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From Flashcardlet > Fluids & Electrolytes (ch 14) > Flashcards

Fluids & Electrolytes (ch 14) Flashcards

0
Q

Normal range for Potassium

A

3.5-5.0 mEq/L

Even minor variations are significant

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1
Q

Normal range for Sodium

A

135-145 mEq/L

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2
Q

Normal range for Calcium

A

8.6-10.2 mg/dL

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3
Q

Normal range for Magnesium

A

1.3-2.3 mg/dL

  • approximately 1/3 of serum magnesium is bound to protein
  • remaining 2/3 exist as free cations
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4
Q

Normal range for Phosphorus

A

2.5-4.5 mg/dL in adults

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5
Q

Normal range for Chloride

A

97-107 mEq/L

  • major anion (-) of ECF
  • found more in interstitial and lymph fluid than blood
  • produced in the stomach, where it combines with hydrogen to form HCl
  • chloride control depends on intake and excretion and reabsorption of its ions in kidneys
  • small amount lost in feces
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6
Q

Osmosis

A
  • The process by which fluid moves across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration.
  • the process continues until the solute concentrations are equal on both sides of membrane.
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7
Q

Diffusion

A
  • process by which salutes move from an area of higher concentration to one of lower concentration.
  • does not require energy
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8
Q

Active transport

A
  • physiologic pump that moves fluid from an area of low concentration to one of higher concentration.
  • requires ATP (adenosine triphosphate) for energy
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9
Q

Skin

A
  • sensible perspiration: visible water and electrolytes loss through skin (sweating)
  • chief solutes in sweat = sodium, chloride, potassium
  • continuous water loss by evaporation (approx 600 mL/day) occurs through skin as insensible perspiration (nonvisible form of water loss)
  • fever increases insensible water loss through lungs and skin
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10
Q

Lungs

A
  • normally eliminate water vapor (insensible loss) at rate of 300 mL every day
  • loss much greater with increased RR or depth or in dry climate.
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11
Q

Gastrointestinal Tract

A
  • usual loss is 100-200 mL daily

- approximately 8 L of fluid circulates through GI system every 24 hours

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12
Q

Organs Involved in Homeostasis

A
  • kidneys
  • lungs
  • heart
  • adrenal glands
  • parathyroid glands
  • pituitary gland
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13
Q

Kidney Functions

A
  • usual daily urine volume in adult 1-2 L
  • approximately 1 mL urine/kg body weight/hour in all ages groups
  • regulation of ECF volume and osmolality by selective retention and excretion of body fluids
  • regulation of normal electrolyte levels in ECF by selective electrolyte retention and excretion
  • regulation of pH of the ECF by retention of hydrogen ions
  • excretion of metabolic wastes and toxic substances
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14
Q

Heart and Blood Vessel Functions

A
  • pumping action of heart circulates blood through kidneys under sufficient pressure to allow for urine formation.
  • failure of this pumping action interferes with renal perfusion and thus water and electrolyte regulation.
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15
Q

Lung Functions

A

-through exhalation, lungs remove approximately 300 mL of water daily in normal adult

  • hyperpnea (abnormally deep respirations) or continuous coughing increase this loss.
  • mechanical ventilation with excessive moisture decreases it.

-play a major role in maintaining acid-base balance

16
Q

Pituitary Functions

A
  • hypothalamus manufactures ADH—–ADH is stored posterior pituitary gland and released as needed to conserve water
  • function of ADH: maintaining osmotic pressure of cells by controlling the retention or excretion of water by the kidneys and by regulating blood volume
17
Q

Adrenal Functions

A
  • 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
18
Q

Parathyroid Functions

A
  • embedded in thyroid gland
  • regulate calcium and phosphate balance by mean of PTH (parathyroid hormone)
  • PTH influences bone resorption, calcium absorption from the intestines, and calcium reabsorption from the renal tubules.
19
Q

Effects of Aging on Fluid and Electrolyte Regulation

A
  • normal physiologic changes:
    - reduced cardiac, renal, and respiratory function and reserve
    - alterations in ratio of body fluids to muscle mass
  • decreased respiratory function can cause impaired pH regulation
  • renal function declines with age
  • muscle mass and daily exogenous creatinine production decreases. (High-normal and minimally elevated serum creatinine values may indicate substantially reduced renal function in older adults)
  • use of multiple medications a can affect renal and cardiac function–increasing likelihood of fluid and electrolyte disturbances.
20
Q 
Hypovolemia 
FVD (fluid volume deficit)
A
  • occurs when loss of ECF volume exceeds the intake if fluid
  • when water and electrolytes are lost in the same proportion as they exist in normal body fluids, so ratio of serum electrolytes to water remains the same
  • should not be confused with dehydration (water loss only)—FVD may occur alone or in combination with other imbalances
21
Q

Pathophysiology of Hypovolemia

A
  • abnormal fluid losses resulting from vomiting, diarrhea, GI suctioning, and sweating
  • decreased intake (nausea or lack of access to fluids)
  • third-space fluid shifts (movement of fluid from vascular system to other body systems (edema formation in burns, ascites with liver dysfunction)
22
Q

