4Electrolytes Solutes that form ions (electrical charge) Cation (+)Anion (-)Major body electrolytes:Na+, K+, Ca++, Mg++Cl-, HCO3-, HPO4--, SO4-
5Fluid & Electrolytes Fluid: Water Electrolytes: ions dissolved in waterSodium, potassium, bicarbonate, etc.Also used medically for non ions (glucose)Osmolarity – osmols/kg solventOsmolality – osmols/liter solutionIn clinical practice are used interchangeably
6Electrolyte Distribution Major ICF ionsK+HPO4--Major ECF ionsNA+CL-, HCO3-Intravascular (IVF) vs Interstitial (ISF)Similar electrolytes, but IVF has proteins
7Mechanisms Controlling Fluid and Electrolyte Movement DiffusionSelective PermeabilityFacilitated diffusionActive transportOsmosis2*Na + BUN + Glucose/18Hydrostatic pressureOncotic pressure
12Sodium is the largest Determinant of Osmolality Na+: 135 – 145 mEq/LCa+: 8.5 – 10.5 mEq/LK+: 3.5 – 5 mEq/LOsmolality~ 2*(Na+) = 2*( mEq/L)Normal (Isotonic) 280 – 300Low (hypotonic) < 280High (hypertonic) > 300
13Fluid Exchange Between Capillary and Tissue: Sum of Pressures Fig. 17-8
14Fluid Shifts Plasma to interstitial fluid shift results in edema Elevation of hydrostatic pressureDecrease in plasma oncotic pressureElevation of interstitial oncotic pressure
15Fluid Movement between ECF and ICF Water deficit (increased ECF)Associated with symptoms that result from cell shrinkage as water is pulled into vascular systemWater excess (decreased ECF)Develops from gain or retention of excess water
16Fluid SpacingFirst spacing: Normal distribution of fluid in ICF and ECFSecond spacing: Abnormal accumulation of interstitial fluid (edema)Third spacing: Fluid accumulation in part of body where it is not easily exchanged with ECF (e.g. ascites)
17Regulation of Water Balance Hypothalamic regulationPituitary regulationAdrenal cortical regulationRenal regulationCardiac regulationGastrointestinal regulationInsensible water loss
28Electrolyte Disorders Signs and Symptoms HypomagnesemiaHyperactive DTRsCNS changesHypermagnesemiaLoss of deep tendon reflexes (DTRs)Depression of CNSDepression of neuromuscular functionMagnesium (Mg)HypocalcemiaTetanyChvostek’s, Trousseau’s signsMuscle twitchingECG changesHypercalcemiaThirstCNS deteriorationIncreased interstitial fluidCalcium (Ca)DeficitExcessElectrolyte
29Hypernatremia Manifestations Impaired LOC Produced by clinical states Thirst, lethargy, agitation, seizures, and comaImpaired LOCProduced by clinical statesCentral or nephrogenic diabetes insipidusReduce levels gradually to avoid cerebral edema
30Hypernatremia Treatment Treat underlying causeIf oral fluids cannot be ingested, IV solution of 5% dextrose in water or hypotonic salineDiuretics if necessary
31Hyponatremia Results from loss of sodium-containing fluids Sweat, diarrhea, emesis, etc.Or from water excessInefficient kidneysDrowning, excessive intakeManifestationsConfusion, nausea, vomiting, seizures, and coma
32Treatment Oral NaCl If caused by water excess Fluid restriction is neededIf Severe symptoms (seizures)Give small amount of IV hypertonic saline solution (3% NaCl)If Abnormal fluid lossFluid replacement with sodium- containing solution
33Hyperkalemia High serum potassium caused by Massive intakeImpaired renal excretionShift from ICF to ECF (acidosis)DrugsCommon in massive cell destructionBurn, crush injury, or tumor lysisFalse High: hemolysis of sample
34Hyperkalemia Manifestations Weak or paralyzed skeletal muscles Ventricular fibrillation or cardiac standstillAbdominal cramping or diarrhea
36Treatment Emergency: Calcium Gluconate IV Stop K intake Force K from ECF to ICFIV insulinSodium bicarbonateIncrease elimination of K (diuretics, dialysis, Kayexalate)
37Hypokalemia Low serum potassium caused by Abnormal losses of K+ via the kidneys or gastrointestinal tractMagnesium deficiencyMetabolic alkalosis
38Hypokalemia Manifestations Most serious are cardiac Skeletal muscle weaknessWeakness of respiratory musclesDecreased gastrointestinal motility
39Hypokalemia KCl supplements orally or IV Should not exceed 10 to 20 mEq/hrTo prevent hyperkalemia and cardiac arrestNo Pee no Kay!!!!!!!!!!!!!!!!!!!!!!!!!
