Ch 17 Fluid and Electrolytes

8/13/2019 Ch 17 Fluid and Electrolytes

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Copyright 2010, 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved.

Focus on

Fluid and Electrolytes(Relates to Chapter 17,

Fluid, Electrolytes, and Acid-Base Imbalances,

in the textbook)


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Homeostasis State of equilibrium in body Naturally maintained by adaptive

responses Body fluids and electrolytes are

maintained within narrow limits


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Water Content of the Body

60% of body weight in adult

45% to 55% in older adults 70% to 80% in infants

Varies with gender, body mass, andage


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Changes in Water Content with Age

Fig. 17-1


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Fluid Compartments of the Body

Fig. 17-2


7/125Copyright 2010, 2007, 2004, 2000, Mosby, Inc., an affiliate of Elsevier Inc. All Rights Reserved.

Intracellular Fluid (ICF)

Located within cells

42% of body weight



Extracellular Fluid (ECF)

One third of body weight

Between cells (interstitial fluid),lymph, plasma, and transcellular

fluid



Transcellular Fluid

Part of ECF

Small but important Approximately 1 L



Transcellular Fluid (Contd)

Includes fluid in Cerebrospinal fluid Gastrointestinal tract Pleural spaces Synovial spaces Peritoneal fluid spaces



Electrolytes

Substances whose molecules

dissociate into ions (chargedparticles) when placed into water Cations: positively charged Anions: negatively charged



Measurement of Electrolytes

International standard is millimoles

per liter (mmol/L) U.S. uses milliequivalent (mEq)

Ions combine mEq for mEq



Electrolyte Composition

ICF Prevalent cation is K+

Prevalent anion is PO43

ECF Prevalent cation is Na+

Prevalent anion is Cl



Mechanisms Controlling Fluid and

Electrolyte Movement Diffusion Facilitated diffusion Active transport Osmosis Hydrostatic pressure Oncotic pressure



Diffusion

Movement of molecules from high

to low concentration Occurs in liquids, solids, and gases Membrane separating two areas must

be permeable to diffusing substance Requires no energy



Diffusion (Contd)

Fig. 17-4



Facilitated Diffusion

Movement of molecules from high

to low concentration without energy Uses specific carrier molecules to

accelerate diffusion



Active Transport

Process in which molecules move

against concentration gradient Example: sodiumpotassium pump External energy required



Sodium-Potassium Pump

Fig. 17-5


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Osmosis

Movement of water between twocompartments by a membranepermeable to water but not to solute

Moves from low solute to highsolute concentration

Requires no energy


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Osmosis (Contd)

Fig. 17-6


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Osmotic Pressure

Amount of pressure required to stop

osmotic flow of water Determined by concentration ofsolutes in solution


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Hydrostatic Pressure

Force within a fluid compartment

Major force that pushes water out ofvascular system at capillary level


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Oncotic Pressure

Osmotic pressure exerted by colloids

in solution (colloidal osmoticpressure) Protein is major colloid


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Fluid Movement in Capillaries

Amount and direction of movement

determined by Capillary hydrostatic pressure Plasma oncotic pressure Interstitial hydrostatic pressure Interstitial oncotic pressure


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Fluid Exchange Between Capillary

and Tissue

Fig. 17-8


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Fluid Shifts

Plasma to interstitial fluid shift

results in edema Elevation of hydrostatic pressure Decrease in plasma oncotic pressure Elevation of interstitial oncotic

pressure


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Fluid Shifts (Contd)

Interstitial fluid to plasma Fluid drawn into plasma space with

increase in plasma osmotic or oncoticpressure

Compression stockings decrease

peripheral edema


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Fluid Movement between

ECF and ICF Water deficit (increased ECF)

Associated with symptoms that resultfrom cell shrinkage as water is pulledinto vascular system


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Fluid Movement between

ECF and ICF (Contd) Water excess (decreased ECF)

Develops from gain or retention ofexcess water


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Fluid Spacing

First spacing Normal distribution of fluid in ICF and

ECF

Second spacing Abnormal accumulation of interstitial

fluid (edema)


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Fluid Spacing (Contd)

Third spacing Fluid accumulation in part of body

where it is not easily exchanged withECF


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Regulation of Water Balance

Hypothalamic regulation

Pituitary regulation

Adrenal cortical regulation

Renal regulation


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Regulation of Water Balance (Contd)

