fluids and electrolytes

F L U I D SAND

ELECTROLYTES

Water overview*Water comprises about 60% -70% of the total body weight *Varies with

ageweightgender

Factors that Determine the Amount of Water Content

Age – the older we get, water content is lesser

Sex/Gender – males have more water than females

Body size/Weight – thin people have more water than chubby ones

Normal Composition in Average Man

• When a person loses more than 10% of his total body fluids,he can DIE!!!

Functions of Water in the BodyFunctions of Water in the Body• -Transporting nutrients to cells and wastes from cells • -Transporting hormones, enzymes, blood platelets, and red and white blood cells• -Facilitating cellular metabolism and proper cellular chemical functioning• -Facilitating digestion and promoting elimination• -Acting as a solvent for electrolytes and non-electrolytes• -Acting as a tissue lubricant and cushion• -Helping maintain normal body temperature

• Intracellular fluid (ICF) (60-70%)- fluid within cells- K is the major component

• Extracellular fluid (ECF) (20-30%)- fluid outside cells- Na & Cl

Two Compartments of Fluid in the Body

Interstitial – between the cellsIntravascular – inside the blood vesselTranscellular – CSF, saliva, GIT secretions and tears

LOSS of WATER

Routes and daily body fluid excretion

SENSIBLE

- An individual is aware of losing that water.

GIT / FecesWater loss through defecation/feces is 200cc

KIDNEYS / UrineWater loss through urination is 1,500ml

INSENSIBLE

- An individual is unaware of losing that water.

SKIN / PerspirationWater loss through perspiration is

600ml

LUNGS / RespirationWater loss through respiration is about 300ml – 350ml

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

Electrolytes

Electrolytes

Ion -atom or molecule carrying an electrical charge

cation –develop a positive charge ex. Na, K, Ca, Mg anions –develop a negative charge ex. Cl, HCO, PO4

These charges are the basis of chemical interactions inThe body necessary for metabolism and other function

• An electrolyte is a substance, that when dissolved in water, gives a solution that can conduct electricity

Functions of electrolytes-promotes neuromascular irritability

-maintenance of body fluid osmolarity-regulation of water balance-distribution of body fluids between compartments-Conduct an electric current that transports energy thoughout the body

Effects of Electrolytes

· The loss of electrolytes in the body can lead to an unbalance of fluids in the body and the pH, and a damage of the electric potential between the nerve cells that transmit the nerve signals (Encarta)

Major Electrolytes/Chief FunctionSodium- support muscle contraction and nerve

impulse transmissionPotassium — chief regulator of cellular enzyme activity and water contentCalcium- formation of bones and teeth, nerve impulse, blood clotting, muscle contraction, B12 absorptionMagnesium — support bone mineralization, protein building, muscular contraction, nerve impulse t.Chloride — 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

• Osmosisfluid move across a semi -permeable membrane from an area of low solute concentration to an area of high solute

concentration until equilibrium is achieved.

Regulation of Body Fluid Compartments

Processes:

Diffusion• The movement of particles in all directions through a

solution.• The process by which a solute (substance that is

dissolved) may spread through a solution or solvent (solution in which the solute is dissolved).

•Active Transport Physiologic pump that moves from an area of

lower concentration to higher concentration with the use of ATP.

The sodium-potassium pump is an example of active transport.

OsmolarityDescribes the concentration of solutes or dissolved particles

Filtration is the movement of solutes and solvents by hydrostatic pressure. - the movement is from an area of greater pressure to an area of lesser pressure. Osmotic pressure is the amount of hydrostatic pressure needed to stop the flow of water by osmosis -pressure exerted by proteins Hydrostatic pressure pressure exerted by fluid on blood vessel wall

Types of IV Solutions ISOTONIC – balance osmotic pressure Solute concentration is equal to that of the

serum Fluid doesn’t shift because they’re equally

concentrated and already in balance Solution has the same osmolality as the

extracellular fluid.Examples:D5W ; Normal Saline

* Doesn’t cause shrinking or swelling of the cell

HYPERTONIC SOLUTION Greater pressure than that of the blood

serum Fluids tend to move out of the less

concentrated solution into the more concentrated

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

Examples : 3% saline; 5% saline

* Causes the cell to shrink

HYPOTONIC SOLUTION Lesser pressure than that of the blood

serum Fluid shifts from the hypotonic solution into

the more concentrated compartment to equalize the concentrations

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

* Causes the cell to swell

WATER BALANCE

1. THIRST – hypothalamus

2. Hormonesa. ADH – posterior pituitary gland

- reabsorption of waterb. Aldosterone – adrenal gland

- Na retention, H2O retention

ADH Hypothalamus senses low blood volume

pituitary gland secretes ADH into the bloodstream ADH causes the kidney to retain water water retention boosts blood volume

