Fluids & Electrolytes Fluids & Electrolytes ImbalancesImbalances
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Body Fluid Compartments• 2/3 (65%) of TBW is intracellular fluid (ICF)
• 1/3 extracellular fluid (ECF)– 25 % interstitial fluid (ISF)– 5- 8 % in plasma [(IVF) intravascular fluid]– 1- 2 % in transcellular fluids – CSF, intraocular
fluids, serous membranes, and in GI, respiratory and urinary tracts (third space)
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Function of Body HFunction of Body H22OOTransports nutrients, electrolytes, & O2
Excretion of Waste Products
Regulates Body Temperature
Lubrication of Joints & Muscles
Medium for Food Digestion
(Kee & Paulanka, 2000, p. 2)
5
• Fluid compartments are separated by membranes that are freely permeable to water.
• Movement of fluids due to:– Diffusion– Osmotic pressure– Active transport– Hydrostatic pressure– Reabsorption
Movement of FluidsMovement of Fluids
DIFFUSION
•Solutes shift from an area of greater concentration to an area of higher concentration•Passive process
OSMOSIS
•Movement of fluid across membrane from a lower solute concentration to a higher solute concentration
•Passive process
ACTIVE TRANSPORT
•Solutes move from an area of lower concentration to an area of higher concentration
•Process requires energy
Hydrostatic Pressure•Capillary filtration
•Movement of fluid through capillaries results from blood pushing against walls of the capillary. It forces fluids and solutes through the capillary wall
REABSORPTION
•Prevents too much fluid from leaving capillaries no matter how much hydrostatic static pressure is inside them
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• Capillary colloid osmotic pressure– Colloids do not cross the membrane and pull
water into the blood stream– Aka plasma expander
• Albumin, plasma protein fraction, dextran, hetastarch
• Interstitial hydrostatic pressure
• Tissue colloid osmotic pressure
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Solutes – Dissolved Particles• Electrolytes – charged particles
– Cations – positively charged ions
• Na+, K+ , Ca++, H+
– Anions – negatively charged ions
• Cl-, HCO3- , PO4
3-
• Non-electrolytes - Uncharged • Proteins (i.e. albumin), urea, glucose,
O2, CO2
13
• Body fluids are:
– Electrically neutral
– Osmotically maintained
• Specific number of particles per volume of fluid
14
Homeostasis maintained by:
• Ion transport
• Water movement
• Kidney function
15
TONICITY:Isotonic – A solution that has the same solute
concentration as another solution to which it’s being compared
• i.e. sodium in blood vs. 0.9% NSS
16
• Hypertonic - A solution that has a higher solute concentration than another solution to which it’s being compared
• Dextrose 5% in NSS
TONICITY:
17
• Hypotonic - A solution that has a lower solute concentration than another solution to which it’s being compared
• 0.45%NSS
TONICITY:
18
Balance• Fluid and electrolyte homeostasis is
maintained in the body
• Neutral balance: input = output
• Positive balance: input > output
• Negative balance: input < output
Fluid Gain & LossFluid Gain & LossRoutes of Gain and Loss:Routes of Gain and Loss:
Kidneys (urine)
Skin (perspiration)
Lungs (respiration)
GI Tract (feces)
(Smeltzer et al, 2008)
Fluid Gain & LossFluid Gain & LossAverage Intake of Body H2O
= 2600 ml/day
Liquid = 1500 ml
Solid Foods = 800 ml
Oxidation = 300 ml
(Priff, 2006, p.6)
Fluid Gain & LossFluid Gain & LossSensible Loss• Fluid loss that can be measured
– Urination– Defecation– Bleeding– Wound drainage– Gastric drainage– Vomiting
(Priff, 2006, p.6)
Fluid Gain & LossFluid Gain & LossInsensible Loss• Fluid loss that cannot be measured
– Perspiration– Respiration– Changes in humidity levels, respiratory rate
and depth, and fever affect insensible loss
(Priff, 2006, p.6)
Fluid Gain & LossFluid Gain & LossAverage Output of Body H2O
= 2600 ml/day
Urine = 1500 ml
Feces = 100 ml
Lungs = 400 ml
Skin = 600 ml
(Priff, 2006, p.6)
24
25
Balancing SystemsBalancing SystemsRenal System (kidneys)
– RF = difficulty maintaining fluid balance
– Na+ & K+ are either filtered or reabsorbed via the renal system
Balancing SystemsBalancing SystemsAntidiuretic Hormone (ADH)
– Water-retaining hormone
– Hypothalamus senses low blood volume & increased serum osmolality; triggers its release from the pituitary gland
– Prompts kidneys to retain H2O
– Increases concentration of urine
Balancing SystemsBalancing SystemsRenin-Angiotensin-Aldoseterone
System (RAAS)– Release of renin triggered by low
pressures
– Angiotensin II potent vasoconstrictor and triggers the release of aldosterone from the adrenal cortex
– Aldosterone = fluid retention and secretion of K+; triggers the thirst center
Balancing SystemsBalancing SystemsAtrial Natriuretic Peptide (ANP)
– Released when atrial pressures increase– Opposes the RAAS (shuts it off)– Key Functions of ANP:
• Suppresses serum renin levels• Decreases aldosterone release• Increases glomerular filtration rate (excretion of
Na+ and H2O)
• Decreases ADH release• Decreases vascular resistance by causing
vasodilation
Balancing SystemsBalancing SystemsThirst Mechanism
– Simplest mechanism in maintaining fluid balance
– Increases after even small fluid loss– Increase in salty foods dries mucous
membranes, which stimulates the thirst center in the hypothalamus
HypovolemiaHypovolemiaA decreased blood volume that may be caused by internal or external bleeding, fluid losses, or inadequate fluid intake.
