Ebook Fluids and electrolytes with clinical application (8/E): Part 2

(BQ) Part 2 book Fluids and electrolytes with clinical application has contents: Metabolic acidosis and alkalosis, respiratory acidosis and alkalosis, respiratory acidosis and alkalosis, fluid problems of the older adult,... and other contens.

C H A P T E R

and Alkalosis

Metabolic Acidosis and Alkalosis

William C Rose, PhD

INTRODUCTION

Two types of metabolic acid-base imbalance are

metabolic acidosis and metabolic alkalosis With

metabolic acidosis, there is either an excess acidproduction, e.g., excess hydrogen ions and ketonebodies, or a base (bicarbonate) deficit With meta-bolic alkalosis, there is an acid (hydrogen ion)deficit or (more likely) a base (bicarbonate) excess.Metabolic acidosis and metabolic alkalosis are dis-cussed separately in this chapter

The laboratory values most useful for identifying metabolic

.The laboratory value for identifying respiratory acidosis and

Acid-base balance is maintained by 1 part of acid and

20 parts of base Figure 13-1 demonstrates the normalacid-base balance, and the blood tests for pH, , baseexcess (BE), are utilized in determining metabolic acidosisand alkalosis

4.

When the acid-base scale tips to the left, it is an indication

When the scale tips to the right, the type of acid-base

5.

H(Acid)

(Acid)

(Acid)HCO 3

(Bicarbonate)

Deficit

HCO

pHHCO , BE

pHHCO , BE

-+

+

7. decreased; excess; less

Metabolic alkalosis is characterized by a(n)(increased/decreased) bicarbonateconcentration or loss of hydrogen ions (strong acid) in theextracellular fluid

to the questions Refer to the tables as needed

11.

With severe or chronic diarrhea, the anion that is lost from the

in excess of the chloride ions The chloride ions combine with

Shock, trauma, severe infection, and fever can cause cellular

frequently released from the cells are

12. Nonvolatile acids such as

lactic acid result from

cellular breakdown.

13. The liver produces fatty

acids, which leads to

ketone body production.

Chronic diarrhea Loss of bicarbonate ions in the small intestines is in excess Also, the

loss of sodium ions exceeds that of chloride ions combines with , producing a strong acid (HCl).

Renal Abnormalities

Kidney failure Kidney mechanisms for conserving sodium and water and for

excreting fail.

Hormonal Influence

Diabetic ketoacidosis Failure to metabolize adequate quantities of glucose causes the liver to

increase metabolism of fatty acids Oxidation of fatty acids produces ketone bodies which cause the ECF to become more acid Ketones require a base for excretion.

Hyperthyroidism, thyrotoxicosis An overactive thyroid gland can cause cellular catabolism (breakdown)

due to a severe increase in metabolism which increases cellular needs.

Others

Trauma, shock Trauma and shock cause cellular breakdown and the release

of acids.

Excess exercise, severe infection, Excessive exercise, fever, and severe infection can cause cellular

fever catabolism and acid accumulation.

Table 13-2 Causes of Metabolic Alkalosis

Gastrointestinal Abnormalities

Vomiting, gastric suction With vomiting and gastric suctioning, large amounts of chloride and

hydrogen ions that are plentiful in the stomach are lost Bicarbonate anions increase to compensate for chloride loss.

Peptic ulcers Excess of alkali in ECF occurs when a patient ingests excessive amounts

of acid neutralizers such as NaHCO3to ease ulcer pain.

Hypokalemia Loss of potassium from the body is accompanied by loss of chloride.

a Diabetic ketoacidosis

b Overtreated peptic ulcer

c Severe diarrhea

d Shock, trauma

e Vomiting, gastric suction

f Fever, severe infection

g Excessive exercise

CLINICAL APPLICATIONS

Anion gap is a useful indicator for determining the

pres-ence or abspres-ence or metabolic acidosis

used to compute the anion gap, as follows:

Anion gap (mEq/L)⫽[Na⫹]⫹[K⫹]⫺[Cl⫺]⫺[HCO3⫺]

17. overtreated peptic ulcer,

vomiting, gastric suction,

and loss of potassium

18. a M Ac; b M Al;

c M Ac; d M Ac;

e M Al; f M Ac;

g M Ac

If the anion gap is greater than 20 mEq/L, metabolic acidosis

is suspected

Which of the following acid-base imbalances are indicated

by an anion gap that exceeds 20 mEq/L:

20.

