Fluid and

electrolytes

Body Fluids

Intracellular

Intravascular

InterstitialExtracellular40%

16%

4%

Body Water (~40L) = 60% of body weight

Body fluid compartments

Intracellular fluid

s

Interstitialfluid

Intravascularfluid

Intracellular Fluid (ICF)

– Fluid within the cells– Located primarily in skeletal muscle mass–Provide nutrients for metabolism:

• High in potassium, phosphate, & protein•Moderate levels of Mg, SO4

–Assists in cellular metabolism

Extracellular fluid (ECF)• Intravascular

- plasma (half of total blood volume)

• Interstitial- surround all cells (eg. lymph)

* Some interstitial fluid is TRANSCELLULAR or under the influence of metabolic activity- respiratory fluid - pericardial fluid - GI digestive fluid - peritoneal fluid - CSF - intraocular fluid

- pleural fluid - synovial fluid- gland secretions (sweat, enzymes)

Extracellular fluid (ECF)• Surrounds cells • Transport medium for nutrients, gases, waste products

and other substances between blood and body cells• Back-up fluid reservoir• Nutrients for cell functioning– Na– Ca– Cl– Glucose– Fatty acids– Amino Acids

Fluid Movement• Fluid movement is constant and is influenced

by:1. membrane permeability

• Active : require energy to transport eg. Na/K pump• Passive : osmosis, diffusion, hydrostatic force

2. colloid osmotic pressure (plasma proteins)

3. hydrostatic pressure (cap. bed pressure)• Mechanical force of water pushing against membrane• Forces H2O, Na, glucose to go across membrane to

interstitial fluid

Renal Regulation• Kidneys are the most important regulators

of volume and composition of body fluids• Hormonal Control–Antidiuretic hormone (ADH)–Renin-angiotensin-aldosterone system(RAA)–Natriuretic peptides (NUP)

ADH regulatory mechanism

NUP regulatory mechanism

RAA regulatory mechanism

Daily Intake & Output

• Intake 2,500 – 3,000 ml– Liquids 1,500 – 2,000 ml– Water in food 700 ml– Water of oxidation 250 ml

• Output 1,400-2,300 ml– Respiration & Perspiration (insensible) 600-900 ml – Urine 800-1500 ml– Stool 250 ml

Water lossNormal Other causes

1. Skin – 0 – 1000ml/day-Perspiration

2. Lungs - ~300-400 ml/day-Increases with increased respiratory rate or depth or dry climate

3. GI Tract - ~ 100-200 ml/day

4. Kidneys - ~ 1-2 L/day

5. Insensible loss ~ 600 ml/day (evaporation)

1. Fever2. Burns 3. Diarrhea4. Vomiting5. N-G Suction6. Fistulas 7. Wound drainage8. Mechanical ventilation9. Increased metabolism10. Diabetes Insipidus11. Uncontrolled DM12. ATN

Serum Osmolarity (Concentration)

• Normal value = 275 -295– >295 = concentrated (dehydrated)– <275 = dilute (fluid overloaded)

• Serum Osmo = 2(Na) + glucose/18 +BUN/2.8

• Serum Osmo = Sodium x 2 (quick reference)

Serum Laboratory Findings (Normal)

• Serum sodium : 135-145 mEq/L • Serum potassium : 3.5 – 5 mEq/L• Serum chloride : 95 – 105 mEq/L• Serum osmolarity : 275-295 mOsm/L • Urea : 15 – 40 mg/dL• Creatinine : 0.6 – 1.5 mg/dL• BUN: creatinine : 10:1 ratio• Hematocrit (males 40-52% , females 37-46%)• Total protein : 6.5 - 8.0 g/dL

Fluid volume deficit– Output > Intake -> Water extracted from ECF

• ECF hypertonic (water moves out of cell -> cell dehydration) + osmotic pressure increased (stimulates thirst receptor in hypothalamus)

• ICF hypotonic with decreased osmotic pressure -> posterior pituitary secretes more ADH

• Decreased ECF volume -> adrenal glands secrete Aldosterone

Lab– Increased HCT– Increased BUN out of proportion to Cr– High serum osmolarity– Increased urine osmolarity– Increased specific gravity– Decreased urine volume, dark color

