Fluid and Electrolyte Fluid and Electrolyte ImbalancesImbalances

11

22

Body Fluid Body Fluid CompartmentsCompartments 2/3 (65%) of TBW is intracellular (ICF)2/3 (65%) of TBW is intracellular (ICF)

1/3 extracellular water1/3 extracellular water– 25 % interstitial fluid (ISF)25 % interstitial fluid (ISF)– 5- 8 % in plasma (IVF intravascular fluid)5- 8 % in plasma (IVF intravascular fluid)– 1- 2 % in transcellular fluids – CSF, 1- 2 % in transcellular fluids – CSF,

intraocular fluids, serous membranes, intraocular fluids, serous membranes, and in GI, respiratory and urinary tracts and in GI, respiratory and urinary tracts (third space) (third space)

33

44

55

Fluid compartments are separated by Fluid compartments are separated by membranes that are freely permeable membranes that are freely permeable to water.to water.

Movement of fluids due to:Movement of fluids due to:– hydrostatic pressurehydrostatic pressure – osmotic pressureosmotic pressure

Capillary filtration (hydrostatic) pressureCapillary filtration (hydrostatic) pressure Capillary colloid osmotic pressureCapillary colloid osmotic pressure Interstitial hydrostatic pressureInterstitial hydrostatic pressure Tissue colloid osmotic pressureTissue colloid osmotic pressure

66

77

BalanceBalance Fluid and electrolyte homeostasis is Fluid and electrolyte homeostasis is

maintained in the bodymaintained in the body Neutral balance: input = outputNeutral balance: input = output Positive balance: input > outputPositive balance: input > output Negative balance: input < outputNegative balance: input < output

88

99

Solutes – dissolved particlesSolutes – dissolved particles Electrolytes – charged particlesElectrolytes – charged particles

– Cations – positively charged ionsCations – positively charged ions NaNa++, K, K++ , Ca , Ca++++, H, H++

– Anions – negatively charged ionsAnions – negatively charged ions ClCl--, HCO, HCO33

-- , PO , PO443-3-

Non-electrolytes - Uncharged Non-electrolytes - Uncharged Proteins, urea, glucose, OProteins, urea, glucose, O22, CO, CO22

1010

Body fluids are:Body fluids are:– Electrically neutralElectrically neutral– Osmotically maintainedOsmotically maintained

Specific number of particles per Specific number of particles per volume of fluidvolume of fluid

1111

Homeostasis Homeostasis maintained by:maintained by: Ion transportIon transport Water movement Water movement Kidney functionKidney function

1212

1313

MW (Molecular Weight) = sum of the weights of atoms in a molecule

mEq (milliequivalents) = MW (in mg)/ valence

mOsm (milliosmoles) = number of particles in a solution

1414

Tonicity

Isotonic

Hypertonic

Hypotonic

1515

1616

Cell in a hypertonic solution

1717

Cell in a hypotonic solution

1818

Movement of body fluids “ Where sodium goes, water follows.”

Diffusion – movement of particles down a concentration gradient.

Osmosis – diffusion of water across a selectively permeable membrane

Active transport – movement of particles up a concentration gradient ; requires energy

1919

Regulation of body Regulation of body waterwater

ADH – antidiuretic hormone + thirstADH – antidiuretic hormone + thirst Triggered byTriggered by

– Decreased amount of water in bodyDecreased amount of water in body– Increased amount of Na+ in the bodyIncreased amount of Na+ in the body– Increased blood osmolalityIncreased blood osmolality– Decreased circulating blood volumeDecreased circulating blood volume

Stimulate osmoreceptors in Stimulate osmoreceptors in hypothalamushypothalamusADH released from posterior pituitaryADH released from posterior pituitaryIncreased thirstIncreased thirst

2020

2121

2222

Result:increased water consumptionincreased water conservation

Increased water in body, increased volume and decreased Na+ concentration

2323

Dysfunction or trauma can cause:Decreased amount of water in bodyIncreased amount of Na+ in the bodyIncreased blood osmolalityDecreased circulating blood volume

2424

Edema is the accumulation of fluid within the interstitial spaces.

