Dehydration

1

• Dehydration
• Paul R. Earl
• Facultad de Ciencias Biológicas
• Universidad Autónoma de Nuevo León
• San Nicolás, N. L., Mexico
• pearl_at_dsi.uanl.mx

2

• Dehydration or volume depletion is
  classified as mild, moderate or severe based
  on how much body fluid is lost. When
  severe, dehydration is a life-threatening
  emergency. Volume depletion denotes lessening of
  the total intravascular plasma, whereas
  dehydration denotes loss of plasma-free water
  disproportionate to the loss of sodium. Potassium
  and other electrolytes including buffers líke
  phosphates need to be considered. Children,
  especially those younger than 4 years old, are
  more susceptible to volume depletion as a result
  of vomiting, diarrhea or increases in insensible
  water losses.

3

• Dehydration can be caused by losing too much
  fluid, not drinking enough water or fluids, or
  both. Vomiting and diarrhea are common causes.
• Dehydration is classified as mild, moderate or
  severe based on how much body's fluid is lost.
  Symtons include
• Dry or sticky mouth.
• Dizziness.
• Low or no urine output concentrated urine is
  dark yellow.
• Not producing tears.
• Sunken eyes.
• Markedly sunken fontanelles (the soft spot on the
  top of the head in a baby).
• Lethargic or comatose.

4

• In addition to the symptoms of actual
  dehydration, you may also have
• vomiting and
• diarrhea.

5

• Drinking fluids is usually sufficient for mild
  dehydration. It is better to 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 one time. Drinking too
  much fluid at once can bring on more vomiting.
• Electrolyte solutions or freezer pops are
  especially effective. These are available at
  pharmacies. Sport drinks contain a lot of sugar
  and can cause or worsen diarrhea. In infants and
  children, avoid using water as the primary
  replacement fluid.
• Intravenous fluids and hospitalization may be
  necessary for moderate to severe dehydration. The
  doctor will try to identify and then treat the
  cause of the dehydration.

6

• Treatment includes starting NS_at_20ml/kg slow push
  until signs of severe dehydration disappear.
  Avoid Ringer Lactate till patient passes urine.
  Maintainence fluid depends on body weight. Either
  DNS or RL may be used 10kg and less 100ml/Kg
  10-20 Kg 1000mL50ml/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 over
  the next 16 hours
• Precautions
• check for pulmonary oedema replenish Potassium as
  required Chills may occur due to fluid
  administration rule out infectious causes

7

• Most cases of stomach viruses (also called viral
  gastroenteritis) tend to resolve on their own
  after a few days.
• Boxers under hot lights sip water, then usually
  spit it out. They dont seem to know that that
  water could save them from a coma during heat
  prostration !

8

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

9

• Volume depletion denotes lessening of the total
  intravascular plasma, whereas dehydration denotes
  loss of plasma-free water disproportionate to the
  loss of sodium. The distinction is important
  because volume depletion can exist with or
  without dehydration, and dehydration can exist
  with or without volume depletion.

10

• In children with dehydration, the most common
  underlying problem actually is volume depletion,
  not dehydration. Intravascular sodium levels are
  within the reference range, indicating that
  excess free water is not being lost from plasma.
  Rather, the entire plasma pool is contracted with
  solutes (mostly sodium) and solvents (mostly
  water) lost in proportionate quantities. This is
  volume depletion without dehydration. The most
  common cause is excessive extrinsic loss of
  fluids.

11

• Pediatric patients, especially those younger than
  4 years, tend to be more susceptible to volume
  depletion as a result of vomiting, diarrhea, or
  increases in insensible water losses. Significant
  fluid losses may occur rapidly. The turnover of
  fluids and solute in infants and young children
  can be as much as 3 times that of adults. This is
  because of the following
• Higher metabolic rates
• Increased body surface area to mass index
• Higher body water contents (Water comprises
  approximately 70 of body weight in infants, 65
  in children, and 60 in adults.)

12
Sodium considerations

• Volume depletion can be concurrent
  with hyponatremia. This is characterized by
  plasma volume contraction with free water excess.
  An example is a child with diarrhea who has been
  given tap water to replete diarrheal losses. Free
  water is replenished, but sodium and other
  solutes are not.

13

• In hyponatremic volume depletion, the person may
  appear more ill 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 seizures. If
  intravascular free water excess is not corrected
  during volume replenishment, the shift of free
  water to the intracellular fluid compartment may
  cause cerebral edema.With true dehydration,
  plasma volume contracts with disproportionate
  further 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 diluted infant
  formula. Volume has been restored, but free water
  has not.

14

• In hypernatremic volume depletion, the patient
  may appear less ill clinically than fluid losses
  indicate. The degree of volume depletion may be
  underestimated. Usually, at least a 10 volume
  deficit exists with hypernatremic volume
  depletion.As in hyponatremia, hypernatremic
  volume depletion may result in serious central
  nervous system (CNS) effects as a result of
  structural changes in central neurons. However,
  cerebral shrinkage occurs instead of cerebral
  edema. This may result in intracerebral
  hemorrhage, seizures, coma, and death. For this
  reason, volume restoration must be performed
  gradually over 24 hours or more. Gradual
  restoration prevents a rapid shift of fluid
  across the blood-brain barrier and into the
  intracellular fluid compartment.