(Taber’s Online Dictionary, 2007)
A.K.A. Fluid Volume Deficit (FVD) or Extracellular Fluid Volume Deficit
(ECFVD)
HypovolemiaHypovolemiaFVD occurs when the loss of ECF
exceeds the intake of fluid.(Smeltzer et al, 2008)
Hypovolemia or FVD ≠ dehydration
Dehydration is loss of H2O only!!
FVD → Fluid Loss = Electrolyte LossRatio Remains the Same (usually)
HypovolemiaHypovolemiaSigns & Symptoms
Weight Loss
Decreased Skin Turgor
Oliguria
Concentrate Urine
Postural Hypotension
Weak, rapid pulse
Flattened Neck Veins
Signs & Symptoms
Increased Temp
Cool, clammy skin
Thirst
Anorexia
Nausea
Muscle Weakness
Muscle Cramps
HypovolemiaHypovolemiaTreatment:Treatment:
Infusion of Isotonic IV solutions for hypotensive patients
Infusion of Hypotonic IV solutions for normotensive patients
Hypovolemia d/t blood loss – blood transfusion
HypervolemiaHypervolemiaECF → H2O gain is balanced with retention
of sodium
Usually secondary to retention of sodium
Concentration of sodium to H2O is balanced – serum sodium levels usually WNL
A.K.A. Extracellular Fluid Volume Excess (ECFVE)
HypervolemiaHypervolemiaHormonal Imbalances - ADH
Can occur secondary to heart failure, renal failure, or cirrhosis of liver
Fluid overload related to administration of excessive IV fluids
Dietary: Excessive sodium intake
HypervolemiaHypervolemiaSigns & SymptomsSigns & Symptoms
JVDEdema
CracklesTachycardiaElevated B/PWeight Gain
Increased Urine OutputSOB/Wheezing
HypervolemiaHypervolemiaTreatment:Treatment:
Treat the underlying cause!!!
Renal Failure – dialysisHeart Failure – diuretics, etc.
Dietary – low-salt diet and/or fluid restriction
Discontinuation of IV infusions
Intracellular Fluid Intracellular Fluid Volume ExcessVolume Excess
A.K.A. Water Intoxication
An excess of H2O or decrease in solute concentration in the intravascular
space (Kee & Paulanka, 2000, p.34)
Causes cellular edema
Usually occurs in cerebral cells first
Intracellular Fluid Intracellular Fluid Volume ExcessVolume Excess
Causes:Causes:
Excessive non-solute water intake
Solute deficit (electrolyte & protein)
Increased secretion of ADH
Kidney Dysfunction
Intracellular Fluid Intracellular Fluid Volume ExcessVolume ExcessSigns & SymptomsSigns & Symptoms
Headaches & ↑ Perspiration (early s/s)
Apprehension, irritabilityConfusion, disorientation
Increase ICP → ↑ B/P, ↓ HR, ↑ RRNausea/vomiting
Weight Gain
Intracellular Fluid Intracellular Fluid Volume ExcessVolume Excess
Treatment:Treatment:
Goal: Decrease excess H2O intake and promote H2O excretion
Extracellular Fluid Extracellular Fluid Volume ShiftVolume Shift
A.K.A. “Third-spacing”
Permanent fluid shift from intravascular space to interstitial
space
Nonfunctional fluid shift & physiologically useless
Extracellular Fluid Extracellular Fluid Volume ShiftVolume Shift
Simple: Blister or Sprain
Serious: Massive injuries, burns, ascites, abdominal surgery
ELECTROLYTESELECTROLYTES
ELECTROLYTESELECTROLYTES
Compounds, that when placed in a solution, conduct an electric current and emit dissociated
particles of electrolytes (ions) that carry either a positive charge (cation) or negative charge
(anion)
(Kee & Paulanka, 2000, p. 42)
ELECTROLYTESELECTROLYTES
Na+ & Cl- → ECF
K+ → ICF
Mg+ = → ICF
Ca+ → almost equal in ICF & ECF
(Kee & Paulanka, 2000, p. 42)
ELECTROLYTESELECTROLYTESTerms:
Anabolism → formation of new tissue
Catabolism → tissue breakdown
(Kee & Paulanka, 2000, p. 46)
PotassiumPotassium
Reference Range:3.5 – 5.1 mEq/L
PotassiumPotassium
Potassium is gained by intake and lost by excretion.