Causes:increased hydrostatic pressure

lowered plasma osmotic pressure

increased capillary membrane permeability

lymphatic channel obstruction

2525

Hydrostatic pressure increases due to:

Venous obstruction:

thrombophlebitis (inflammation of veins)

hepatic obstruction

tight clothing on extremities

prolonged standing

Salt or water retention

congestive heart failure

renal failure

2626

Decreased plasma osmotic pressure:

↓ plasma albumin (liver disease or protein malnutrition)

plasma proteins lost in :

glomerular diseases of kidney

hemorrhage, burns, open wounds and cirrhosis of liver

2727

Increased capillary permeability:

Inflammation

immune responses (allergic reactions)

Lymphatic channels blocked:

surgical removalinfection involving lymphatics

lymphedema

2828

Fluid accumulation:

increases distance for diffusion

may impair blood flow

= slower healing

increased risk of infection

pressure sores over bony prominences

Psychological effects

2929

Edema of specific organs can be life threatening (larynx, brain, lung)

Water is trapped, unavailable for metabolic processes. Can result in dehydration and shock. (severe burns)

Electrolyte balanceElectrolyte balance

Na Na ++ (Sodium) (Sodium) – 90 % of total ECF cations90 % of total ECF cations– 136 -145 mEq / L136 -145 mEq / L

– Pairs with ClPairs with Cl-- , HCO , HCO33-- to neutralize charge to neutralize charge

– Low in ICF Low in ICF – Most important ion in regulating water Most important ion in regulating water

balancebalance– Important in nerve and muscle functionImportant in nerve and muscle function

3030

3131

Regulation of SodiumRegulation of Sodium

Renal tubule reabsorption Renal tubule reabsorption affected by hormones:affected by hormones:– AldosteroneAldosterone– Renin/angiotensinRenin/angiotensin– Atrial Natriuretic Peptide (ANP)Atrial Natriuretic Peptide (ANP)

Increased secretion of Na, Increased secretion of Na, decreased lood volumedecreased lood volume

3232

PotassiumPotassium

Major intracellular cationMajor intracellular cation ICF conc. = 150- 160 mEq/ LICF conc. = 150- 160 mEq/ L Resting membrane potentialResting membrane potential Regulates fluid, ion balance inside Regulates fluid, ion balance inside

cellcell pH balancepH balance

3333

Regulation of Regulation of PotassiumPotassium Through kidneyThrough kidney

– AldosteroneAldosterone– InsulinInsulin

3434

Isotonic alterations in water Isotonic alterations in water balancebalance

– Loses plasma or ECFLoses plasma or ECF– Isotonic fluid loss Isotonic fluid loss

↓↓ECF volume, weight loss, dry ECF volume, weight loss, dry skin and mucous membranes, skin and mucous membranes, ↓↓ urine output, and hypovolemia urine output, and hypovolemia ( rapid heart rate, flattened neck ( rapid heart rate, flattened neck veins, and normal or veins, and normal or ↓↓ B.P. – B.P. – shock)shock)

3535

Isotonic fluid excessIsotonic fluid excess– Excess IV fluidsExcess IV fluids– Hypersecretion of aldosteroneHypersecretion of aldosterone– Effect of drugs – cortisoneEffect of drugs – cortisone

Hypervolemia – weight gain, decreased Hypervolemia – weight gain, decreased hematocrit, diluted plasma proteins, hematocrit, diluted plasma proteins, distended neck veins, distended neck veins, ↑ B.P.↑ B.P.

Can lead to edema (↑ capillary Can lead to edema (↑ capillary hydrostatic pressure) pulmonary edema hydrostatic pressure) pulmonary edema and heart failureand heart failure

3636

Electrolyte Electrolyte imbalances: Sodiumimbalances: Sodium Hypernatremia (high levels of Hypernatremia (high levels of

sodium)sodium)– Plasma Na+ > 145 mEq / LPlasma Na+ > 145 mEq / L– Due to Due to ↑ ↑ Na + or Na + or ↓↓ water water– Water moves from ICF Water moves from ICF → → ECFECF– Cells dehydrateCells dehydrate

