Amjad Bani Hani Ass.Prof. of Cardiac Surgery & Intensive Care FLUIDS AND ELECTROLYTES

Transcription

1 Amjad Bani Hani Ass.Prof. of Cardiac Surgery & Intensive Care FLUIDS AND ELECTROLYTES

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3 Body Water Content

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15 Water Balance: Normal Metab Food Fluids Stool Breath Sweat Urine 0 Output Intake

16 Water Output: Normal vs.exercise Stool Breath Sweat Urine Normal Exercise

17 Water Intake: Normal vs Exercise Metab Food Fluids Normal Exercise

18 Electrolytes

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20 Electrolytes Solutes that form ions (electrical charge) Cation (+) Anion (-) Major body electrolytes: Na+, K+, Ca++, Mg++ Cl-, HCO 3 -, HPO 4 --, SO 4 -

21 Electrolyte Distribution Major ICF ions K+ HPO 4 -- Major ECF ions Na+ CL-, HCO 3 - Intravascular (IVF) vs Interstitial (ISF) Similar electrolytes, but IVF has proteins

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23 Mechanisms Controlling Fluid and Electrolyte Movement Diffusion Selective Permeability Facilitated diffusion Active transport Osmosis 2*Na + BUN + Glucose/18 Hydrostatic pressure Oncotic pressure

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27 Cells are selectively permeable

28 Sodium is the largest Determinant of Osmolality Na+: meq/l Ca+: meq/l K+: meq/l Osmolality~ 2*(Na+) = 2*( meq/l) Normal (Isotonic) Low (hypotonic) < 280 High (hypertonic) > 300

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30 Fluid Exchange Between Capillary and Tissue: Sum of Pressures Fig. 17-8

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33 Fluid compartments ICF Interstitial ECF

34 Fluid compartments ICF Interstitial ECF

35 Fluid compartments Capillary Membrane ICF Interstitial ECF

36 Fluid compartments Capillary Membrane ICF Interstitial ECF

37 Fluid compartments Capillary Membrane Cell Membrane ICF Interstitial ECF

38 Colloid osmotic pressure Capillary Membrane Capillary membrane freely permeable to water and electrolytes but not to large molecules such as proteins (albumin). Interstitial ECF

39 Colloid osmotic pressure Capillary Membrane Capillary membrane freely permeable to water and electrolytes but not to large molecules such as proteins (albumin). Interstitial ECF

40 Colloid osmotic pressure Capillary Membrane H 2 O Capillary membrane freely permeable to water and electrolytes but not to large molecules such as proteins (albumin). The albumin on the plasma side gives rise to a colloid osmotic pressure gradient favouring movement of water into the plasma Interstitial H 2 O ECF

41 Colloid osmotic pressure Capillary Membrane H 2 O H 2 O Interstitial Capillary membrane freely permeable to water and electrolytes but not to large molecules such as proteins (albumin). The albumin on the plasma side gives rise to a colloid osmotic pressure gradient favouring movement of water into the plasma This is balanced out by the hydrostatic pressure difference 120/80 H 2 O H 2 O ECF

42 Cell Membrane Cell Membrane H 2 O Interstitial H 2 O ICF Cell membrane is freely permeable to H 2 0 but

43 Cell Membrane Cell Membrane H 2 O Interstitial K + H 2 O Na + ICF Cell membrane is freely permeable to H 2 0 but Na and K are pumped across this membrane to maintain a gradient!

44 Cell Membrane Cell Membrane H 2 O Interstitial K + H 2 O Na - ICF [K + ] =4 Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

45 Cell Membrane Cell Membrane H 2 O Interstitial K + H 2 O Na - ICF [K + ] =4 [K + ] =150 Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

46 Cell Membrane Cell Membrane Na + = 144 Interstitial Na - K + H 2 O H 2 O ICF [K + ] =4 [K + ] =150 Cell membrane is freely permeable to H20 but Na and K are pumped across this membrane to maintain a gradient!

