Fluid & Electrolyte Imbalances

primary physiological concepts with fluid and electrolyte imbalances

• fluid volume changes

• symptoms of electrolyte imbalance

• symptoms of acidosis/alkalosis

what happens to body water over life span?

percent of body weight that is water decreases as we age

intracellular fluid (ICF)

mostly electrolytes and H2O

• rich in potassium

• low in sodium

extracellular fluid (ECF)

all body fluid outside cell

• lower in potassium

• higher in sodium

2 parts of extracellular fluid

1. interstitial fluid

2. plasma (intravascular fluid)

interstitial fluid

in between and around vessels

plasma (intravascular fluid)

make of proteins (albumin specifically) and helps maintain pressure in the vessels

major cation of plasma/extracellular fluid

sodium/Na+

major anions of plasma/extracellular fluid

• Chloride/Cl- (majority)

• HCO3-

• proteins

major cations in the intracellular fluid

potassium/K+

major anions in intracellular fluid

• PO4³- mostly

• proteins

4 mechanisms controlling fluid and electrolyte movement

1. diffusion

2. facilitated diffusion

3. active transport

4. osmosis

diffusion

movement of electrolytes form high concentration to low concentration

facilitated diffusion

use of protein carriers to help move electrolytes from high concentrations to low

active transport

use of ATP (energy) to move molecules against concentration gradient (sodium/potassium pump)

osmosis

H2O moves through a semi-permeable membrane to cause equilibrium on both sides (H2O follows solutes for equilibrium)

hypotonic solution

swelling occurs due to H2O moving into the cell, following solutes

isotonic solution

no net volume change

hypertonic solution

shrinkage occurs due to H2O moving out of the cell, following solutes

how many types of fluid spacing are there

3

first spacing

normal distribution in ICF ECF

second spacing

abnormal accumulation of interstitial fluid (edema)

third spacing

fluid is trapped where it is difficult to impossible for it to move back into cells or blood vessels (Ex. ascites, edema)

ascites

fluid leaking into abdominal cavity with peritonitis or pancreatitis

edema can be caused by

burns, trauma, or sepsis

water balance regulation involves …

intake, use, and excretion

an average healthy adult needs ______ to ________ mL of water a day

2000-3000 mL/day

water ingestion equals water loss with … (3 things)

free access to water, intact thirst and ADH mechanism, and normally functioning kidneys

primary role of the hypothalamus/pituitary gland in water balance

thirst

• increases water intake where ADH retains water leading to decreased urine output

primary role of the kidneys in water balance

balance center

• regulate fluid and electrolytes in response to ADH and aldosterone

primary role of the adrenal cortex in water balance

aldosterone

• retains Na+ and water while excreting K+

primary role of the heart in water balance

ANP/BNP

• excretes Na+ and water which decreases volume

• opposes ADH/aldosterone/RAAS

primary role of the GI tract in water balance

reabsorbs water

• vomiting/diarrhea cause fluid and electrolyte loss

ADH and water

holds water

aldosterone and water

holds Na+ and water

ANP/BNP and water

lets Na+ and water go

causes of ECF imbalances (HYPOVOLEMIA)

• perspiration, fever, heatstroke

• diabetes insipidus

• hemorrhage

• GI loss (vomiting, NG suction, diarrhea)

• diuretics overuse

• inadequate fluid intake

• burns

causes of ECF imbalances (HYPERVOLEMIA)

• excess isotonic/hypotonic fluids

• heart failure

• renal failure

• SIADH (inappropriate diuretic hormone)

• cushing’s syndrome

• long term use of corticosteroids

signs & symptoms of ECG imbalances (HYPOVOLEMIA)

• restless, drowsy, lethargy, confusion

• thirst, dry mucous membranes

• cold, clammy skin

• decreased skin turgor and capillary refill

• increased HR and RR

• decreased urine output

• weak, dizzy

• weight loss

• seizure or coma

signs & symptoms of ECG imbalances (HYPERVOLEMIA)

• headache, confusion, lethargy

• peripheral edema

• JVD

• bounding pulse, inc HR

• dyspnea, crackles, pulmonary edema

• polyuria

• muscle spasms

• weight gain

• seizure or coma

interprofessional care for fluid volume deficit

correct the underlying cause and replace water and electrolytes

how to replace water and electrolytes for fluid volume deficit

• orally (less severe)

• blood products

• isotonic IV solutions

interprofessional care for fluid volume excess

remove fluid without changing electrolyte balance or osmolarity of ECF

how to remove fluid without changing electrolyte balance for fluid volume excess

• diuretics

• fluid restriction

• possible restriction of Na+ intake

• removal of fluid (paracentesis, thoracentesis)

7 nursing managements of fluid volume changes

1. daily weights

2. I/O

3. labs

4. cardiovascular care (vitals)

5. respiratory care

6. patient safety

7. skin care (turgor)

