Fluid and Electrolytes 12142021 1 Compartments Intracellular fluid

Fluid and Electrolytes 12/14/2021 1

Compartments Intracellular fluid (ICF) ¡ Extracellular fluid (ECF) ¡ Intravascular (plasma) ¡ Interstitial (between cells; lymph) ¡ ¡ Transcellular See Figure 16 -2 in Lewis 6 th ed. 12/14/2021 2

Intracellular Fluid (ICF) l Fluid located within cells l 42% of body weight; 2/3 of body water l Potassium (K+): most prevalent intracellular cation l Phosphate (PO 4 -): most prevalent intracellular anion 12/14/2021 3

Extracellular Fluid (ECF) ¡ Interstitial (between cells; lymph) (Cl-): most prevalent anion l (Na+): most prevalent cation l 2/3 of ECF is in interstitial l ¡ Intravascular (IV) Within vascular space l Measured with blood tests l 1/3 of ECF is intravascular l 12/14/2021 4

Transcellular Small but important fluid compartment ¡ Approximately 1 Litre ¡ Includes ¡ l l l 12/14/2021 CSF GI tract Pleural space Synovial spaces Peritoneal space 5

Mechanisms Controlling Fluid and Electrolyte Movement ¡ Diffusion l ¡ Facilitated diffusion l ¡ molecules move from high to low concentration involves carrier molecules Active transport l l l movement against concentration gradient requires energy E. g. : keeping Na out and K in the cells (requires ATP) 12/14/2021 6

Mechanisms Controlling Fluid and Electrolyte Movement ¡ Osmosis l l ¡ Hydrostatic pressure l ¡ H 2 O movement between compartments separated by membrane from area of high to low solute concentration Membrane is permeable to water, not solutes Force within fluid compartment Oncotic pressure= colloid osmotic pressure l Osmotic pressure exerted by colloids [e. g. , protein] n solution; “pulls” fluid into vascular space 12/14/2021 7

Fluid Shifts: Plasma to interstitial space ¡ ¡ Results in edema Due to: l Elevated venous hydrostatic pressure ¡ l Decreased plasma oncotic pressure ¡ l e. g. , low plasma protein r/t malnutrition Elevated interstitial oncotic pressure ¡ 12/14/2021 e. g. , CHF, varicose veins plasma proteins accumulated in interstitium, pulling water - e. g. , burns 8

Fluid Movement Between Extracellular and Intracellular ¡ Excess water in ECF l Cells are more concentrated. Thus: ¡ ¡ ¡ Water moves into cells → Cells swell Water deficit in ECF : water is pulled from cells → Cells shrink Both of above cause neurological symptoms 12/14/2021 9

Fluid Spacing ¡ First spacing l ¡ Second spacing l ¡ Abnormal accumulation of interstitial fluid (e. g. , edema associated with varicose veins, pulmonary edema) Third spacing l 12/14/2021 Normal distribution of fluid in ICF and ECF Fluid accumulation in part of body where it is not easily exchanged with rest of ECF (e. g. , edema due to burns, ascites [in peritoneal space) 10

Regulation of Water Balance ¡ ¡ ¡ Hypothalamic regulation (controls pituitary) Pituitary regulation (ADH) Adrenal cortical regulation (aldosterone – enhances Na and H 20 retention) ¡ ¡ 12/14/2021 Renal regulation Cardiac regulation Gastrointestinal regulation (fluid intake) Insensible water loss 11

Insensible Water Loss ¡ Invisible vaporization from lungs and skin ¡ Approximately 900 ml per day is lost ¡ No electrolytes are lost with insensible water loss l 12/14/2021 Excessive sweating is not an insensible loss. Diaphoresis leads to loss of water and electrolytes. 12

Sodium 12/14/2021 ¡ Plays major role in maintaining ECF concentration (osmolality) and volume ¡ Main cation in ECF; primary determinant of osmolality (a measure of solute concentration) ¡ Important in generation and transmission of nerve impulses ¡ Important in acid-base balance 13

Hypernatremia ¡ Hypernatremia due to l l ¡ Hypernatremia results in l ¡ 12/14/2021 Water loss or Sodium gain Hyperosmolality → water shifts out of cells → cellular dehydration Primary protection against hypernatremia is thirst 14

Hypernatremia ¡ ¡ ¡ 12/14/2021 Manifestations include thirst, lethargy, agitation, seizures, and coma Hypernatremia secondary to water deficiency often due to impaired LOC or inability to get fluids Also due to deficiency in ADH 15

