx of underlyign disease
2) improve inotropy
3) improve cardiac output
4) plasma volume vontraction: sodium restriction; diuretics |
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Term
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Definition
| - accumulation of third-spaced fluid in peritoneal cavity |
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Term
| What are the safety factors for the development of ascites? |
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Definition
1) lymphatic drainage
2) increased abdominal pressure |
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Term
| What is the overflow hypothesis for ECF expansion with cirrhosis? |
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Definition
| 1) sodium retention precedes the development of ascites despite normal kidney function, asbence of edema, appropriate suppression of renin, and no overt change in systemic hemodynamics. Extra fluid extravagates into abdominal cavity |
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Term
| Describe the underfill hypothesis for ECF expansion in cirrhosis |
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Definition
1) increased intra-sinusoidal pressure leads to fluid sequestration in the abdominal cavity and ascites formation
2) decreased plasma volume due to hypoalbuminemia
3) neurohumoral response is stimulated in response to a reduction in effective circulating volume and leads to Na retention |
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Term
| What is treatment of cirrhosis induced edema? |
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Definition
1) improve liver function
2) reduce ECF volume: restric Na, diuretics, paracentesis, leg elevation, peritoneo-venous shunt |
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Term
| What are characteristics of nephrotic syndrome? |
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Definition
1) impaired glomerular barrier function with heavy proteinuria (>3.5g/dL)
2) hypoalbuminemia
3) Na retention - precedes underfilled state due to hypoalbuminemia
4) underfill with albumin <2g/dL |
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Term
| What are treatments of nephrotic syndrome? |
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Definition
1) treatunderlying kidney disease
2) decrease urinary protein leak by changing glomerular hemodynamics (ACE_I)
3) decrease ECF volume - sodium restriction, diuretics |
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Term
What is the channel/enzyme inhibited, site of action, and complications seen with the following drug:
acetazolamide? |
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Definition
1) carbonic anhydrase
2) proximal tubule
3) metabolic acidosis |
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Term
What is the channel/enzyme inhibited, site of action, and complications seen with the following drug:
furosemide
Bumetanide
Torsemide
Ethacrynic acid |
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Definition
1) Na/K/2Cl cotransporter
2) Loop of Henle
3) hypokalemia, Metabolic alkalosis, Hypomagnesemia, hypocalcemia |
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Term
What is the channel/enzyme inhibited, site of action, and complications seen with the following drug:
thiazides, chlorathalidone, metolazone |
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Definition
1) Na/Cl-cotransport
2) distal tubule
3) hypokalemia, metabolic alkalosis, hyponatremia, hypercalcemia |
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Term
What is the channel/enzyme inhibited, site of action, and complications seen with the following drug:
spironolactone, amiloride, triamterene |
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Definition
1) Na-channel
2) cortical collecting tubule
3) hyperkalemia |
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Term
What is the channel/enzyme inhibited, site of action, and complications seen with the following drug:
V2-receptor blockers (vaptans) |
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Definition
1) aquaporins
2) collecting duct
3) hypernatremia |
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