F L U I D SF L U I D SAND AND

ELECTROLYTESELECTROLYTES

Nelia B. Perez RN, MSNIV Preceptor

Water overview*Water comprises about

60% -70% of the total body weight

*Varies withageweightgender

Water Loss

ROUTES OF WATER LOSS

-SENSIBLE -INSENSIBLE Urine Lungs Feces Sweat

Causes of Increased Water Loss

•Fever•Diarrhea•Diaphoresis•Vomiting•Gastric suctioning•Tachypnea

Causes of Increased Water Gain

•Increased sodium intake•Increased sodium retention•Excessive intake of water•Excess secretion of ADH

•Intracellular fluid (ICF) (70%)— fluid within cells - large amounts of K+, PO4--, Mg++

•Extracellular fluid (ECF) (30%)— fluid outside cells

- large amounts of Na+,Ca+,Cl-,HCO3-- - Includes intravascular(15%) and interstitial fluids(5%)

Two Compartments of Fluid in the Body

FLUIDS AND ELECTROLYTES

There is a continuous exchange of fluid between the fluid compartment , of these spaces only the plasma is directly influenced by the intake or elimination of fluid from the body.There is also the so called third space fluid shift or “third spacing” where there is a loss of ECF into a space that does not contribute to the equilibrium between ICF & ECF.

FLUIDS AND ELECTROLYTES

“ Third spacing” occurs in: Ascites Burns Peritonitis Bowel obstruction Massive bleeding into body cavity or joints

Electrolytes

-An electrolyte is a substance, that when dissolved in water,

gives a solution that can conduct electricity.

Importance of electrolytes

-Maintain voltages across cell membranes -Carry electrical impulses to other cells-Found in blood or the human body in the form of acids, bases or salts (Sodium, calcium, potasium, chlorine, magnesium, bicarbonate) -Conduct an electric current that transports energy thoughout the body

Major Electrolytes/Chief FunctionSodium — controls and regulates volume of body

fluidsPotassium — chief regulator of cellular enzyme activity and water contentCalcium — nerve impulse, blood clotting, muscle contraction, B12 absorptionMagnesium — metabolism of carbohydrates and proteins, vital actions involving enzymesChloride — maintains osmotic pressure in blood, produces hydrochloric acidBicarbonate — body’s primary buffer systemPhosphate — involved in important chemical reactions in body, cell division and hereditary traits

•Osmosis - the movement of water from an area of lower solute concentration to an area of higher solute concentration.

•Semi-permeable membrane•membrane must be more permeable to water•a greater concentration of solutes on one side of the membrane

Regulation of Body Fluid Compartments

•Facilitated Diffusion•Requires a carrier molecule.•Lipid insoluble substances cannot cross the plasma membrane (glucose).•ATP is not expended.•Movement of the particles is from an area of higher concentration to an area of lower concentration.

•Active Transport movement of a substance across the cell

membrane from an area of lower concentration to an area of higher concentration.

ATP is expended. The sodium-potassium pump is an example of

active transport.

Fluid Volume Deficit

- Involves either volume or distribution of water or electrolytes

•Hypovolemia — deficiency in amount of water and electrolytes in ECF with near normal water/electrolyte proportions

•Dehydration — decreased volume of water and electrolyte change

•Third-space fluid shift — distributional shift of body fluids into potential body spaces

Fluid Volume Excess

Hypervolemia — excessive retention of water and sodium in ECF

Overhydration — above normal amounts of water in extracellular spaces

Edema — excessive ECF accumulates in tissue spaces

Interstitial-to-plasma shift — movement of fluid from space surrounding cells to blood

Types of IV Solutions

ISOTONIC-solution has the same osmolality as the extracellular fluid.

Examples: D5W ; Normal Saline

Hypertonic solutions have a higher concentration of solute and are more concentrated than extracellular fluids. Net movement intracellular to extracellular

Examples : 3% saline; 5% saline

Hypotonic solutions have a lower concentration of solutes and is more dilute than extracellular fluid .Net movement extracellular to intracellular

Examples : 1/2 Normal Saline; 1/3 Normal Saline

Electrolyte ImbalancesSODIUM (Na+) 135-145 mEq/L Functions

•Maintains osmolality•Participates in active transport•Helps regulate body fluids•Participates in the action potential

Hyponatremia:serum sodium level falls below 130 mEq/L.Cells become swollen.Neurological Disturbances :cerebral edema,headache, lethargy,depression, confusion,convulsions,comaCardiovascular Disturbances: postural hypotension,shockHypernatremia: Serum sodium is more than 150 mEq/L.Cells shrink. Complications:Osmotic Diuresis,cellular dehydration,circulation decreases

POTASSIUM (K+): 3.5-5.0 mEq/LFunctions

•Transmission of nerve impulses•Resting membrane potential•Acid-base balance•Promotes myocardial, skeletal, and smooth muscle contractility

Hypokalemia: <3 mEq/LCardiovascular: dysrhythmias, hypotension, digitalis toxicity, myocardial damage, cardiac arrest