Hypernatremia ¡ Management includes: l l l ¡ 12/14/2021 Treating the underlying cause Hypotonic IV fluids if oral fluids cannot be ingested Administering diuretics (promotes excretion of sodium) Serum sodium levels must be reduced gradually to avoid cerebral edema 16

Hyponatremia ¡ Due to: l l 12/14/2021 loss of Na-containing fluids, or water excess (dilutional hyponatremia) ¡ Hyponatremia → hypoosmolality → water moves into cells ¡ Clinical manifestations include confusion, nausea, vomiting, seizures, and coma 17

Hyponatremia ¡ ¡ 12/14/2021 If caused by water excess, fluid restriction is needed If severe symptoms (seizures) occur, small amount of intravenous hypertonic saline solution (3% Na. Cl) is given 18

Hyponatremia ¡ If associated with abnormal fluid loss (diarrhea, polyuria, etc. ): Ø fluid replacement with Nacontaining solution (eg. Normal saline [0. 9% Na. Cl]) 12/14/2021 19

Potassium ¡ Potassium major ICF cation ¡ Potassium is necessary for l l 12/14/2021 Transmission and conduction of nerve impulses Normal cardiac rhythms Skeletal muscle contraction Acid-base balance 20

Potassium ¡ Critical to action membrane potential l 12/14/2021 Sources of potassium ¡ Fruits and vegetables (bananas and oranges) ¡ Salt substitutes ¡ Potassium medications (PO, IV) ¡ Stored blood 21

Hyperkalemia ¡ Causes l l l 12/14/2021 Increased retention ¡ Renal failure ¡ Potassium sparing diuretics Increased intake Mobilization from ICF ¡ Tissue destruction ¡ Acidosis 22

Hyperkalemia ¡ 12/14/2021 Clinical Manifestations l Skeletal muscles weak or paralyzed l Ventricular fibrillation or cardiac standstill l Abdominal cramping or diarrhea 23

Nursing Management of Hyperkalemia Eliminate oral and parenteral K intake ¡ Increase elimination of K (diuretics, dialysis, Kayexalate) ¡ Force K from ECF to ICF with IV insulin (or sodium bicarbonate if hyperkalemia is due to acidosis) ¡ 12/14/2021 24

Hypokalemia ¡ Causes l Increased loss ¡ Certain diuretics ¡ GI losses ¡ Associated with Mg deficiency ¡ Movement into cells 12/14/2021 25

Hypokalemia Clinical Manifestations Potentially lethal ventricular arrhythmias ¡ Increased digoxin toxicity in those taking the drug ¡ ECG changes ¡ Skeletal muscle weakness and paralysis ¡ Muscle cell breakdown ¡ 12/14/2021 26

Hypokalemia Clinical Manifestations ¡ Decreased GI motility ¡ Altered airway responsiveness ¡ 12/14/2021 Impaired regulation of arterial blood flow ¡ Diuresis ¡ Hyperglycemia 27

Nursing Management of Hypokalemia ¡ Replacement PO or IV l l l ¡ 12/14/2021 Never push IV Painful in peripheral veins Never give with anuric renal failure Teach prevention methods (e. g. diet) 28

Electrolyte Disorders Summary Signs and Symptoms 12/14/2021 Electrolyte Excess Deficit Sodium (Na) Hypernatremia Thirst CNS deterioration Increased interstitial fluid Hyponatremia CNS deterioration Potassium (K) Hyperkalemia Ventricular fibrillation ECG changes CNS changes Hypokalemia Bradycardia ECG changes CNS changes 29

Electrolyte Disorders Signs and Symptoms Electrolyte Excess Deficit Calcium (Ca) Hypernatremia Thirst CNS deterioration Increased interstitial fluid Hypocalcemia Tetany Chvostek’s, Trousseau’s Muscle twitching CNS changes EKG changes Magnesium (Mg) Hypermagnesemia Loss of deep tendon reflexes (DTRs) Depression of CNS Depression of neuromuscular function Hypomagnesemia Hyperactive deep tendon reflexes CNS changes EKG changes 12/14/2021 30

Protein Imbalances ¡ ¡ Plasma proteins(especially albumin) are important determinants of plasma volume Hyperproteinemia is rare l 12/14/2021 Occurs with dehydration-induced hemoconcentration 31

Hypoproteinemia ¡ Caused by l l l 12/14/2021 Anorexia Malnutrition Starvation Fad dieting Poorly balanced vegetarian diets 32

Hypoproteinemia ¡ ¡ ¡ Poor absorption d/t GI malabsorptive diseases Inflammation → protein can shift out of intravascular space Hemorrhage 12/14/2021 33

