Fluid and electrolyte imbalance

1. ICF

2. ECF

Two main fluid compartments of the body:

Intravascular fluid

Fluid inside blood vessels:

Interstitial fluid (IS)

Fluid that bathes and coates outside of cells

Intracellular fluid

Fluid that is actually inside cells

Potassium (K+)

Most abundant ion in intracellular fluid (inside cells)

Sodium (N+)

Most abundant extracellular ion:

Isotonic state

water will move between compartments to restore sodium to what state?

More sodium concentration inside of the cells, water moves along osmotic gradient to balance. Cell expands/swells

What happens to cells in hypotonic environment?

There is more sodium outside of cells than inside, water moves out of cells along osmotic gradient to balance. Cells shrink/shrivel

What happens to cells in a hypertonic environment?

osmotic pressure

pulls fluid into vessels

Hydrostatic pressure

Pushes fluid out of vessels

Net filtation

Osmotic and hydrostatic pressure working against each other

Plasma proteins exert osmotic pressure against the hydrostatic pressure to pull flid out of the interstitial space and keep fluid inside vessels

How does albumin keep fluid in vessels?

1. Renin-angiotensin-aldosterone mechanism

2. Atrial natriuretic peptide (ANP)

Sodium related mechanisms for fluid/electrolyte balance [2]

1. sodium related mechanisms

2. fluid shifts

3. thirst

4. kidney/renal (ADH)

Mechanisms for fluid/electrolyte balance: [4]

of the blood

What does the suffix -emia mean?

Hypovolemia

Not enough water in the IV space

1. decreased fluid intake

2. Increased renal clearance of water (due to impaired renal function/inability to concentrate urine)

3. Hemorrhage

4. excessive diaphoresis

Causes of hypovolemia: [4]

1. decreased blood pressure

2. Increased HR, SOB, pale and cool (HPA axis response)

Initial signs and symptoms of hypovolemia: [2]

BP= HRx volume and force of contraction X peripheral vascular resistance

fomula for blood pressure:

Fluid shift

COMPENSATION for hypovolemia:

1. ADH

2. Renin-angiotensin-aldosterone

Correction mechanisms for hypovolemia: [2]

water shifts from interstitial or intracellular spaces into the IV space

Where does fluid shift to compensate for hypovolemia

1. dry skin

2. poor turgor

3. dry mucous membranes

4. confusion (brain cells are dehydrated)

SIgns and symptoms of intracellular dehydration

1. increased osmolarity of blood

2. decreased circulating blood volume decreases BP

3. dryness of mucous membranes of the mouth

How is thirst mechanism triggered? [3]

1. Osmoreceptors in the hypothalamus are triggered

2. stimulates the posterior pituitary to release ADH

3. ADH adds pores to renal tubular cells

4. Water reabsorption is increased

5. Decreased amount of concentrated urine (oliguria)

How does ADH correct hypovolemia? [5]

1. Decreased sodium concentration stimulates renin

2. Acts on juxtaglomerular cells in the kidneys

3. stimulates formation of angiotensin I

4. Angiotensin I converted to angiotensin II by converting enzyme

5. Stimulates secretion of aldoterone AND PVR to increase BP

6. Increased sodium reabsorption (water follows sodium)

7. Oliguria

How does RAA correct hypovolemia?

Aldosterone

Mineral corticosteroid that is synthesized and secreted from the adrenal cortex. Increases reabsorption of sodium and secretion of potassium by distal tubule of kidney

Hypervolemia

Too much water in intravascular space

1. decreased kidney function

2. Kidney disease

3. excessive administration of IV solution

4. hypernatremia

5. cortisone administration

6. Hypersecretion of aldosterone (Cushing’s)

Causes of hypervolemia:

1. Jugular veinous distention

2. Hypertension

3. Bounding pulse (increased cardiac output, arteries are “full”)

4. Weight gain

5. Decreased hemoglobin and hematocrit

Clinical manifestation of hypervolemia: [5]

Heart is not squeezing blood out into the ventricles, can back up into pulmonary circuit or periphery

How can heart failure cause hypervolemia?

Fluid shift

Compensation mechanism for hypervolemia:

Fluid shift from intravascular to interstitial space

Fluid shift for hypervolemia:

Peripheral edema or pulmonary edema (fluid being pushed into lungs)

Signs and symptoms of fluid shift for hypervolemia: [2]

1. ANP released

2. to increase GFR and inhibit RAA

3. Decreased sodium reabsorption

4. increased sodium excretion by kidneys (risk for hyponatremia)

Correction mechanism for hypervolemia:

1. Polyuria

2. Dilute urine

3. K+ reabsorption (risk for hyperkalemia)

Signs and symptoms of correction for hypervolemia (increased urine output due to ANP) [3]

135-145 mEq/L

Normal sodium values:

1. increased sodium loss (N/V, burns, etc.)

2. decreased sodium intake (rare)

3. decreased aldosterone

4. dilution of sodium

Causes of hyponatremia

Sweating stimulates thirst, there is an increased water intake that dilutes sodium. Need for electrolytes

How can water dilute sodium after exercising?

Hypochloremia: (<97mEq/L)

Hyponatremia is associated with which other electrolyte imbalance?