ALDOSTERONE Produced as a result of the renin-

angiotensin mechanism Acts to regulate fluid volume

Angiotensin II stimulate the adrenal gland to release aldosterone

Aldosterone causes the kidneys to retain Na and water

Increases fluid volume and sodium levels

Renin - angiotensin system

BP decreased renin angiotensinogen

angiotensin 1

angiotensin 2

Renin – angiotensinsystem

Angiotensin 2

aldosterone peripheralvasoconstriction

increase Na reabsorption

increase water reabsorption

Increase plasma volume

increase blood pressure

VOLUME DISTURBANC

ES

FLUID VOLUME DEFICIT

Description: Dehydration in which the body’s intake is

not sufficient to meet the body’s fluid needs.

The goal of treatment is to restore fluid volume, replace electrolytes as needed, and eliminate the cause of the fluid volume deficit.

CAUSES Diabetes insipidus Fever Diarrhea Renal failure Lack of fluid intake Malnutrition Vomiting Diaphoresis

Poor skin turgor Sunken fontanels Dry mouth Scanty urine No perspiration Sunken eyeballs Weight loss No tears Weak Lethargy Dizziness Extreme thirst Dry skin

SIGNS AND SYMPTOMS

Encourage increase oral fluid intake

Administer IVF (LR or NSS)

Monitor I & O Replace fluid loss

gradually over 48 hours

Monitor Na levels, urine specific gravity

MANAGEMENT

FLUID VOLUME EXCESS Increase water

CAUSES1. Excess fluid or sodium intake

a. IV administration of NSS or LRb. High intake of dietary Na

2. Fluid and Na retention3. Fluid shift into the intravascular space

a. Burnb. use of plasma CHON or albumin

Edema Increase in weigHt Puffy eyelids Poor skin turgor Tachypnea Dyspnea

Signs and symptoms

MANAGEMENT

Monitor I & O Limit water Skin care Turn patient every 2 hours O2 Limit Na Monitor electrolyte values

ELECTROLYTE IMBALANCES

SODIUM (Na+) 135-145 mEq/L

-principal cation in ECF-average daily requirements 2-4 grms/day-responsible for:

-serum osmolality-water retention-neuromuscular activity “Na pump action”-acid- base balance

-foods high in Na-salted foods ex. ham, corned beef, cheese

etc.-regulated by the kidneys-influenced by hormone aldosterone-Chloride frequently appears in combination with Na+ion.

Hyponatremia: serum sodium level falls below 135 mEq/L. Cells become swollen.

Etiology:

◦a. loss of Na◦b. gains of water◦c. Disease states associated with ◦ ADH (Vasopressin)

Clinical manifestations(Hyponatremia) <135mEq/L

CNS changes◦ Lethargy, headaches◦ Confusion◦ Seizures◦ Coma

nausea/vomiting Hemiparesis Diarrhea, abdominal cramps Pale dry skin

Nursing Intervention

1.Evaluate precipitating cause is corrected

2.monitor Na serum level3.Evaluate clinical manifestations of Na loss

4.Maintain pts. safety5.Administer prescribed treatment, IV therapy

Hypernatremia: Serum sodium is more than 150 mEq/L. Cells shrink. Etiology:

◦ Water deprivation Excessive salt ingestion Increased insensible loss Water loss diarrhea Prolong fever or diaphoresis w/o water

replacement◦ Na containing parenteral solutions, corticosteroids,

some antibiotics◦ Near salt water drowning◦ Diabetes insipidus- polyuria, polydipsia

Clinical manifestations (hypernatremia)

Serum Na+>145 mEq/L◦ Thirst◦ Nausea and vomiting◦ Flushed, dry skin◦ Fever◦ Dry sticky membranes◦ Rough, dry, swollen tongue

CNS effects◦ Restlessness, agitation◦ Muscular twitching, tremor, hyper-reflexia◦ Disorientation, hallucinations◦ Stupor, coma

Nursing Interventions

1.Evalute precipitating cause and correct

2.Monitor serum Na level3.Evaluate clinical manifestations of hypernatremia

4.Administer prescribed treatment5.Report abnormal findings to MD6.Patient education for future prevention

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

-Principal cation in ICF, 97%-Cannot be measured in the cells-Acute abnormal levels are life threatening

1. K+<2.5 or>7.0-cardiac arrest2. K+<3.5-hypokalemia3. K+>5.5-hyperkalemia

-Responsible for:• Conduction of nerve impulses• Skeletal and cardiac muscle activity• Intracellular osmolality• Enzyme action for cellular metabolism

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

-80-90% excreted in the GIT in urine-10-20% excreted in by GIT in feces-Poorly stored in the body-Daily intake is essential (40-60mEq/L)-Foods high in K+