Hypoproteinemia: Clinical Manifestations ¡ Edema (b/c insufficient oncotic pressure to “hold” water in vascular space) Slow healing ¡ Anorexia ¡ Fatigue ¡ Anemia ¡ Muscle loss ¡ Ascites (same reason as edema) ¡ 12/14/2021 34

Hypoproteinemia ¡ 12/14/2021 Management l High-carbohydrate, high-protein diet l Dietary protein supplements l Enteral nutrition or total parenteral nutrition 35

Extracellular Fluid Volume Imbalances ¡ Hypovolemia due to: l l l ¡ Hypervolemia due to: l l l 12/14/2021 loss of normal body fluids (diarrhea, fistula drainage, hemorrhage) decreased intake or plasma-to-interstitial fluid shift excessive intake of fluids abnormal retention of fluids (CHF) or interstitial-to-plasma fluid shift 36

Extracellular Fluid Volume Imbalances ¡ Hypovolemia: l ¡ Hypervolemia l l 12/14/2021 Treat with fluid replacement (NS, Ringer’s, blood) Remove excess fluid (diuretics, dialysis) Fluid restriction, sodium restriction 37

Nursing Diagnoses: Hypervolemia l l l 12/14/2021 Excess fluid volume Ineffective airway clearance Risk for impaired skin integrity Disturbed body image PC: pulmonary edema, ascites 38

Nursing Diagnoses: Hypovolemia 12/14/2021 l Fluid volume deficit l Decreased cardiac output l PC: hypovolemic shock 39

Nursing Implementation for Volume Imbalances 12/14/2021 ¡ I&O ¡ Cardiovascular status (BP, pulse strength, JVD, HR, orthostatic hypotension) ¡ Respiratory status (crackles, RR) ¡ Neurological function ¡ Daily weights (1 kg = 1000 ml) ¡ Skin assessment (turgor, edema) 40

Nursing Implementation for Volume Imbalances ¡ Neurologic function l l l 12/14/2021 LOC PERLA Voluntary movement of extremities Muscle strength Reflexes 41

IV Fluids Purposes 1. Maintenance ¡ 2. Replacement ¡ 12/14/2021 When oral intake is not adequate When losses have occurred 42

Solution Types ¡ Hypotonic l l l 12/14/2021 Provides more water than electrolytes Dilutes ECF, thus water moves from ECF → ICF Examples: 0. 45 Na. Cl 43

Solution Types ¡ Isotonic l l l 12/14/2021 Same osmolality as ECF Expands only ECF (what goes in ECF stays in ECF; no shifting to ICF) Examples: Normal saline (0. 9% Na. Cl), Lactated Ringers (Ringer’s Lactate) 44

Solution Types ¡ Hypertonic l l l 12/14/2021 More concentrated than ECF Expands ECF volume Increased osmolality draws water from cells into ECF 45

D 5 W ¡ Isotonic l ¡ A source of calories ¡ A source of “free water: metabolism of glucose) l 12/14/2021 But becomes hypotonic after dextrose is metabolized b/c only water remains (as above b/c of Moves into ICF 46

D 5 W ¡ ¡ 12/14/2021 Prevents ketosis Supports edema formation – do not use in clients with cerebral edema! Decreased chance of IV fluid overload Usually compatible with medications 47

Normal Saline (NS; 0. 9% Na. Cl) 12/14/2021 ¡ Isotonic ¡ No calories ¡ More Na. Cl than ECF (could cause hypernatremia, hyperchloremia) 48

Normal Saline (NS; 0. 9% Na. Cl) ¡ Expands IV volume l l 12/14/2021 Preferred fluid for immediate response Risk for fluid overload higher ¡ Does not change ICF Volume ¡ Blood products ¡ Compatible with most medications 49

Lactated Ringer’s ¡ Isotonic ¡ More similar to plasma than NS (b/c has electrolytes) l 12/14/2021 Commonly used postoperatively ¡ Expands ECF, IV ¡ Common replacement fluid 50

D 5 ½ NS ¡ ¡ ¡ 12/14/2021 Hypertonic (becomes Hypotonic in body after dextose is absorbed) Common maintenance fluid KCl added for maintenance or replacement 51

D 5 ½ NS (Hypertonic) ¡ Provides calories l 12/14/2021 Prevents ketosis ¡ Moves into ICF ¡ Usually compatible with medications 52

Plasma Expanders (Hypertonic) Pull fluid from interstitium into vascular space ¡ Colloids ¡ l l l 12/14/2021 Packed RBCs Albumin Plasma 53