Cardiac regulation

Gastrointestinal regulation

Insensible water loss


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Hypothalamic Regulation

Osmoreceptors in hypothalamussense fluid deficit or increase Stimulates thirst and antidiuretic

hormone (ADH) release Result in increased free water and

decreased plasma osmolarity


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Pituitary Regulation

Under control of hypothalamus,posterior pituitary releases ADH

Stress, nausea, nicotine, and

morphine also stimulate ADH

release


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Adrenal Cortical Regulation

Releases hormones to regulatewater and electrolytes Glucocorticoids

Cortisol

Mineralocorticoids Aldosterone


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Factors Affecting Aldosterone

Secretion

Fig. 17-9


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Renal Regulation

Primary organs for regulating fluidand electrolyte balance Adjusting urine volume

Selective reabsorption of water and

electrolytes

Renal tubules are sites of action of ADHand aldosterone


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Effects of Stress on F&E Balance

Fig. 17-10


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Cardiac Regulation

Natriuretic peptides are antagoniststo the RAAS Produced by cardiomyocytes in

response to increased atrial pressure Suppress secretion of aldosterone,

renin, and ADH to decrease bloodvolume and pressure


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Gastrointestinal Regulation

Oral intake accounts for most water

Small amounts of water are

eliminated by gastrointestinal tract

in feces

Diarrhea and vomiting can lead tosignificant fluid and electrolyte loss


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Insensible Water Loss

Invisible vaporization from lungs andskin to regulate body temperature Approximately 600 to 900 ml/day

is lost No electrolytes are lost


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Gerontologic Considerations

Structural changes in kidneysdecrease ability to conserve water

Hormonal changes lead to decrease

in ADH and ANP

Loss of subcutaneous tissue leads toincreased loss of moisture


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Gerontologic Considerations (Contd)

Reduced thirst mechanism results indecreased fluid intake

Nurse must assess for these changes

and implement treatment

accordingly


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Fluid and Electrolyte Imbalances

Common in most patients withillness Directly caused by illness or disease

(burns or heart failure) Result of therapeutic measures

(IV fluid replacement or diuretics)


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Extracellular Fluid Volume

Imbalances ECF volume deficit (hypovolemia)

Abnormal loss of normal body fluids(diarrhea, fistula drainage,hemorrhage), inadequate intake, orplasma-to-interstitial fluid shift

Treatment: replace water andelectrolytes with balanced IV solutions


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Extracellular Fluid Volume

Imbalances (Contd) Fluid volume excess (hypervolemia)

Excessive intake of fluids, abnormalretention of fluids (CHF), or interstitial-to-plasma fluid shift

Treatment: remove fluid without

changing electrolyte composition orosmolality of ECF


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Nursing Management

Nursing Diagnoses Hypovolemia

Deficient fluid volume Decreased cardiac output Potential complication: hypovolemic

shock


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Nursing Management

Nursing Diagnoses (Contd) Hypervolemia

Excess fluid volume Ineffective airway clearance Risk for impaired skin integrity Disturbed body image

Potential complications: pulmonaryedema, ascites


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Nursing Management

Nursing Implementation I&O

Monitor cardiovascular changes

Assess respiratory status and

monitor changes

Daily weights

Skin assessment


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Nursing Management

Nursing Implementation (Contd) Neurologic function

LOC PERLA Voluntary movement of extremities Muscle strength

Reflexes


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Electrolyte Disorders

Signs and SymptomsElectrolyte Excess Deficit

Sodium (Na) Hypernatremia

Thirst

CNS deterioration

Increased interstitial fluid

Hyponatremia

CNS deterioration

Potassium (K) Hyperkalemia

Ventricular fibrillationECG changes

CNS changes

Hypokalemia

BradycardiaECG changes

CNS changes


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Electrolyte Disorders

Signs and Symptoms (Contd)Electrolyte Excess Deficit

Calcium (Ca) Hypercalcemia

Thirst

CNS deterioration

Increased interstitial fluid

Hypocalcemia

Tetany

Chvosteks, Trousseaus signs

Muscle twitching

CNS changes

ECG changes

Magnesium

(Mg)

Hypermagnesemia

Loss of deep tendon reflexes(DTRs)

Depression of CNS

Depression of neuromuscular

function

Hypomagnesemia

Hyperactive DTRsCNS changes


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Sodium

Imbalances typically associatedwith parallel changes in osmolality

Plays a major role in ECF volume and concentration Generation and transmission of

nerve impulses Acidbase balance


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Hypernatremia

Elevated serum sodium occurringwith water loss or sodium gain

Causes hyperosmolality leading to

cellular dehydration

Primary protection is thirst from

hypothalamus


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Differential Assessment of

ECF VolumeFig. 17-12


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Imbalances in ECF Volume

Fig. 17-13


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Hypernatremia

Manifestations Thirst, lethargy, agitation, seizures,

and coma Impaired LOC Produced by clinical states

Central or nephrogenic diabetesinsipidus


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Hypernatremia (Contd)