15
Potassium considerations

• Potassium shifts between intracellular and
  extracellular fluid compartments occur more
  slowly than free water shifts. Serum potassium
  level may not reflect intracellular potassium
  levels. Although a potassium deficit is present
  in all patients with volume depletion, it is not
  usually clinically significant. However, failure
  to correct for a potassium deficit during volume
  repletion may result in clinically significant
  hypokalemia. Potassium should not be added to
  replacement fluids until adequate urine output is
  obtained.

16
Acid and base problems

• Clinicians may observe derangements of acid-base
  balance with volume depletion. Some degree
  of metabolic acidosis is common, especially in
  infants.Mechanisms include bicarbonate loss in
  stool and ketone production. Hypovolemia causes
  decreased tissue perfusion and increased lactic
  acid production. Decreased renal perfusion causes
  decreased glomerular filtration rate, which, in
  turn, leads to decreased hydrogen (H) ion
  excretion. These factors combine to produce a
  metabolic acidosis.

17

• In most patients, acidosis is mild and easily
  corrected with volume restoration (as increased
  renal perfusion permits excretion of excess H
  ions in the urine). Administration of
  glucose-containing fluids further decreases
  ketone production.

18
Frequency

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

19

• International
• According to the Centers for Disease Control and
  Prevention (CDC), for children younger than 5
  years, the annual incidence of diarrheal illness
  is approximately 1.5 billion, while deaths are
  estimated between 1.5 and 2.5 million. Though
  these numbers are staggering, they actually
  represent an improvement from the early 1980s,
  when the death rate was approximately 5 million
  per year.

20
Mortality/Morbidity

• Morbidity varies with the degree of volume
  depletion and the underlying cause.
• The severely volume-depleted infant or child is
  at risk for death from cardiovascular collapse.
• Hyponatremia resulting from replacement of free
  water alone may cause seizures.
• Improper management of volume repletion may cause
  iatrogenic morbidity or mortality.

21
Age

• Infants and younger children are more susceptible
  to volume depletion than older children.

22
Clinical History

• The goal of the history and physical examination
  is to determine the severity of the child's
  condition. Classifying the degree of dehydration
  as mild, moderate, or severe accurately allows
  for appropriate therapy and disposition of the
  patient in a timely fashion.
• Obtaining a complete history from the parent or
  caregiver is important because it provides clues
  to the type of dehydration present.

23

• The emergency physician should be diligent in
  obtaining the following information
• Feeding pattern and fluids given
• Number of wet diapers compared with normal
• Fluid loss (eg, vomiting, oliguria or anuria,
  diarrhea)
• Possible ingestions
• Activity
• Medications
• Heat and sunlight exposures

24
Physical

• The following table highlights the physical
  findings seen with different levels of pediatric
  dehydration.

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Symptom Mild (lt3 body weight lost) Moderate (3-9 body weight lost) Severe (gt9 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
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Mucous membranes Moist Dry Parched
Skin turgor Instant recoil Recoil lt2 seconds Recoil gt2 seconds
Capillary refill lt2 seconds Prolonged Minimal
Extremities Warm Cool Mottled, cyanotic
Symptom Mild (lt3 body weight lost) Moderate (3-9 body weight lost) Severe (gt9 body weight lost)
Mental status Normal, alert Restless or fatigued, irritable Apathetic, lethargic, unconscious
Heart rate Normal Normal to increased Tachycardia or bradycardia
27
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 lt2 seconds Recoil gt2 seconds
Capillary refill lt2 seconds Prolonged Minimal
Extremities Warm Cool Mottled, cyanotic
28

• Of these, the most accurate in identifying the
  level of dehydration are capillary refill, skin
  turgor, and breathing. The least accurate are
  mental status, heart rate and fontanelle
  appearance.

29
Causes

• In most cases, volume depletion in children is
  from fluid losses from vomiting or diarrhea.
• Vomiting may be caused by any of the following
  systems or processes
• CNS (eg, infections, space-occupying lesions)
• GI (eg, gastroenteritis, obstruction, hepatitis,
  liver failure, appendicitis, peritonitis, intussus
  ception, volvulus, pyloric stenosis, toxicity
  ingestion, overdose, drug effects)
• Endocrine (eg, diabetic ketoacidosis
  DKA, congenital adrenal hypoplasia, Addisonian
  crisis)
• Renal (eg, infection, pyelonephritis, renal
  failure, renal tubular acidosis)
• Psychiatric (eg, psychogenic vomiting) - This is
  not seen in infants and is rare in children
  compared with adults.

30

• Diarrhea may be caused by any of the following
  systems or processes
• GI (e.g., gastroenteritis, malabsorption,
  intussusception, irritable bowel, inflammatory
  bowel disease, short gut syndrome)
• Endocrine (eg, thyrotoxicosis, congenital adrenal
  hypoplasia, Addisonian crisis, diabetic
  enteropathy)
• Psychiatric (eg, anxiety)

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• Volume depletion not caused by vomiting or
  diarrhea may be divided into renal or extrarenal
  causes.
• Renal causes include use of diuretics, renal
  tubular acidosis, and renal failure (eg, trauma,
  obstruction, salt-wasting nephritis). The effects
  of diabetes insipidus, hypothyroidism, and
  adrenal insufficiency also fall into this
  category.
• Extrarenal causes include third-space
  extravasation of intravascular fluid (eg,
  pancreatitis, peritonitis, sepsis, heart
  failure) insensible losses from fever, sweating,
  burns, or pulmonary processes poor oral intake
  and hemorrhage.