A patient’s serum values are Na, 142 mEq/L; K, 4mEq/L; Cl,

21.

Conditions associated with an anion gap that is greater than

20 mEq/L are diabetic ketoacidosis, lactic acidosis, poisoning,and renal failure

Indicate which of the following conditions might apply to ananion gap of 25 mEq/L:

26 mEq/L; yes; The anion

gap is greater than 20

mEq/L.

21.a, d, e, f

22.metabolic alkalosis;

There is excess alkali in

the extracellular fluid.

142 ⫹ 4 ⫺ 102 ⫺ 18 ⫽

is a respiratory compensatory mechanism for the purpose

of decreasing acid content in the blood

With metabolic alkalosis, excitability of the CNS occurs.These symptoms may include irritability, mental confusion,tetany-like symptoms, and hyperactive reflexes Hypoventi-lation may occur, and it acts as a compensatory mechanismfor metabolic alkalosis and conserves the hydrogen ionsand carbonic acid

Table 13-3 lists the clinical manifestations related tometabolic acidosis and alkalosis Study the table and refer

to it as needed when answering the questions

23.

With metabolic acidosis, the CNS is (depressed/excited)

.With metabolic alkalosis, the CNS is (depressed/excited)

23. depressed; excited

Table 13-3 Clinical Manifestations of Metabolic Acidosis

and Metabolic Alkalosis

disorientation, stupor, coma symptoms, hyperactive reflexes

vigorous breathing

heart rate and cardiac output

Indicate which of the following CNS abnormalities areassociated with metabolic acidosis (M Ac) and metabolicalkalosis (M Al)

establish balance

.When these two mechanisms fail, what happens to the

plasma pH?

27.

acid excess; decreased.

26.The kidneys excrete

more and retain

28. The kidneys excrete

more bicarbonate and

acid excess; acid;

a Lungs blow off CO2or

acid; b Kidneys excrete

acid or and conserve

bicarbonate

30. remove cause,

administer IV alkali

solution (e.g., NaHCO3),

and restore H2O and

.When these mechanisms fail, what happens to the plasma pH?

CLINICAL MANAGEMENT

Figure 13-2 outlines the body’s normal defense actions andvarious methods of treatment for restoring balance in meta-bolic acidosis and alkalosis Study this figure carefully, withparticular attention to the cause of each imbalance, thebody’s defense action, the pH of the urine as to whether it

is acidic or alkaline, and the treatment for these ances Refer to the figure whenever you find it necessary

imbal-29.

What is metabolic acidosis?

What are the body’s defense actions against it?

What is metabolic alkalosis?

What are the body’s defense actions against it?

Treatment: Remove the cause Administer an IV alkali solution, e.g., sodium bicarbonate

or sodium lactate Restore water, electrolytes, and nutrients.

Treatment: Remove the cause Administer an IV solution of chloride, e.g., sodium chloride.

Replace potassium deficit.

Metabolic Acidosis(Deficit of bicarbonate or excess acid in the extracellular fluid)

Metabolic Alkalosis(Excess of bicarbonate in the extracellular fluid)

Kidney

Kidney

( ) a Bicarbonate excess( ) b Bicarbonate deficit( ) c Carbonic acid excess( ) d Carbonic acid deficit

imbal-ance due to

Later her pH is 7.34, PaCO2is 31, and HCO3is 20 Fluid withsodium bicarbonate was given IV As a nurse, you should re-assess her laboratory findings

6. rapid, vigorous breathing

and excretion of acid

urine

7. inadequate excretion H⫹

PLAN

METABOLIC ACIDOSIS AND METABOLIC ALKALOSIS

Assessment Factors

occur-ring Recognize the patient’s health problems that are ciated with metabolic acidosis, i.e., starvation, severe orchronic diarrhea, kidney failure, diabetic ketoacidosis, se-vere infection, trauma, and shock, and with metabolic alka-losis, i.e., vomiting, gastric suction, peptic ulcer, andelectrolyte imbalance (hypokalemia, hypochloremia) Poi-soning, either accidental or through intentional self harm,can cause metabolic acidosis or alkalosis, depending onthe substance ingested

and base excess ( 2 mEq/L) are indicative of metabolic

(2 mEq/L) are indicative of metabolic alkalosis

signs Note if there are any cardiac dysrhythmias and/orbradycardia that may result from a severe acidotic state.Check respirations for Kussmaul breathing This is a sign

of metabolic acidosis; such as diabetic ketoacidosis

9.yes; Lungs are blowing

off CO2and less CO2

means less carbonic acid.