Signs and symptoms• Acute weight loss• Decreased skin turgor• Oliguria• Concentrated urine• Weak, rapid pulse• CRT >2s• Decreased BP• Increased pulse• Sensations of thirst, weakness,

dizziness, muscle cramps• Sunken eyeballs• Depressed fontanels

Management• Major goal : correction and prevention of ARF• Encourage oral fluids• IV fluids– Isotonic solutions (0.9% NS or Hartmann) until BP back to

normal, then hypotonic (0.45% NS)• Monitor I & O, urine specific gravity, daily weights• Monitor skin turgor• Monitor VS and mental status• Evaluation– Normal skin turgor, increased UOP with normal specific

gravity, normal VS, alert and conscious, good oral intake of fluids

Fluid volume excess• Hypervolemia• Isotonic expansion of ECF caused by abnormal

retention of water and sodium • Fluid moves out of ECF into cells and cells swell• Causes– Cardiovascular – Heart failure– Urinary – Renal failure– Hepatic – Liver failure, cirrhosis– Other – Cancer, thrombus, PVD, drug therapy (i.e.,

corticosteriods), high sodium intake, protein malnutrition

Signs and symptoms• Physical assessment

– Weight gain– Distended neck veins– Periorbital edema, pitting edema– Lungs crepitation– Dyspnea– Mental status changes– Generalized or dependent edema

• VS– High CVP/PAWP– ↑ cardiac output

• Lab data– ↓ Hct (dilutional)– ↓ BUN (dilutional)– Low serum osmolality– Low specific gravity

Signs and symptoms• Radiography– Pulmonary vascular

congestion– Pleural effusion– Pericardial effusion– Ascites

Management• Sodium restriction (foods/water high in

sodium)• Fluid restriction, if necessary• Closely monitor IVF• If dyspnea or orthopnea > Semi-Fowler’s• Strict I & O, lung sounds, daily weight, degree

of edema, reposition q 2 hr • Promote rest and diuresis

IV fluidsCrystalloids Colloids

HypertonicIsotonicHypotonic

AlbuminHetastarchDextransGelofusine

CrystalloidsHypotonic Isotonic Hypertonic

-lower solute concentration than the serum

-infusion decreases the solute concentration in the vascular space into the intracellular and interstitial spaces where the solute concentration is higher

-fluid moves into the cells

Examples½ Normal Saline (154)0.33% NaCl (103)D2.5W (126)

-osmolarity equals serum

-stays in the intravascular space thus expanding the volume

-good choice for hydration

ExamplesLactate Ringer (275)Hartmann (255)Normal saline (304)D5W (260)Plasma-lyte (295)

-solute concentration higher than the solute concentration of the serum

-infusion causes an increase in the solute concentration of the serum, pulling fluid from the interstitial space to the vascular space through osmosis

ExamplesD5 ½ Normal Saline (408)D5 Normal Saline (560)

Content of crystalloids

Electrolytes• Major intracellular electrolytes– Potassium (cation)– Phosphorus (anion)

• Major extracellularelectrolytes– Sodium (cation)– Chloride (anion)* Sodium is the determinant of osmolality (tonicity)

since it is the major ECF cation

Sodium• Normal 135-145 mEq/L• Major cation in ECF• Regulates voltage of action potential;

transmission of impulses in nerve and muscle fibers, one of main factors in determining ECF volume

• Elderly at risk• Helps maintain acid-base balance

HypernatremiaCauses

Inadequate water intake

Fluid loss Salt gain

GI : Diarrhea, vomiting, fistula

Renal :Diabetes insipidus, osmotic diuresis(glucose, mannitol), diuretic therapy

a) Excessive sodium intakeb) Mineralocorticoid excess- Hyperaldosteronism- Cushing ‘ssyndrome

• Symptoms- extreme thirst - tachycardia- dry mucous membranes - low grade fever- irritability - weakness/lethargy- spasticity - oliguria/polyuria

Lab• Increased serum Na• Increased serum osmolality• Increased urine specific gravity

ManagementWater depletion• Oral hydration if tolerated• IV infusion D5% or 0.45%

NaCl• Give maintenance fluid

requirement (40ml/kg/day)

Salt gain• Remove sodium using

potent diuretic (eg. IV furosemide) with D5% infused

• In severe cases dialysis may be necessary

*Assessment1) Normal level of serum Na2) Resolution of signs and symptoms

Hyponatremia• Decrease in measured serum Na concentration

below 135 mEq/L– Mild 125-134mEq/L– Moderate 110-124mEq/L– Severe 100-109mEq/L

• Evaluate serum osmolarity– If osmolarity is hypotonic, evaluate volume status:• Hypervolemia• Euvolemia• Hypovolemia

Causes• Results from excess Na loss or water gain– GI losses, diuretic therapy, severe renal dysfunction,

severe diaphoresis, DKA, unregulated production of ADH associated with cerebral trauma, narcotic use, lung cancer, some drugs (eg. Thiazides, carbamazepine, desmopressin, oxytocin)

• Clinical manifestations– ↓ BP, confusion, headache, lethargy, seizures,

decreased muscle tone, muscle twitching and tremors, vomiting, diarrhea, and cramps