1. increased intake

2. hypertonic solutions containing sodium

3. Hperaldosteroneism (Cushing’s)

4. Renal failure

5. Increased water loss

6. Diabetes insipidus

Causes of hypernatremia:

Fluid shift

Compensation mechanisms for sodium imbalance

1. RAA/Aldosterone

2. ANP

Correction mechanisms for sodium imbalance: [2]

Fluid shift from intravascular (IV) to interstitial (IS). We want less volume

Compensation for hyponatremia

1. edema

2. Intravascular hypovolemia

Result of fluid shift from hyponatremia:

1. edema (extra fluid in interstitial space, can leave to increased ICP and cerebral edema)

2. IV hypovolemia (decreased BP and increased HR(HPA))

3. Behavioural/neurological changes (less sodium to depolarize, cell swelling)

Hyponatremia signs and symptoms

1. ANP

2. Thirst

Mechanisms for correcting hypernatremia [2]

Fluid shift from intracellular to IV

Compensation for hypernatremia:

1. Intracellular dehydration

2. hypervolemia

Fluid shift for hypernatremia results in what? [2]

1. thirst

2. dry mucous memranes

3. Restlessness/ confusion (water loss from brain cells)

4. Agitation, seizures, coma, muscle spasms

Intracellular dehydration from hypernatremia S+S: [4]

Increases GFR, and inhibits RAA.

Results in decreased sodium reabsorption.

How does ANP correct hypernatremia?

3.5-5.0 mEq/L

Normal values for potassium in IV space:

1. decreased intake due to elderly, alcoholism, eating disorders associated with purging

2. loss of potassium

Causes of hypokalemia:

1. renal disorders

2. GI disorders

3. continuous NG suctioning

4. Diabetic ketoacidosis

5. Laxative abuse

6. hyperaldosteronism

7. Diuretic use

Things that can cause a loss of potassium: [7]

HAHA TRICK QUESTION no signs or symptoms for mild LOSSES💜

Mild loss of potassium signs and symptoms

1. skeletal muscle weakness

2. depressed ventillation

3. smooth muscle weakness

4. decreased nutrient absorption

5. cardiac muscle weakness

6. cardiac arrythmias can lead to cardiac arrest

Severe potassium loss signs and symptoms:

1. increased intake

2. Shift of potassium from cells to ECF

3. decreased renal excretion

4. K+ sparing diuretics

5. diabetic ketoacidosis

Causes of hyperkalemia:

1. cell trauma (burns)

2. insulin deficiency

3. hypoxia

causes for K+ shift from cells to ECF: [3]

HAHA TRICK QUESTION no signs or symptoms for mild LOSSES💜

signs and symptoms for mild excess of potassium

1. skeletal muscle weakness

2. neuromuscular irritability

3. cardac muscle weakness

4. cardiac arythmias

severe hyperkalemia signs and symptoms:

Tetany

Hypomagnesemia can lead to what?

Calcium

Magnesium aids in absorption and metabolism of what?

1. CNS issues

2. respiratory paralysis

3. coma

4. heart block

5. cardiac arrest

Hypermagnesemia can lead to what?

1. CHO metabolism

2. protein synthesis

3. nucleic acid synthesis

4. musclular contraction

Magnesium is important for what? [4]

0.74-1.07 mmol/L

Normal magnesium levels

1. muscular contraction

2. cardiac function

3. transmission of nerve impulses

4. blood clotting

Calcium is important for what? [4]

1/16-1/32 mmol/L

Normal ionized calcium levels

1. tetany

2. convulsions

Hypocalcemia can lead to what? [2]

1. cardiac issues

2. coma

Hypercalcemia can lead to what? [2]

1. physical signs

2. checking serum electrolyte levels

3. Consider IV fluids/NPO status

4. do I&O

What to look for when assessing fluid/electrolyte imbalances: [4]

600-800 to account for insensible losses

How much to add to output when calculating I&O?

1. Sodium

2. where do you want the water to go?

Choice of IV solution depends largely on what? [2]

0.45% NaCl, 0.33% NaCl, D₅W

Hypotonic crystalloid IV solution:

D₅W with R/L

D₅W with 0.45%NaCl

D₅W with 0.9% NaCl

Hypertonic crystalloid IV solution: [3]

0.9%NaCl, R/L, 2/3 & 1/3

Isotonic crystalloid isotnic solution

Hypertonic

What type of solution to give hypovolemic patient?

Hypotonic

Iv solution to give patient with intracellular dehydration

Combinations of dextrose and saline (2/3 and 1/3. Glucose for energy, free water, electrolytes)

What to give in maintenance IV:

0.9% NaCl : Isotonic

If extremely hyponatremic, hypertonic slowly in small amounts

IV fluid to give hyponatremia

Hypotonic D5W. (dexrose gets metabolized to CO2 and H20, dlutes the sodium)

IV solution to give hypernatremia:

Diuretics

drugs to give hypervolemia:

Will need both hyper and hypotronic but correct vascular problems FIRST!

what happens if a patient has severe hypovolema AND intracellular dehydration?

Increased sodium means some sodium will be exchanged for potassium and potassium will be lost.

Why are patients receiving 0.9% NaCl at risk for hypokalemia?