3737

3838

Hypernatremia Due to:Hypernatremia Due to:– Hypertonic IV soln.Hypertonic IV soln.– Oversecretion of aldosteroneOversecretion of aldosterone– Loss of pure waterLoss of pure water

Long term sweating with chronic Long term sweating with chronic feverfever

Respiratory infection Respiratory infection → → water water vapor lossvapor loss

Diabetes – polyuriaDiabetes – polyuria– Insufficient intake of water Insufficient intake of water

(hypodipsia)(hypodipsia)3939

Clinical manifestationsClinical manifestationsof Hypernatremiaof Hypernatremia

ThirstThirst LethargyLethargy Neurological dysfunction due to Neurological dysfunction due to

dehydration of brain cellsdehydration of brain cells Decreased vascular volumeDecreased vascular volume

4040

Treatment of Treatment of HypernatremiaHypernatremia Lower serum Na+Lower serum Na+

– Isotonic salt-free IV fluidIsotonic salt-free IV fluid– Oral solutions preferable Oral solutions preferable

4141

HyponatremiaHyponatremia Overall decrease in Na+ in ECFOverall decrease in Na+ in ECF Two types: depletional and dilutionalTwo types: depletional and dilutional Depletional HyponatremiaDepletional Hyponatremia

Na+ loss:Na+ loss:– diuretics, chronic vomitingdiuretics, chronic vomiting– Chronic diarrheaChronic diarrhea– Decreased aldosteroneDecreased aldosterone– Decreased Na+ intakeDecreased Na+ intake

4242

Dilutional Hyponatremia:Dilutional Hyponatremia:– Renal dysfunction with Renal dysfunction with ↑ intake of ↑ intake of

hypotonic fluidshypotonic fluids– Excessive sweatingExcessive sweating→ → increased thirst increased thirst → →

intake of excessive amounts of pure intake of excessive amounts of pure waterwater

– Syndrome of Inappropriate ADH (SIADH) Syndrome of Inappropriate ADH (SIADH) or oliguric renal failure, severe or oliguric renal failure, severe congestive heart failure, cirrhosis all congestive heart failure, cirrhosis all lead to:lead to: Impaired renal excretion of waterImpaired renal excretion of water

– Hyperglycemia – attracts waterHyperglycemia – attracts water4343

Clinical manifestations of Clinical manifestations of HyponatremiaHyponatremia

Neurological symptomsNeurological symptoms– Lethargy, headache, confusion, apprehension, Lethargy, headache, confusion, apprehension,

depressed reflexes, seizures and comadepressed reflexes, seizures and coma Muscle symptoms Muscle symptoms

– Cramps, weakness, fatigueCramps, weakness, fatigue Gastrointestinal symptomsGastrointestinal symptoms

– Nausea, vomiting, abdominal cramps, and diarrheaNausea, vomiting, abdominal cramps, and diarrhea

4444

HypokalemiaHypokalemia

Serum KSerum K++ < 3.5 mEq /L < 3.5 mEq /L Beware if diabeticBeware if diabetic

– Insulin gets KInsulin gets K++ into cell into cell– Ketoacidosis – HKetoacidosis – H++ replaces K replaces K++, ,

which is lost in urinewhich is lost in urine ββ – adrenergic drugs or – adrenergic drugs or

epinephrineepinephrine4545

Causes of HypokalemiaCauses of Hypokalemia

Decreased intake of KDecreased intake of K++

Increased KIncreased K++ loss loss– Chronic diureticsChronic diuretics– Acid/base imbalanceAcid/base imbalance– Trauma and stressTrauma and stress– Increased aldosteroneIncreased aldosterone– Redistribution between ICF and Redistribution between ICF and

ECF ECF 4646

Clinical manifestations of Clinical manifestations of HypokalemiaHypokalemia

Neuromuscular disordersNeuromuscular disorders– Weakness, flaccid paralysis, respiratory arrest, Weakness, flaccid paralysis, respiratory arrest,

constipationconstipation Dysrhythmias, appearance of U waveDysrhythmias, appearance of U wave Postural hypotensionPostural hypotension Cardiac arrestCardiac arrest Treatment-Treatment-

