Prep/U Chapter 10: Fluid and Electrolytes ❤️

ahhhhhhhhh help meee

acidosis

increase in H+ concntration (decrease pH)

alkalosis

reduction in H+ concentration or increase in bicarbonate concentration (increased blood pH)

colloid

a fluid containing particles that are nonsoluble and evenly distributed throughout the solution

colloid oncotic pressure:

osmotic pressure created by the protein (mainly albumin) in the bloodstream

crystalloid

a fluid containing soluble mineral ions and water in solution

hydrostatic pressure:

the pressure created by the weight of fluid against the wall that contains it. In the body, hydrostatic pressure in blood vessels results from the weight of fluid itself and the force resulting from cardiac contraction

hypertonic solution:

a solution with an osmolality higher than that of serum

hypotonic solution:

a solution with an osmolality lower than that of serum

isotonic solution:

a solution with the same osmolality as blood

in general, do younger or older people have more body fluid?

younger

The major cations in body fluid are

sodium, potassium, calcium, magnesium, and hydrogen ions.

The major anions in body fluid are

chloride, bicarbonate, phosphate, sulfate, and negatively charged protein ions.

Changes in potassium within the ECF can cause

cardiac rhythm disturbances and hyperkalemia can cause cardiac arrest

hyper- HIGH T wave

hypo- low/inverted T wave

osmosis

diffusion of water caused by fluid and solute concentration gradients

Crystalloid solutions are commonly used to

replace fluid in hypovolemia

Colloid solutions are commonly used as

temporary blood replacement until the correct type of blood is available for infusion

Is blood a crystalloid or colloid solution?

colloid

Tonicity is

the ability of solutes to cause an osmotic driving force that promotes water movement from one compartment to another.

Osmotic diuresis is

the increase in urine output caused by the excretion of solutes, such as glucose or mannitol.

The sodium concentration is greater in the ECF or ICF?

ECF

Serum osmolality primarily reflects

the concentration of sodium

(although blood urea nitrogen (BUN) and glucose also play a major role in determining serum osmolality)

In healthy adults, normal serum osmolality is

275 to 290 mOsm/kg

Urine specific gravity measures the

density of urine compared to water. It is a measure of the concentration of solutes in the urine.

The normal range of urine specific gravity is

1.005 to 1.030

BUN is a laboratory value that measures the amount of

urea in the bloodstream.

The normal range of BUN is

10 to 20 mg/dL (3.6 to 7.2 mmol/L).

BUN can increase due to

renal dysfunction, dehydration, high protein diet, GI bleeding, fever, and sepsis

Factors that decrease BUN include

end-stage liver disease, a low protein diet, starvation (due to low protein), and any condition that results in expanded fluid volume which dilutes urea in the blood (e.g., pregnancy).

is BUN or creatine a better measure of renal function?

creatine because it does not vary with protein intake or hydration status

creatinine is

a breakdown product of muscle metabolism that is almost totally cleared from the bloodstream and excreted by the kidney.

The normal serum creatinine is approximately

0.7 to 1.4 mg/dL (62 to 124 mmol/L); however, its concentration depends on lean body mass and varies from person to person.

Serum creatinine levels increase when

renal function decreases

Hematocrit measures the

percentage of red blood cells in a volume of whole blood

normal hematocrit range in men

42% to 52%

normal hematocrit range in women

35% to 47%

Urine sodium values change with

sodium intake and the status of fluid volume:

(As sodium intake increases, excretion increases; as the circulating fluid volume decreases, sodium is conserved)

Normal urine sodium levels range from

75 to 200 mEq/24 h (75 to 200 mmol/24 h).

The normal range is typically 135-145 millimoles per liter (mmol/L)

Urine sodium levels are used to assess

volume status and are useful in the diagnosis of hyponatremia and acute kidney injury

the kidneys normally filter how much of plasma every day?

180L

how much urine do the kidneys excrete everyday?

1-2 L

When the lungs have a decrease in breathing rate, what happens to the pH of blood?