Green vegetables Dry fruits Nuts Meat Cocoa, brewed coffee

Hypokalemia: <3 mEq/L

Etiology

◦GI loss Diarrhea, GI suction, vomiting, laxatives

◦Renal loss K loss diuretics, aldosterone, steroids Glucocorticoids, sweat, some antibiotic

◦Shift into cells Insulin, alkalosis,TPN

◦Poor intake Anorexia, alcoholism, debilitation, neglect

Clinical manifestations ( hypokalemia)

◦Fatigue, weakness◦Cramps, restless legs◦Decreased reflexes◦Quadra-paralysis

Respiratory muscle -Renal

◦ Impaired conc. Of urine◦Dilute frequent urination◦Resistance to ADH, kidney exchange Na for

K -CV

◦Sensitivity to digoxin◦Decreased BP

Cont. Clinical manifestation (hypokalemia)

-ECG changes◦Flat T waves◦U wave◦Arrhythmias/cardiac arrest

-GI◦Decreased motility, paralytic ileus◦Anorexia, nausea, vomiting

Nursing interventions

Be aware of pt.at risk for K excess Assess pt.taking K+P.O. for GI upset Be aware that there are many forms of K+ supplements available. Check physicians order carefully

Assess and educate pt.concerning nutrition for adequate K+ intake

Hyperkalemia: serum value of >6 mEq/L

Etiology:

Pseudo hyperkalemia Excess K+ intake Renal excretion Drugs Shift of K+ out of cells

Clinical manifestations (hyperkalemia)

-ABD cramping, nausea, diarrhea -Lower extremities muscle weakness -Irritability -Paresthesias of face, tongue, feet and

hands -Flaccid muscle paralysis -Bradycardia, irregular heart rate, cardiac

standstill -ECG changes

Tall, peaked T waves, prolonged PR Widened QSR

Hyperkalemia: serum value of >6 mEq/L

Nursing Interventions

Monitor serum K+ report value >5.3 Caution hyperkalemia pts.to avoid foods high in K+ like:◦Chocolates, coffee, tea, dried fruits and

beans, meat and eggs, bananas Monitor for U/O Administer fresh blood as ordered Regulate IV w/ K+ carefully Utilized good phlebotomy techniques

CALCIUM :

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

Functions:

• Formation of bone and teeth • Contraction of muscle, relaxation, activation

and excitation• Maintaining cardiac contraction• Cellular strength and permeability• Blood coagulation• Blocks sodium transport into the cell • Transmission of nerve impulses

Calcium ImbalancesEtiology

Hypocalcemia <4.5/9 mg/dl

Diet Chronic renal failure Mal absorption

syndromes Alcoholism Acute pancreatitis Loop diuretics Citrated blood alkalosis

Hypercalcemia >5.5/11 mg/dl

98%◦ Hyperparathyroidism◦ Thiazide diuretics ◦ malignancy

Immobility Vit.A & D overdose Ca cont. antacids Renal dysfunction Steroid acidosis

Clinical manifestations (hypocalcemia)

◦Irritability◦Decreased memory◦Delusions, hallucinations◦Hyperreflexia◦Parasthesias◦+ Chvostek’s sign◦+ Trousseau’s sign◦Laryngeal spasm, resp.arrest◦Tetany, seizures◦Abd’l. cramps◦ECG Prolonged QT interval

Nursing Interventions

Monitor serum Ca, VS, ECG Give PO Ca supp.30 mins.before eating

Be aware of safe administration of IV Ca

Teach clients to eat food high in Ca, Vit.D, protein

Take necessary precautions for confusion, seizure

Assess for prolong bleeding

Clinical manifestation (Hypercalcemia)

Headache, confusion Decreased memory Psychosis, stupor, coma Muscle weaknesses, fatigue Depressed reflexes Anorexia, N/V Bone pain, fractures Polyuria, dehydration Nephrolithiasis ( kidney stones) ECG

◦ Shortened QT interval

Nursing Interventions

Monitor serum Ca, VS, ECG Mobilization and wt. bearing activity Diet low in Ca

◦Dilute urine to prevent renal calculi formation

Hydrate w/ isotonic solutions Promote excretion w/loop diuretic Watch for digitalis toxicity

