Fluid & electrolytes cld part 1

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Fluid and Electrolyte including fluid volume disorders: dehydration, hypovolemia, hypervolemia, water intoxication

Text of Fluid & electrolytes cld part 1

  • 1.Fluid & electrolytesPrepared by:Maria Carmela L. Domocmat, RN, MSN

2. http://www.mayoclinic.com/images/image_popup/fn7_waterinbody.jpg 3. 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. 4. Factors affecting body fluids Age Gender Body fat 5. 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 6. Water, Electrolyte Of the 40 liters ofwater in the bodyof an averageadult male, abouttwo-thirds isintracellular, andone-third isextracellular 7. Fluid Compartments 8. 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 9. Fluid & ElecComposition 10. Electrolyte Composition of Body Fluids 11. ContinuousMixing of BodyFluids 12. Water intake and output 13. Water Balance 14. 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%) 15. intake output Oral fluids Solid foods Metabolism Others Parenteral fluids Enemas Irrigating fluids Urine Insensible fluid loss Perspiration Feces Vaporization from lungs Others Emesis Drainage from fistula 16. Water Balance urineproduction ismostimportant intheregulation ofwaterbalance 17. Water Intake and Output 18. Water output Urine (60%) and feces (4%) Insensible losses (28%), sweat (8%) Increases in plasma osmolality trigger thirst andrelease of antidiuretic hormone (ADH) 19. 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.. 20. 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).. 21. Regulation of Water Output Dehydration osmotic pressure increases inextracellular fluids osmoreceptors inhypothalamus stimulated hypothalamus signalsposterior pituitary to releaseADH urine output decreases Excess Water Intake osmotic pressure decreasesin extracellular fluids osmoreceptors stimulated inhypothalamus hypothalamus signalsposterior pituitary todecrease ADH output urine output increases 22. 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 12% Via baroreceptor input, angiotensin II, and otherstimuli 23. 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) 24. Regulationof WaterIntake:ThirstMechanism 25. REGULATORY PROCESSES OF FLUIDAND ELECTROLYTE BALANCE 26. 1. FILTRATION( SOLVENT FLOW) movement of water throughcells and blood vessels becauseof hydrostatic pressure, that isfrom greater amount ofpressure to membrane withlesser pressure. 27. 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. 28. CLINICAL FUNCTION ANDSIGNIFICANCE 29. 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. 30. 2. DIFFUSION (SOLUTE FLOW) 31. 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. 32. 2. DIFFUSION (SOLUTE FLOW) 33. 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. 34. 3.OSMOSIS (WATER FLOW) 35. 2. Tonicity determines the direction ofwater flow 36. 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). 37. 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. 38. CLINICAL SIGNIFICANCE ANDFUNCTION 39. Regulationof WaterIntake:ThirstMechanism 40. Movement of FluidsBetween Compartments Net movementsof fluids betweencompartmentsresult fromdifferences inhydrostatic andosmoticpressures 41. 4. ACTIVE TRANSPORTmovement of a solute across the cellmembrane with expenditure of energy(ATP) from high to low concentration or low tohigh concentration 42. 4. ACTIVE TRANSPORT 43. CLINICAL SIGNIFICANCECells use active transport tocontrol cell volume.All cells function best when theirinternal environments aremaintained separately fromthe changes occurring in theECF environment. 44. Hormonal regulation 45. FLUID AND ELECTROLYTE BALANCEHormones secreted by the adrenal cortex is eitherstimulated by decreased level of Na+ in ECF orincreased Na+ level in urine. 46. Hormones1. Aldosterone2. Antidiuretic hormone (ADH) or vasopressin3. Natriuretic peptides (NPs) 47. 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. 48. Aldosterone 49. 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. 50. 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 51. MechanismsandConsequencesof ADHRelease 52. 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 53. 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 54. Figure 26.10MechanismsandConsequencesof ANP Release 55. Pathway of RAAS 56. Disorders of Water Balance 57. Fluid ImbalancesDehydrationHypovolemiaHypervolemiaWater intoxication 58. 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 59. 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 60. Disorders of Water Balance:DehydrationExcessive loss of H2O fromECF1 2 3ECF osmoticpressure risesCells lose H2Oto ECF byosmosis; cellsshrink(a) Mechanism of dehydration 61. 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 s