If either is altered, hyperkalemia or hypokalemia may result!
Regulated by aldosterone and insulin
PotassiumPotassiumPotassium levels directly affect
cell, nerve, & muscle function:– Maintains the electrical neutrality and
osmolality of cells– Aids in neuromuscular transmission of
nerve impulses– Assists skeletal and cardiac muscle
contraction and electrical conductivity– Affects acid-base balance in relationship
to hydrogen (another cation)
PotassiumPotassium
Hypokalemia is K+ < 3.5
Hyperkalemia is K+ > 5.1
HypokalemiaHypokalemia
Levels < 3.5
Mildly Low Levels usually asymptomatic
If level < 3.2, usually accompanied by symptoms
HypokalemiaHypokalemiaCauses of Hypokalemia:
Increased Urine Output Malnutrition
Vomiting and/or DiarrheaHypomagnesemia
DKA
HypokalemiaHypokalemia
May be a result of acid-base imbalances = alkalosis
In alkalosis, potassium moves into the cell to maintain balance,
which may lead to hypokalemia
TreatmentTreatment• Oral or IV Potassium Chloride
Replacement• D/C or adjust medications that
may cause hypokalemia• Reverse alkalosis, if cause• Monitor closely for arrhythmias• Monitor Respiratory Status• Monitor LOC• Monitor GI symptoms
HyperkalemiaHyperkalemia
Levels > 5.1
Mildly elevated levels usually asymptomatic
HyperkalemiaHyperkalemiaCauses of Hyperkalemia:
Renal FailureMeds (ACEIs, ARBs, K+ sparing
diuretics, NSAIDs)Addison’s Disease
Aldosterone InsufficienciesDig Overdose
Beta-Blocker Therapy
HyperkalemiaHyperkalemia
May be a result of acid-base imbalances = acidosis
In acidosis, excess hydrogen ions move into cells and push
potassium into ECF, which may lead to hyperkalemia as potassium moves out of the cell to maintain
balance.