1 kg (2.2 lbs) = ________ mL (___L) of fluid

1000 mL (1L) fluid

what labs to monitor with hypovolemia

monitor for a high BUN, sodium, and HCT

what labs to monitor with hypervolemia

monitor for low BUN, sodium, and HCT

what should be monitored in cardiovascular care for hypovolemia

• pulse weak/thread

• check for orthostatic changes

• potential hypotension

what should be monitored in cardiovascular care for hypervolemia

• pulse full/bounding

• JVC

• potential hypertension

what should be monitored in respiratory care for hypovolemia

high respiratory range due to low tissue perfusion and hypoxia

what should be monitored in respiratory care for hypervolemia

pulmonary congestion/edema, SOB, crackles

what should be assessed in skin care (turgor) for hypovolemia

diminished turgor with tenting

what should be assessed in skin care (turgor) for hypervolemia

edematous skin can feel cool; grade edema

how does a sodium imbalance primarily impact in the body

brain function

therapeutic range for sodium

135-145 MEQ/L

GI tract absorbs sodium from …

food

what organ mainly regulates sodium balance

kidneys

how do the kidneys regulate sodium balance

• control ECF concentration (excreting or retaining water with ADH)

• aldosterone promotes reabsorption in renal tubules (nerve impulses and muscle contractions)

how does sodium leave the body

urine, sweat, feces

serum Na+ levels reflect the ratio of _____ to ______, not necessarily the amount of sodium in the body

sodium to water

what four processes does sodium play a major role in

1. ECF volume and concentration (H2O)

2. generating and transmitting nerve impulses

3. muscle contractility

4. regulating acid-base balance

hypernatremia

Na+: > 145 mEq/L

(sodium gain with water loss)

2 step thinking process for identifying volume status with sodium status

1. is sodium elevated?

2. what is the patients volume status (dry → normal → wet)

how can you determine the pt’s volume status

does the PT look dry, normal, or wet (ECF)

hypernatremia will cause cells to …

shrink

hypovolemic hypernatermia (dry)

loss of water AND sodium (more water loss than sodium)

hypovolemic hypernatermia assessment/identification

• dry mucous membranes

• poor skin turgor

• hypotension

• tachycardia

causes of hypovolemic hypernatermia

• vomiting/diarrhea

• diuretics

• excessive sweating

isovolemic hypernatremia (normal)

loss of free water only & volume appears normal

isovolemic hypernatremia assessment/identification

• normal BP

• normal skin turgor

• excessive thirst

• large amounts of dilute urine

isovolemic hypernatremia classic cause

diabetes insipidus

hypervolemic hypernatremia (wet)

excess sodium gain and water follows the sodium

hypervolemic hypernatremia assessment/identification

• edema

• weight gain

• bounding pulse

• crackles

hypervolemic hypernatremia causes

• hypertonic saline

• sodium bicarbonate

• excess sodium intake

serum sodium is a __________, not a measure of how much total sodium is in the body

concentration

memory trick for hypo, iso, and hypervolemic hypernatremia

DNW

dry → hypovolemic

normal → isovolemic

wet → hypervolemic

ALL WITH HIGH SODIUM

nursing interventions for hypovolemic hypernatremia

restore fluid volume first (NS) then finish with ½ NS

nursing interventions for isovolumic hypernatremia

oral fluids/replace free water D5W

nursing interventions for hypervolemic hypernatremia

loop diuretics and D5W to dilute Na+

hyponatremia

Na+: < 135 mEq/L

(too much water compared to sodium)

hyponatremia will cause cells to …

swell

hypovolemic hyponatremia

loss of water AND sodium

• more sodium loss than water

hypovolemic hyponatremia assessment/identification

• dry mucous membranes

• poor skin turgor

• hypotension

• tachycardia

hypovolemic hyponatremia causes

• vomiting/diarrhea

• diuretics

• excess sweating

isovolemic hyponatremia

gain of free water only and no obvious fluid overload

isovolemic hyponatremia assessment/identification

• normal BP

• no edema

• headache, confusion, nausea

isovolemic hyponatremia classic causes

• SIADH

• excess water intake

hypervolemic hyponatremia

gain of sodium and water with more water gained than sodium

hypervolemic hyponatremia assessment/identification

• edema

• weight gain

• crackles

• JVD

hypervolemic hyponatremia causes

• heart failure

• liver failure

• kidney failure

nursing considerations for hypovolemic hyponatremia

replace fluids

nursing considerations for isovolemic hyponatremia

restrict free water

nursing considerations for hypervolemic hyponatremia

remove excess fluid

how does a potassium imbalance primarily impact in the body

heart, nerves, and muscles

therapeutic potassium range

3.5-5.0 mEq/L

potassium is the major ___ cation, with ___ of the body potassium being in cells

ICF; 98%

potassium is necessary for what processes (5)

• resting membrane potential of nerve and muscle cells

• regulates intracellular osmolality

• promotes cellular growth

• maintenance of cardiac rhythms

• acid-base balance

hyperkalemia

K+: > 5 mEq/L

hyperkalemia causes

“the body CARED too much about K+”

C - cellular movement of K+ from ICF to ECF (burns, tissue damange, etc)

A - adrenal insufficiency with Addison’s disease

R - renal failure

E - excessive K+ intake

D - drugs (K+ sparing drugs: spironolactone, ACE, NSAIDs)