10.Sodium bicarbonate

restores the bicarbonate

level in ECF.

Metabolic Acidosis Nursing Diagnosis 1

Imbalanced nutrition: less than body requirements tional intake insufficient to meet metabolic needs

Nutri-Interventions and Rationale

fluid intake

sugar, and arterial blood gases (ABGs) Some abnormal ings associated with metabolic acidosis are hyperkalemia,decreased base excess, elevated blood sugar (slightly ele-vated with trauma and shock and highly elevated withuncontrolled diabetes mellitus), and decreased arterial bi-

respi-rations that relate to diabetic ketoacidosis or severe shock.Compare results of vital signs with baseline findings

acido-sis, i.e., CNS depression (apathy, restlessness, weakness,dis-orientation, stupor); deep, rapid, vigorous breath-ing (Kussmaul respirations); and flushing of the skin(vasodilation resulting from sympathetic nervous systemdepression)

bi-carbonate as prescribed by the healthcare provider tocorrect severe acidotic state

Nursing Diagnosis 2

Deficient fluid volume related to nausea, vomiting, and creased urine output

in-Interventions and Rationale

dys-rhythmia During severe acidosis, the heart rate decreasesand dysrhythmias can occur causing a decrease in cardiacoutput

⬍7.35

⬍24

Nursing Diagnosis 3

Impaired memory related to disorientation, weakness, andstupor

Interventions and Rationale

in-creased disorientation and stupor

Metabolic Alkalosis Nursing Diagnosis 1

Deficient fluid volume related to vomiting or nasogastricsuctioning

Interventions and Rationale

fluid loss via vomiting and gastric suctioning Hydrogenand chloride are lost with the gastric secretions, whichincreases the pH level, causing metabolic alkalosis

0.45–0.9% sodium chloride (normal saline) Encourageoral fluids if able to retain and as prescribed by thehealthcare provider

state is present

shal-low and sshal-low

neutralizers that contain bicarbonate compounds, such asBromo-Seltzer

CNS excitability (tetany-like symptoms, irritability, sion, hyperactive reflexes) and shallow breathing

confu-Risk for injury related to CNS excitability secondary tometabolic alkalosis.

Interventions and Rationale

irritable, such as bedside rails and assistance with basicneeds

tetany-like symptoms

Evaluation/Outcomes

alkalosis has been corrected or controlled

acidosis or metabolic alkalosis: patient’s ABGs are ing to or have returned to normal range

of metabolic acidosis and metabolic alkalosis; vital signshave returned to normal range, especially respiration

living

C H A P T E R

and Alkalosis

Respiratory Acidosis and Alkalosis

William C Rose, PhD

INTRODUCTION

Two types of respiratory acid-base imbalance are

respiratory acidosis and respiratory alkalosis

Res-piratory acidosis is mainly due to acid excess, ticularly carbonic acid (H2CO3) The major problemcausing respiratory acidosis is carbon dioxide (CO2)retention due to a respiratory disorder With respi-ratory alkalosis, there is a bicarbonate deficit Theresult of respiratory alkalosis is mostly due to aloss of carbonic acid Blowing off of CO2can be due

par-to increased anxiety (overbreathing), excess cise, etc Respiratory acidosis and respiratory alka-losis are discussed separately in this chapter

respiratory acidosis and alkalosis

The pH of arterial blood gases (ABGs) can determine the

4.

PATHOPHYSIOLOGY

5.

Respiratory acidosis is characterized by a(n)

extracellular fluid

6.

Respiratory alkalosis is characterized by a decrease in the

de-7. more; 45; less; 35

HCO 3

H CO(Acid) 3

(Bicarbonate)

Deficit

HCO

pH PaCO

Explain how an inadequate exchange of gases in the lungs can

9.

Narcotics, sedatives, chest injuries, respiratory distresssyndrome, pneumonia, and pulmonary edema can cause acuterespiratory acidosis Acute respiratory acidosis results from the

Causes of Respiratory Acidosis

chest injuries decreases CO2excretion, thus increasing carbonic acid

concentration.