DEHYDRATION

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

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

Dehydration: Definition

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: Definition

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

vomiting or diarrhea acute illness where there is loss of appetite and

vomiting Excessive urine output ex. diabetes or diuretic

use Excessive sweating (sports) Burns

Causes of Dehydration

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

History taking and do a thorough physical examination

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:Checking the main symptoms

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

Dehydration: Classification

Clinical signs of dehydration

Look at condition

Eyes Tears

Mouth and tongue Thirst

Well , alert

NormalPresentMoistDrinks

normally, not thirsty

*restless,irritable

sunkenabsent

dry*thirsty,drink

s eagerly

*Lethargic or unconscious;flopp

yvery sunken & dry

absentvery dry

drinks poorly or not able to drink *

Feel skin pinch

Goes back quickly

*goes back slowly*

*Goes back very slowly

Decide

The patient has

no sign of dehydration

If the patient has 2 or more

signs, including at

least 1 *signs*, there

is Some Dehydration

If the patient has 2 or more signs, including at least 1 *sign* , there is

Severe Dehydration

TreatUse

treatment Plan A

Weigh the patient , if

possible and use

treatment Plan B

Weigh the patient and use treatment Plan C URGENTLY

Poor Skin Turgor

Three rules of home treatment:

1. give extra fluids2. continue feeding3. advise when to return to the

doctor

(if the child develops blood in the stool,

drinks poorly, becomes sicker, or is not better in three days).

WHO Treatment Plan A

ORS(ml)

the mother slowly gives the recommended amount of ORS by spoonfuls or sips

Note: If the child is breastfed, breast-feeding should continue.

After 4 hours, reassess and reclassify dehydration, and begin feeding to provide required amounts of potassium and glucose.

WHO Treatment Plan B

WHO Treatment Plan B

If there are no more signs of dehydration, do Plan A.

If there is still some dehydration, repeat

Plan B.

If the child now has severe dehydration, do Plan  C.

WHO Treatment Plan C-Give IV infusion-If IV infusion is not possible, fluids should be given by nasogastric tube. -If none of these are possible and the child can drink, ORS must be given by mouth.

Note: In areas where cholera cannot be excluded for patients less than 2 years old with severe dehydration, antibiotics are recommended. Start Cotrimoxazole.

WHO Treatment Plan C

Normal saline does not correct acidosis or replace potassium losses, but can be used. Plain glucose or dextrose solutions are not acceptable for the treatment of severe dehydration.

REMEMBER:Do not give:

Very sweet tea, soft drinks, and sweetened fruit drinks.

(These are often hyperosmolar (high sugar content).

Can cause osmotic diarrhea, worsening dehydration and hyponatremia.

Also to be avoided are fluids with purgative action and stimulants (e.g., coffee, some medicinal teas or infusions).

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.

Assessment 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.

Summary of Management According to Degree of Dehydration

Degree ofDehydration

Amount of Fluid

Type of Fluid

Feeding

None Vol. per vol. replacement orafter each diarrhea stool: 50-100 ml (1/4-1/2 cup) if < 2yrs; 100-200 ml (1/2 -1 cup) if 2-10 yrs; ad libitum for older children

Suitable home fluids (not salty or highly sweetened), ORS, rice water, vegetable or chicken soup

Usual diet or formula, continue breastfeeding

Summary of Management According to Degree of Dehydration

Degree ofDehydration

Signs Fluids Feeding

Mild Slightly dry mucus mem- brane increased thirst, slightly reduced urine flow

ORS, 30-50 ml/kg in 4-6 hrs

Breastfeeding, full-strength cows milk or lactose-contg. formula, undil. lactose-free formula

Moderate Sunken eyes, sunken fontanelle, loss of skin turgor, dry mucus membrane

ORS, 60-90 ml/kg in 4-6 hrs

Same as above

Summary of Management According to Degree of Dehydration

Degree ofDehydration

Signs Fluids Feeding

Severe Signs of mod. dehydration plus one or more of ff: rapid, thready pulse, cyanosis, rapid breathing, delayed capillary refill time, lethargy, coma

IV fluids (Lactated Ringers or NSS),30ml/kg in 1/2 hr (1 hr for infants) then 70 ml/kg in 2 1/2 hrs for adult and 5 hrs for infants)

Begin after clinically improved and ORS has begun

IV TUBING

Calculating Administration Rates

One must know two key components before using the formula:Drop factor of the IV administration set

Amount of solution to be infused over one hour

Rate Calculations

Macrodrip Set10 drops = 1 ml15 drops = 1 ml20 drops = 1 ml

Microdrip Set60 drops = 1 ml

Blood Set10 drops = 1 ml

- Calibrated in drops per ml-this calibration is needed in calculating flow rates.

- Macrodrip set is used for routine adult IV administration, depending on the manufacturer and the type of tubing.

- 10/15, 15/60, 20/60, commonly drop factor.

- A macrodrip set is used when more exact measurements are needed, such as in pediatric units.

FORMULA

Drip Rate (gtts or mgtts/min) =

Total no. of ml x Drip Factor Total no. of min.