47 Cell Membrane Cell Membrane Na + = 144 Na - K + H 2 O Na + = 10 H 2 O Interstitial ICF [K + ] =4 [K + ] =150 Cell membrane is freely permeable to H 2 0 but Na and K are pumped across this membrane to maintain a gradient!

48 Hypernatremia Manifestations Thirst, lethargy, agitation, seizures, and coma Impaired LOC Produced by clinical states Central or nephrogenic diabetes insipidus Reduce levels gradually to avoid cerebral edema

49 Hyponatremia Results from loss of sodium-containing fluids Sweat, diarrhea, emesis, etc. Or from water excess Inefficient kidneys Drowning, excessive intake Manifestations Confusion, nausea, vomiting, seizures, and coma

50 Hyperkalemia High serum potassium caused by Massive intake Impaired renal excretion ( acidosis ) Shift from ICF to ECF Drugs Common in massive cell destruction Burn, crush injury, or tumor lysis False High: hemolysis of sample

51 Hyperkalemia Manifestations Weak or paralyzed skeletal muscles Ventricular fibrillation or cardiac standstill Abdominal cramping or diarrhea

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53 Hypokalemia Low serum potassium caused by Abnormal losses of K + via the kidneys or gastrointestinal tract Magnesium deficiency Metabolic alkalosis

54 Hypokalemia Manifestations Most serious are cardiac Skeletal muscle weakness Weakness of respiratory muscles Decreased gastrointestinal motility

55 Calcium Obtained from ingested foods More than 99% combined with phosphorus and concentrated in skeletal system Inverse relationship with phosphorus Otherwise

56 Calcium Bones are readily available store Blocks sodium transport and stabilizes cell membrane Ionized form is biologically active Bound to albumin in blood Bound to phosphate in bone/teeth Calcified deposits

57 Calcium Functions Transmission of nerve impulses Myocardial contractions Blood clotting Formation of teeth and bone Muscle contractions

58 Calcium Balance controlled by Parathyroid hormone Calcitonin Vitamin D/Intake Bone used as reservoir

59 Hypercalcemia High serum calcium levels caused by ( cases Hyperparathyroidism (two thirds of ( tumor Malignancy (parathyroid Vitamin D overdose Prolonged immobilization

60 Hypercalcemia Manifestations Decreased memory Confusion Disorientation Fatigue Constipation

61 Hypocalcemia Low serum Ca levels caused by Decreased production of PTH Acute pancreatitis Multiple blood transfusions Alkalosis Decreased intake

62 Hypocalcemia Manifestations Weakness/Tetany Positive Trousseau s or Chvostek s sign Laryngeal stridor Dysphagia Tingling around the mouth or in the extremities

63 IV Fluids Purposes 1. Maintenance When oral intake is not adequate 2. Replacement When losses have occurred

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65 Kinds of IV Fluid solutions Hypotonic - 1/2NS Isotonic - NS, LR, albumen Hypertonic Hypertonic saline. Crystalloid Colloid

66 Hypotonic D5W (0.45%) NS NS ½ ½ Crystalloids Isotonic (0.9%) NS Lactated Ringer IV Fluids Hypertonic Albumin Plasmalyte 3% Saline D5W in ½ NS Colloids Dextran FFP D10W PRBCs

67 D5W (Dextrose = Glucose) Hypotonic Provides 170 cal/l Free water Moves into ICF Increases renal solute excretion Used to replace water losses and treat hyponatremia Does not provide electrolytes

68 ( NS ) Normal Saline Isotonic No calories More NaCl than ECF 30% stays in IVF 70% moves out of IV space

69 ( NS ) Normal Saline Expands IV volume Preferred fluid for immediate response Risk for fluid overload higher Does not change ICF volume Blood products Compatible with most medications

70 Lactated Ringer s Isotonic More similar to plasma than NS Has less NaCl Has K, Ca, PO 43, lactate (metabolized to HCO 3 ) CONTRAINDICATED in lactic acidosis Expands ECF

71 Plasma Expanders Stay in vascular space and increase osmotic pressure ( solutions Colloids (protein Packed RBCs Albumin Plasma Dextran

72 THANK YOU