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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, especially líke phosphates need to be considered. Children, especially those younger than 4 years old, are more susceptible to those younger than 4 years old, are more susceptible to volume depletion as a result of vomiting, diarrhea or volume depletion as a result of vomiting, diarrhea or increases in insensible water losses. 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 head Markedly sunken fontanelles (the soft spot on the top of the head

in a baby). in a baby). Lethargic or comatose. Lethargic or comatose.

In addition to the symptoms of actual dehydration, you may also have: In addition to the symptoms of actual dehydration, you may also have:

– vomiting andvomiting and

– diarrhea.diarrhea. Drinking fluids is usually sufficient for mild dehydration. It is better to Drinking fluids is usually sufficient for mild dehydration. It is better to

have frequent, small amounts of fluid (using a teaspoon or syringe for have frequent, small amounts of fluid (using a teaspoon or syringe for an infant or child) rather than trying to force large amounts of fluid at an infant or child) rather than trying to force large amounts of fluid at one time. Drinking too much fluid at once can bring on more vomiting. one time. Drinking too much fluid at once can bring on more vomiting.

Electrolyte solutions or freezer pops are especially effective. These are Electrolyte solutions or freezer pops are especially effective. These are available at pharmacies. Sport drinks contain a lot of sugar and can available at pharmacies. Sport drinks contain a lot of sugar and can cause or worsen diarrhea. In infants and children, avoid using water as cause or worsen diarrhea. In infants and children, avoid using water as the primary replacement fluid.the primary replacement fluid.

Intravenous fluids and hospitalization may be necessary for moderate Intravenous fluids and hospitalization may be necessary for moderate to severe dehydration. The doctor will try to identify and then treat to severe dehydration. The doctor will try to identify and then treat the cause of the dehydration.the cause of the dehydration.

Treatment includes starting NS@20ml/kg slow push until signs of Treatment includes starting NS@20ml/kg slow push until signs of severe dehydration disappear. Avoid Ringer Lactate till patient severe dehydration disappear. Avoid Ringer Lactate till patient passes urine. Maintainence fluid depends on body weight. Either passes urine. Maintainence fluid depends on body weight. Either DNS or RL may be used 10kg and less 100ml/Kg 10-20 Kg DNS or RL may be used 10kg and less 100ml/Kg 10-20 Kg 1000mL+50ml/kg 20+ Kg 1500ml+ 20 ml/kg It may be advisable to 1000mL+50ml/kg 20+ Kg 1500ml+ 20 ml/kg It may be advisable to give half the calculated fluid in the first 8 hours and the remaining give half the calculated fluid in the first 8 hours and the remaining over the next 16 hoursover the next 16 hours

Precautions Precautions check for pulmonary oedema replenish Potassium as required Chills check for pulmonary oedema replenish Potassium as required Chills

may occur due to fluid administration rule out infectious causes may occur due to fluid administration rule out infectious causes

Most cases of stomach viruses (also called viral gastroenteritis) tend to Most cases of stomach viruses (also called viral gastroenteritis) tend to resolve on their own after a few days. resolve on their own after a few days.

Boxers under hot lights sip water, then usually spit it out. They don`t seem to Boxers under hot lights sip water, then usually spit it out. They don`t seem to know that that water could save them from a coma during heat prostration!know that that water could save them from a coma during heat prostration!

PathophysiologyPathophysiology

Pediatric dehydration is frequently the result of Pediatric dehydration is frequently the result of gastroenteritis, characterized , characterized by vomiting and by vomiting and diarrhea. However, other causes of dehydration may include . However, other causes of dehydration may include poor oral intake due to diseases such as stomatitis, insensible losses due to poor oral intake due to diseases such as stomatitis, insensible losses due to fever, or osmotic diuresis from uncontrolled diabetes mellitus.fever, or osmotic diuresis from uncontrolled diabetes mellitus.

PathophysiologyPathophysiology

Pediatric dehydration is frequently the result of Pediatric dehydration is frequently the result of gastroenteritis, characterized by , characterized by vomiting and vomiting and diarrhea. However, other causes of dehydration may include poor . However, other causes of dehydration may include poor oral intake due to diseases such as stomatitis, insensible losses due to fever, or oral intake due to diseases such as stomatitis, insensible losses due to fever, or osmotic diuresis from uncontrolled diabetes mellitus.osmotic diuresis from uncontrolled diabetes mellitus.