Serum sodium levels must bereduced gradually to avoid cerebral

edema


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Nursing Management

Nursing Diagnoses Risk for injury

Potential complication: seizures and

coma leading to irreversible brain

damage


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Nursing Management

Nursing Implementation Treat underlying cause

If oral fluids cannot be ingested, IV

solution of 5% dextrose in water or

hypotonic saline

Diuretics


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Hyponatremia

Results from loss of sodium-containing fluids or from water

excess

Manifestations Confusion, nausea, vomiting, seizures,

and coma


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Nursing Management


Potential complication: severe

neurologic changes


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Nursing Management

Nursing Implementation Caused by water excess

Fluid restriction is needed

Severe symptoms (seizures) Give small amount of IV hypertonic

saline solution (3% NaCl)


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Nursing Management

Nursing Implementation (Contd) Abnormal fluid loss

Fluid replacement with sodium-

containing solution


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Potassium

Major ICF cation

Necessary for Transmission and conduction of nerve

and muscle impulses Maintenance of cardiac rhythms

Acidbase balance


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Potassium (Contd)

Sources Fruits and vegetables (bananas and

oranges) Salt substitutes Potassium medications (PO, IV)

Stored blood


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Hyperkalemia

High serum potassium caused by Massive intake Impaired renal excretion Shift from ICF to ECF

Common in massive cell destruction Burn, crush injury, or tumor lysis


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Hyperkalemia (Contd)

Manifestations Weak or paralyzed skeletal muscles Ventricular fibrillation or cardiac

standstill Abdominal cramping or diarrhea


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Nursing Management


Potential complication:

dysrhythmias


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Nursing Management

Nursing Implementation Eliminate oral and parenteral K

intake

Increase elimination of K (diuretics,

dialysis, Kayexalate)


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Nursing Management

Nursing Implementation (Contd) Force K from ECF to ICF by IV insulin

or sodium bicarbonate

Reverse membrane effects of

elevated ECF potassium byadministering calcium gluconate IV


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Hypokalemia

Low serum potassium caused by Abnormal losses of K+via the kidneys

or gastrointestinal tract Magnesium deficiency Metabolic alkalosis


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Hypokalemia (Contd)

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


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Nursing Management



dysrhythmias


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Nursing Management

Nursing Implementation KCl supplements orally or IV

Should not exceed 10 to 20 mEq/hr To prevent hyperkalemia and cardiac

arrest


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Calcium

Obtained from ingested foods More than 99% combined with

phosphorus and concentrated inskeletal system

Inverse relationship with

phosphorus


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Calcium (Contd)

Bones are readily available store Blocks sodium transport and

stabilizes cell membrane Ionized form is biologically active


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Calcium (Contd)

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

Muscle contractions


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Calcium (Contd)

Balance controlled by Parathyroid hormone Calcitonin Vitamin D


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Hypercalcemia

High serum calcium levels caused by Hyperparathyroidism (two thirds of

cases) Malignancy Vitamin D overdose

Prolonged immobilization


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Hypercalcemia (Contd)

Manifestations Decreased memory Confusion Disorientation Fatigue

Constipation


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Nursing Management



dysrhythmias


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Nursing Management

Nursing Implementation Excretion of Ca with loop diuretic

Hydration with isotonic saline

infusion Synthetic calcitonin

Mobilization


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Hypocalcemia

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

Decreased intake


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Hypocalcemia (Contd)

Manifestations Positive Trousseaus or Chvosteks sign Laryngeal stridor Dysphagia Tingling around the mouth or in the

extremities


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Tests for Hypocalcemia

Fig. 17-15


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Nursing Management


Potential complication: fracture or

respiratory arrest


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Nursing Management

Nursing Implementation Treat cause

Oral or IV calcium supplements Not IM to avoid local reactions

Treat pain and anxiety to preventhyperventilation-induced

respiratory alkalosis


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Phosphate

Primary anion in ICF

Essential to function of muscle, red

blood cells, and nervous system Deposited with calcium for bone and

tooth structure


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Phosphate (Contd)

