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DehydrationDehydration

Paul R. EarlPaul R. Earl

Facultad de Ciencias BiológicasFacultad de Ciencias Biológicas

Universidad Autónoma de Nuevo Universidad Autónoma de Nuevo LeónLeón

San Nicolás, N. L., MexicoSan Nicolás, N. L., Mexico

pearl@dsi.uanl.mxpearl@dsi.uanl.mx

Dehydration or volume depletion is classified as mild, Dehydration or volume depletion is classified as mild,

moderate or severe based on how much body fluid is moderate or severe based on how much body fluid is

lost. When severe, dehydration is a lost. When severe, dehydration is a life-threatening life-threatening

emergency.emergency. Volume depletion denotes lessening of the Volume depletion denotes lessening of the

total intravascular plasma, whereas dehydration denotes total intravascular plasma, whereas dehydration denotes

loss of plasma-free water disproportionate to the loss of loss of plasma-free water disproportionate to the loss of

sodium. Potassium and other electrolytes including buffers sodium. Potassium and other electrolytes including buffers

líke phosphates need to be considered. Children, líke phosphates need to be considered. Children,

especially those younger than 4 years old, are more especially those younger than 4 years old, are more

susceptible to volume depletion as a result of vomiting, susceptible to volume depletion as a result of vomiting,

diarrhea or increases in insensible water losses. diarrhea or increases in insensible water losses.

DehydrationDehydration can be caused by losing too much fluid, not can be caused by losing too much fluid, not

drinking enough water or fluids, or both. Vomiting and diarrhea drinking enough water or fluids, or both. Vomiting and diarrhea

are common causes.are common causes.

Dehydration is classified as mild, moderate or severe based on Dehydration is classified as mild, moderate or severe based on

how much body's fluid is lost. Symtons include: how much body's fluid is lost. Symtons include:

Dry or sticky mouth. Dry or sticky mouth.

Dizziness.Dizziness.

Low or no urine output; concentrated urine is dark yellow. Low or no urine output; concentrated urine is dark yellow.

Not producing tears. Not producing tears.

Sunken eyes. Sunken eyes.

Markedly sunken fontanelles (the soft spot on the top of the Markedly sunken fontanelles (the soft spot on the top of the

head in a baby). head in a baby).

Lethargic or comatose. Lethargic or comatose.

In addition to the symptoms of actual dehydration, you may In addition to the symptoms of actual dehydration, you may

also have: also have:

– vomiting andvomiting and

– diarrhea.diarrhea.

Drinking fluids is usually sufficient for mild dehydration. It is Drinking fluids is usually sufficient for mild dehydration. It is

better to have frequent, small amounts of fluid (using a better to have frequent, small amounts of fluid (using a

teaspoon or syringe for an infant or child) rather than trying teaspoon or syringe for an infant or child) rather than trying

to force large amounts of fluid at one time. Drinking too to force large amounts of fluid at one time. Drinking too

much fluid at once can bring on more vomiting. much fluid at once can bring on more vomiting.

Electrolyte solutions or freezer pops are especially Electrolyte solutions or freezer pops are especially

effective. These are available at pharmacies. Sport drinks effective. These are available at pharmacies. Sport drinks

contain a lot of sugar and can cause or worsen diarrhea. In contain a lot of sugar and can cause or worsen diarrhea. In

infants and children, avoid using water as the primary infants and children, avoid using water as the primary

replacement fluid. replacement fluid.

Intravenous fluids and hospitalization may be necessary for Intravenous fluids and hospitalization may be necessary for

moderate to severe dehydration. The doctor will try to moderate to severe dehydration. The doctor will try to

identify and then treat the cause of the dehydration. identify and then treat the cause of the dehydration.

