Fluid Management Flashcards
norovirus
not the most common cause of gastroenteritis and dehydration in the US
hypovolemia and dehydration
not the most common cause of gastroenteritis and dehydration in the US
Degrees of dehydration
Mild 3-5%
Moderate:6-10%
Severe: greater than 10 %
most accurate measurement of dehydration
The most accurate measurement is weight. Every gram of weight loss acutely is equivalent to 1 ml of fluid loss. Therefore a 1 kilogram weight loss of a 10 kilogram baby is a 10% loss. If you don’t have a recent weight you must rely on clinical signs and symptoms for weight loss estimate.
Systemic signs
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Increased thirst
Irritable
Lethargic
urine output
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Decreased
Decreased (
mucous membranes
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Tacky
Dry
Parched
skin turgor
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Normal
Reduced
Tenting
capillary refill
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Normal
Mildly delayed
Markedly delaye
skin temperature
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Normal
Cool
Cool, mottled
anterior fontanelle
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Normal
Sunken
Markedly sunken
heart rate
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Normal
Increased
Markedly increased or ominously low
blood pressure
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Normal
Normal to low
Low
respirations
Dehydration
Mild (3%–5%)
Moderate (6%–9%)
Severe (≥10%)
Normal
Deep, may be increased
Deep and increased or decreased to absent
hyptension in dehydration
very late finding and is ominous if present
hyponatremicdehydration
may appear more dehydrated than they are as fluid moves from the extracellular space to the intracellular space resulting in clinical findings more profound than the actual level of dehydration.
normal serum osmolality
270 mOsm/kg.
hyponatremia
overestimate the degree of dehydration
hypernatremia
underestimate the degree of dehydration
urinalysis includes
SG, pH, glucose, leukocytes, nitrites, bilirubin and hemoglobin
What do you think is the most important components of a BMP and urinalysis to evaluate dehydration?
CO2 or bicarb below 17 on initial evaluation implies a
significant amount of dehydration
isonatremic
Isonatremicdehydration occurs when roughly an equal amount of water and solute are lost. This is represented by a sodium of 130-150 mEq/liter.
hyponatremic
Hyponatremicdehydration occurs when there is greater solute lost than water. This is represented by a sodium less than 130 mEq/liter.
hypernatremic
Hypernatremicdehydration occurs when there is a greater loss of water relative to solute as represented by a sodium greater than 150 mEq/liter.
RISKS:
Hyponatremia-risk of protracted seizures
Hypernatremia-risks of cerebral edema, seizures and death on rehydration
Goals of treatment
To recognize the degree and type of dehydration
Restore cardiovascular stability and restore any water and electrolyte deficiencies while also meeting maintenance requirements and keeping up with ongoing losses.
If, based on clinical findings a child is deemed severely dehydrated, IV therapy should be instituted. Moderate dehydration usually requires IV therapy, but if closer to mild, may be able to successfully be managedwith oral rehydration.
Formal assessment of fluid and electrolyte losses can be calculated. We will go through the basic science of this, however, in clinical practice it is much simpler.
Daily loss of sodium is roughly 3 mEq/100 mlfor Potassium it is 2 mEq/100 ml. these are lost through urination and must be replaced as maintenance.
Acute fluid losses from GE usually are 60% extracellular and 40% intracellular. Therefore, for every 100 ml fluid loss you lose 8.4 mEqof sodium and 6 mEqof potassium. 140 mEqNa/literx 0.6 divided by 10 and potassium intracellular 150mEq/liter x 0.4 divided by 10. Hyperacutelosses are often completely extracellular.
Isonatremic dehydration treatment
Mild to moderate dehydration, oral rehydration may suffice. Ideally, utilizing rehydration solutions such as Pedialyteor Enfalyteor the WHO rehydration solution is the best. In the ED you will use these solutions. Often attempting to correct50-100 ml/kg body weight over 2-4 hrs, if needed you can use an NG tube.