Clinical manifestations of Hypovolemia

A
  • can develop rapidly
  • severity depends on degree of fluid loss
  • acute weight loss
  • decreased skin turgor
  • oliguria
  • concentrated urine
  • orthostatic hypotension due to volume depletion
  • weak, rapid heart rate
  • flattened neck veins
  • increased temperature
  • thirst
  • delayed or decreased capillary refill
  • decreased central venous pressure
  • cool, clammy, pale skin r/t peripheral vasoconstriction
  • anorexia
  • nausea
  • latitude
  • muscle weakness
  • cramps
23
Q

Hypovolemia: Assessment and Diagnostic Findings

A

-BUN elevated out of proportion to serum creatinine (ratio greater than 20:1)
(can be elevated due to dehydration or decreased renal perfusion and function)
-hematocrit level greater than normal because of decreased plasma volume

Serum & Electrolyte Changes

  • hypokalemia occurs w/ GI and renal losses
  • hyponatremia occurs w/ increased thirst and ADH release
  • hyperkalemia occurs with adrenal insufficiency
  • hypernatremia results from increased insensible losses and diabetes insibidus
24
Q

Medical Management of Hypovolemia

A
  • oral route preferred if deficit not severe
  • acute or severe? IV route–isotonic electrolyte solutions (lactated ringers, 0.9% sodium chloride) used because they expand plasma volume

-accurate and frequent assessments of I&O, weight, vital signs, central venous pressure, level of consciousness, breath sounds, skin color

25
Q

Administration of a Fluid Challenge

A
  • administering 100-200 mL of normal saline solution over 15 minutes.
  • goal: provide fluids rapidly enough to attain adequate tissue perfusion w/o compromising the CV system.
26
Q

Nursing Management of Hypovolemia

A
  • monitors and measures fluid I&O @ least every 8 hrs
  • daily body weights monitored (acute loss of 0.5 kg-1 lb-represents fluid loss of approx 500 mL)
  • vital signs closely monitored
  • skin & tongue turgor monitored on a regular basis
  • urine concentration monitored
27
Q

Hypervolemia

A
  • fluid volume excess (FVE)
  • isotonic expansion of ECF caused by abnormal retention of water and sodium in approx same proportions in which they normally exist in ECF.
28
Q

Hypervolemia Pathophysiology

A
  • r/t simple fluid overload or diminished function of homeostatic mechanisms responsible for regulating fluid balance
  • contributing factors: heart failure, renal failure, cirrhosis of liver
29
Q

Clinical Manifestations of Hypervolemia

A
  • result from expansion of ECF
  • edema
  • distended neck veins
  • crackles (abnormal lung sounds)
  • tachycardia
  • increased BP
  • increased pulse pressure
  • increased central venous pressure
  • increased weight
  • increased urine output
  • shortness of breath
  • wheezing
30
Q

Hypervolemia: Assessment & Diagnostic Findings

A
  • BUN and hematocrit values may be decreased because of plasma dilution, low protein intake, or anemia
  • urine sodium level increased if kidneys attempting to excrete excess volume
  • chest x-ray may reveal chest congestion
31
Q

Medical Management of Hypervolemia

A
  • directed at causes
  • symptomatic treatment: administering diuretics and restricting fluids and sodium
  • diuretics prescribed when dietary restriction of sodium alone is insufficient to reduce edema by inhibiting absorption of sodium and water by the kidneys.
  • hemodialysis or peritoneal dialysis may be used to remove nitrogen wastes and control potassium and acid-base balance, and remove sodium and fluid.
  • dietary restriction of sodium
32
Q

Nursing Management of Hypervolemia

A
  • measures I&O @ regular intervals to identify excessive fluid retention
  • weighed daily
  • breath sounds assessed
  • monitors degree of edema
33
Q

Role of Sodium

A

-controlling water distribution throughout the body, because it does not easily cross the cell wall membrane and because of its abundance and high concentration in the body,

34
Q

Hyponatremia

A

-serum sodium level less than 135 mEq/L

  • can occur because of
    - low total body sodium with a lesser reduction in total body water,
    - a normal total body sodium content with excess total body water, OR
    - an excess of total body sodium with an even greater excess of total body water
35
Q

Pathophysiology of Hyponatremia

A
  • primarily due to imbalance of water
  • urine sodium helps differentiate between renal and nonrenal causes:
    - low urine sodium occurs as kidneys retain sodium to compensate for nonrenal fluid loss (vomiting, diarrhea, sweating)
    - high urine sodium associated with renal salt wasting (diuretic use)
  • deficiency of aldosterone
  • use of certain medications:
    - anticonvulsants
    - SSRIs
36
Q

Clinical Manifestations of Hyponatremia

A

.

37
Q

Assessment & Findings of Hyponatremia

A
  • focused neurological exam
  • evaluation of signs and symptoms
  • evaluation of lab results
  • identification of current IV fluids
  • review of all medications
  • when due primarily to sodium loss, urinary sodium content less than 20 mEq/L, suggesting increased proximal reabsorption of sodium secondary to ECF volume depletion, and specific gravity is low (1.002-1.004).
  • when due to SIADH, urinary sodium content is greater than 20 mEq/L, and urine specific gravity is usually greater than 1.012.

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