Total number of mlqtts/min= × drop factor

Total number of hours

1000ml = × 20gtts/ml

8hours

= 41-42gtts/min

Doctor’s Order: Start D5LR 1L to infuse over 8 hours the drop factor is 20qtts/ml,compute for the drops/minute.

Ex. gtts/min.Doctor’s order: Start 500ml of NS to

infuse over 300 minutes. The drop factor is 10 gtts/ml. compute for the gtts/min.?

Gtts/min = total no. of ml X drop factor

total no. of hour

= 500ml X 10gtts/ml

300mins.

= 16.66 gtts/min

Gtts/min = total no. of ml X drop factor

total no. of hour

= 500ml X 10gtts/ml 5 hours 60

= 16.66 gtts/min

Ex. gtts/min.Doctor’s order: Start 500ml of NS

to infuse over 300 minutes. The drop factor is 10 gtts/ml. compute for the gtts/min.?

FORMULA

ml per hour =

Total no. of mlTotal no of hours

total number of ml

Cc /hr=total number of hours

1000ml =

80ml/hour

= 12.5hour

Doctor’s Order: 1000ml of D5NM to infuse at a rate of 80cc/hour. A nurse determine that it will take, how many hours for 1L to infuse?

total number of ml

Cc/hour =c

total number of mlcc/hour=

total number of hour

1000cc =

10hours

= 100cc/hour

Start D5LR 1L to run for 10 hours. Compute for cc/hour?

Ex. Gtts/minD5NM 1L has been ordered by Dr. Dy for

his post-mastectomy patient to be infused at rate of 20gtts/minute. In how many hours will the said IVF last?

Gtts/min = _____total no. of ml_____ X drop factor total no. of hour

= __1,000ml__ X 15 20 gtts/min 60

= 15,000 1,200

= 12.5 hours

Other factors affecting Flow Rate:

1. Gauge of the catheter

2. Viscosity of the infusate

3. Height of the IV stand

4. Condition of the veins

5. Condition of the patient

COMPLICATIONS

Circulatory Overload can occur if an IV is not regulated and IV fluids infuse to rapidly for the patient’s body to handle.

Signs of fluid over load:

Tachycardia Increase Blood pressure Headache Anxiety Wheezing or signs of respiratory distress Diaphoresis Restlessness Distended neck veins Chest pain

- If an IV is running behind schedule-colaborate with the physician to determine the patients ability to tolerate an increased flow rate particularly patients with cardiac, pulmonary and renal problem.

A nurse should never arbitrarily speed up an IV to catch up if the IV is running behind the schedule.

Whenever an IV rate is increased the nurse should assess the patient for increased heart rate, increase respiration or lung congestion-indication of fluid overload.

AFTERCARE

Regulating IV fluids is an ongoing process from the time that an IV is started until it is completed. Hourly checks of an IV should include assessing the pt’s response to the IV, the rate of an IV flow, how much fluid has infused, how much fluid remains to be infused, and the condition of the IV insertion site. Adjust the rate if the IV is not flowing at the rate that was ordered.

If IV fluid is flowing in slowly, the nurse should check for a kink in the tubing or a position of problem. If an IV is flowing to rapidly, it may be leaking out around the IV insertion site. The whole system from the insertion site to the IV bag should be examined.

Thank you very much for listening

MAINTENANCE REQUIREMENTS HOLIDAY-SEGAR METHOD BODY SURFACE AREA METHOD

HOLIDAY-SEGAR METHOD

Estimates caloric expenditure in fixed weight categories

Assumption◦ 100 cal metabolized : 100 mL water

Not suitable for neonates < 14 days◦ Overestimates fluid needs

HOLIDAY-SEGAR METHOD

BODY WEIGHT

ml/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

EXAMPLE

What is the maintenance fluid rate for a an 8 year old child weighing 25 kg using the Holiday-Segar Method?

100 x 10 = 1000 ml+ 50 x 10 = 500 ml+ 20 x 5 = 100 ml 1600 ml/day

4 x 10 = 40 ml+ 2 x 10 = 20 ml+ 1 x 5 = 5 ml

65 ml/hr

EXERCISE

Using the Holiday-Segar Method, what is the full maintenance requirement and rate for a 10 year old patient who weighs 37 kg?

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

EXAMPLE

Using the BSA method, what is the maintenance requirement of an 8 year old who weighs 25 kg and is 132 cm tall?

BSA Formula

0.92 m2= 132 cm x 25 kg3600

Water = 1500ml/0.92/day= 1630 ml

Na+ = 40 mEq/0.92/day= 43.5 mEq

K+ = 30 mEq/0.92/day= 32.6 mEq

EXERCISE

Using the BSA Method, what is the maintenance requirement of a 12 year old boy who weighs 37 kg and is 142 cm tall?