Treatment includes starting NS@20ml/kg slow push until Treatment includes starting NS@20ml/kg slow push until

signs of severe dehydration disappear. Avoid Ringer signs of severe dehydration disappear. Avoid Ringer

Lactate till patient passes urine. Maintainence fluid depends Lactate till patient passes urine. Maintainence fluid depends

on body weight. Either DNS or RL may be used 10kg and on body weight. Either DNS or RL may be used 10kg and

less 100ml/Kg 10-20 Kg 1000mL+50ml/kg 20+ Kg 1500ml+ less 100ml/Kg 10-20 Kg 1000mL+50ml/kg 20+ Kg 1500ml+

20 ml/kg It may be advisable to give half the calculated fluid 20 ml/kg It may be advisable to give half the calculated fluid

in the first 8 hours and the remaining over the next 16 hoursin the first 8 hours and the remaining over the next 16 hours

Precautions Precautions

check for pulmonary oedema replenish Potassium as check for pulmonary oedema replenish Potassium as

required Chills may occur due to fluid administration rule out required Chills may occur due to fluid administration rule out

infectious causesinfectious causes

Most cases of stomach viruses (also called viral Most cases of stomach viruses (also called viral

gastroenteritis) tend to resolve on their own after a few gastroenteritis) tend to resolve on their own after a few

days. days.

Boxers under hot lights sip water, then usually spit it out. Boxers under hot lights sip water, then usually spit it out.

They don`t seem to know that that water could save them They don`t seem to know that that water could save them

from a coma during heat prostration !from a coma during heat prostration !

PathophysiologyPathophysiology

Pediatric dehydration is frequently the result of Pediatric dehydration is frequently the result of 

gastroenteritis, characterized by vomiting and , characterized by vomiting and diarrhea. .

However, other causes of dehydration may include poor oral However, other causes of dehydration may include poor oral

intake due to diseases such as stomatitis, insensible losses intake due to diseases such as stomatitis, insensible losses

due to fever, or osmotic diuresis from uncontrolled diabetes due to fever, or osmotic diuresis from uncontrolled diabetes

mellitus.mellitus.

Volume depletionVolume depletion denotes lessening of the total denotes lessening of the total

intravascular plasma, whereas dehydration denotes loss of intravascular plasma, whereas dehydration denotes loss of

plasma-free water disproportionate to the loss of sodium. plasma-free water disproportionate to the loss of sodium.

The distinction is important because volume depletion can The distinction is important because volume depletion can

exist with or without dehydration, and dehydration can exist exist with or without dehydration, and dehydration can exist

with or without volume depletion.with or without volume depletion.

In children with dehydration, the most common underlying In children with dehydration, the most common underlying

problem actually is volume depletion, not dehydration. problem actually is volume depletion, not dehydration.

Intravascular sodium levels are within the reference range, Intravascular sodium levels are within the reference range,

indicating that excess free water is not being lost from plasma. indicating that excess free water is not being lost from plasma.

Rather, the entire plasma pool is contracted with solutes (mostly Rather, the entire plasma pool is contracted with solutes (mostly

sodium) and solvents (mostly water) lost in proportionate sodium) and solvents (mostly water) lost in proportionate

quantities. This is volume depletion without dehydration. The quantities. This is volume depletion without dehydration. The

most common cause is excessive extrinsic loss of fluids.most common cause is excessive extrinsic loss of fluids.

Pediatric patients, especially those younger than 4 years, Pediatric patients, especially those younger than 4 years,

tend to be more susceptible to volume depletion as a tend to be more susceptible to volume depletion as a

result of vomiting, diarrhea, or increases in insensible result of vomiting, diarrhea, or increases in insensible

water losses. Significant fluid losses may occur rapidly. water losses. Significant fluid losses may occur rapidly.

The turnover of fluids and solute in infants and young The turnover of fluids and solute in infants and young

children can be as much as 3 times that of adults. children can be as much as 3 times that of adults. This is This is

because of the following:because of the following:

Higher metabolic rates Higher metabolic rates

Increased body surface area to mass index Increased body surface area to mass index

Higher body water contents (Water comprises Higher body water contents (Water comprises

approximately 70% of body weight in infants, 65% in approximately 70% of body weight in infants, 65% in

children, and 60% in adults.)children, and 60% in adults.)

Sodium considerationsSodium considerations

Volume depletion can be concurrent with Volume depletion can be concurrent with 

hyponatremia.. This is characterized by plasma This is characterized by plasma

volume contraction with free water excess. An volume contraction with free water excess. An

example is a child with diarrhea who has been given example is a child with diarrhea who has been given

tap water to replete diarrheal losses. Free water is tap water to replete diarrheal losses. Free water is

replenished, but sodium and other solutes are not.replenished, but sodium and other solutes are not.

