Simulation Lab
Teenage Athlete with Fluid and Electrolyte Imbalance
Student Preparation
1. Review the pathophysiology of dehydration
The distribution of total body water in children differs from that in adults. Normal newborns have about 75%total
body water as a percentage of weight. Older children gradually approach the adult proportion of 60%.The reduction
in total bodywater over time is primarily from the extracellular fluid compartment The intravascular volume, of
primary importance in hemodynamics, is about one third that of the total extracellular fluid compartment. Normally,
two-thirds of total bodywater is in the intracellular fluid compartment and one third in the extracellular fluid
compartment (of which one quarter is plasma and one third is total blood volume). Sodium is found predominantly
in the extracellular fluid compartment and is the primary solute that regulates the distribution of water between
intracellular fluid and extracellular fluid compartments. If sodium is lost, the extracellular fluid compartment, and
therefore intravascular volume, decreases. In precise terms, volume depletion, but not dehydration, involves loss of
solutes, and therefore of extracellular fluid. Conversely, dehydration means loss of water. Because cell membranes are
for the most part freely permeable to water, dehydration affects the intracellular and extracellular compartments equally
and results in symptoms of increased serum tonicity, such as thirst and altered mental status. In dehydration, water is
lost in proportion to bodywater distribution. Plasma volume loss accounts for only one quarter of the extracellular
space, which is one third of total body water. Therefore, onlyone 12th of total losses in dehydration come from
intravascular plasma volume, explaining the relative preservation of intravascular volume and hemodynamic
parameters.
2. Which types of dehydration are most often associated with heat-related illnesses?
Moderate-Severe, Skin Loss Dehydration
3. What electrolyte imbalances would you expect to find with dehydration?
Mayshow hypernatremia, isonatremia, or hyponatremia; enteral losses: associated with hypokalemia and low
bicarbonate level; crush injuries and burns: may be associated with hyperkalemia. Urine Osmolalityusually >450
mOsm/kg. The urine specific gravity of normally functioning kidneys: >1.025; abnormally functioning kidneys:
normal or inappropriately low
4. What assessment findings are consistent with dehydration?
Mental status, activity level assessment: this provides critical diagnostic information. Infants and small children who
are inconsolable or listless, or do not seem to resist invasive or uncomfortable procedures should be assumed to have
serious illness. Mucous membranes: dryor tacky mucous membranes are seen with hypovolemia; pallid mucous
membranes suggest chronic blood loss. Capillary refill: classically, volume depletion is associated with a prolonged
capillary refill time (>3 seconds).This is most likely to be true in the setting of gradual volume depletion, as is seen
in gastroenteritis. Ameta-analysis concluded that the 3 most useful clinical findings in a child with volume depletion
and dehydration were prolonged capillary refill time, decreased skin turgor, and abnormal respiratory pattern.
However, in burns, anaphylaxis, and sepsis, capillary refill time may not be prolonged (<3 seconds). Therefore,
determining capillary refill time is not a reliable clinical test in all cases.
Skin turgor can be notably affected in severe cases of volume depletion, particularly those associated with
hypernatremia or hyperosmolarity. Adoughy consistency is reported in hyponatremic states. Because children have
more skin elasticity than adults, this is often a relatively late sign in the progression of volume depletion.Assessing
skin turgor bypinching a small fold of skin on the abdomen adjacent to the umbilicus and observing recoil is
recommended. Bruises or signs of neglect: children presenting with hypovolemia from internal bleeding as a result of
no accidental trauma may have evidence of prior trauma. Importantly, these signs may be completely absent. The
lack of external findings is not sufficiently reassuring to preclude further investigation.Abdominal exam: abdominal
tenderness is common in gastroenteritis, intra-abdominal hemorrhage, and small-bowel obstruction.Active bowel
, sounds are heard in gastroenteritis. Bowel sounds are diminished insepsis, hypokalemia, some kinds of
abdominal trauma, and generalized severe illness.