DEFICIT THERAPY

Calculated Assessment Clinical Assessment

CALCULATED ASSESSMENT

Fluid deficit (L) = preillness weight (kg) – illness weight (kg)

% Dehydration = (preillness weight – illness weight)/preillness weight x 100%

CLINICAL ASSESSMENTDEHYDRATION MILD MODERATE SEVERE

Skin turgor Normal Tenting None

Skin touch Normal Dry Clammy

Buccal mucosa Moist Dry Parched/cracked

Eyes Normal Deep set Sunken

Tears Present Reduced None

Fontanelles Flat Soft Sunken

CNS Consolable Irritable Lethargic/obtunded

Pulse rate Normal Sl increased Increased

Pulse quality Normal Weak Peeble

Capillary refill Normal ~ 2 secs >3 secs

Urine output Normal Decreased anuric

FLUID REPLACEMENTMild (in 8 hours)

Moderate (1/4 in 2 hrs then ¾ in the next 6 hours)

Severe (1/3 in 2 hrs then 2/3 in the next 6 hours)

Infant/< 15 kg

50ml/kg 100 ml/kg

150 ml/kg

Older child/ > 15 kg

30 ml/kg 60 ml/kg 90 ml/kg

ICF & ECF COMPARTMENTS

Composition Intracellular (mEq/L)

Extracellular (mEq/L)

Na 20 133-145

K 150 3-5

Cl - 98-110

HCO3 10 20-25

PO4 110-115 5

CHON 75 10

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

BASIC MATH CONCEPTS

DECIMALS

All figures to the left of the decimal point are whole numbers

All figures to the right of the decimal point are decimal fractions

. 385 = . 3 8 5te

nth

s

thou

san

dth

s

hu

nd

red

ths

.385 = 385

1000

.38 = 38

100

.3 = 3

10

CHANGING FRACTIONS TO DECIMALS: Fractions can be changed to decimals by dividing the

numerator and the denominator

¾ = 3 ÷ 4 = 0.75

PERCENTAGE

Percentage ( % ) means hundredths Percent ( % ) is the same as a fraction with

denomination as 100.

3% = 3

100

45

10045% =

CHANGING PERCENT TO A DECIMAL & CHANGING DECIMAL TO PERCENT

To change percent to a decimal, remove the percent sign and divide the number by 100 or move the decimal point two places to the left.

4% = 4/100 = .04 or 0.04

To change a decimal to a percent, multiply by 100 or move the decimal point two places to the right and place % sign.

0.04 X 100 = 4% or 0.04 = 4%

RATIOA Ratio consists of two numbers as separated

by a colon ( : )

e.g. 1 : 4A ratio indicates that there is a relationship between the two numbers.A ratio is an indicated fraction.

e.g. ¼ = 1 : 4

The numbers in ratio must be expressed in the same terms.

e.g. 3 inches : 2 feet = 3 : 24(feet changes to

inches)

PROPORTION

It is a statement showing that the two ratios have equivalent values

1 : 50 = 2 : 100

If one value is not known, it can be solved by using the term X.

1 : X = 2 : 100 or 1 2

X 100~

means

extremes

THE METRIC SYSTEM

It is the international decimal system of weights and measures¤ In the metric system, fractions are expressed

as decimals¤ In the decimal system, the fraction ½ is

written as 0.5

METRIC SYSTEMLiter = vol. of fluids milli = one thousandths

Gram = weights of solids centi = one hundredthsMeter = measure of length deci = one tenth

mcg = one thousandths

RULE OF CONVERSION

When converting from a larger unit of measure to a smaller unit, multiply the larger unit by (1000, 100, 10) or move the decimal to the right.When converting a smaller unit of measure to a larger unit, divide the smaller unit by (1000, 100, 10) or move the decimal to the left.

e.g. 2.5 grams = ___________ mg.

APOTHECARIES SYSTEM

Grain (gr) Dram Ounce Minims Pounds

Approximate Equivalent Value:1 gr = 60 mg1 ml = 15 minims (16 minims)1 ounce= 30 ml1 ounce= 30 Gm1 kg = 2.2 pounds

e.g. 60 gr = _________ mg. 4 oz = _________ ml.

HOUSEHOLD MEASURES

1 teaspoon (tsp) = 4 – 5 ml1 Tablespoon (Tbsp) = 3 teaspoons (tsp)1 Tablespoon = 15 ml1 milliliter = 15 drops (gtts)

e.g. 5 ml = ______

CONVERSION OF TEMPERATURENormal Temperature = 37°C = 98°F

Conversion of Centigrade (Celsius) to Fahrenheit:

Conversion of Fahrenheit to Centigrade (Celsius):°C = 5 ( °F ) – 32

9

°F = 9 ( °C ) + 32

5

Interpretation of Doctor’s Order for Drugs

The nurse must understand the order perfectly before acting on it > The Drug > The Dose > The Route > The Frequency

If any of the above are unclear or open for interpretations, it is the Responsibility of the nurse to clarify the order with the physician.

