Did you know?● The total amount of water in the body of anaverage adult is 37 litres.● Human brains are 75% water.● Human bones are 25% water.● Human blood is 83% water.
Factors affecting body fluids• Age• Gender• Body fat
FACTORS AFFECTING BODY FLUIDS1. AGE - Older adults have less water contentthan younger adults because of muscle mass lossand decreased ratio of lean body mass to totalbody weight.2. GENDER - Males have more water contentthan females because of increased stature andlean body mass. Females have more body fats.3. BODY FAT - contain little water
Water, Electrolyte• Of the 40 liters ofwater in the bodyof an averageadult male, abouttwo-thirds isintracellular, andone-third isextracellular
Composition of Body Fluids• Water is the universal solvent• Solutes are broadly classified into▫ Electrolytes inorganic salts, all acids and bases, some proteins▫ Nonelectrolytes glucose, lipids, creatinine, urea• Electrolytes have greater osmotic power thannonelectrolytes• Water moves according to osmotic gradients
Water Balance and ECF Osmolality• To remain properly hydrated, water intake mustequal water output• Water intake sources▫ Ingested fluid (60%) and solid food (30%)▫ Metabolic water or water of oxidation (10%)
• Water output▫ Urine (60%) and feces (4%)▫ Insensible losses (28%), sweat (8%)• Increases in plasma osmolality trigger thirst andrelease of antidiuretic hormone (ADH)
Regulation of Water Output1. KIDNEY• kidney excrete 1-2 L/day• Obligatory urine output/day = 400-600mLdepending on fluid intake• What if you have less than 400mL outputin 24hrs?▫ effect: retention of waste products▫ can lead to lethal electrolyte imbalances, acidosisand toxic buildup of nitrogen..
2. INSENSIBLE WATER LOSS• Water loss from skin, lungs and stool is 15-20mL/kg/day in healthy adult.• Excessive insensible water loss result in more hypertonicECF with smaller volume• If this loss is not balanced by intake, the hypertonic anddehydration can lead to hypernatremia (elevated serumlevel)..
Regulation of Water Intake• The hypothalamic thirst center is stimulated:• (increase in osmotic pressure of extracellular fluid stimulatesosmoreceptors in thirst center)▫ By a decline in plasma volume of 10%–15%▫ By increases in plasma osmolality of 1–2%▫ Via baroreceptor input, angiotensin II, and otherstimuli
Regulation of Water Intake• Thirst is quenched as soon as we begin to drinkwater• water is absorbed• osmotic pressure of extracellular fluid returns tonormal• Feedback signals that stimulate nerve impulses thatinhibit thirst center include:▫ Drinking - moistening of the mucosa of the mouth andthroat▫ distension of the stomach by water (activation ofstomach and intestinal stretch receptors)
REGULATORY PROCESSES OF FLUIDAND ELECTROLYTE BALANCE
1. FILTRATION( SOLVENT FLOW)• movement of water throughcells and blood vessels becauseof hydrostatic pressure, that isfrom greater amount ofpressure to membrane withlesser pressure.
CLINICAL FUNCTION ANDSIGNIFICANCEBlood pressure is a hydrostatic filtering force thatmoves whole blood from the heart to tissue areawhere exchange of water, nutrients and wasteproducts occur when blood arrives at the tissuecapillary.
2. DIFFUSION (SOLUTE FLOW)Solutes move or spread from areas of highconcentration to areas of low concentration untilthe particles are evenly distributed throughout aspace.If the membrane is impermeable to substance, itis "helped" across by carrier proteins - theprocesscalled facilitated diffusion.
CLINICAL SIGNIFICANCE• Diffusion is important in control and transport of gasesand in the movement of most electrolytes, atoms, andmolecules through cell membrane.• Unlike capillaries, cell membranes are selective.• They permit some substances while inhibit movement ofother substances.• Ex. Even though glucose is higher in ECF, it cannot passthrough the cell without the help of insulin.
