F&E

• All body fluids contain electrolytes
• Electrolytes are normally gained and lost in relatively equal amounts
• Signs and symptoms of electrolyte imbalance


  • Subtle if imbalance is minimal
  • Multisystem effects occur and can lead to death if imbalance is moderate to severe
• 2,300ml of fluid daily for intake
• Minimum amount of urine output per day needed to excrete waste products is 400 - 600ml
• Insensible fluid loss is 500-1000ml
• Intracellular fluid


  • Solutes: oxygen, electrolytes, glucose
  • Cations: potassium, magnesium
  • Anions: phosphate, sulfate
  • 2/3 vital to cell function, 40% body weight
• Extracellular fluid


  • Principal electrolytes: sodium, chloride, bicarbonate
  • Interstitial fluid (surrounds cells), 75%
  • Intravascular fluid (plasma), 20%
  • Purpose: the transport system to and from the cells
  • 1/3 vital to cell function, 20% body weight
• Osmosis


  The movement of water only through a semipermeable membrane to achieve equilibrium of osmolality
• Diffusion


  Particles (solutes) spread/move through random motion from an area of higher concentration to an area lower concentration until equilibrium is reached
• Filtration


  The movement of fluid (water) through a cell or blood vessel membrane because of hydrostatic pressure differences on either side of the membrane
• Osmolality


  Concentration of solutes
• Tonicity


  Osmolality of solution
• Types of fluids


  • Isotonic (normal saline, no cellular shifts)
  • Hypertonic (higher osmolality, pulls fluid into vascular)
  • Hypotonic (lower osmolality, pushes fluid into cells)
• ADH & renin release

  1. Low blood volume

  2. Low BP

  3. Low blood sodium

  4. Low blood O2
• Volume retention

  Vasoconstriction=Renin-Angiotensin-Aldosterone system
• Volume wasting

  ANP & BNP (peptide hormones) form heart in response to excess blood volume and stretching cardiac wall - Promotes sodium wasting and acts as a potent diuretic
• Fluid volume deficit


  Increase blood osmolality→ osmoreceptors in hypothalamus stimulate posterior pituitary to secrete ADH→ ADH increases distal tube permeability→ increase reabsorbtion of H20 in blood→ urine output decreases-serum/blood osmolality decreases as the water dilutes body fluids
• Fluid volume excess


  Decrease blood osmolality→ ADH is suppressed→ ADH causes distal tubules to become less permeable to water→ decrease reabsorption of H20 into blood→ urine output increases, serum osmolality returns to normal
• Isotonic imbalances


  • Fluid loss not balanced by intake (HEMORRhage, POLYuria, V/D, CROHN's)
• Hypotonic (hyponatremic) dehydration


  • Greater loss of SODIUM than water (EXcessive sweating, heat STRoke/EXhaustion)
• Hypertonic (hypernatremic) dehydration


  • Sodium loss PROPORTIONATELY less than water loss (CONfusion, DEMENtia, DECreased intake, ability)
• Fluid volume deficit


  • Decreased in intravascular, interstitial and/or intracellular fluids
  • Can develop rapidly or slowly
• Causes of excessive fluid loss


  • Hemorrhage
  • GI suctioning
  • Intestinal fluids
  • Vomiting
  • Diarrhea
  • Renal disease
  • Endocrine issues
  • Abuse of laxatives
  • Heat
• Causes of insufficient fluid intake

  • Lack of fluid access
  • Oral trauma
  • Swallowing difficulty
  • Altered thirst mechanism
  • Confusion
  • Mobility issues
• Clinical manifestations of fluid volume deficit

  • Mucous membranes: dry may be sticky, decrease tongue size, longitudinal furrows increases
  • Urinary: decrease urine output, oliguria (severe FVD), increase urine specific gravity
  • Musculoskeletal: fatigue
  • Neurologic: altered mental status, anxiety, restlessness, diminished alter ness/cognition, possible coma (severe FVD)
  • Integumentary: diminished skin turgor, dry skin, pale cool extremities
  • Cardiovascular: tachycardia, orthostatic hypotension (moderate FVD), falling systolic/diastolic pressure (severe FVD), flat neck veins, decrease venous filling, decrease pulse volume, decrease capillary refill, increase hematocrit
  • Metabolic processes: decrease body temperature for isotonic FVD, increase body temperature for dehydration, thirst, weight loss
• Fluid volume deficit treatment


