Alterations in Fluid& Electrolyte Lecture 9

Introduction Fluid is dynamic state. Body fluid: is body water that has solutes dissolve on it. Some solutes are electrolyte. Electrolyte such as Na, K, Ca, CL and Mg.

Water may serve as: Medium of metabolic reaction with cells. Transporter for nutrients, waste products, and other substance. A lubricant. Shock absorber. Regulate and maintain body temperature.

General Concepts Intake = Output = Fluid Balance Sensible losses Urination Defecation Wound drainage Insensible losses Evaporation from skin Respiratory loss from lungs

Fluid Compartments Intracellular Extracellular 40% of body weight Two types Interstitial (between) Intravascular (inside) Transcellular: includes cerebrospinal fluid, pleural, peritoneal and synovial fluid.

Function of ICF & ECF: ICF: is vital organ to normal cell function, its contain solutes such as oxygen, electrolytes and glucose. It provides a medium in which metabolic process. ECF: it is the transport system that carries nutrients and waste product from the cell.

Composition of Fluids plasma interstitial intracellular Cations Na 140 146 12 K 4 4 150 Ca 5 3 10 Mg 2 1 7 Anions Cl 103 104 3 HCO 24 27 10 SO4 1 1 - HPO4 2 2 116 Protein 16 5 40

Pediatric Differences ECF/ICF ratio varies with age. Neonates and infants have proportionately larger ECF volume Infants: high daily fluid requirement with little fluid reserve; this makes the infant vulnerable to dehydration.

Excretion is via the urine, feces, lungs and skin Have greater daily fluid loss than older child More dependent upon adequate intake Greater about of skin surface (BSA), therefore greater insensible loss. Respiratory and metabolic rates are higher therefore, dehydrate more rapidly

FIGURE 23–2 The newborn and infant have a high percentage of body weight comprised of water, especially extracellular fluid, which is lost from the body easily. Note the small stomach size which limits ability to rehydrate quickly. Jane W. Ball and Ruth C. Bindler Child Health Nursing: Partnering with Children & Families © 2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Pediatric differences <2yr kidneys immature less able to conserve or excrete water and solutes effectively Infants have weaker transport system (ion, bicarbonate) greater risk for acid/base imbalances Difficulty regulating electrolyte such as Na, Ca

Fluid and Electrolyte Transport PASSIVE TRANSPORT SYSTEMS Diffusion Filtration Osmosis ACTIVE TRANSPORT SYSTEM Pumping Requires energy expenditure

1. Diffusion Molecules move across a biological membrane from an area of higher to an area of lower concentration Membrane types Permeable Semi-permeable

2. Filtration Movement of solute and solvent across a membrane caused by hydrostatic (water pushing) pressure Occurs at the capillary level If normal pressure gradient changes (as occurs with right-sided heart failure) edema results from “third spacing”

3. Osmosis Movement of solvent from an area of lower solute concentration to one of higher concentration Occurs through a semipermeable membrane using osmotic (water pulling) pressure

Sodium is the major determinant of serum osmolality. Solutes are substance dissolved in liquid. Solvent: is the component of solution that can dissolve in the solutes. Crystalloid: salts that dissolved readily in to true solution. Colloids: substance such as large protein molecules that do not dissolved in true solution. Sodium is the major determinant of serum osmolality.

4. Active Transport System Solutes can be moved against a concentration gradient Also called “pumping” Dependent on the presence of ATP

Regulation of ECF

Hormonal regulation

Fluid Volume Imbalances Dehydration: loss of ECF fluid and sodium. Caused by: vomiting, diarrhea, hemorrhage, burns, NG suction. Manifested by wt loss, poor skin turgor, dry mucous memb., V/S changes, sunken fontanel Fluid overload: excess ECF fluid and excess interstitial fluid volume with edema. Causes: fluid overload, CHF. Manifested by wt.gain, puffy face and extremities, enlarged liver.

