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Fluids and Electrolytes

Fluids and Electrolytes. Ahmed Mayet, Pharm.D., BCPS Associate Professor KSU. Learning Objectives. Total Body Fluid Intravascular Volume Depletion Fluid resuscitation vs. Maintenance IV Fluid Osmolarity of IV Fluids Hyponatremia Hypernatremia Hypokalemia Hyperkalemia Hypomagnesemia

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Fluids and Electrolytes

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  1. Fluids and Electrolytes Ahmed Mayet, Pharm.D., BCPS Associate Professor KSU

  2. Learning Objectives • Total Body Fluid • Intravascular Volume Depletion • Fluid resuscitation vs. Maintenance IV Fluid • Osmolarity of IV Fluids • Hyponatremia • Hypernatremia • Hypokalemia • Hyperkalemia • Hypomagnesemia • Hpermagmesemia

  3. Hypophosphatemia • Hyperphosphatemia • Hypocalcemia • Hypercalcermia

  4. Fluids • Body weight of • adult male 55-60% • Female 50-55% • Newborn 75-80% • Very little in adipose tissues • Loss of 20% - fatal • Elderly - decreases to 45-50% of body weight • Decreased muscle mass, smaller fat stores, and decrease in body fluids

  5. Body Fluid Compartments: ICF: 28L 2/3 TBW Extravascular Interstitial Fluid 8.4L 3/4 1/3 ECF Intravascular plasma 5.6L 1/4

  6. Compartments • Intracellular (ICF) • Fluid within the cells themselves • 2/3 of body fluid • Located primarily in skeletal muscle mass • High in K, Po4, protein • Moderate levels of Mg

  7. Compartments • Extracellular (ECF) • 1/3 of body fluid • Comprised of 3 major components • Intravascular • Plasma • Interstitial • Fluid in and around tissues • Transcellular • Over or across the cells

  8. Compartments • Extracellular • Nutrients for cell functioning • Na • Ca • Cl • Glucose • Fatty acids • Amino Acids

  9. Compartments • Intravascular Component • Plasma • fluid portion of blood • Made of: • water • plasma proteins • small amount of other substances

  10. Compartments • Interstitial component • Made up of fluid between cells • Surrounds cells • Transport medium for nutrients, gases, waste products and other substances between blood and body cells • Back-up fluid reservoir

  11. Compartments • Transcellular component • 1% of ECF • Located in joints, connective tissue, bones, body cavities, CSF, and other tissues • Potential to increase significantly in abnormal conditions

  12. Body Fluid Compartments: ICF: 28L • Male 60% of LBW is fluid • female 50% of LBW is fluid • 70 kg male • BW x 0.6 = TBW • 70kg x 0.6 = 42 L • ICF= 2/3 x 42 = 28L • ECF= 1/3 x 42 = 14L • ECF • 1/4 is intravascular plasma • 1/4 x 14 = 5.6L • 3/4 is interstitial • 3/4 x 14 = 8.4L 2/3 TBW Extravascular Interstitial Fluid 8.4L 3/4 1/3 ECF Intravascular plasma 5.6L 1/4

  13. Water Steady State • Amount Ingested = Amount Eliminated • Pathological losses • vascular bleeding (H20, Na+) • vomiting (H20, H+) • diarrhea (H20, HCO3-).

  14. Fluid Requirement • The average adult requires approximately 35-45 ml/kg/d • NRC* recommends 1 to 2 ml of water for each kcal of energy expenditure *NRC= National research council

  15. Fluid Requirement • 1st 10 kilogram 100 cc/kg • 2nd 10 kilogram 50 cc/kg • Rest of the weight 20 to 30 cc/kg Example: 50 kg patient 1st 10 kg x 100cc = 1000 cc 2nd 10 kg x 50cc = 500cc Rest 30 kg x 30cc = 900cc total = 2400 cc

  16. Fluid • Fluid needs are altered by the patient's functional cardiac, hepatic, pulmonary, and renal status • Fluid needs increase with fever, diarrhea, hemorrhage, surgical drains, and loss of skin integrity like burns, open wounds

  17. Regulation of Fluids: Response to Decreased volume and Blood pressure

  18. Regulation of Fluids: Response to increased volume and Blood pressure

  19. Hypovolemia

  20. Causes of Hypovolemia • Hypovolemia • Abnormally low volume of body fluid in intravascular and/or interstitial compartments • Causes • Vomiting • Diarrhea • Excess sweating • Diabetes insipidus • Uncontrolled diabetes mellitus

  21. Other Causes of Water Loss • Fever • Burns • N-G Suction • Fistulas • Wound drainage

  22. Signs and Symptoms • Acute weight loss • Decreased skin turgor • Concentrated urine • Weak, rapid pulse • Increased capillary filling time • Sensations of thirst, weakness, dizziness, muscle cramps

  23. Signs of Hypovolemia: • Diminished skin turgor • Dry oral mucus membrane • Oliguria - <500ml/day - normal: 0.5~1ml/kg/h • Tachycardia (100 beats/min) • Hypotension (SBP < 90 mm Hg) • Hypoperfusion  cyanosis • Altered mental status

  24. Clinical Diagnosis of Hypovolemia: • Thorough history taking: poor intake, GI bleeding…etc • BUN : Creatinine > 20 : 1 • Increased specific gravity • Increased hematocrit • Electrolytes imbalance • Acid-base disorder

  25. Labs • Increased HCT • Increased BUN out of proportion to Cr • High serum osmolality • Increased urine osmolality • Increased specific gravity • Decreased urine volume, dark color

  26. Complications • Reduced cardiac function, organ hypo perfusion and multi-organ failure, renal failure, shock and death.