In hyponatremic volume depletion, the person may appear more ill clinically In hyponatremic volume depletion, the person may appear more ill clinically

than fluid losses indicate. The degree of volume depletion may be clinically than fluid losses indicate. The degree of volume depletion may be clinically

overestimated. Serum sodium levels less than 120 mEq/L may result in overestimated. Serum sodium levels less than 120 mEq/L may result in

seizures. If intravascular free water excess is not corrected during volume seizures. If intravascular free water excess is not corrected during volume

replenishment, the shift of free water to the intracellular fluid compartment may replenishment, the shift of free water to the intracellular fluid compartment may

cause cerebral edema.cause cerebral edema.

With true dehydration, plasma volume contracts with disproportionate further With true dehydration, plasma volume contracts with disproportionate further

free water loss. An example is the child with diarrhea whose fluid losses have free water loss. An example is the child with diarrhea whose fluid losses have

been replenished with hypertonic soup, boiled milk, baking soda, or improperly been replenished with hypertonic soup, boiled milk, baking soda, or improperly

diluted infant formula. Volume has been restored, but free water has not.diluted infant formula. Volume has been restored, but free water has not.

In hypernatremic volume depletion, the patient may appear In hypernatremic volume depletion, the patient may appear

less ill clinically than fluid losses indicate. The degree of less ill clinically than fluid losses indicate. The degree of

volume depletion may be underestimated. Usually, at least a volume depletion may be underestimated. Usually, at least a

10% volume deficit exists with hypernatremic volume 10% volume deficit exists with hypernatremic volume

depletion.depletion.

As in hyponatremia, hypernatremic volume depletion may As in hyponatremia, hypernatremic volume depletion may

result in serious central nervous system (CNS) effects as a result in serious central nervous system (CNS) effects as a

result of structural changes in central neurons. However, result of structural changes in central neurons. However,

cerebral shrinkage occurs instead of cerebral edema. This cerebral shrinkage occurs instead of cerebral edema. This

may result in intracerebral hemorrhage, seizures, coma, and may result in intracerebral hemorrhage, seizures, coma, and

death. For this reason, volume restoration must be performed death. For this reason, volume restoration must be performed

gradually over 24 hours or more. Gradual restoration gradually over 24 hours or more. Gradual restoration

prevents a rapid shift of fluid across the blood-brain barrier prevents a rapid shift of fluid across the blood-brain barrier

and into the intracellular fluid compartment.and into the intracellular fluid compartment.

Potassium considerationsPotassium considerations

Potassium shifts between intracellular and extracellular fluid Potassium shifts between intracellular and extracellular fluid

compartments occur more slowly than free water shifts. Serum compartments occur more slowly than free water shifts. Serum

potassium level may not reflect intracellular potassium levels. potassium level may not reflect intracellular potassium levels.

Although a potassium deficit is present in all patients with Although a potassium deficit is present in all patients with

volume depletion, it is not usually clinically significant. volume depletion, it is not usually clinically significant.

However, failure to correct for a potassium deficit during However, failure to correct for a potassium deficit during

volume repletion may result in clinically significant volume repletion may result in clinically significant

hypokalemia. Potassium should not be added to replacement hypokalemia. Potassium should not be added to replacement

fluids until adequate urine output is obtained.fluids until adequate urine output is obtained.

Acid and base problemsAcid and base problems

Clinicians may observe derangements of acid-base balance with Clinicians may observe derangements of acid-base balance with

volume depletion. Some degree of volume depletion. Some degree of metabolic acidosis is common, is common,

especially in infants.especially in infants.

Mechanisms include bicarbonate loss in stool and ketone production. Mechanisms include bicarbonate loss in stool and ketone production.

Hypovolemia causes decreased tissue perfusion and increased lactic Hypovolemia causes decreased tissue perfusion and increased lactic

acid production. Decreased renal perfusion causes decreased acid production. Decreased renal perfusion causes decreased

glomerular filtration rate, which, in turn, leads to decreased hydrogen glomerular filtration rate, which, in turn, leads to decreased hydrogen

(H+) ion excretion. These factors combine to produce a metabolic (H+) ion excretion. These factors combine to produce a metabolic

acidosis.acidosis.