  1. Accurately record intake and output as indicated

  2. Weigh daily

  3. Monitor vital signs, lab values, & LOC

  4. Reposition every 2 hours

  5. Institute safety precautions: teach prevention of orthostatic hypotension

  6. Oral rehydration (safest, most effective in alert patients, gradual, especially in older adults)

  7. Intravenous fluids (when deficit severe or pt unable to ingest fluids, isotonic electrolyte solutions initially, administer via electronic pump)
• Fluid volume excess


  • ECF volume excess occurs from too much fluid in the extracellular compartment, usually results from conditions causing retention of sodium and water, other causes: high sodium foods, meds, IV fluids
• Clinical manifestations of fluid volume excess


  • Circulatory overload = heart failure symptoms
  • Weight gain >5% body weight
  • Full bounding pulse
  • Distended neck, peripheral veins
  • Increased central venous pressure
  • Cough, dyspnea, orthopnea, crackles
  • Polyuria
  • Ascites, peripheral edema, anasare
  • Decreased hematocrit and BUN
  • Altered mental status and anxiety
• Fluid volume excess treatment


  1. Accurately record intake and output as indicated

  2. Weigh daily

  3. Monitor vital signs, lab values, & LOC

  4. Reposition every 2 hours

  5. Institute safety precautions: teach prevention of orthostatic hypotension

  6. Pharmacologic therapy: loop diuretics, thiazide-type diuretics, potassium-sparing diuretics

  7. Fluid management: restrict fluids, restrict foods high in fluids

  8. Dietary management: low-sodium diet
• Fluid volume considerations in pregnancy


  • FVD: Morning sickness, Hyperemesis Gravidarum, 80% experience in MS in 1st trimester, Miscarriage, Postpartum hemorrhage
  • FVE: Pregnancy Induced Hypertension, Pre-Eclampsia, Polyhydramnios
  • Irritable, Lethargic, Sunken fontanels & eyes, No tears
  • Vomiting & Diarrhea are most common causes as well as Fever which increases metabolic rate
  • Mild <5%, Moderate=6.9%, Severe >10%, Can deteriorate quickly (seek care early!), Mild may have little symptoms
  • Treatments: Oral rehydration is FIRST intervention for mild to moderate dehydration depending on cause, IV therapy with fluids and potentially electrolytes if dehydration is severe (10-20 ml/kg)
• Fluid volume considerations in older adults


  • Neuro: Reduced thirst reflex, Decreased cognition
  • Skin: Loss of elasticity, Decreased turgor, Decreased reserves
  • Muscular: Decreased muscle mass, Difficulty w ambulation
  • Endocrine: Adrenal atrophy
  • Increased risk for those requiring assistance with ADLs
  • Manifestations difficult to recognize in this population→ change in mental status is an early sign
  • Medications increase risk (ANTACIDS, DIURETICS, LAXATIVES, etc.)
  • Less total body volume as you age
  • Chronic illness: kidney dx, heart failure, diabetes, etc.
  • Assessment: use skin over sternum or on forehead instead of back of hand
• Hematocrit

  • % of whole blood composed of RBC's in relation to plasma
  • Normal range for male: 42 - 52%
  • Normal range for female: 37 -47%
• Hemoglobin

  • Proteins that carry O2
  • Normal range for male: 14 -18 g/dl
  • Normal range for female: 12- 16 g/dl
• Specific gravity

  • Normal range→ 1.005 - 1.030
  • FVD: increases
  • FVE: decreases
• Osmolality (serum & urine), Hematocrit, Specific Gravity

  • FVD: increases
  • FVE: decreases
• interrelated concepts for fluid and electrolytes

  • elimination
  • nutrition
  • acid-base balance
  • gas exchange
  • perfusion
  • cognition
  • hormonal regulation
  • mobility