Mild Dehydration: by history. Hard to detect because the child may be alert, have moist mucous membranes and normal skin turgor. Wt loss may be up to 5% of body weight. The infant might be irritable; the older child might be thirsty vital signs will probably be normal Capillary refill will most likely be normal Urine output may be normal or less

Moderate Dehydration dry mucous membranes; delayed cap refill >2 sec; Wt loss 6-9% of body weight irritable, lethargic, unable to play, restless decreased urinary output: <1ml/kg/hr; dark urine with SG > 1.015 (in child >2yr) Sunken fontanel HR increased, BP decreased. Postural vital signs

Severe Dehydration wt loss > 10% body weight lethargic/comatose rapid weak pulse with BP low or undetectable; RR variable and labored. dry mucous membranes/parched; sunken fontanel decr or absent urinary output. Cap refill >4sec

Types of Dehydration and Sodium Loss Sodium may be: Low High Or normal

1. Isotonic Dehydration or Isonatremic Dehydration Loss of sodium and water are in proportion Most of fluid lost is from extracellular component Serum sodium is normal (130-150mEq/L). Most practitioners consider below 135 and above 148 a more conservative parameter (138-148) Most common form of dehydration in young children from vomiting and diarrhea.

2. Hypotonic or Hyponatremic Dehydration Greater loss of sodium than water Serum sodium below normal Compensatory shift of fluids from extracellular to intracellular makes extracellular dehydration worse. Caused by severe and prolonged vomiting and diarrhea, burns, renal disease. Also by treatment of dehydration with IV fluids without electrolytes.

3. Hypertonic or Hypernatremic Dehydration Greater loss of water than sodium Serum sodium is elevated Compensatory shift from intracellular to extracellular which masks the severity of water loss (dehydration) delaying signs and symptoms until condition is quite serious. Caused by concentrated IV fluids or tube feedings.

Etiology of dehydration Vomiting and diarrhea, nasogastric suction and burn. Water loss = under the warmer. Accumulation of fluid in third space. Over use diuretics. Excessive exercise

Rotavirus Common viral form of diarrhea All ages but 3 mo-2yrs most common Fecal/oral route Virus remains active; 10 days on hard, dry surfaces 4 hrs on human hands 1 wk on wet areas

Rotavirus (cont.) Incubation period 1-3 days Symptoms: mild/mod fever, stomach ache, frequent watery stools (20/day) Treatment: prevention! Hand washing and isolation of the infected child. Fluid rehydration for diarrhea, advanced to bland diet for older children Breast milk for the infant who BF

Clinical Management for Dehydration Blood may be drawn to assess electrolytes, BUN and Creatinine levels an IV may be placed the same time Oral Rehydration Solution is the treatment of choice for mild-moderate dehydration 1-3 tsp of ORS every 10-15min to start (even if vomits some) 50ml/Kg/Hr is the goal for rehydration.

Why are drinks high in glucose avoided during rehydration? Simple sugars increases the osmotic effect in the intestine by pulling water into the colon, thereby increasing diarrhea and subsequent fluid/electrolyte loss Drinks high in glucose: apple juice, sodas, jello water.

Recommended foods during rehydration progression: starches, cooked fruits & vegetables, soups, yogurt, formula, breast milk. Recent research has shown no difference than return to normal diet with some attention to lactose containing foods, depending upon the child’s response.

IV Therapy Used for severe dehydration or in the child who will not/cannot tolerate ORS 24hr maintenance plus replacement given within first 6-8hr (in ER) to rapidly expand the intravascular space. Usually a normal saline bolus. slower IV rate for the remainder of the first 24hrs nurse records IV volume infused hourly

Calculation of intravenous fluid needs: maintenance For the 1st 10 Kg, replace at 100ml/Kg for the second 10 Kg, replace at 50ml/Kg for >20kg, replace at 20ml/Kg

Example of Maintenance Fluid Calculation Your patient is a 10 yr old weighing 35 Kg. You want to determine this patient’s 24hr maintenance fluid needs: for the first 10 Kg give 100ml/Kg = 1000ml for the second 10 Kg: 50ml/Kg = 500ml for the remaining 15 Kg (35-20Kg) , replace at 20 ml/Kg = 20 (15) = 300ml 1000 + 500+ 300= 1800ml/day.