40Calcium Obtained from ingested foods More than 99% combined with phosphorus and concentrated in skeletal systemInverse relationship with phosphorusOtherwise…
41Calcium Bones are readily available store Blocks sodium transport and stabilizes cell membraneIonized form is biologically activeBound to albumin in bloodBound to phosphate in bone/teethCalcified deposits
42Calcium Functions Transmission of nerve impulses Myocardial contractionsBlood clottingFormation of teeth and boneMuscle contractions
43Calcium Balance controlled by Bone used as reservoir Parathyroid hormoneCalcitoninVitamin D/IntakeBone used as reservoir
44Hypercalcemia High serum calcium levels caused by Hyperparathyroidism (two thirds of cases)Malignancy (parathyroid tumor)Vitamin D overdoseProlonged immobilization
46Treatment Excretion of Ca with loop diuretic Hydration with isotonic saline infusionSynthetic calcitoninMobilization
47Hypocalcemia Low serum Ca levels caused by Decreased production of PTH Acute pancreatitisMultiple blood transfusionsAlkalosisDecreased intake
48Hypocalcemia Manifestations Weakness/Tetany Positive Trousseau’s or Chvostek’s signLaryngeal stridorDysphagiaTingling around the mouth or in the extremities
49Treatment Treat cause Oral or IV calcium supplements Not IM to avoid local reactionsTreat pain and anxiety to prevent hyperventilation-induced respiratory alkalosis
50Phosphate Primary anion in ICF Essential to function of muscle, red blood cells, and nervous systemDeposited with calcium for bone and tooth structure
51PhosphateInvolved in acid–base buffering system, ATP production, and cellular uptake of glucoseMaintenance requires adequate renal functioningEssential to muscle, RBCs, and nervous system function
52Hyperphosphatemia High serum PO43 caused by Manifestations Acute or chronic renal failureChemotherapyExcessive ingestion of phosphate or vitamin DManifestationsCalcified deposition: joints, arteries, skin, kidneys, and corneasNeuromuscular irritability and tetany
53Hyperphosphatemia Management Identify and treat underlying cause Restrict foods and fluids containing PO43Adequate hydration and correction of hypocalcemic conditions
54Hypophosphatemia Low serum PO43 caused by Malnourishment/malabsorptionAlcohol withdrawalUse of phosphate-binding antacidsDuring parenteral nutrition with inadequate replacement
55Hypophosphatemia Manifestations CNS depression Confusion Muscle weakness and painDysrhythmiasCardiomyopathy
56Hypophosphatemia Management Oral supplementation Ingestion of foods high in PO43IV administration of sodium or potassium phosphate
57Magnesium 50% to 60% contained in bone Coenzyme in metabolism of protein and carbohydratesFactors that regulate calcium balance appear to influence magnesium balance
58Magnesium Acts directly on myoneural junction Important for normal cardiac function
59Hypermagnesemia High serum Mg caused by Increased intake or ingestion of products containing magnesium when renal insufficiency or failure is present
60Hypermagnesemia Manifestations Lethargy or drowsiness Nausea/vomiting Impaired reflexes***Respiratory and cardiac arrest
61Hypermagnesemia Management Prevention Emergency treatment IV CaCl or calcium gluconateFluids to promote urinary excretion
62Hypomagnesemia Low serum Mg caused by Prolonged fasting or starvation Chronic alcoholismFluid loss from gastrointestinal tractProlonged parenteral nutrition without supplementationDiuretics
63Hypomagnesemia Manifestations Confusion Hyperactive deep tendon reflexesTremorsSeizuresCardiac dysrhythmias
64Hypomagnesemia Management Oral supplements (MgO, MgSO4) Increase dietary intakeParenteral IV or IM magnesium when severe
70Interpretation of ABGs Diagnosis in six stepsEvaluate pHAnalyze PaCO2Analyze HCO3-Determine if Balanced or UnbalancedDetermine if CO2 or HCO3- matches the alterationDecide if the body is attempting to compensate
71Interpretation of ABG pH over balance PaCO2 = “respiratory” balance HC03- = “metabolic” balanceIf all three normal = balancedMatch direction. e.g., if pH and PaCO2 are both acidotic, then primary respiratory acidosisIf other is opposite, then partial compensation; if pH normal, then fully compensated.
72Interpretation of ABGs pH 7.36PaCO2 67 mm HgPaO2 47 mm HgHCO3 37 mEq/LWhat is this?
73Interpretation of ABGs pH 7.18PaCO2 38 mm HgPaO2 70 mm HgHCO3- 15 mEq/LWhat is this?
74Interpretation of ABGs pH 7.60PaCO2 30 mm HgPaO2 60 mm HgHCO3- 22 mEq/LWhat is this?
75Interpretation of ABGs pH 7.58PaCO2 35 mm HgPaO2 75 mm HgHCO3- 50 mEq/LWhat is this?
76Interpretation of ABGs pH 7.28PaCO2 28 mm HgPaO2 70 mm HgHCO3- 18 mEq/LWhat is this ?
77Putting it all together Always pay attention toPatient historyVital signsSymptoms and physical exam findingsLab ValuesAlways ask:What is causing this abnormal finding?What can be done to fix it?
78D5WHypotonic½ NS½ NS (0.45%)CrystalloidsIsotonicNS (0.9%)Lactated RingerHypertonicPlasmalyteFluids3% SalineAlbuminD5W in ½ NSDextranColloidsD10WFFPPRBCs
79IV Fluids Purposes Maintenance Replacement When oral intake is not adequateReplacementWhen losses have occurred
80D5W (Dextrose = Glucose) HypotonicProvides 170 cal/LFree waterMoves into ICFIncreases renal solute excretionUsed to replace water losses and treat hyponatremiaDoes not provide electrolytes
81Normal Saline (NS) Isotonic No calories More NaCl than ECF 30% stays in IVF70% moves out of IV space
82Normal Saline (NS) Expands IV volume Does not change ICF volume Preferred fluid for immediate responseRisk for fluid overload higherDoes not change ICF volumeBlood productsCompatible with most medications
83Lactated Ringer’s Isotonic More similar to plasma than NS Expands ECF Has less NaClHas K, Ca, PO43, lactate (metabolized to HCO3)CONTRAINDICATED in lactic acidosisExpands ECF
84D5 ½ NS Hypertonic Common maintenance fluid KCl added for maintenance or replacement
85D10WHypertonicMax concentration of dextrose that can be administered in peripheral IVProvides 340 kcal/LFree waterLimit of dextrose concentration may be infused peripherally
86Plasma Expanders Stay in vascular space and increase osmotic pressure Colloids (protein solutions)Packed RBCsAlbuminPlasmaDextran