In most patients, acidosis is mild and easily corrected with In most patients, acidosis is mild and easily corrected with

volume restoration (as increased renal perfusion permits volume restoration (as increased renal perfusion permits

excretion of excess H+ ions in the urine). Administration of excretion of excess H+ ions in the urine). Administration of

glucose-containing fluids further decreases ketone glucose-containing fluids further decreases ketone

production. production.

FrequencyFrequency

United StatesUnited States Pediatric dehydration, particularly that due to Pediatric dehydration, particularly that due to

gastroenteritis, is a common ED complaint. gastroenteritis, is a common ED complaint.

Approximately 200,000 hospitalizations and 300 Approximately 200,000 hospitalizations and 300

deaths per year are attributed to gastroenteritis each deaths per year are attributed to gastroenteritis each

yearyear..

InternationalInternational

According to the Centers for Disease Control and According to the Centers for Disease Control and

Prevention (CDC), for children younger than 5 years, Prevention (CDC), for children younger than 5 years,

the annual incidence of diarrheal illness is the annual incidence of diarrheal illness is

approximately 1.5 billion, while deaths are estimated approximately 1.5 billion, while deaths are estimated

between 1.5 and 2.5 million. Though these numbers are between 1.5 and 2.5 million. Though these numbers are

staggering, they actually represent an improvement staggering, they actually represent an improvement

from the early 1980s, when the death rate was from the early 1980s, when the death rate was

approximately 5 million per year.approximately 5 million per year.

Mortality/MorbidityMortality/Morbidity

Morbidity varies with the degree of volume depletion and Morbidity varies with the degree of volume depletion and

the underlying cause. the underlying cause.

The severely volume-depleted infant or child is at risk for The severely volume-depleted infant or child is at risk for

death from cardiovascular collapse. death from cardiovascular collapse.

Hyponatremia resulting from replacement of free water Hyponatremia resulting from replacement of free water

alone may cause seizures. alone may cause seizures.

Improper management of volume repletion may cause Improper management of volume repletion may cause

iatrogenic morbidity or mortality.iatrogenic morbidity or mortality.

AgeAge

Infants and younger children are more susceptible to Infants and younger children are more susceptible to

volume depletion than older children.volume depletion than older children.

Clinical HistoryClinical History

The goal of the history and physical examination is to The goal of the history and physical examination is to

determine the severity of the child's condition. Classifying determine the severity of the child's condition. Classifying

the degree of dehydration as mild, moderate, or severe the degree of dehydration as mild, moderate, or severe

accurately allows for appropriate therapy and disposition of accurately allows for appropriate therapy and disposition of

the patient in a timely fashion.the patient in a timely fashion.

Obtaining a complete history from the parent or caregiver Obtaining a complete history from the parent or caregiver

is important because it provides clues to the type of is important because it provides clues to the type of

dehydration present. dehydration present.

The emergency physician should be diligent in obtaining the The emergency physician should be diligent in obtaining the

following information:following information:

Feeding pattern and fluids given Feeding pattern and fluids given

Number of wet diapers compared with normal Number of wet diapers compared with normal

Fluid loss (eg, vomiting, oliguria or anuria, diarrhea) Fluid loss (eg, vomiting, oliguria or anuria, diarrhea)

Possible ingestions Possible ingestions

Activity Activity

Medications Medications

Heat and sunlight exposuresHeat and sunlight exposures

PhysicalPhysical

The following table highlights the physical findings seen The following table highlights the physical findings seen

with different levels of pediatric dehydration.with different levels of pediatric dehydration.

SymptomMild (<3% body weight lost)

Moderate (3-9% body weight lost)

Severe (>9% body weight lost)

Mental status

Normal, alertRestless or fatigued, irritable

Apathetic, lethargic, unconscious

Heart rate Normal Normal to increasedTachycardia or bradycardia

Quality of pulse

Normal Normal to decreasedWeak, thready, impalpable

Breathing Normal Normal to increasedTachypnea and hyperpnea

Eyes Normal Slightly sunken Deeply sunken

Fontanelles

Normal Slightly sunken Deeply sunken

Tears Normal Normal to decreased Absent

Mucous membranes

Moist Dry Parched

Skin turgor Instant recoil Recoil <2 seconds Recoil >2 seconds

Capillary refill

<2 seconds Prolonged Minimal

Extremities Warm Cool Mottled, cyanotic

SymptomMild (<3% body weight lost)