TreatmentTreatmentMedications:
– Cation-exchange resins (bind with K+ and excreted via feces)
– IVP insulin and glucose (K+ binds to insulin)– IV Ca++ (protect the heart from the effects of
hyperkalemia)– Sodium bicarbonate (to reverse acidosis)– Diuretics (non-K+ sparing)– Beta2 Adrenergic agonists (epinephrine, albuterol)
D/C meds that may cause hyperkalemiaRestrict foods with K+
Dialysis for renal failure Monitor closely for arrhythmiasMonitor Blood PressureMonitor GI symptoms
SodiumSodium
Reference Range:136 – 145 mEq/L
SodiumSodium• Accounts for 90% of ECF cations• Almost all Na+ is found in ECF; 10%
in ICF• Na+ attracts fluid and helps
preserve ECF volume and fluid distribution
• Na+ helps transmit impulses in nerve and muscle fibers and combines w/ Cl- abd HCO3 to regular acid-base balance
SodiumSodium• Excreted mainly via the kindeys
(GU)– Also via the GI tract and perspiration
• Increased Na+ levels trigger thirst and the ADH
• Sodium-Potassium pump helps maintain normal Na+ levels– Pump also creates an electrical charge for
both cardiac and neuromuscular function
SodiumSodium
Hyponatremia is Na+ < 136
Hypernatremia is Na+ > 145
HyponatremiaHyponatremia
Causes an osmotic fluid shift from plasma into brain cells
HyponatremiaHyponatremiaSigns & Symptoms:Signs & Symptoms:
Nausea/VomitingHeadacheMalaise
ConfusionDiminished Reflexes
ConfusionConvulsions
Stupor or Coma
HyponatremiaHyponatremiaCauses of Hyponatremia:
↑ Vasopressin/ADHSIADH
Adrenal InsufficiencyDiuretics
HypervolemiaLiver FailureHeart Failure
TreatmentTreatment• Administration of oral or IV Na+
(3%) Supplements• Encourage foods high in Na+
• Fluid restriction• Monitor Neuro Status• Monitor for Arrhythmias• Normovolemic hyponatremia
– Vaprisol (conivaptan) – IV infusion– Samsca (tolvaptan) - PO
HypernatremiaHypernatremiaCauses• Dehydration/Hypovolemia• Diabetes Insipidus• Ingestion of Hypertonic Solutions• IV Infusion of Hypertonic Solutions• Cushing’s Syndrome• Hyperaldosteronism• Loss of pure water
– (excessive sweating or respiratory infections)
Signs & SymptomsSigns & Symptoms• Thirst• Lethargy • Neurologic Dysfuntion
– Due to dehydration of brain cells– Irritablility– Weakness– Seizures– Coma
• Edema• Decreased vascular volume
TreatmentTreatment• Administration of IV Fluids
– (Isotonic Salt-Free)
• Encourage foods low in Na+
• Push P.O. Fluids• Monitor Neuro Status• Monitor for Arrhythmias
MagnesiumMagnesium
Reference Range:1.8 – 2.4 mEq/L
MagnesiumMagnesium• 2nd most abundant ICF cation (K+ #1)• 60% Mg+ found in bones, < 1% ECF• Mg+ performs the following
functions:– Promotes enzyme reactions in carbohydrate
metabolism– Helps produce ADP (adenosine triphosphate)– Helps with protein synthesis– Influences vasodilation (normal CV function)– Helps Na+ and K+ ions cross cell membranes
MagnesiumMagnesium• Mg+ performs the following
functions:– Regulates muscle contractions– Affects irritability and contractility of
cardiac and skeletal muscle– Influences Ca++ levels
• maintain Ca++ levels in ECF
MagnesiumMagnesium
Hypomagnesemia is Mg+ < 1.8
Hypermagnesemia is Mg+ > 2.4
HypomagnesemiaHypomagnesemiaResults in cardiac dysrhythmias and
irritates the nervous system (tetany)
HypomagnesemiaHypomagnesemiaCauses of Hypomagnesia:
MalnutritionChronic Diarrhea
MalabsorptionETOH Abuse
DiureticsAMI
Pancreatitis
HypomagnesemiaHypomagnesemia
Does not produce specific EKG changes
May contribute to arrhythmias caused by digoxin toxicity,
ischemia, or potassium imbalances
(Woods et al, 2005, p. 358)
HypomagnesemiaHypomagnesemiaReplacement of Mg – PO or IV
PO = Mg Oxide 400mg tabs
MgSo4 IV administration is usually given at a rate of 1 gram/hr (1
gram/100 ml)
Encourage foods high in magnesium
HypomagnesiaHypomagnesiaMonitor…
Monitor EKG for Arrhythmias
Monitor for muscle cramps
HypermagnesemiaHypermagnesemia
Severe hypermagnesemia is associated with AV
blocks and intraventricular
conduction disturbances
CalciumCalcium
Reference Range:8.5 – 10.1 mg/dl
CalciumCalcium• 99% Ca++ in bones; 1% in serum &
soft tissue (measured in blood serum levels)
• Is found in both ECF and ICF• Can be measured in 2 ways:
– Total serum calcium (total Ca++in blood)– Ionized calcium level (various forms of Ca++ in
ECF)