3.OSMOSIS (WATER FLOW)The movement of water across cell membrane in thedirection where there is a high concentration of solute butlower concentration of water until both spaces containsame proportion of solutes and solvent.A simple rule to remember is: SALT SUCKSSalt is a solute. When it is concentrated inside or outside the cell, itwill suck the water in its direction.
2. Tonicity determines the direction ofwater flow
CLINICAL SIGNIFICANCE ANDFUNCTION• The thirst mechanism is how osmosis helps maintain balance.• When a person loses body water through sweats and most solutesremain in• ECF volume decreases that lead to increase osmolarity(soluteconcentration).
CLINICAL SIGNIFICANCE ANDFUNCTION• The cells in the thirst center shrinks as water moves to thehypertonic ECF(higher solute conc.) cells in the thirst center shrinksas water moves to the hypertonic ECF(higher solute conc.).• The shrinking of cells trigger a person to drink enough water torestore amount of water lost thorough sweats and therefore restoreECF normal fluid osmolarity(fluid volume.
CLINICAL SIGNIFICANCECells use active transport tocontrol cell volume.All cells function best when theirinternal environments aremaintained separately fromthe changes occurring in theECF environment.
a. Aldosterone• Protects Na+ balance by preventing Na+ loss.• Because Na+ exerts osmotic (water pulling)pressure, water attempts to follow Na+ inproportionate amount. As a result this Na+ -water relationship and aldosterone secretionhelps regulate water balance.
b. Anti-diuretic hormone• vasopressin• In an increased blood Na+ level( increasedosmolarity) result in shrinkage of cell andtriggers ADH release from posterior pituitarygland. ADH acts on kidney tubules andcollecting ducts making them more permeable towater. As a result more water is reabsorbed andreturned to the blood making it more dilute.
Influence and Regulation of ADH• Water reabsorption in collecting ducts isproportional to ADH release• Low ADH levels produce dilute urine and reducedvolume of body fluids• High ADH levels produce concentrated urine• Hypothalamic osmoreceptors trigger or inhibit ADHrelease• Factors that specifically trigger ADH release includeprolonged fever; excessive sweating, vomiting, ordiarrhea; severe blood loss; and traumatic burns
c. Lymph• extra fluid that leaks from the capillaries.• It is returned from the systemic circulation bylymph vessels to prevent blood volume deficitsand edema in the interstitial spaces
d. Natriuretic peptides• hormones secreted by special cells that line thehearts atria and ventricles in response to increasedblood volume and pressure, which stretch the hearttissue.• NP binds to the receptor sites in the nephrons,creating effects that oppose renin-angiotensinsystem.• When either ANP or BNP is secreted, kidneyreabsorption of Na+ is inhibited.• The outcome is increased urine output with highNa+ content which result in decreased circulatingvolume and decreased blood osmolarity
Disorders of Water Balance:Dehydration• Water loss exceeds water intake and the body isin negative fluid balance• Causes include:▫ hemorrhage, severe burns, prolonged vomiting ordiarrhea, profuse sweating, water deprivation, anddiuretic abuse
Disorders of Water Balance:Dehydration• Signs and symptoms:▫ cottonmouth, thirst, dry flushed skin, and oliguria• Prolonged dehydration may lead to weight loss,fever, and mental confusion• Other consequences include hypovolemic shockand loss of electrolytes
Disorders of Water Balance:DehydrationExcessive loss of H2O fromECF1 2 3ECF osmoticpressure risesCells lose H2Oto ECF byosmosis; cellsshrink(a) Mechanism of dehydration
• Renal insufficiency or an extraordinary amountof water ingested quickly can lead to cellularoverhydration, or water intoxication• ECF is diluted – sodium content is normal butexcess water is present• The resulting hyponatremia promotes netosmosis into tissue cells, causing swelling• These events must be quickly reversed toprevent severe metabolic disturbances,particularly in neuronsDisorders of Water Balance:Hypotonic Hydration
Figure 26.7bDisorders of Water Balance:Hypotonic HydrationExcessive H2O entersthe ECF1 2 ECF osmoticpressure falls3 H2O moves intocells by osmosis;cells swell(b) Mechanism of hypotonic hydration
Clinical Correlates of DehydrationSeverity Fluid Deficit in mL/kg(percent body wt)*SignsInfants AdolescentsMild 50 (5%) 30 (3%) Slightly dry buccal mucousmembranes, increased thirst, slightlydecreased urine outputModerate 100 (10%) 50–60 (5–6%) Dry buccal mucous membranes,tachycardia, little or no urine output,lethargy, sunken eyes and fontanelles,loss of skin turgorSevere 150 (15%) 70–90 (7–9%) Same as moderate plus a rapid, threadypulse; no tears; cyanosis; rapidbreathing; delayed capillary refill;hypotension; mottled skin; coma*Standard estimates for children between infancy and adolescence have not been established. For children between these ageranges, clinicians must estimate values between those for infants and those for adolescents based on clinical judgment.