Example:The order reads : Inderal 2 x4

a. What is the Drug?b. What is the Dose?c. What is the Route?d. What is the Frequency?e. Do

es this order need clarification?

The order reads : Lasix 10 mg IV 1 ml O.D. a. What is the Drug?b. What is the Dose?c. What is the Route?d. What is the Frequency?e. Does this order need clarification?

BASIC MATH CONCEPTS

DECIMALS

All figures to the left of the decimal point are whole numbersAll figures to the right of the decimal point are decimal fractions

. 385 = . 3 8 5

ten

ths

thou

san

dth

s

hu

nd

red

ths

.385 = 385

1000

.38 = 38

100

.3 = 3

10

CHANGING FRACTIONS TO DECIMALS: Fractions can be changed to decimals by dividing the

numerator and the denominator

¾ = 3 ÷ 4 = 0.75

PERCENTAGE

Percentage ( % ) means hundredths Percent ( % ) is the same as a fraction with

denomination as 100.

3% = 3

100

45

10045% =

CHANGING PERCENT TO A DECIMAL & CHANGING DECIMAL TO PERCENT

To change percent to a decimal, remove the percent sign and divide the number by 100 or move the decimal point two places to the left.

4% = 4/100 = .04 or 0.04

To change a decimal to a percent, multiply by 100 or move the decimal point two places to the right and place % sign.

0.04 X 100 = 4% or 0.04 = 4%

RATIOA Ratio consists of two numbers as separated

by a colon ( : )

e.g. 1 : 4A ratio indicates that there is a relationship between the two numbers.A ratio is an indicated fraction.

e.g. ¼ = 1 : 4

The numbers in ratio must be expressed in the same terms.

e.g. 3 inches : 2 feet = 3 : 24(feet changes to

inches)

PROPORTION

It is a statement showing that the two ratios have equivalent values

1 : 50 = 2 : 100

If one value is not known, it can be solved by using the term X.

1 : X = 2 : 100 or 1 2

X 100~

means

extremes

THE METRIC SYSTEM

It is the international decimal system of weights and measures

¤ In the metric system, fractions are expressed as decimals

¤ In the decimal system, the fraction ½ is written as 0.5

METRIC SYSTEMLiter = vol. of fluids milli = one

thousandthsGram = weights of solids centi = one hundredths

Meter = measure of length deci = one tenthmcg = one thousandths

RULE OF CONVERSION

When converting from a larger unit of measure to a smaller unit, multiply the larger unit by (1000, 100, 10) or move the decimal to the right.

When converting a smaller unit of measure to a larger unit, divide the smaller unit by (1000, 100, 10) or move the decimal to the left.

e.g. 2.5 grams = ___________ mg.

APOTHECARIES SYSTEM

Grain (gr) Dram Ounce Minims Pounds

Approximate Equivalent Value:1 gr = 60 mg1 ml = 15 minims (16 minims)1 ounce= 30 ml1 ounce= 30 Gm1 kg = 2.2 pounds

e.g. 60 gr = _________ mg. 4 oz = _________ ml.

HOUSEHOLD MEASURES

1 teaspoon (tsp) = 4 – 5 ml1 Tablespoon (Tbsp) = 3 teaspoons (tsp)1 Tablespoon = 15 ml1 milliliter = 15 drops (gtts)

e.g. 5 ml = ______

CONVERSION OF TEMPERATURENormal Temperature = 37°C = 98°F

Conversion of Centigrade (Celsius) to Fahrenheit:

Conversion of Fahrenheit to Centigrade (Celsius):°C = 5 ( °F ) – 32

9

°F = 9 ( °C ) + 32

5

Interpretation of Doctor’s Order for Drugs

The nurse must understand the order perfectly before acting on it > The Drug > The Dose > The Route > The Frequency

If any of the above are unclear or open for interpretations, it is the Responsibility of the nurse to clarify the order with the physician.

Example:The order reads : Inderal 2 x4

a. What is the Drug?b. What is the Dose?c. What is the Route?d. What is the Frequency?e. Does this order need clarification?

The order reads : Lasix 10 mg IV 1 ml O.D. a. What is the Drug?b. What is the Dose?c. What is the Route?d. What is the Frequency?e. Does this order need clarification?

GENERAL FORMULA FOR DRUG CALCULATION

1. D x QS

2. Calculation by Ratio : Proportion

8 mg : x = 16 mg : 1 tab

(works for any computation of Dosage if you have a given and a need to determine the unknown).