CO2 is retained in the alveoli and bloodstream, which increases acid content of the blood.(lower pH)

When the lungs have an increase in breathing rate, what happens to the pH of blood?

CO2 is blown off, lost from the bloodstream, which decreases acid content of the blood (higher pH)

Increased secretion of aldosterone causes

sodium retention (and thus water retention) and potassium loss.

decreased secretion of aldosterone causes

sodium and water loss and potassium retention.

high levels of cortisol can cause

sodium and fluid retention

what secretes ADH

pituitary gland (stored in posterior portion)

what are baroreceptors and where are they located?

located in the left atrium and the carotid and aortic arches. These receptors respond to changes in the circulating blood volume

As arterial pressure decreases, baroreceptors do what in response?

the barorecptors will transmit fewer impulses from the carotid and the aortic arches to the vasomotor center. A decrease in impulses stimulates the sympathetic nervous system, which stimulates the sinoatrial (SA) node in the heart. The outcome is an increase in heart rate, conduction, and contractility and an increase in blood pressure. Sympathetic stimulation constricts renal arterioles, which in turn triggers renin release and stimulation of the renin–angiotensin–aldosterone system

how does the renin–angiotensin–aldosterone system (RAAS) work? (draw it out!)

1. When the kidneys sense low perfusion or diminished blood pressure, they secrete renin from the juxtaglomerular apparatus

2. Renin circulates to the liver and converts angiotensinogen into angiotensin I.

3. Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II.

4. Angiotensin II stimulates potent peripheral arterial vasoconstriction which increases arterial blood pressure. Angiotensin II also stimulates the adrenal gland to secrete aldosterone.

5. Aldosterone increases sodium and water reabsorption at the nephron into the bloodstream. This raises blood volume and blood pressure. Aldosterone also stimulates secretion of potassium into the nephron tubules, which in turn causes potassium excretion by the kidney

When increased osmolality is sensed by the brain, the posterior pituitary is stimulated to release

ADH

what does ADH do

acts at the kidney nephrons to increase water reabsorption into the bloodstream

what do osmosensors do? where are they ocated?

Located on the surface of the hypothalamus, osmoreceptors sense changes in sodium concentration. As osmotic pressure increases, the neurons become dehydrated and quickly release impulses to the posterior pituitary, which increases the release of ADH

hypovolemia vs dehydration

hypovolemia is the loss of water and electrolytes. the ratio of serum electrolytes to water remains the same. dehydration is just water loss and it causes increased serum sodium levels

causes of FVD (hypovolemia)

abnormal fluid losses (ex vomiting, diarrhea, GI suctioning, and sweating), decreased intake, third-space fluid shifts, or the movement of fluid from the vascular system to other body spaces (e.g., with edema formation in burns, ascites with liver dysfunction).

Additional causes include diabetes insipidus (a decreased ability to concentrate urine due to either a deficit of ADH or nephron resistance to ADH), adrenal insufficiency, osmotic diuresis, hemorrhage, and coma

Normal BUN to serum creatinine concentration ratio is

10:1

someone experiencing FVD may have what as a BUN to serum creatine ratio and why?

A volume-depleted patient has a BUN elevated out of proportion to the serum creatinine (ratio greater than 20:1) because urea becomes concentrated in FVD

GI and renal losses can cause what electrolyte imabalnce?

Hypokalemia can occur with GI and renal losses as these organs are major regulators of potassium.

adrenal insufficency can cause what electroylte imbalance?

Hyperkalemia can occur with adrenal insufficiency due to aldosterone deficiency which causes lack of potassium excretion.

increased thirst and ADH release can cause what electroylte imbalance?

Hyponatremia can occur with increased thirst and ADH release, which increases water content of the bloodstream.