Dehydration• Loss of body fluids increasedconcentration of solutes in the blood and arise in serum Na+ levels• Fluid shifts out of cells into the blood torestore balance• Cells shrink from fluid loss and can no longerfunction properly
Clients at Risk•Confused•Comatose•Bedridden•Infants•Elderly•Enterally fed
What Do You See?• Irritability• Confusion• Dizziness• Weakness• Extreme thirst• urine output• Fever• Dryskin/mucousmembranes• Sunken eyes• Poor skin turgor• Tachycardia
Management• Fluid restoration▫ Oral rehydration▫ IV rehydration• Correction of underlyingproblem▫ Antiemetic▫ Antidiarrheal▫ Antibiotics▫ Antipyretics• Fluid Replacement - oral or IVover 48 hrs.• Monitor symptoms and vitalsigns• Maintain I&O• Maintain IV access• Daily weights• Skin and mouth care
Composition of Appropriate OralRehydration SolutionsSolutionCarbo-hydrate(g/dL)Sodium(mEq/L)Potassium(mEq/L)Base(mEq/L)Osmo-lalityPedialyte 2.5 45 20 30 250Infalyte 3 50 25 30 200Rehydralyte 2.5 75 20 30 310WHO/UNICEF* 2 90 20 30 310* World Health Organization/United Nations Childrens Fund
Composition of Inappropriate OralRehydration SolutionsSolutionCarbohydrate (g/dL)Sodium(mEq/L)Potassium(mEq/L)Base(mEq/L)OsmolalityApple juice 12 0.4 26 0 700Ginger ale 9 3.5 0.1 3.6 565Milk 4.9 22 36 30 260Chickenbroth0 2 3 3 330
Hypovolemia• Isotonic fluid lossfrom theextracellularspace• Can progress tohypovolemicshock• Caused by:▫ Excessive fluidloss(hemorrhage)▫ Decreased fluidintake▫ Third spacefluid shifting
What Do You See?• Mental statusdeterioration• Thirst• Tachycardia• Delayed capillaryrefill• Orthostatichypotension• Urine output < 30ml/hr• Cool, paleextremities• Weight loss
What Do We Do?• Fluid replacement• Albuminreplacement• Blood transfusionsfor hemorrhage• Dopamine tomaintain BP• MAST trousersfor severe shock• Assess for fluidoverload withtreatment
Hypervolemia• Excess fluid in the extracellular compartmentas a result of fluid or sodium retention,excessive intake, or renal failure• Occurs when compensatory mechanisms failto restore fluid balance• Leads to CHF and pulmonary edema
What Do You See?• Tachypnea• Dyspnea• Crackles• Rapid, bounding pulse• Hypertension• S3 gallop• Increased CVP,pulmonary arterypressure and pulmonaryartery wedge pressure(Swan-Ganz)• JVD• Acute weight gain• Edema
Edema• Fluid is forced into tissues by the hydrostaticpressure• First seen in dependent areas• Anasarca - severe generalized edema• Pitting edema• Pulmonary edema
Disorders of Water Balance: Edema• Atypical accumulation of fluid in the interstitialspace, leading to tissue swelling• Caused by anything that increases flow of fluidsout of the bloodstream or hinders their return• Factors that accelerate fluid loss include:▫ Increased blood pressure, capillary permeability▫ Incompetent venous valves, localized blood vesselblockage▫ Congestive heart failure, hypertension, high bloodvolume
Edema• Hindered fluid return usually reflects animbalance in colloid osmotic pressures• Hypoproteinemia – low levels of plasmaproteins▫ Forces fluids out of capillary beds at the arterialends▫ Fluids fail to return at the venous ends▫ Results from protein malnutrition, liver disease,or glomerulonephritis
Edema• Blocked (or surgically removed) lymph vessels:▫ Cause leaked proteins to accumulate in interstitialfluid▫ Exert increasing colloid osmotic pressure, whichdraws fluid from the blood• Interstitial fluid accumulation results in lowblood pressure and severely impaired circulation