Causes of Respiratory Alkalosis

Hyperventilation

Psychologic effects: anxiety, Excessive blowing off of CO2through the lungs results in

overbreathing hypocapnia (decreased partial pressure of CO2in the blood) Pain Overstimulation of the respiratory center in the medulla

Fever results in hyperventilation.

Brain tumors, meningitis, encephalitis

Early salicylate poisoning

With chronic obstructive pulmonary disease (COPD), the

hydrogen ions and conserving bicarbonate ions The type ofrespiratory acidosis that occurs with COPD is (acute/chronic)

plasma to maintain the bicarbonate-to-carbonic-acid ratio

Explain the difference between respiratory alkalosis and

*

*

9. chronic

10.These conditions weaken

the respiratory muscles,

Is there metabolic (renal) compensation?

an exam How do you think you might help with respiratory

CLINICAL MANIFESTATIONS

With respiratory acidosis, hypercapnia (elevated PaCO2)causes an increased pulse rate, an elevated blood pressure,and a reflex attempt to increase ventilation, which oftenmanifests as dyspnea (difficulty in breathing) The skinmay be warm and flushed due to vasodilation from the in-creased CO2concentration

When respiratory alkalosis occurs, there is CNS citability and a decrease in cerebral blood flow Tetany-likesymptoms and dizziness frequently result

hyperex-Table 14-3 lists the clinical manifestations related torespiratory acidosis and alkalosis Study the table carefully.Refer to the table as needed when answering the questions

17. Encourage the patient to

breathe slowly and

deeply There is a lack of

CO2, so giving CO2(e.g.,

rebreathing CO2from a

paper bag) can also help.

Respiratory patterns of breathing are clues to the type ofrespiratory acid-base imbalance

The characteristic breathing pattern associated with

Table 14-3 Clinical Manifestations of Respiratory Acidosis and

Respiratory Alkalosis

Tachycardia Palpitations Blood pressure

Depression, paranoia tingling of fingers and toes, positive Weakness Chvostek and Trousseau signs Stupor (later) Hyperactive reflexes

Vertigo (dizziness) Unconsciousness (later)

Laboratory Values

pH ⬍7.35 (when compensatory ⬎7.45 (when compensatory

mechanisms fail) mechanisms fail)

With respiratory acidosis, the renal and respiratorymechanisms try to re-establish balance

Explain how the renal mechanism works to compensate forthis imbalance

How do you think the renal mechanism works to

When these mechanisms fail, what happens to the blood pH?

*

CLINICAL MANAGEMENT

Figure 14-2 outlines the body’s normal defense actions andvarious methods of treatment for restoring balance in res-piratory acidosis and alkalosis Study the figure carefully,with particular attention to the factors causing the acid-base imbalances, the pH of the urine as to whether it is acid

or alkaline, and the treatment for these imbalances Refer

to the figure as needed

21. CO2 stimulates the

respiratory center to

attempt to increase the

rate and depth of

acidosis, the respiratory

system is affected and

not able to accomplish

this.); More acid is

excreted in the urine,

and less base

What is the basic cause of respiratory acidosis? *

In compensated respiratory acidosis, the urine is(acidic/alkaline)

a How does the respiratory system try to

Lungs are affected: insufficient gas

exchange and/or ventilation High

PaCO2 causes a reflexive attempt to

Urine is alkaline Kidneys excrete base (bicarbonate) and retain acid.

Treatment: Remove the cause Administer an IV alkali solution Deep breathing

exercise or use of a ventilator.

Treatment: Remove the cause Rebreathe expired air, e.g., CO , from a paper bag.

Antianxiety drugs, e.g., Valium (diazepam), Ativan (lorazepam).

Respiratory Acidosis(Excess of carbonic acid in the extracellular fluid)

Respiratory Alkalosis(Deficit of carbonic acid in the extracellular fluid due to hyperventilation)

Kidneys Compensate

Kidney

2

24. carbonic acid excess;

acidic; a There is an

attempt to increase

ventilation.

b Kidneys excrete acidic

urine and conserve base

(bicarbonate).

In compensated respiratory alkalosis, the urine is(acidic/alkaline)

if needed

25. Any three of: removal of

cause, deep breathing

alkaline; Kidneys excrete

base (HCO3) and retain

acid ( ).