DI and increased insensible water loss can cause what electroylte imbalance

Hypernatremia can result from increased insensible water losses and diabetes insipidus.

causes of hypervolemia

Compromised regulatory mechanisms, such as kidney injury, heart failure, and cirrhosis; overzealous administration of sodium-containing fluids; and fluid shifts (i.e., treatment of burns). Prolonged corticosteroid therapy, severe stress, and hyperaldosteronism augment fluid vol

signs and symptoms of hypovolemia

Acute weight loss, ↓ skin turgor, oliguria, concentrated urine, capillary filling time prolonged, low CVP, ↓ BP, flattened neck veins, dizziness, weakness, thirst and confusion, ↑ pulse, muscle cramps, sunken eyes, nausea, increased temperature; cool, clammy, pale skin

lab findings in hypovolemia

↑ hemoglobin and hematocrit, ↑ serum and urine osmolality and specific gravity, ↓ urine sodium, ↑ BUN and creatinine, ↑ urine specific gravity and osmolality

signs and symptoms of hypervolemia

Acute weight gain, peripheral edema and ascites, distended jugular veins, crackles, elevated CVP, shortness of breath, ↑ BP, bounding pulse and cough, ↑ respiratory rate, ↑ urine output

lab findings in hypervolemia

↓ hemoglobin and hematocrit, ↓ serum and urine osmolality, ↓ urine sodium and specific gravity

sodium normal range

135 to 145 mEq/L

sodium is importnt because it is the primary determinate of

ECF volume and osmolality

what can cause hyponatremia

loss of sodium, as in use of diuretics, loss of GI fluids, renal disease, and adrenal insufficiency. Gain of water, as in excessive administration of D5W and water supplements for patients receiving hypotonic tube feedings; disease states associated with SIADH, such as head trauma and oat-cell lung tumor; medications associated with water retention (oxytocin and certain tranquilizers); and psychogenic polydipsia. Hyperglycemia and heart failure cause a loss of sodium

signs and symptoms of hyponatremia

anorexia, nausea and vomiting, headache, lethargy, dizziness, confusion, muscle cramps and weakness, muscular twitching, seizures, papilledema, dry skin, ↑ pulse, ↓ BP, weight gain, edema, decreased skin turgor, dry skin turgor, altered mental status, coma, seizure and cerebral edema can occur

labs of hyponatremia

↓ serum and urine sodium, ↓ urine specific gravity and osmolality

hypernatremia causes

Fluid deprivation in patients who cannot respond to thirst, hypertonic tube feedings without adequate water supplements, diabetes insipidus, heatstroke, hyperventilation, watery diarrhea, burns, and diaphoresis. Excess corticosteroid, sodium bicarbonate, and sodium chloride administration, and saltwater nonfatal drowning victims.

hypernatremia signs/symtpoms

Thirst, elevated body temperature, swollen dry tongue and sticky mucous membranes, hallucinations, lethargy, restlessness, irritability, simple partial or tonic–clonic seizures, pulmonary edema, hyperreflexia, twitching, nausea, vomiting, anorexia, ↑ pulse, and ↑ BP

hypernatremia labs

↑ serum sodium, ↓ urine sodium, ↑ urine specific gravity and osmolality, ↓ CVP

management of hyponatremia

• careful administration of sodium by mouth, nasogastric tube, or a parenteral route.

• lactated Ringer’s solution or isotonic saline (0.9% sodium chloride) solution may be prescribed.

• fluid restriction

• AVP receptor antagonist

When administering fluids to patients with cardiovascular disease, the nurse assesses for

hemodynamic signs of circulatory overload (e.g., cough, dyspnea, jugular venous distention, dependent edema, 1–2 lb weight gain in 24 h). The lungs should be auscultated for crackles as this can indicate pulmonary edema.

In patients with hyponatremia, highly hypertonic sodium solutions (2–23% sodium chloride) should be administered

slowly. The patient needs close monitoring, because only small volumes are needed to elevate the serum sodium concentration.

treatment of hypernatremia

gradual lowering of the serum sodium level by the infusion of a hypotonic solution (e.g., 0.45% sodium chloride) or an isotonic nonsaline solution (e.g., dextrose 5% in water [D5W]). D5W can be used when water needs to be replaced without sodium but be careful as the sodium reduction is less gradual

why is it important to slwoly reduce serum sodium

to prevent cerebral edema

alterations in K+ concentration can change

myocardial irritability and rhythm.