  27. Fluid Replacement • Crystalloids Normal saline (0.9% NaCl) Dextrose 5% • Colloids Albumin 5%, 25% Hetastarch

  28. Parenteral Fluid Therapy: • Crystalloids: (0.9% NaCl) Contain Na, and Cl as the main osmotically active particle do not freely cross into cells but they will distribute evenly in the EC ( IV + IT) • Crystalloids: (D5W) D5W - H2O + CO2 Water will distribute in TBW

  29. Body Fluid Compartments: ICF: 28L If 1 liter of NS is given, only 250 ml will stay in intravascular. 1000ml x 1/4 = 250 ml (Intravascular) 1000ml x 3/4 = 750 ml (Interstitial) 2/3 TBW Extravascular Interstitial Fluid 8.4L If 1 liter of D5W is given, only about 100 ml will stay in intravascular. 1000ml x 2/3 = 667ml (ICF) 1000ml x 1/3 = 333 ml (ECF) 333 ml x 1/4 = 83 ml (IV) 333 ml x 3/4 = 250 ml (IT) 3/4 1/3 ECF Intravascular plasma 5.6L 1/4

  30. Crystalloids: • Isotonic crystalloids - Lactated Ringer’s, 0.9% NaCl - only 25% remain intravascularly • Hypotonic solutions - D5W - less than 10% remain intra- vascularly, inadequate for fluid resuscitation

  31. Colloid Solutions: • Contain high molecular weight substances too large to cross capillary walls • Preparations - Albumin: 5%, 25% - Dextran - Hetastrach

  32. Body Fluid Compartments: ICF: 28L If 1 liter of 5% albumin is given, all will stay in intravascular because of its large molecule that will not cross cell membrance. 1000ml x 1 = 1000 ml 2/3 TBW Extravascular Interstitial Fluid 8.4L If 100 ml of 25% albumin is given, it will draw 5 times of its volume in to intravascular compartment. 100ml x 5 = 500 ml 3/4 1/3 ECF Intravascular plasma 5.6L 1/4

  33. The Influence of Colloid & Crystalloid on Blood Volume: Blood volume Infusion volume 200 600 1000 1000cc NS or Lactated Ringers 500cc 5% Albumin 500cc 6% Hetastarch 100cc 25% Albumin

  34. Fluid Resuscitation • Calculate the fluid deficit base on serum sodium level (assume patient Na is 120 mmole/l and patient weight is 70 kg) Fluid deficit = BW x 0.5 ( Avg Na – pt Na ) Na avg = 70 x 0.5 ( 140 – 120) 140 = 5 L

  35. Fluid Resuscitation • Calculate the fluid deficit base on patient actual weight if you know the patient weight before the dehydration then simply subtract patient current weight from patient previous weight Pt wt before dehydration – pt current wt Exp if pt weight was 70 kg before and now pt weight 65 kg then 70 kg – 65 kg = 5 kg equal to 5 L of water loss (s.g for water is 1)

  36. Fluid Resuscitation • Use crystalloids (NS or Lactate Ranger) • Colloids is not superior to crystalloids • Administer 500-1000 ml/hr bolus(30-60 mins) and then 250-500 ml/hr for 6 to 8 hours and rest of the fluid within 24 hours • Maintain IV fluid (D5 ½ NS) until vital signs are normalized and patient is able to take adequate oral fluid

  37. Regulation of Fluids in Compartments • Osmosis • Movement of water through a selectively permeable membrane from an area of low solute concentration to a higher concentration until equilibrium occurs • Movement occurs until near equal concentration found • Passive process

  38. Regulation of Fluids • Diffusion • Movement of solutes from an area of higher concentration to an area of lower concentration in a solution and/or across a permeable membrane (permeable for that solute) • Movement occurs until near equal state • Passive process

  39. Osmosis versus Diffusion • Osmosis • Low to high • Water potential • Diffusion • High to low • Movement of particles • Both can occur at the same time

  40. Regulation of Fluids • Active Transport • Allows molecules to move against concentration and osmotic pressure to areas of higher concentration • Active process – energy is expended

  41. Active Transport • Na / K pump • Exchange of Na ions for K ions • More Na ions move out of cell • More water pulled into cell • ECF / ICF balance is maintained

  42. Active Transport • Insulin and glucose regulation • CHO consumed • Blood glucose peaks • Pancreas secretes insulin • Blood glucose returns to normal

  43. Osmolarity • Concentration of body fluids – affects movement of fluid by osmosis • Reflects hydration status • Measured by serum and urine • Solutes measured - mainly urea, glucose, and sodium • Measured as solute concentration/L

  44. Osmolarity • Serum Osm/L = (serum Na x 2) + BUN/3 + Glucose/18 • Serum Osm/L = (serum Na x 2) + BUN + Glucose • Normal serum value - 280-300 mOsm/L • Serum <240 or >320 is critically abnormal • Normal urine Osm – 250 – 900 mOsm / L

  45. Factors that affect Osmolarity • Serum • Increasing Osm • Free water loss • Diabetes Insipidus • Na overload • Hyperglycemia • Uremia

  46. Factors that affect Osmolarity • Serum • Decreasing Osm • SIADH • Renal failure • Diuretic use • Adrenal insufficiency

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