Involved in acidbase bufferingsystem, ATP production, and

cellular uptake of glucose Maintenance requires adequate

renal functioning

Essential to muscle, RBCs, and

nervous system function


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Hyperphosphatemia

High serum PO43 caused by

Acute or chronic renal failure Chemotherapy Excessive ingestion of phosphate or

vitamin D


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Hyperphosphatemia (Contd)

Manifestations Calcified deposition in soft tissue such

as joints, arteries, skin, kidneys, andcorneas

Neuromuscular irritability and tetany


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Hyperphosphatemia (Contd)

Management Identify and treat underlying cause Restrict foods and fluids containing

PO43

Adequate hydration and correction of

hypocalcemic conditions


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Hypophosphatemia (Contd)

Low serum PO43 caused by

Malnourishment/malabsorption Alcohol withdrawal Use of phosphate-binding antacids During parenteral nutrition with

inadequate replacement


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Manifestations CNS depression Confusion Muscle weakness and pain Dysrhythmias

Cardiomyopathy


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Management Oral supplementation

Ingestion of foods high in PO43

IV administration of sodium orpotassium phosphate


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Magnesium

50% to 60% contained in bone

Coenzyme in metabolism of protein

and carbohydrates Factors that regulate calcium

balance appear to influence

magnesium balance


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Magnesium (Contd)

Acts directly on myoneural junction

Important for normal cardiac

function


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Hypermagnesemia

High serum Mg caused by Increased intake or ingestion of

products containing magnesium whenrenal insufficiency or failure is present


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Hypermagnesemia (Contd)

Manifestations Lethargy or drowsiness

Nausea/vomiting Impaired reflexes Respiratory and cardiac arrest


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Hypermagnesemia (Contd)

Management Prevention

Emergency treatment IV CaCl or calcium gluconate

Fluids to promote urinary excretion


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Hypomagnesemia (Contd)

Low serum Mg caused by Prolonged fasting or starvation

Chronic alcoholism Fluid loss from gastrointestinal tract Prolonged parenteral nutrition

without supplementation Diuretics


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Manifestations Confusion

Hyperactive deep tendon reflexes Tremors Seizures

Cardiac dysrhythmias


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Management Oral supplements

Increase dietary intake Parenteral IV or IM magnesium when

severe


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IV Fluids

Purposes1. Maintenance

When oral intake is not adequate2. Replacement When losses have occurred


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IV Fluids (Contd)

Hypotonic More water than electrolytes

Pure water lyses RBCs Water moves from ECF to ICF by

osmosis

Usually maintenance fluids


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IV Fluids (Contd)

Isotonic Expands only ECF

No net loss or gain from ICF


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IV Fluids (Contd)

Hypertonic Initially expands and raises the

osmolality of ECF Require frequent monitoring of

Blood pressure

Lung sounds Serum sodium levels


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D5W

Isotonic Provides 170 cal/L

Free water Moves into ICF Increases renal solute excretion


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D5W (Contd)

Used to replace water losses andtreat hyponatremia

Does not provide electrolytes


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Normal Saline (NS)

Isotonic

No calories

More NaCl than ECF 30% stays in IV (most)

70% moves out of IV


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Normal Saline (NS) (Contd)

Expands IV volume Preferred fluid for immediate response

Risk for fluid overload higher Does not change ICF volume Blood products

Compatible with most medications


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Lactated Ringers

Isotonic

More similar to plasma than NS Has less NaCl Has K, Ca, PO4

3, lactate (metabolizedto HCO3)

Expands ECF


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D5 NS

Hypertonic

Common maintenance fluid

KCl added for maintenance orreplacement


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D10W

Hypertonic

Provides 340 kcal/L

Free water Limit of dextrose concentration may

be infused peripherally


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Plasma Expanders

Stay in vascular space and increaseosmotic pressure

Colloids (protein solutions) Packed RBCs Albumin

Plasma


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Case Study


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Case Study

76-year-old male is brought toemergency department with

confusion and lethargy

He has a history of chronic heart

failure, type 2 diabetes, andhypertension


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Case Study (Contd)

Lab values reveal low potassiumlevels and Hct 56%

Poor skin turgor

BP 110/58 mm Hg


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Case Study (Contd)

Heart rate 135 beats/min

Respiratory rate 26 breaths/min

Temperature 99F

Recent flu


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Case Study (Contd)

Patient forgot he took furosemide(Lasix) and doubled dose twice in 1

week

Started on 0.45 NaCl and IV

potassium chloride


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Discussion Questions

1. What important teaching shouldbe done with him?

2. What resources are available tohelp him manage his medications?

Ch 17 Fluid and Electrolytes

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