Lab & ManagementLab investigation– Increased HCT, K– Decreased Na, Cl, Bicarbonate, UOP with low Na and Cl

concentration– Urine specific gravity ↓ 1.010

Management– Mild

• Water restriction if water retention problem• Increase Na in foods if loss of Na

– Moderate• IV 0.9% NS, 0.45% NS, Hartmann

– Severe• 3% NS – short-term therapy in ICU setting

Potassium• Normal 3.5-5.5 mEq/L• Major ICF cation• Vital in maintaining normal cardiac and

neuromuscular function, influences nerve impulse conduction, important in carbohydrate(CHO) metabolism, helps maintain acid-base balance, control fluid movement in and out of cells by osmosis

Hypokalemia• Serum potassium level below 3.5 mEq/L• Causes– Loss of GI secretions (diarrhea, vomiting, villous adenoma,

ileostomy or uterosigmoidostomy, fistula)– Excessive renal excretion of potassium (diuretics,

increased aldosterone secretion, renal tubular damage etc)

– Movement of K into the cells (insulin therapy)– Prolonged fluid administration without K supplementation– Diuretics (thiazide, loop, mannitol)

Signs and symptoms• Skeletal muscle weakness, ↓ smooth muscle

function, ↓ DTR’s• ↓ BP, heart block, AF, VT, VF• ECG changes (small/inverted T, prominent U,

ST depression, prolonged PR intervals)• Constipation, ileus• Metabolic alkalosis• Mental depression and confusion

Management• Mild – moderate (K > 2.5)– Oral KCl 2-4 hourly until return of serum K to at least 3.5– Monitor K level to prevent hyperK– Potassium-sparing diuretics (amiloride, triamterene,

spironolactone) can be given of hypoK is secondary to renal losses

• Severe (< 2.5) and/or with ECG changes– Fast correction 2g KCl in 200ml NS to infuse in 2 hours

(<3g KCl/L)– With ECG monitoring– When ECG and cardiac rhythm normalize, IV infusion

gradually tapered down and discontinue. Oral KCl is initiated.

Hyperkalemia• Serum potassium level above 5.3 mEq/L• Causes

– Excessive K intake (IV or PO) especially in renal failure– Tissue trauma– Acidosis– Catabolic state

Signs and symptoms• ECG changes – tachycardia to bradycardia to possible cardiac

arrest– Tall, tented T waves

• Cardiac arrhythmias• Muscle weakness, paralysis, paresthesia of tongue, face,

hands, and feet, N/V, cramping, diarrhea, metabolic acidosis

Management• Stop K supplements and avoid K in foods, fluids,

salt substitutes• Lytic IV cocktail– Calcium gluconate 10% 10ml in 10 minutes– Insulin 10U in D50 50ml in 30-60min, then maintain

on D5– Sodium bicarbonate 100-200mmol/L over 30min

• Kalimate 5-10g tds/Resonium A 15-30 tds/qid PO or PR (cation exchange solution)

• Beta agonist therapy– IV salbutamol 0.5mg in 15min or 10mg nebulization

Calcium• Normal 4.5-5.5 mEq/L• 99% of Ca in bones, other 1% in ECF and soft

tissues• Total Calcium – bound to protein – levels

influenced by nutritional state • Ionized Calcium – used in physiologic activities

– crucial for neuromuscular activity

• Required for blood coagulation, neuromuscular contraction, enzymatic activity, and strength and durability of bones and teeth

• Nerve cell membranes less excitable with enough calcium

• Ca absorption and concentration influenced by Vit D, calcitriol (active form of Vitamin D), PTH, calcitonin, serum concentration of Ca and Phos

Hypocalcemia• Most common – depressed function or

surgical removal of the parathyroid gland• Hypomagnesemia• Hyperphosphatemia• Administration of large quantities of stored

blood (preserved with citrate)• Renal insufficiency• ↓ absorption of Vitamin D from intestines

Signs and symptoms• Abdominal and/or extremity cramping• Tingling and numbness (circumoral)• Positive Chvostek sign (tapping over facial nerve

-> twitching) • PositiveTrousseau sign (inflate cuff for 5 min over

diastolic P -> carpopaedal spasm)• Tetany; hyperactive reflexes• Irritability, reduced cognitive ability, psychosis,

seizures• Prolonged QT on ECG, hypotension, decreased

myocardial contractility• Abnormal clotting

Management• High calcium diet or oral calcium salts (mild) - √

formulas for calcium content • IV calcium as 10% calcium chloride or 10%

calcium gluconate in D5W– give with caution• Close monitoring of serum Ca and digitalis levels• ↓ Phosphorus levels with calcium carbonate• ↑ Magnesium levels • Vitamin D therapy– D2 (ergocalciferol) 25,000-150,000 IU/day– D3 (cholecalciferol) 50,000-100,000 IU PO daily