Volume depletionVolume depletion denotes lessening of the total intravascular plasma, whereas denotes lessening of the total intravascular plasma, whereas dehydration denotes loss of plasma-free water disproportionate to the loss of dehydration denotes loss of plasma-free water disproportionate to the loss of sodium. The distinction is important because volume depletion can exist with or sodium. The distinction is important because volume depletion can exist with or without dehydration, and dehydration can exist with or without volume depletion without dehydration, and dehydration can exist 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 than In hyponatremic volume depletion, the person may appear more ill clinically than fluid losses indicate. The degree of volume depletion may be clinically 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 less In hypernatremic volume depletion, the patient may appear less ill clinically than fluid losses indicate. The degree of volume ill clinically than fluid losses indicate. The degree of volume depletion may be underestimated. Usually, at least a 10% depletion may be underestimated. Usually, at least a 10% volume deficit exists with hypernatremic volume depletion.volume deficit exists with hypernatremic volume depletion.

As in hyponatremia, hypernatremic volume depletion may result As in hyponatremia, hypernatremic volume depletion may result in serious central nervous system (CNS) effects as a result of in serious central nervous system (CNS) effects as a result of structural changes in central neurons. However, cerebral structural changes in central neurons. However, cerebral shrinkage occurs instead of cerebral edema. This may result in shrinkage occurs instead of cerebral edema. This may result in intracerebral hemorrhage, seizures, coma, and death. For this intracerebral hemorrhage, seizures, coma, and death. For this reason, volume restoration must be performed gradually over reason, volume restoration must be performed gradually over 24 hours or more. Gradual restoration prevents a rapid shift of 24 hours or more. Gradual restoration prevents a rapid shift of fluid across the blood-brain barrier and into the intracellular fluid fluid across the blood-brain barrier and into the intracellular fluid compartment.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 volume Although a potassium deficit is present in all patients with volume depletion, it is not usually clinically significant. However, failure to depletion, it is not usually clinically significant. However, failure to correct for a potassium deficit during volume repletion may result correct for a potassium deficit during volume repletion may result in clinically significant hypokalemia. Potassium should not be in clinically significant hypokalemia. Potassium should not be added to replacement fluids until adequate urine output is added to replacement fluids until adequate urine output is obtained.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 volume In most patients, acidosis is mild and easily corrected with volume restoration (as increased renal perfusion permits excretion of excess restoration (as increased renal perfusion permits excretion of excess H+ ions in the urine). Administration of glucose-containing fluids H+ ions in the urine). Administration of glucose-containing fluids further decreases ketone production. further decreases ketone production.

FrequencyFrequency

United StatesUnited States

Pediatric dehydration, particularly that due to gastroenteritis, is a Pediatric dehydration, particularly that due to gastroenteritis, is a common ED complaint. Approximately 200,000 hospitalizations common ED complaint. Approximately 200,000 hospitalizations and 300 deaths per year are attributed to gastroenteritis each and 300 deaths per year are attributed to gastroenteritis each year.year.

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.

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 the determine the severity of the child's condition. Classifying the degree of dehydration as mild, moderate, or severe 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 is Obtaining a complete history from the parent or caregiver is important because it provides clues to the type of important because it provides clues to the type of dehydration present.dehydration present.

Clinical HistoryClinical History

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

Symptom Mild (<3% body weight lost)

Moderate (3-9% body weight lost)

Severe (>9% body weight lost)

Mental status Normal, alert Restless or fatigued,

irritableApathetic, lethargic, unconscious

Heart rate Normal Normal to increased Tachycardia or bradycardia

Quality of pulse Normal Normal to decreased Weak, thready,

impalpable

Breathing Normal Normal to increased Tachypnea and hyperpnea

Eyes Normal Slightly sunken Deeply sunken

Fontanelles Normal Slightly sunken Deeply sunken

Tears Normal Normal to decreased Absent

PhysicalPhysical The following table highlights the physical findings seen with different levels of The following table highlights the physical findings seen with different levels of

pediatric dehydrationpediatric dehydration..

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

Symptom Mild (<3% body weight lost)

Moderate (3-9% body weight lost)

Severe (>9% body weight lost)

Mental status Normal, alert Restless or fatigued, irritable

Apathetic, lethargic, unconscious

Heart rate Normal Normal to increased Tachycardia or bradycardia

Quality of pulse Normal Normal to decreased

Weak, thready, impalpable

Breathing Normal Normal to increased Tachypnea 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

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

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

children compared with adults.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.