27. removal of cause,

rebreathing expired air,

and antianxiety drugs,

e.g., Ativan (lorazepam)

and diazepam (Valium)

H⫹

5. Respiratory acidosis has a CO2(excess/deficit) ,

?

for increase, the arrow pointed downward for decrease,and—for not involved (except with compensation)

9. Yes; If compensation was

not present, the pH

Table 14-4 Summary of Acid-Base Imbalances

Clinical Manifestations

Kussmaul breathing (rapid and vigorous) Shallow breathing

Flushing of the skin (capillary dilation) Tetany-like symptoms (numbness,

Decrease in heart rate and cardiac output tingling of fingers)

Nausea, vomiting, abdominal pain Irritability, confusion

Laboratory Findings

pH ⬍7.35, HCO3⬍24 mEq/L, pH ⬎7.45, HCO3⬎28 mEq/L, BE⬎⫹2,

BE ⬍⫺2, plasma CO 2 ⬍ 22 mEq/L

Causes

Diabetic ketoacidosis, severe diarrhea or Peptic ulcer, vomiting, gastric suction starvation, tissue trauma, renal and heart

failure, shock, severe infection

Clinical Manifestations

Dyspnea, inadequate gas exchange Rapid shallow breathing

Flushing and warm skin Tetany-like symptoms (numbness,

Assessment Factors

the patient’s health problems that are associated with piratory acidosis, i.e., CNS depressant drugs (narcotics,sedatives, anesthetics), pneumonia, pulmonary edema, andchronic obstructive pulmonary disease (COPD) such as em-physema, chronic bronchitis, bronchiectasis, and severeasthma, and those associated with respiratory alkalosis,i.e., anxiety, fever, severe infection, aspirin toxicity, anddeliberate overbreathing

dyspnea, tachycardia, disorientation, weakness, stupor,and flushed and warm skin, and signs and symptoms re-lated to respiratory alkalosis, i.e., apprehension, rapid,shallow breathing, palpitations, tetany-like symptoms such

as numbness and tingling of the toes and fingers, tive reflexes, and dizziness

future vital signs

than 35 mm Hg is indicative of respiratory alkalosis port abnormal findings

Re-Respiratory Acidosis Nursing Diagnosis 1

Impaired gas exchange related to alveolar capillary brane changes.

mem-Interventions and Rationale

respi-ratory rate, distress, and breathing pattern

respira-tory acidosis If the bicarbonate level (HCO3) is greater than

28 mEq/L, then there is metabolic (renal) compensation.With compensation, the respiratory acidotic state is mostlikely to be chronic rather than acute

wheezing, rhonchi, or crackles that indicate poor gas change

dysrhyth-mias associated with hypercapnia and hypoxemia (oxygendeficit in the blood)

res-piratory distress due to impaired gas exchange

physical therapy, etc., as needed

Nursing Diagnosis 2

Ineffective airway clearance related to thick bronchial cretions and/or bronchial spasms limiting ability to clearairway

se-Interventions and Rationale

to eliminate bronchial secretions and improve gas change

bronchodilator drug Explain the use and frequency ofmedications

4. Administer chest clapping on COPD patients or others tobreak up mucous plugs and secretions in the alveoli.

patients with chronic obstructive pulmonary disease(COPD) Mucous secretions are trapped in overextendedalveoli (air sacs), and breathing exercises and posturaldrainage help to remove secretions and restore gas ex-change (ventilation)

may depress respirations and increase the severity of therespiratory acidosis Hypercapnia (increased partial pres-sure of carbon dioxide) stimulates the respiratory center

highly elevated, it is no longer a stimulus The hypoxemiacontinues to stimulate the respiratory center Too muchoxygen inhibits the respiratory stimulus effect

decrease tenacity of the secretions

Nursing Diagnosis 3

Risk for injury related to hypoxemia and hypercapnia

Interventions and Rationale

dis-orientation due to a lack of oxygen to the brain

patient is disoriented or in a stuporous state

Nursing Diagnosis 4

Activity intolerance related to dyspnea secondary to poorgas exchange

Interventions and Rationale

exer-cises as indicated by the physician

reha-Other Diagnoses to Consider

Ineffective breathing pattern related to inadequate tion

ventila-Respiratory Alkalosis Nursing Diagnosis 1

Anxiety related to hyperventilation secondary to stressfulsituations

Interventions and Rationale

hyperven-tilating to take deep breaths and breathe slowly Properbreathing prevents respiratory alkalosis

