Fluid and Electrolyte Imbalance

Wan Nedra

Introduction to the Principles of Fluid and Electrolyte Therapy

• Important to understand the underlying physiologic principles of a therapy commonly employed in pediatrics

• Understanding basic principles essential for the understanding of the management of more complex disorders such as:– Cholera– Dengue– Pyloric stenosis– Hyperosmotic non-ketotic coma

Crystalloid and Colloid

• Crystalloid: Water and electrolyte solution • Does not remain within the intravascular space but rather

distributes to the entire extracellular space• Only impacts on the intracellular space if it causes a change in

extracellular osmolarity– E.g.: 0.9% NaCl, D5 0.3% NaCl

• Colloid: Contains large particles which tend to remain within the blood vessels

• Colloid preferentially expands the intravascular space because the particles exert oncotic force which retains water within the intravascular space

– E.g.: 5% albumin, blood, dextran solution

Isotonic Saline Solution

• Isotonic saline solution: Solution such as 0.9% NaCl or Ringer’s lactate with a Na concentration similar to that of plasma water – Crystalloid distributes throughout the extracellular space – Infusion of crystalloid will cause a fluid shift into or out of the

intracellular space only if it creates an osmotic gradient between the extracellular and intracellular space

– Isotonic saline does not change the osmolarity of the extracellular space

– Therefore: Isotonic saline solution remains within and expands the extracellular space and has minimal effect on the intracellular space

Composition of Fluids

1. D5W (5 g sugar/100 ml): 252 mOsm/L2. D10W (10 g sugar/100 ml): 505 mOsm/L3. NS (0.9% NaCl) 154 mEq Na/L: 308 mOsm/L4. 1/2 NS (0.45% NaCl): 77 mEq Na/L: 154 mOsm/L5. D5 1/4 NS (34 mEq Na/L): 329 mOsm/L6. 3% NaCl 513 mEq Na/L: 1027 mOsm/L7. 10% NaCl 1.7 mEq/cc8. 20% NaCl 3.4 mEq/cc9. 8.4% NaHCO3 (1 meq/cc Na & HCO3): 2000 mOsm/L

IV fluidsLactated Ringer’s

0-10 gram glucose/100ccNa 130 meq/LNaHCO3 28 meq/L as lactateK 4 meq/L273 mOsm/L

Amino acid 8.5 %8.5 gm protein/100 cc880 mOsm/L

Albumin 25% (salt poor)25 gm protein/100 ccNa 100-160 meq/L300 mOsm/L

Intralipid2.25 gm lipid/100cc 284 mOsm/L

Requirements of FLUID

Increased requirement : Fever Vomiting Renal failure Burn Shock Tachypnea Gastroenteritis Diabetes (Insipidus, mellitus - DKA) Cystic fibrosis

Decreased requirement CHF Postoperatively Oliguric ( RF )

Maintenance Fluid and Electrolyte Requirements

• Maintenance: The replacement of normal ongoing losses– Normally serum Na concentration is approximately 140 meq/l

and serum K concentration is approximately 4 meq/l– Maintenance solution replaces normal losses– Maintenance solution does not have an electrolyte

concentration equal to serum because the electrolyte composition of urine and stool is not equal to that of serum

• Maintenance fluids commonly provided as a 5% dextrose solution – Dextrose provides some energy and prevents hypoglycemia

• Spares protein– Cannot meet patient’s nutritional requirements with 5% (or

10%) dextrose

Maintenance Requirements are a Function of Caloric Requirements

• 0-10 kg: 100 kcal/kg• 10-20 kg: 50 kcal/kg• > 20kg:20 kcal/kg• Examples:

– 8 kg: 8 kg X 100 kcal/kg = 800 kcal.– 12 kg: 10 kg X 100 kcal/kg + 2 kg X 50 kcal/kg = 1000 kcal +

100 kcal = 1100 kcal– 20 kg: 10 kg X 100 kcal/kg + 10 kg X 50 kcal/kg = 1000 kcal