Rule : 1. Units for each ratio must be the same.2. Units for each ratio must be placed in the same

order.

Computation of Dosages:

When the dose prescribed is in milligram (mg) and the dose available is in Gram (Gm) or vice versa.

E.g. The order reads : 0.008 Gm of Morphine Sulfate IV q 4 hours prn for pain. Ampule available is labeled 10 mg/ml.

1. What do you know?0.008 Gm - 8 mg10 mg/ml -

2. What do you need to know? Knownamount in cc for 0.008 Gm dose

3. Setting up the proportion:a. the units for each ratio must be placed in the

same orderb. the units for each ratio must be the same

( mg to mg ) 8mg : X = 10 mg : ml

4. solve for the correct dosage

8 mg : X = 10 mg : ml

10 mg X = 8 mg/ml

X = 8 mg/ml 10 mg

X = .8 ml

When the dose is ordered in one system and the dose on hand is in another system.

E.g. The order reads : codeine sulfate ¼ gr P.O. q 8 hrs PRN for pain. Tablets on hand are labeled 0.015 Gm tablets.

1. What do you know? Known¼ gr 1 gr = 60 mg0.015 Gm / tab 1 Gm =

1000 mg¼ = .25

2. What do you need to know?

# of tablets for ¼ gr dose

3. Setting up the proportiona. the units for each ratio must be

the sameb. the units for each ratio must be

placed in the same order.

.25 gm : X = 0.015 gm : 1 tab

15 mg : x = 15 mg : 1 tab

4. Solve for the correct dosage:

15 mg : x = 15 mg : 1 tab

15 mg x = 15 mg / tab

x = 15 mg / tab 15 mg x = 1 tab

Computation of Correct Insulin Dosage U - 40 means U - 80 means U - 100 means

Insulin syringes are calibrated according to the strength of insulin with which it is to be used.

U 40 insulin needs a U 40 syringe

U 80 insulin needs a U 80 syringe

If this can not be done, the dose can be converted to milliliters

Dose RequiredDose on Hand X 1 ml = ml needed

• Serious error can occur if incorrect syringe or incorrect b calculations are used

• It is essential that all insulin be checked by a second RN to confirm that errors in dosage are not made and error in the type of insulin were not made.

Fractional Dosages in Infants and Children

Children’s Doses Clarks’ Rule:

weight of child in pounds X A.D. = child’s dose

150

Body Surface Area e.g. Wt = 10 kgBSA X A.D. = child’s dose 1.7

BSA = 4(wt in kg) + 7 = BSA in m²wt in kg + 90

= 4(10 kg) + 7 = 47 10+ 90

= .47 m²

Child’s dose = .47 m² X 500 1.7

Youngs’ Formula:

Age of child in Years X A.D. = Child’s dose

Age of child + 12

CALCULATION OF FLUID VOLUME(BASED ON BODY WEIGHT)

1. WEIGHT --- 1 – 10 kg. --- 100ml/kg.Eg. Wt = 8 kg. --- 800cc

2. WEIGHT --- 11 – 20 kg.--- 1,000+50ml/excess b.wt.Eg. Wt = 15 kg. 1,000=250ml = 1,250ml

15 50 -10 X 5 5 250

3. WEIGHT > 20 kg.Eg. Wt = 27 kg. 1,500 + 20 ml/excess b.wt.

1,500 + 140 ml = 1640 ml.27 20

-20 X 7 7 140

Calculation of IV Flow Rates

Calculation of cc/hr is essential in most IV therapy.

Volume # of hrs

E.g. 1 L over 8 hrs = 125 cc/hr

50 cc over 20 minutes = 150 cc/hr

= cc/hr

Calculation of gtt/min (Long Method)

STEPS : 1. Need to know cc/hr to calculate

2. Gtt factor = gtt / mlgtt factors : macrodrip 10, 15, 20 gtts/ml

microdrip 60 gtt/ml

EXAMPLE : LONG METHODDoctors Order : Run 1L D5W over 8 hours

Microdrip - 1000 ml ÷ 8 hours = 125 cc/hr

125 cc x 60 gtt/ml = 125 gtt/ml 60 min 1

10 gtt/ml set 125cc x 10 gtt/ml = 20 – 21 gtt/min 60 min 1

15 gtt/ml set 125cc x 15 gtt/ml = 31 gtt/min 60 min 1

20 gtt/ml set 125 cc x 20 gtt/ml = 41 – 42 gtt/min 60 min 1

SHORT METHOD

cc / hr ÷ 6 for 10 gtt / min

cc / hr ÷ 4 for 15 gtt / min

cc / hr ÷ 3 for 20 gtt / min

cc / hr = gtt / min for microdrip set

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