fluids & electrolytes imbalances - bmh/tele

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)

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• 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

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• Body fluids are:

– Electrically neutral

– Osmotically maintained

• Specific number of particles per volume of fluid

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Homeostasis maintained by:

• Ion transport

• Water movement

• Kidney function

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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

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• Hypertonic - A solution that has a higher solute concentration than another solution to which it’s being compared

• Dextrose 5% in NSS

TONICITY:

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• Hypotonic - A solution that has a lower solute concentration than another solution to which it’s being compared

• 0.45%NSS

TONICITY:

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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)

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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