+ 500 kcal = 1500 kcal– 25 kg: 10 kg X 100 kcal/kg + 10 kg X 50 kcal/kg + 5 kg X 20

kcal/kg = 1000 kcal + 500 kcal + 100 kcal = 1600 kcal

Water and Electrolyte Requirements are Determined by Caloric Requirements

• Requirements per 100 kcal:– 100 ml water (provided as a 5% dextrose solution)– 2-4 meq Na– 2 meq K– 2 meq Cl

• Plasma: Anion is a balance of Cl and base (bicarbonate) – Maintenance solution: Can provide some anion as Cl and

some as base (lactate, citrate, phosphate) or can provide all of it as Cl

– But: Providing large volumes of fluid (e.g., in DKA or hypovolemic shock) with all of the anion as Cl will promote a hyperchloremic metabolic acidosis

Standard Maintenance Solution

• D5W with 20-40 meq/l Na Cl and 20 meq/l KCl (or KAcetate or KPhosphate) will work well as a maintenance solution in most pediatric patients– Can use D5 0.2% (or D5 0.3%) NaCl with 20 meq/l KCl (or

KAcetate or KPhosphate) as maintenance solution– Recent article advocated routine use of isotonic saline solution

for pediatric maintenance solution • Some disease states: Another solution might be appropriate

– E.g.: Sickle cell anemia patients may have a relatively high Na requirement due to high urinary Na losses

– 0.9% NaCl (without dextrose) in head trauma patients – K should be used with caution or omitted in patients with renal

insufficiency

Water and Electrolyte Requirements Based on Weight

• Water:– 0-10 kg: 100 ml/kg– 10-20 kg: 1000 ml plus 50 ml/kg– > 20 kg: 1500 ml plus 20 ml/kg

• Electrolytes:– Na: 2-3 meq/kg– K: 1-2 meq/kg

• Water requirement is the same as with the caloric-based system

• Electrolyte requirement is greater than with caloric-based system: Electrolyte requirement is a direct linear function of weight

Fluids and Electrolytes Principles– Total body water (TBW) = Intracellular fluid (ICF) +

Extracellular fluid (ECF)– ECF) = Intravascular fluid (in vessels : plasma, lymph -

IVF) + Interstitial fluid (between cells - IF)ECF ( intravascular, interstitial &trancelluler) Fluid % in child body ( 75%-80%) • Goals:

– Maintain appropriate ECF volume,– Maintain appropriate ECF and ICF osmolality and ionic

concentrations

Things to consider: Normal changes in TBW, ECF

• All babies are born with an excess of TBW, mainly ECF, which needs to be removed– Adults are 60% water (20% ECF, 40% ICF)– Term neonates are 75% water (40% ECF, 35% ICF) :

lose 5-10 % of weight in first week– Preterm neonates have more water (24 wks: 85%,

60% ECF, 25% ICF): lose 5-15% of weight in first week

Diagnostic Evaluation

1. Anamnesis, Physical, Lab assessment 2. Type of dehydration

Physical Assessment of FE status

– Skin/Mucosa: Altered skin turgor, sunken AF, dry mucosa, edema etc are not sensitive indicators in babies

– Cardiovascular: • Tachycardia too much (ECF excess in CHF) or

too little ECF (hypovolemia)• Delayed capillary refill low cardiac output• Hepatomegaly can occur with ECF excess• BP changes very late

– Urine output

Lab Assessment of FE status

– Serum electrolytes and plasma osmolarity– Urine electrolytes, specific gravity (not very useful if

the baby is on diuretics - lasix etc), FENa

– Blood urea, serum creatinine (values in the first few days reflect mom’s values, not baby’s)

– Acid Base (low pH and bicarb may indicate poor perfusion)