Teenage Athlete with Fluid and Electrolyte Imbalance
Student Preparation
1. Review the pathophysiology of dehydration
The distribution of total body water in children differs from that in adults. Normal newborns have about 75%total
body water as a percentage of weight. Older children gradually approach the adult proportion of 60%.The reduction
in total bodywater over time is primarily from the extracellular fluid compartment The intravascular volume, of
primary importance in hemodynamics, is about one third that of the total extracellular fluid compartment. Normally,
two-thirds of total bodywater is in the intracellular fluid compartment and one third in the extracellular fluid
compartment (of which one quarter is plasma and one third is total blood volume). Sodium is found predominantly
in the extracellular fluid compartment and is the primary solute that regulates the distribution of water between
intracellular fluid and extracellular fluid compartments. If sodium is lost, the extracellular fluid compartment, and
therefore intravascular volume, decreases. In precise terms, volume depletion, but not dehydration, involves loss of
solutes, and therefore of extracellular fluid. Conversely, dehydration means loss of water. Because cell membranes are
for the most part freely permeable to water, dehydration affects the intracellular and extracellular compartments equally
and results in symptoms of increased serum tonicity, such as thirst and altered mental status. In dehydration, water is
lost in proportion to bodywater distribution. Plasma volume loss accounts for only one quarter of the extracellular
space, which is one third of total body water. Therefore, onlyone 12th of total losses in dehydration come from
intravascular plasma volume, explaining the relative preservation of intravascular volume and hemodynamic
parameters.
2. Which types of dehydration are most often associated with heat-related illnesses?
Moderate-Severe, Skin Loss Dehydration
3. What electrolyte imbalances would you expect to find with dehydration?
Mayshow hypernatremia, isonatremia, or hyponatremia; enteral losses: associated with hypokalemia and low
bicarbonate level; crush injuries and burns: may be associated with hyperkalemia. Urine Osmolalityusually >450
mOsm/kg. The urine specific gravity of normally functioning kidneys: >1.025; abnormally functioning kidneys:
normal or inappropriately low
4. What assessment findings are consistent with dehydration?
Mental status, activity level assessment: this provides critical diagnostic information. Infants and small children who
are inconsolable or listless, or do not seem to resist invasive or uncomfortable procedures should be assumed to have
serious illness. Mucous membranes: dryor tacky mucous membranes are seen with hypovolemia; pallid mucous
membranes suggest chronic blood loss. Capillary refill: classically, volume depletion is associated with a prolonged
capillary refill time (>3 seconds).This is most likely to be true in the setting of gradual volume depletion, as is seen
in gastroenteritis. Ameta-analysis concluded that the 3 most useful clinical findings in a child with volume depletion
and dehydration were prolonged capillary refill time, decreased skin turgor, and abnormal respiratory pattern.
However, in burns, anaphylaxis, and sepsis, capillary refill time may not be prolonged (<3 seconds). Therefore,
determining capillary refill time is not a reliable clinical test in all cases.
Skin turgor can be notably affected in severe cases of volume depletion, particularly those associated with
hypernatremia or hyperosmolarity. Adoughy consistency is reported in hyponatremic states. Because children have
more skin elasticity than adults, this is often a relatively late sign in the progression of volume depletion.Assessing
skin turgor bypinching a small fold of skin on the abdomen adjacent to the umbilicus and observing recoil is
recommended. Bruises or signs of neglect: children presenting with hypovolemia from internal bleeding as a result of
no accidental trauma may have evidence of prior trauma. Importantly, these signs may be completely absent. The
lack of external findings is not sufficiently reassuring to preclude further investigation.Abdominal exam: abdominal
tenderness is common in gastroenteritis, intra-abdominal hemorrhage, and small-bowel obstruction.Active bowel
, sounds are heard in gastroenteritis. Bowel sounds are diminished insepsis, hypokalemia, some kinds of
abdominal trauma, and generalized severe illness.