If patient is vomiting Ondansetron has been a very effective antiemetic in this setting or at home. Oral rehydration is contraindicated in infants and children with cardiovascular instability, shock, altered mental status, intractable vomiting , bloody diarrhea, ileus, abnormal serum sodium or glucose malabsorption
Experience with these solutions at home, you will find children often don’t like the taste of them. So while not recommended, using Gatorade, Powerade, water in mild dehydration often suffices. You should avoid juices as this can exacerbate diarrhea. In more significant dehydration, IV fluid may be required.
how do we give IV fluids
If clinically unstable, or showing cardiovascular compromise a bolus of fluid is indicated. This is given in the form of 0.9% normal saline as it is made up of 154 mEqNa/liter. Closely mimicking the actual osmolarityof Intravascular fluid. Following a bolus or two, you can begin to give D5 1/2NS to correct the deficit and maintenance needs. In children with congestive heart failure or cerebral edema more judicious boluses may be indicated. To correct potassium losses and provide maintenance you add 20 mEqKCl/liter after the patient has voided.
We usuallycorrect volume over 24 hrs. One of the keys to safe mgmtof patients is to hurry to stabilize and then slow down as there is no rush. Pushing too aggressively can result in complications in certain circumstances such as DKA.
hypernatremic dehydration treatment
Hypernatremicdehydration: serum sodium greater than 150 mEq/liter.
Because sodium draws more fluid into the extracellular space children may appear less dehydrated than they are. Therefore you should estimate an additional 3-5% dehydration to your clinical estimate. Patients are usually somnolent but may have a high pitched irritable cry when disturbed.
Hypertonicity can result in “brain shrinkage” and rehydration may cause too rapid an expansion of cerebral fluid resulting in cerebral edema. This is the most common cause of iatrogenic death in DKA. But hyperosmolarityin this case is due to excess glucose. Mortality in hypernatremicdehydration can be high for 3 reasons. Patients can develop clotting in small veins or duralsinuses, you can have tearing of vessels due to the shrinkage or during rehydration cerebral edema.
Mortality ranges from 3-20%, neurologic sequelae up to 40-50% and of these 5-10% are severe. Infants with Na over 160mEq/L fare the worst.
Intensive monitoring is required and Na should not be corrected more quickly than 0.5 mEq/hr.To calculate this use the formula Na actual-Na desired/Na actual x 1000ml/L x 0.6 L/kg.
Alternatively you can use 4ml/kg of free water for every mEqNa greater than 145 mEq/L or 3ml/kg of free water for every mEqNa greater than 145 mEq/L if Na is over 170 mEq/L.
The simplest way however, is to use ¼ normal saline with 20 mEqKCl/L to restore deficit and continue maintenance over 48 hrs.
Hypnatremic dehydration treatment
Oral rehydration is contraindicated in this circumstance. Bolus fluids are also given as 0.9% normal saline. If one wants to calculate the excess sodium loss that requires replacement you can use this formula:
mEqNa deficit equals (desired Na-measured Na x 0.6 x weight in kg. Using the child’s baseline weight, maintenance and deficit fluid and electrolytes can be calculated and replaced over 24 hrs. In reality, we use D5 ½ NS with 20KCl/liter as replacement fluids. Sodium should not rise more than 12-15 mEq/liter over the 24 hrs, so frequent reassessment q4-6 hrsmay be necessary.
Too rapid a correction can lead to a rare complication of pontine myelinosis(bleeding in the pontine nucleus) With sodium less than 120 mEq/liter you can see seizures. This can be corrected with 0.9% normal saline or 3% normal saline if too much volume is an issue. This is indeed a rare requirement.
per 100 mls of water you lose
8.4 meq of sodium and 6 meq of potassium
if you have lost 1 kilo of water weight
and you give someone a 20 per kilo bolus they are now only 800ml down
rehydrating rules
100 ml per kilo for the first 10 kilos
next 10 kilos is 50 mls per kilo
next they are 20mls per kilo
4mls per kilo per hour, 2mls per hr, 1ml per hr…….4/2/1 rule
then use d5 half normal saline with 20 kcl per liter
risk becoming hyperkalemic so patient must urinate before you give potassium so you dont send them into tachycardia