• 41% ECF Ca++ is bound to protein; 9% bound to citrate or other organic ions
CalciumCalcium• Ca++ functions in the following
ways:– Responsible for formation of bones and
teeth– Helps maintain cell structure & function– Plays a role in cell membrane permeability
and impulse transmission– Affects contraction of cardiac muscle,
smooth muscle, and skeletal muscle– Participates in blood-clotting process
CalciumCalciumCalcium helps
potassium & sodium move into and out cells in the
sodium-potassium
pump mechanism
HypocalcemiaHypocalcemiaCauses:•Vitamin D Deficiency
– Vitamin D promotes Ca++ absorption in intestines, resorption from bones, and kidney resorption all of which raise Ca+
+ levels
•Deficiency of parathyroid hormone
• Inefficient parathyroid hormone
HypocalcemiaHypocalcemiaCauses:•Deficiency of parathyroid
hormone (PTH)– Calcitonin, secreted by PTH, helps
regulate Ca++– Decreases absorption of Ca++ and
enhances its excretion by the kidneys
HypocalcemiaHypocalcemiaHypocalcemia May Cause…
Laryngospasm
Cardiac Arrhythmias
EKG Δ’s → prolonged QT interval
HypocalcemiaHypocalcemiaManagement…
PO or IV calcium replacement(depends on severity of symptoms or
deficiency)
Vitamin D supplement
Encourage foods high in calcium
HypercalcemiaHypercalcemiaCauses of Hypercalcemia:
Excessive calcium release
Increased intestinal calcium absorption
** Decreased renal calcium excretion **
HypercalcemiaHypercalcemiaHypercalcemia May Cause…
Cardiac Arrhythmias
EKG Δ’s → shortened QT interval
HypercalcemiaHypercalcemiaSevere Hypercalcemia (>
15mg/dl) is a…
Medical Emergency
May result in
Coma or Cardiac ArrestComa or Cardiac Arrest
HypercalcemiaHypercalcemiaSigns & Symptoms…
FatigueDepressionConfusionAnorexia
N/VConstipationPancreatitis
Increased Urination
HypercalcemiaHypercalcemiaTreatment…
HydrationIncreased Salt Intake
DiureticsDialysis (renal failure)
Glucocorticoids
Renal FunctionRenal Function
Renal FunctionRenal Function
The main function of the renal system is to excrete bio-waste, regulate water and electrolyte levels, and release of hormones that
affect RBC production, bone metabolism, and
hypertension.
Renal FunctionRenal Function
Minimal urine output = 30 ml/hr
Output affected by fluid intake, hormones, & medications
Renal impairment causes imbalances of both fluids and
electrolytes
Blood Urea NitrogenBlood Urea NitrogenReference Range: 5 -20 mg/dlReference Range: 5 -20 mg/dl
An end-product of protein metabolism
Excreted by the kidneys
Elevated levels are indicators of possible dehydration, pre-renal
failure, or renal failure
Blood Urea NitrogenBlood Urea NitrogenReference Range: 5 -20 mg/dlReference Range: 5 -20 mg/dl
If BUN ↑ (up to 35 mg/dl) but the creatinine is WNL =
DEHYDRATION
Usually as a result of…Diarrhea, vomiting, and/or
inadequate fluid intake
BUN WNL after hydration. If not, may indicate pre-renal or renal
failure
CreatinineCreatinineReference Range: 0.8 – 1.3 mg/dlReference Range: 0.8 – 1.3 mg/dl
A by-product of muscle catabolism
Excreted by glomerular filtration
More specific indicator of renal failure
Not influenced by diet or fluid intake
CreatinineCreatinineReference Range: 0.7 – 1.5 mg/dlReference Range: 0.7 – 1.5 mg/dl
If creatinine ↑ (> 2.5 mg/dl) this could be indicative of renal
impairment
IF both BUN and creatinine are elevated, then renal disorder is
present
BUN/Creatinine RatioBUN/Creatinine RatioReference Range: 10 - 20Reference Range: 10 - 20
Low – Suspect acute tubular necrosis, malnutrition, low protein intake, pregnancy, liver disease,
hemodialysis
High – Reduced renal perfusion (dehydration, heart failure), glomerular disease, tissue or
muscle destruction, high protein intake, azotemia (elevated urea
levels)
ReferencesReferencesKee, J. L. (2005). Laboratory and diagnostic tests with nursing
implications (7th ed.). Upper Saddle River, NJ: Pearson Prentice Hall.
Kee, J. L. & Paulanka, B. J. (2000). Handbook of fluid, electrolyte, and acid-base imbalances. Scarborough, Canada: Delmar Publishers.
Priff, N. (ed.). (2006). Nurse’s quick check: Fluids and electrolytes. Ambler, PA: Lippincott, Wilkins, and Williams.
Smeltzer, S. C. et al. (2008). Brunner and suddarth’s textbook of medical-surgical nursing (11th ed.). Philadelphia, PA: Lippincott Williams and Wilkins.
Taber’s On-Line Medical Dictionary