The normal serum potassium concentration ranges from

3.5 to 5 mEq/L

hypokalemia contributing factors

Diarrhea, vomiting, gastric suction, corticosteroid administration, hyperaldosteronism, carbenicillin, amphotericin B, bulimia, osmotic diuresis, alkalosis, starvation, diuretics, and digoxin toxicity

hypokalemia signs and symptoms

Fatigue, anorexia, nausea and vomiting, muscle weakness, polyuria, decreased bowel motility, ventricular asystole or fibrillation, paresthesias, leg cramps, ↓ BP, ileus, abdominal distention, hypoactive reflexes.

hypokalemia ECG results

ECG: flattened T waves, prominent U waves, ST depression, prolonged PR interval

hyperkalemia contributing factors

Pseudohyperkalemia, oliguric kidney injury, use of potassium-conserving diuretics in patients with renal insufficiency, metabolic acidosis, Addison disease, crush injury, burns, stored bank blood transfusions, rapid IV administration of potassium, and certain medications such as ACE inhibitors, NSAIDs, cyclosporine

hyperkalemia signs and symptoms

Muscle weakness, tachycardia → bradycardia, arrhythmias, flaccid paralysis, paresthesias, intestinal colic, cramps, abdominal distention, irritability, anxiety.

hyperkalemia ECG results

tall tented T waves, prolonged PR interval and QRS duration, absent P waves, ST depression

hypokalemia medical management

The oral route is ideal to treat mild to moderate hypokalemia. IV route can be used for severe cases.

risk in oral K supplements

Oral potassium supplements can produce small bowel lesions; therefore, the patient must be assessed for and cautioned about abdominal distention, pain, or GI bleeding.

Potassium is never given by

IV push or intramuscularly to avoid replacing potassium too quickly. Potassium is extremely irritating to tissues. IV potassium must be given using an infusion pump.

IV potassium must be given using an

infusion pump.

If serum potassium levels are dangerously elevated, it may be necessary to administer

IV calcium gluconate.

hypocalcemia contributing factors

Hypoparathyroidism (may follow thyroid surgery or radical neck dissection), malabsorption, pancreatitis, alkalosis, vitamin D deficiency, massive subcutaneous infection, generalized peritonitis, massive transfusion of citrated blood, chronic diarrhea, decreased parathyroid hormone, diuretic phase of acute kidney injury, ↑ PO4, fistulas, burns, alcoholism

hypocalcemia signs and symptoms and ECG

Numbness, tingling of fingers, toes, and circumoral region; positive Trousseau sign and Chvostek sign; seizures, carpopedal spasms, hyperactive deep tendon reflexes, irritability, bronchospasm, anxiety, impaired clotting time, ↓ prothrombin, diarrhea, ↓ BP.

ECG: prolonged QT interval and lengthened ST

hypocalcemia labs

↓ Mg++

hypercalcemia contributing factors

Hyperparathyroidism, malignant neoplastic disease, prolonged immobilization, overuse of calcium supplements, vitamin D excess, oliguric phase of acute kidney injury acidosis, corticosteroid therapy, thiazide diuretic use, increased parathyroid hormone, and digoxin toxicity

The normal adult total serum calcium level is

8.8 to 10.4 mg/dL

hypercalcemia signs and symptoms and ECG

Muscular weakness, constipation, anorexia, nausea and vomiting, polyuria and polydipsia, dehydration, hypoactive deep tendon reflexes, lethargy, deep bone pain, pathologic fractures, flank pain, calcium stones, hypertension.

ECG: shortened ST segment and QT interval, bradycardia, heart blocks

tetany

Tetany, the most characteristic manifestation of hypocalcemia and hypomagnesemia, refers to the entire symptom complex induced by increased neural excitability. (ex Chvostek sign and Trousseau sign)

Trousseau sign can be elicited by

inflating a blood pressure cuff on the upper arm to about 20 mm Hg above systolic pressure; within 2 to 5 minutes, carpal spasm will occur

Acute symptomatic hypocalcemia is life-threatening and requires prompt treatment with

IV administration of a calcium salt.