Moderate (3-9% body weight lost)

Severe (>9% body weight lost)

Mental status Normal, alertRestless or fatigued, irritable

Apathetic, lethargic, unconscious

Heart rate Normal Normal to increasedTachycardia or bradycardia

Quality of pulse NormalNormal to decreased

Weak, thready, impalpable

Breathing Normal Normal to increasedTachypnea and hyperpnea

Eyes Normal Slightly sunken Deeply sunken

Fontanelles Normal Slightly sunken Deeply sunken

Tears NormalNormal to decreased

Absent

Mucous membranes

Moist Dry Parched

Skin turgorInstant recoil

Recoil <2 seconds Recoil >2 seconds

Capillary refill <2 seconds Prolonged Minimal

Extremities Warm Cool Mottled, cyanotic

Of these, the most accurate in identifying the level of Of these, the most accurate in identifying the level of

dehydration are capillary refill, skin turgor, and breathing. dehydration are capillary refill, skin turgor, and breathing.

The least accurate are mental status, heart rate and The least accurate are mental status, heart rate and

fontanelle appearance.fontanelle appearance.

CausesCauses In most cases, volume depletion in children is from fluid losses from vomiting In most cases, volume depletion in children is from fluid losses from vomiting

or diarrhea. or diarrhea.

Vomiting may be caused by any of the following systems or processes:Vomiting may be caused by any of the following systems or processes:

CNS (eg, infections, space-occupying lesions) CNS (eg, infections, space-occupying lesions)

GI (eg, gastroenteritis, obstruction, hepatitis, liver failure, GI (eg, gastroenteritis, obstruction, hepatitis, liver failure, appendicitis, ,

peritonitis, peritonitis, intussusception, volvulus, , volvulus, pyloric stenosis, toxicity [ingestion, , toxicity [ingestion,

overdose, drug effects]) overdose, drug effects])

Endocrine (eg, Endocrine (eg, diabetic ketoacidosis [DKA],  [DKA], congenital adrenal hypoplasia, ,

Addisonian crisis) Addisonian crisis)

Renal (eg, infection, Renal (eg, infection, pyelonephritis, renal failure, renal tubular acidosis) , renal failure, renal tubular acidosis)

Psychiatric (eg, psychogenic vomiting) - This is not seen in infants and is Psychiatric (eg, psychogenic vomiting) - This is not seen in infants and is

rare in children compared with adults.rare in children compared with adults.

Diarrhea may be caused by any of the following Diarrhea may be caused by any of the following

systems or processes:systems or processes:

GI (e.g., gastroenteritis, GI (e.g., gastroenteritis, malabsorption, intussusception, , intussusception,

irritable bowel, inflammatory bowel disease, short gut irritable bowel, inflammatory bowel disease, short gut

syndrome) syndrome)

Endocrine (eg, Endocrine (eg, thyrotoxicosis, congenital adrenal , congenital adrenal

hypoplahypoplasia, Addisonian crisis, diabetic enteropathy) sia, Addisonian crisis, diabetic enteropathy)

Psychiatric (eg, anxiety) Psychiatric (eg, anxiety)

Volume depletion not caused by vomiting or diarrhea may be divided Volume depletion not caused by vomiting or diarrhea may be divided

into renal or extrarenal causes. into renal or extrarenal causes.

– Renal causes include use of diuretics, renal tubular acidosis, and Renal causes include use of diuretics, renal tubular acidosis, and

renal failure (eg, trauma, obstruction, salt-wasting nephritis). The renal failure (eg, trauma, obstruction, salt-wasting nephritis). The

effects of diabetes insipidus, hypothyroidism, and adrenal effects of diabetes insipidus, hypothyroidism, and adrenal

insufficiency also fall into this category. insufficiency also fall into this category.

– Extrarenal causes include third-space extravasation of Extrarenal causes include third-space extravasation of

intravascular fluid (eg, pancreatitis, peritonitis, sepsis, heart intravascular fluid (eg, pancreatitis, peritonitis, sepsis, heart

failure); insensible losses from fever, sweating, burns, or failure); insensible losses from fever, sweating, burns, or

pulmonary processes; poor oral intake; and hemorrhage.pulmonary processes; poor oral intake; and hemorrhage.