Neurological: lethargy, confusion, depression

Gastrointestinal : paralytic ileusSkeletal Muscle: weakness, flaccid paralysis, weakness of respiratory muscles, respiratory arrestRenal System: decreased ability to concentrate urine, water loss, kidney damageAcid-Base Balance: metabolic alkalosis

Electrolyte Imbalances

Hyperkalemia: serum value of >6 mEq/L

Nervous System : ParaesthesiaNeuromuscular: Muscle twitching, muscle weakness, paralysisCardiovascular : Bradycardia, Cardiac arrest

CALCIUM :8.5-10.5 mg/dl or 4.5-5.8 mEq/L

Electrolyte Imbalances

Functions•Formation of bone and teeth•Contraction of muscle•Blood coagulation•Blocks sodium transport into the cell •Transmission of nervous impulses

•-Nervous System• Paraesthesia

•-Muscular System• Tetany, Laryngeal • spasms

•-Cardiovascular System• congestive heart failure• decreased cardiac • output• cardiac dysrhythmias

•Hypocalcemia<0.9 mmo/L ionized Calcium

•Hypercalcemia>12 mg/dL total Calcium or >1.5 mmol/L ionized Calcium

•-Neurological Manifestation• lethargy, confusion, coma

•-Skeletal Manifestations• deep bone pain; fractures

•-Renal Manifestations:stones•-Gastrointestinal Manifestations

• Constipation;anorexia• Nausea and Vomiting

•-Cardiovascular Manifestations• Shortened QT interval,•Bradycardia• Cardiac arrest

"the excessive loss of water and electrolytes from the body“

can be caused by losing too much fluid, not drinking enough water or fluids, or both.

Infants and children are more susceptible to dehydration than adults because of their smaller body weights and higher turnover of water and electrolytes.

So are the elderly and those with illnesses

dehydration occurs when losses are not replaced adequately and a deficit of water and electrolytes develop.

These may occur in Vomiting or diarrheaPresence of an acute illness where there is

loss of appetite and vomiting: Pneumonia DHF Other Acute Ilnesses

Excessive urine output, such as with uncontrolled diabetes or diuretic use

Excessive sweating (sports)Burns

Since diarrhea and vomiting are the most common causes of dehydration in children, the volume of fluid loss may vary from 5 ml/kg (normal) to 200 ml/kg

Concentration of electrolytes lost also varies

NaCl and K are the most common electrolytes lost through stools

In order to diagnose the type of dehydration, you need to know the History and you must do a thorough physical examination

We classify type of dehydration depending on the amount of water and electrolytes lost

These are reflected by the signs and symptoms the child will present

Dehydration is classified as no dehydration, some dehydration, or severe dehydration based on how much of the body's fluid is lost or not replenished.

When severe, dehydration is a life-threatening emergency

Graded according to the signs and symptoms that reflect the amount of fluid lost.

There are usually no signs or symptoms in the early stages

As dehydration increases, signs and symptoms develop. Initially, thirst, restlessness, irritability, decreased skin turgor, sunken eyes and sunken fontanelles.

As more losses occur, these effects become more pronounced.

Assesment of Dehydration

Signs of hypovolemic shock (SEQUELAE)

1. diminished sensorium (lethargy)2. Lack of urine output3. Cool moist extremities4. A rapid and feeble pulse5. Decreased BP6. Peripheral cyanosis7. DEATH.

MAINTENANCE REQUIREMENTS

HOLIDAY-SEGAR METHODBODY SURFACE AREA METHOD

HOLIDAY-SEGAR METHODEstimates caloric expenditure in fixed weight categories

Assumption 100 cal metabolized : 100 mL water

Not suitable for neonates < 14 days Overestimates fluid needs

HOLIDAY-SEGAR METHODBODY

WEIGHTml/kg/day ml/kg/hr Electrolytes

(mEq/100ml fluid)

First 10 kg 100 4 Na+ 3

Second 10 kg 50 2 Cl- 2

Each additional kg

20 1 K+ 2

BODY SURFACE AREA METHOD

Assumption: caloric expenditure is related to BSA

Not used in children < 10 kg

BSA METHOD

Component

Values

Water 1500 ml/m2/24 hrs

Na+ 30-50 mEq/m2/24 hrs

K+ 20-40 mEq/m2/24 hrs

STANDARD VALUES FOR USE IN BODY SURFACE AREA METHOD

BSA Formula

Surface area (m2) = ht (cm) x wt (kg)

3600

ICF & ECF COMPARTMENTS

In dehydration, there are variable losses from the extracellular and intracellular compartments

Percentage of deficit is based on total duration of illness

Sources:

Fluids & Electrolytes, Lippincott Williams & Wilkins

Fluids & Electrolytes, Walters Kluwer Nelson’s Texbook of Pediatrics WHO department of child and adolescent

development (Medline Plus)

http://www.nlm.nih.gov/MEDLINEPLUS/ency/article/000982.htm