Type of Dehydration

1. Isotonic (affect ECF ,Na = 135meq /l)2. Hypotonic( loss in ECF 2 correct ICF, Na = less than

135meq/l )3. Hypertonic ( sever loss in ICF ,Na = more than 150meq/l

Physical Signs of Dehydration

Signs & sympt. MILD Moderate Severe

General Thirsty, allert, restless

Thirsty, irritable, or drowsy

Drowsy – limp, skin cold / sweaty

Radial pulse Normal rate Rapid, weak Rapid, feeble

Respiration Normal Deep Deep & rapid Anterior font. Normal Sunken Very sunken Skin turgor Pinch retracts

immediately Retracts slowly Poor

Eyes Normal Sunken Grossly sunken

Tears Present Absent Absent Mucous memb. Moist Dry Very dry Urine flow Normal Dark &

decreased Oliguria / anuria

Pediatric Fluid Therapy Pediatric Fluid Therapy PrinciplesPrinciples

I. Assess water deficit by:1. weight:weight loss (Kg) = water loss (L)

OR2. Estimation of water deficit by physical exam:

Mild moderate severeInfants < 5 % 5 - 10 % >10 %Older children < 3 % 3 - 6 %> 6 %

Pediatric Fluid Therapy Pediatric Fluid Therapy PrinciplesPrinciples

II. Maintenance H2O needs:

Weight in Kg H2O fluid needs

1-10 100cc /kg /day11-20 1000+50cc/kg/day> 20 1500 + 20cc/kg/day

Add 12 % for every 0C

Therapeutic management of fluid loss Oral rehydration therapy Parenteral fluid therapy Meet ongoing daily loss Replace previous deficit Replace ongoing abnormal losses

Correction of Dehydration1. Estimate Fluid Deficit (% :- Mild, Moderate, Severe). 2. Moderate to severe dehydration:

IV push 10-20 cc / Kg Normal saline, May repeat.Half deficit over 8 hours, and half over 16 hours.

3. Find Type of Dehydration (Isonatremic, Hyponatremic, Hypernatremic).

4. Give daily Maintenance.5. Give Deficit as follows: Half volume over 8 hours, half volume over 16 hours

(Exception: in Hypernatremic Dehydration, replace deficit over 48 hours).

Disturbance of F&E balance

1. Na 2. K 3. Ca( Na is the primary osmatic farce ) Serum OsmolalityDefined as the number of particles per liter.May be approximated by:

2(Na) + Glucose (mg/dl)/18 + BUN(mg/dl)/2.8Normal range: 275-295 mOsm/L

300-500 cc/M2/dayLess in patients on the ventillator

When administrating I.V fluid

Monitors the response of the fluids. Considering the fluid volume. Content of fluid. Patient clinical status.

1. Isotonic fluids:

-Have a total osmolality close to that of extra cellular fluids (ECF) and don't cause RBCs to shrink or swell.

- 3 L of isotonic solutions are needed to replace 1 L of blood, so pt should be carefully monitored for signs of fluid overload.

Examples of Isotonic fluids:D5W: has a serum osmolality of 252 mosm/L.

D5W s mainly used supply water and to correct an increased serum osmolality

NORMAL SALINE SOLUTION

NS (0.9% Sodium chloride with TO of 308NS osmolality is contributed by electrolytes- So the solution remains within ECF.- NS is used to treat ECF deficit.- Ringer's solutions: Contains Ca, K and NaCl

2. Hypotonic Fluids

- The purpose of hypotonic fluids is to replace cellular fluids, because it is hypotonic as compared with plasma.

- It also used to provide free water for excretion of body wastes.

- It may used to treat hypernatramia (hypotonic Na solutions).

Examples of hypotonic solutions: 0.45% Nacl Half-strength saline.

Complications of excessive use of hypotonic solutions include:

Intravascular fluid depletion. Decreased blood pressure. Cellular edema. Cell damage

3.Hypertonic Solutions

• Hypertonic solutions exert an osmotic pressure greater than that of ECF

• Examples• * High concentrations of dextrose such as 50%

dextrose in water are used to help meet caloric requirements.

• These hypertonic solutions must be administered into control veins so that they can be diluted by rapid blood flow.

• Saline solutions are also available in osmolar pressures greater than that of ECF and cause cells to shrink.

• If administered rapidly or in large quantities, they may cause an extra cellular volume excess and cause circulatory overload and dehydration.