Management• Restriction of Sodium andfluids• Monitor vital signs• Hourly I&O• Breath sounds• Monitor ABGs and labs• Elevate HOB and give O2 asordered• Maintain IV access• Skin & mouth care• Daily weights• Promote urine output▫ Diuretics▫ ACE inhibitors, ARBs(angiotensin II receptorblockers), low-dose beta-blockers, aldactoneantagonists
Water Intoxication• Hypotonicextracellular fluidshifts into cells toattempt to restorebalance• Cells swell
Water Intoxication• Causes:▫ SIADH▫ Rapid infusion of hypotonic solution▫ Excessive tap water NG irrigation or enemas▫ Psychogenic polydipsia
What Do You See?• Signs and symptoms of increased intracranialpressure▫ Early: change in LOC, N/V, muscle weakness,twitching, cramping▫ Late: bradycardia, widened pulse pressure,seizures, coma
What Do We Do?• Prevention is the besttreatment• Assess neuro status• Monitor I&O and vital signs• Fluid restrictions• IV access• Daily weights• Monitor serum Na+• Seizure precautions
1. History data – Gordon’s Functional HealthPatterna. INTAKE AND OUTPUTexact intake and output volume.amount of fluids and foods ingestedto determine amount of osmolarity.b. MEDICATIONScheck laxatives, diuretics with dosage and the length oftime taken and adherence with drug regimen. Misuseand over use of thesedrugs can lead to serious imbalance.
c. WEIGHTdaily weight measurement and body weight changes,thirst or excessive drinking, exposure to hotenvironments, and presence of disorders such as kidneyand endocrine diseases.(DM, Addisons disease,Cushings and diabetic insipidus).d. Level of consciousnessawareness of time, place and person. confusionassociated with electrolyte imbalance.
PHYSICAL ASSESSMENTa. Hydrationalert, moist eyes and mucous membranes.b. Urine output nearly the same with amountingested with urine specific gravity of 1.015.
c. Good skin turgorPinch a fold of skin in areas that have little fattissue such as over the sternum, forehead orback of hand. Folded skin should returnimmediately to its original shape. Decreasedturgor is a sign of dehydration when the foldslowly rebounds. (tenting) Older person is hardto assess because of loss of skin elasticity relatedto aging.• Check for dryness of skin including nose, eyes,conjunctiva and mucous membranes. A dry,sticky, cottony mouth, the absence of tears,weight loss and decreased urine output allindicate decreased fluid volume.
d. NEUROLOGIC AND BEHAVIORALASSESSMENTIn hypertonic states, neuron shrinkage mayinduce nervous excitability, hyperactivity andconvulsions, coma and death.Muscle tone and strength, movement,coordination and tremorse. CARDIAC SYSTEMHeart rate, strength of contractions and presence ofdysrhythmias
f. GASTROINTESTINAL SYSTEMPeristalsis may indicate changes of excitable membranefunction. Decreased or increased motilityg. INSENSIBLE WATER LOSSFluid loss from wounds, gastric or intestinal drainage,hemorrhage and other body secretions.
h. Previous FindingsMental status, physical exam, and laboratorydata. Fluid and electrolyte imbalance can occurquickly, be familiar with the patients baselineassessment data to detect changes.
3. PSYCHOSOCIAL ASSESSMENTDepressed clients may refuse fluids.Clients with bulimia or anorexia nervosa mayabuse laxatives or may induce vomiting.Alcohol or drug abuse