– Increase KIncrease K++ intake, but intake, but slowlyslowly, preferably by , preferably by foodsfoods

4747

HyperkalemiaHyperkalemia Serum K+ > 5.5 mEq / LSerum K+ > 5.5 mEq / L Check for renal diseaseCheck for renal disease Massive cellular traumaMassive cellular trauma Insulin deficiencyInsulin deficiency Addison’s disease Addison’s disease Potassium sparing diureticsPotassium sparing diuretics Decreased blood pHDecreased blood pH Exercise causes K+ to move out of cellsExercise causes K+ to move out of cells

4848

Clinical manifestations of Clinical manifestations of HyperkalemiaHyperkalemia

Early – hyperactive muscles , Early – hyperactive muscles , paresthesiaparesthesia

Late - Muscle weakness, flaccid Late - Muscle weakness, flaccid paralysisparalysis

Change in ECG patternChange in ECG pattern DysrhythmiasDysrhythmias Bradycardia , heart block, cardiac Bradycardia , heart block, cardiac

arrestarrest

4949

Treatment of Treatment of HyperkalemiaHyperkalemia

Decrease intake and increase Decrease intake and increase renal excretionrenal excretion

Insulin + glucoseInsulin + glucose BicarbonateBicarbonate CaCa++++ counters effect on heart counters effect on heart

5050

Calcium ImbalancesCalcium Imbalances Most in ECFMost in ECF Regulated by:Regulated by:

– Parathyroid hormoneParathyroid hormone↑↑Blood CaBlood Ca++++ by stimulating by stimulating osteoclastsosteoclasts

↑↑GI absorption and renal GI absorption and renal retentionretention

– Calcitonin from the thyroid glandCalcitonin from the thyroid glandPromotes bone formationPromotes bone formation↑ ↑ renal excretionrenal excretion

5151

HypercalcemiaHypercalcemia Results from:Results from:

– Hyperparathyroidism Hyperparathyroidism – Hypothyroid statesHypothyroid states– Renal diseaseRenal disease– Excessive intake of vitamin DExcessive intake of vitamin D– Milk-alkali syndromeMilk-alkali syndrome– Certain drugsCertain drugs– Malignant tumors – hypercalcemia of malignancyMalignant tumors – hypercalcemia of malignancy

Tumor products promote bone breakdownTumor products promote bone breakdown Tumor growth in bone causing CaTumor growth in bone causing Ca++++ release release

5252

HypercalcemiaHypercalcemia Usually also see hypophosphatemiaUsually also see hypophosphatemia Effects:Effects:

– Many nonspecific – fatigue, weakness, lethargyMany nonspecific – fatigue, weakness, lethargy– Increases formation of kidney stones and pancreatic Increases formation of kidney stones and pancreatic

stonesstones– Muscle crampsMuscle cramps– Bradycardia, cardiac arrestBradycardia, cardiac arrest– PainPain– GI activity also commonGI activity also common

Nausea, abdominal crampsNausea, abdominal cramps Diarrhea / constipationDiarrhea / constipation

– Metastatic calcificationMetastatic calcification5353

HypocalcemiaHypocalcemia Hyperactive neuromuscular reflexes and tetany Hyperactive neuromuscular reflexes and tetany

differentiate it from hypercalcemiadifferentiate it from hypercalcemia Convulsions in severe casesConvulsions in severe cases Caused by:Caused by:

– Renal failureRenal failure– Lack of vitamin DLack of vitamin D– Suppression of parathyroid functionSuppression of parathyroid function– Hypersecretion of calcitoninHypersecretion of calcitonin– Malabsorption statesMalabsorption states– Abnormal intestinal acidity and acid/ base bal.Abnormal intestinal acidity and acid/ base bal.– Widespread infection or peritoneal inflammationWidespread infection or peritoneal inflammation

5454

HypocalcemiaHypocalcemia Diagnosis:Diagnosis:

– Chvostek’s sign– Trousseau’s sign

TreatmentTreatment– IV calcium for acuteIV calcium for acute– Oral calcium and vitamin D for chronicOral calcium and vitamin D for chronic

5555