*Management and Nsg Care for certain fluid and electrolyte balance disturbances

• 1-Water depletion- Provide replacement of fluid.-Determine and correct cause of water

depletion.- Measure intake and output.- Monitor V/S

• 2- Water Excess:- Limit fluid intake.- Administer diuretics.- Monitor V/S- Determine and treat cause.- Analyze laboratory electrolyte measurement

frequently

• 3- Hyponatremia - Determine and treat cause - Administer I.V fluids with appropriate saline

concentration • 4- Hypernatramia:- Determine and treat cause.Administer fluids as prescribed.- Measure intake and output.- Monitor lab. Data.

• 5- Hypokalemia:

- Determine and treat cause.- Monitor V/S and ECG.- Administer supplemental K. - Assess for adequate renal output before

administration.IV: administered slowly.Oral: after high K fluids and foods.

• 6- Hyperkalemia - Determine and treat cause.- Monitor V/S and ECG - Administer I.V fluids if prescribed.- Monitor serum potassium levels. 7- Hypocalcaemia: - Determine and treat cause. - Administer calcium supp. as prescribed and administered slowly.- Monitor serum calcium levels.- Monitor serum protein level• 8- Hypocalcaemia: - Determine and treat cause.- Monitor serum Ca levels.- Monitor ECG.

SODIUM • Na+ are very important for regulating blood and interstitial fluid pressures

as well as nerve and muscle cell conduction of electrical currents. Aldosterone causes retention of Na+.

a. HYPONATREMIA:-• Vomiting, diarrhea, sweating, and burns cause Na+ loss. Dehydration,

tachycardia and shock (see above) can result. Intake of plain water worsens the condition. Pedialyte is a better fluid to drink. Explain this.

b. HYPERNATREMIA • Severe water deprivation, salt retention or excessive sodium intake causes

this. Increased Na+ draws water outside of cells, resulting in tissue dehydration. Thirst, fatigue and coma result.

CHLORIDE

• Cl- anion is necessary for the making of HCl, hyper polarization of neurons, regulating proper acid levels, and balancing osmotic pressures between compartments.

CHLORIDE

• a. HYPOCHLOREMIA • Excessive vomiting causes chloride loss,

resulting in blood and tissue alkalosis, and a depressed respiration rate.

• b. HYPERCLOREMIA • Dehydration or chloride gain can result in

renal failure or acidosis (increases in Cl- are accompanied by increases in H+).

POTASSIUM

• K+ is important in the intracellular fluid. Aldosterone causes excretion of K+.

• a. HYPOKALEMIA • Caused by diarrhea, exhaustion phase of stress,

excessive aldosterone secretions in adrenal cortical hyperplasia and some diuretics. K+ loss from cells contributes to tissue dehydration and acidosis. Flattened T waves, bradycardia, muscle spasms, a lengthened P-R, and mental confusion can also result.

POTASSIUM

• b. HYPERKALEMIA • Caused by eating large amounts of "light salt"

(KCl), kidney failure, and decreased aldosterone secretions in Addison's Disease; resulting in elevated T waves and fibrillation of the heart. The movement of K+ into cells accompanies tissue alkalosis.

CALCIUM

• Calcium Ca++ cations are needed for bone, muscle contraction, and synaptic transmission.

CALCIUM

• a. HYPOCALCEMIA • Excessive calcitonin, inadequate PTH,

decreased Vita. D, or reduced Ca++ intake results in muscle cramps, and convulsions.

• b. HYPERCALCEMIA • Increased PTH, Vita. D or calcium intake can

cause kidney stones, bone spurs, and lethargy.

Child vs. Adult in medication administration

1. Water %2. Body service area 3. Type of food 4. Stomach acidity (infant much less than adult )5. Enzyme chains not maturity 6. Rate of break down of drug ( growth

&development rate )TPN replacement for chronic case

7. % of protein binding & fat distributions 8. Drug half life 9. Excretion10. Gastric empty time 11. Eating habits12. Exercise pattern 13.sexual development

Child vs. Adult in medication administration (2)

Steps to give medication

1. Identification the child 2. Oral medication ( infant…preschool …school

age)3. Teach the child how to swallowing ( liqide

need ½ hr ,Tablet (1/2-1hr)* Safe storage of medication* Determination of the correct dosage