Encour-age the patient to seek professional help for psychologicproblems

Nursing Diagnosis 2

Ineffective breathing pattern related to hyperventilationand anxiety

Interventions and Rationale

de-crease overbreathing, which causes respiratory alkalosis

restore a normal breathing pattern

Nursing Diagnosis 3

Risk for injury related to tissue hypoxia and sensory function

dys-Interventions and Rationale

lightheaded

leads to syncope (fainting)

respiratory alkalosis.

Evaluation/Outcomes

respira-tory alkalosis is corrected or is controlled Patient’s ABGsare returning to or have returned to normal ranges

of respiratory acidosis or respiratory alkalosis; vital signsare within normal ranges

sounds have improved

without breathlessness

medical regimen

Upon completion of this unit, the reader will be able to:

● Identify physiological factors that are influenced byfluid, electrolyte, and acid-base imbalances for pa-tients across the life span

● Identify the impact of fluid changes on normal trolyte values for sodium, chloride, potassium, cal-cium, magnesium, and phosphates for patients inshock or experiencing select chronic diseases, GIsurgery, and acute renal failure

elec-● Discuss the physiological responses to fluid volumeexcess in select disorders for patients of all ages

● Discuss the physiological responses to fluid volumedeficits in select disorders for patients of all ages

● Discuss normal regulatory mechanisms for pH trol for patients experiencing select chronic dis-eases, GI surgery, and trauma

con-● Identify symptoms of acid-base imbalances forpatients across the life span experiencing selectchronic diseases, GI surgery, and trauma

● Differentiate the symptoms of metabolic acidosisfrom the symptoms of metabolic alkalosis in selectchronic diseases

● Differentiate the symptoms of respiratory acidosisfrom the symptoms of respiratory alkalosis in selectchronic diseases

● Identify important assessment factors in ing fluid and electrolyte balance in patients acrossthe life span

determin-U N I T

V

U N I T

V

who are experiencing fluid and electrolyte imbalances.

● Identify age-appropriate nursing interventions specific toselect diagnoses associated with fluid balance problems

● Understand the rationale for nursing interventions cific to fluid and electrolyte imbalances

spe-● Discuss the clinical management of patients across thelife span with fluid and electrolyte imbalances

● Describe potential complications associated with themanagement of fluid and electrolyte imbalances

INTRODUCTION

In clinical and home care settings health professionals vide care for persons experiencing a variety of problems re-lated to fluid and electrolytes Unit V addresses clinicalsituations The first two chapters focus on potential devel-opmental fluid and electrolyte issues related to infants,children, and the older adult The remaining chapters focus

pro-on trauma and shock, gastrointestinal (GI) surgery, renalfailure, and chronic diseases including heart failure, dia-betic ketoacidosis, and chronic obstructive pulmonary dis-ease (COPD) In order to assess the patient’s needs and toprovide the appropriate care needed for persons with se-lected health problems, the health professional must have

a working knowledge and understanding of the concepts lated to fluid and electrolyte imbalance Knowledge of theseconcepts allows the health professional to assess physio-logic changes that occur with fluid, electrolyte, and acid-base imbalances and to plan appropriate interventions toassist patient as they adapt to these changes

re-In each clinical situation the participant will becomeacquainted with patients who have fluid and electrolyteimbalances Patients are presented as part of a clinicalsituation The participant in this program will gain an un-derstanding of the physiologic changes involved in eachclinical situation

An asterisk (*) on an answer line indicates a word answer The meanings for the following symbols are:

multiple-↑ increased, ↓ decreased, greater ⬎ than, less ⬍ than

● Compare the total body fluid volume in infantsand children to the total body fluid volume inthe mature adult.