Hypercalcemia• Causes– Mobilization of Ca from bone– Malignancy– Hyperparathyroidism– Immobilization – causes bone loss– Thiazide diuretics– Thyrotoxicosis– Excessive ingestion of Ca or Vit D (milk alkali

syndrome)

Signs and symptoms• Anorexia, constipation, nausea, vomiting• Generalized muscle weakness, lethargy, loss of

muscle tone, ataxia• Depression, fatigue, confusion, coma• Soft tissue and corneal calcification (band

keratopathy)• Dysrhythmias and heart block• ECG : shortened QT intervals• Deep bone pain and demineralization• Polyuria & predisposes to renal calculi• Pathologic bone fractures • Osteitis fibrosa in hyperparathyroidism

Hypercalcemic crisis

• Emergency – level of 8-9 mEq/L• Intractable nausea, dehydration, stupor, coma,

azotemia, hypokalemia, hypomagnesemia, hypernatremia

• High mortality rate from cardiac arrest

Treatment• NS IV – match infusion rate to amount of UOP• I&O hourly• Loop diuretics• Corticosteroids and Mithramycin in cancer

clients to inhibit osteolytic bone resorption• Biphosphonates and/or calcitonin to inhibit

bone resorption and increase renal Ca excretion• Oral phosphate 1-3g/day• Encourage fluids• Dialysis

Magnesium

• Causes vasodilatation • Decreases peripheral vascular resistance • Balance - closely related to K and Ca balance• Intracellular compartment electrolyte• Hypomagnesemia - < 1.5 mEq/L• Hypermagnesemia - > 2.5 mEq/L

Hypomagnesemia

• Causes– Decreased intake or decreased absorption or

excessive loss through urinary or bowel elimination

– Acute pancreatitis, starvation, malabsorption syndrome, chronic alcoholism, burns, prolonged hyperalimentation without adequate Mg

– Hypoparathyroidism with hypocalcemia– Diuretic therapy

Signs and symptoms• Tremors, tetany, ↑ reflexes, paresthesias of feet and legs, convulsions• Positive Babinski, Chvostek and Trousseau signs• Personality changes with agitation, depression or confusion, hallucinations• ECG changes (PVC’S, V-tach and V-fib)

Treatment• Mild

– Diet – Best sources are unprocessed cereal grains, nuts, legumes, green leafy vegetables, dairy products, dried fruits, meat, fish

– Magnesium salts• More severe

– MgSO4 IM – MgSO4 IV slowly

• Monitor Mg q 12 hr• Monitor VS, knee reflexes• Precautions for seizures/confusion• Check swallow reflex

Hypermagnesemia• Most common cause is renal failure, especially if taking large

amounts of Mg-containing antacids or cathartics; DKA with severe water loss

• Signs and symptoms– Hypotension, drowsiness, absent deep tendon reflex, respiratory

depression, coma, cardiac arrest– ECG – Bradycardia, complete HB, cardiac arrest, tall T waves

Treatment

• Withhold Mg-containing products• Calcium chloride or gluconate IV for acute symptoms• IV hydration and diuretics• Monitor VS, LOC• Check patellar reflexes

Phosphorus

• Normal 2.5-4.5 mg/dL • Intracellular mineral• Essential to tissue oxygenation, normal CNS

function and movement of glucose into cells, assists in regulation of Ca and maintenance of acid-base balance

• Influenced by parathyroid hormone and has inverse relationship to Calcium

Hypophosphotemia• Causes

- Malnutrition- Hyperparathyroidism- Certain renal tubular defects- Metabolic acidosis (esp. DKA)- Disorders causing hypercalcemia

• Signs and symptoms– Impaired cardiac function– Poor tissue oxygenation– Muscle fatigue and weakness– N/V, anorexia– Disorientation, seizures, coma

• Treatment of moderate to severe deficiency – Oral or IV phosphate (do not exceed rate of 10 mEq/h)– Identify patients at risk for disorder and monitor– Prevent infections– Monitor levels during treatment

Hyperphosphotemia• Causes

– Chronic renal failure (most common)– Hyperthyroidism, hypoparathyroidism– Severe catabolic states– Conditions causing hypocalcemia

• Signs and symptoms– Muscle cramping and weakness– ↑ HR– Diarrhea, abdominal cramping, and nausea

Treatment• Prevention is the goal • Restrict phosphate-containing foods• Administer phosphate-binding agents • Diuretics• Treat cause• Treatment may need to focus on correcting calcium levels

Thank you for your attention