● Identify normal serum electrolyte values forsodium, potassium, and calcium in infants andchildren

● Discuss how the electrolyte values for sodium,potassium, and calcium vary in response tofluid balance changes in infants and children

● Describe a method to calculate the daily fluidand electrolyte needs of infants and children

● Describe assessment factors important in termining fluid and electrolyte balance in in-fants and children

de-● Develop diagnoses for infants and children periencing fluid balance problems

ex-● Identify interventions specific to select noses associated with fluid balance problems

Children are not just small adults Many anatomic andphysiologic changes occur from the neonatal period,through infancy and childhood, until the child reachesadulthood Infancy, which lasts through the first year oflife, is preceded by a neonatal period of one month Thetoddler period generally begins at 12 months of age andlasts until 24 months Childhood extends from thepreschool years until adolescence, around age 12 Once thechild reaches adolescence, many of the physiological andanatomic characteristics are similar to those of an adult.The health professional’s knowledge of the physiologicdifferences in infants and children is essential Becausethese physiologic differences vary significantly throughoutinfancy and childhood, important regulatory factors arepresented from a developmental perspective Health pro-fessionals need to understand the implications of these de-velopmental characteristics and the potential for fluidbalance problems This chapter addresses those factors aswell as normal chemistry values and physiologic factorsthat influence infants’ and children’s rapid responses tochanges in fluid and electrolyte balance

to various fluid and electrolyte imbalances

The physiologic differences between infants, children,and adults make infants and children more vulnerable tofluid, electrolyte, and acid-base imbalances As body weightincreases with the age of the child, the percentage of bodywater decreases Premature infants have more body waterthen full term newborns Newborns and infants have a pro-portionately higher ratio of extracellular fluid (ECF) to intra-cellular fluid (ICF) than do older children and adults Theproportionally larger extracellular fluid volume is becausethe brain and skin, both rich in interstitial fluid, occupy the

greatest portion of the developing infant’s body weight(London, Ladewig, Ball, & Bindler, 2007).

Because infants and children under 2 years of age lose agreater percentage of body fluid daily than do older chil-dren and adults, they must have an adequate intake of fluiddaily Their small stomach size decreases the ability to re-hydrate rapidly and a limited fluid reserve capacity inhibitsadaptation to fluid losses They also tend to have a greaterinsensible water loss through their skin due to their largebody surface Additional insensible water losses are related

to the increased metabolic and respiratory rates of infantsand young children The kidneys act to maintain a balancebetween fluid loss and replacement by conserving waterand needed electrolytes and excreting waste products Chil-dren under 2, however, are unable to effectively conserveand excrete water and solutes because their renal struc-tures are not fully developed As more water is excreted, in-fants and children become more susceptible to fluid andelectrolyte imbalances Additionally, infants and youngchildren are at risk for acid-base imbalances because thetransport system for ions and bicarbonate is weaker than inolder children and adults When infants and young childrenbecome ill, it is difficult to maintain a balance betweenfluid and electrolyte losses and replacements All of thesefactors increase the infant and young child’s vulnerability

to fluid and electrolyte imbalances

1.

The body is composed mostly of water Body water in the

The low-birth-weight infant’s (premature infant’s) bodywater represents 80–90% of body weight

ANSWER COLUMN

1. 97; 70–80; 60

Complete the percentage of body weight that is representative

of body water in the following:

Give two reasons why the infant needs a higher percentage

of total body water

4.

Water distribution in the infant is not the same as in an adult.Water comprises 65% of the infant’s body weight Of the totalbody water, 25% is ECF The percentage of water to body

The ICF in the infant is 35% of body weight; whereas in the

proportionately higher ratio of ECF volume in the infant

losses of fluid volume; consequently, develops more rapidly in infants than adults

5.

The percentage of the child’s total body water (50%) is close inamount to the percentage of the adult’s (60%) total bodywater; and, the proportion of ECF (10–15%) and ICF (40–45%) isalso similar to that of the adult

*

2. 97; 80–90; 70–80; 60

3. a large body surface

(greater amounts of

water loss through the

skin) and inability to

The extracellular fluid is composed of and

fluid Another name for intracellular fluid is

6.

Increased body surface area in the infant causes excess water

greater the body surface area in proportion to body weight The

7.

It may take 2 years before the child’s kidneys are mature.The infant’s immature kidneys decrease the glomerularfiltration rate (GFR); thus, the kidney’s ability to concentrate

Fluid intake in infants must be carefully monitored to insurethat overhydration does not occur With overhydration, anextracellular fluid volume excess results from too much fluid

in the vascular and interstitial compartment

Giving too much water can cause (dehydration/overhydration)

8. Increased cellular and

muscular growth causes

water to shift from the

ECF space to the ICF

space.