Fluids Flashcards
How much water content is in an infant?
70-80%
What is intracellular fluid?
2/3 of fluid inside cells
Low in Na
High in K
What is extracellular fluid?
1/3 of fluids is outside the cells
Plasma (intravascular)
Between cells (interstitial and lymph) - edema
High in Na
Low in K
What is transcellular fluid?
CSF, GI tract and pleural, synovial and peritoneal spaces
A “third space” syndrome can develop when increase in transcellular fluid occurs at expense of fluid in other compartments
How does water move between intravascular and interstitial and in/out of cells?
Fluid moves between intravascular & interstitial compartments by filtration
Water moves in/out of cells by osmosis
Forces of fluid balance
hydrostatic pressure
osmotic pressure
diffusion
active transport
vesicular transport
What is the major protein that maintains oncotic pressure?
albumin
What are the forces that favor filtration from the capillary?
capillary hydrostatic pressure and interstitial oncotic pressure
What are the forces that oppose filtration?
capillary oncotic pressure and interstitial hydrostatic pressure
In fetus and preterm, where is the largest proportion of water in the body?
45-50% TBW at birth
30% TBW at 2 years
20% TBW at maturity
Differences in infants
highest % of body weight being water at birth
higher ECF
larger body surface area
higher resp and metabolic rate
high daily fluid requirement with little volume reserve
immature kidneys (dilute and concentrate urine, adjust to changes in electrolytes and sodium)
What is the cause of dehydration?
sodium!!! but also glucose and protein in certain conditions
What are the types of dehydration?
Isotonic dehydration
Hypotonic dehydration
Hypertonic dehyrdation
What is isotonic dehydration?
Electrolyte and water deficits are in balanced proportions
Most common
Major loss from ECF (hypovolemic shock)
No osmotic force is present to cause redistribution
What is hypotonic dehydration?
Electrolyte deficit exceeds water deficit
Water transfers from ECF to ICF, brain cells swell
Na < 130 mEq/L
Little losses show severe signs
Sodium normal value
130-140 mEq/L
What is Hypertonic Dehydration?
Water loss in excess of electrolyte loss
Most dangerous (requires specific fluid therapy)
Fluid shifts from ICF to ECF
Na >150 mEq/L
shock less apparent
Seizure more likely, cerebral changes
What are the cerebral changes in hypertonic dehydration?
disturbances of consciousness
poor ability to focus attention
lethargy
increased muscle tone with hyperreflexia
hyperirritability to stimuli (tactile, auditory, bright light)
Causes of hyponatremia
Gain more H20 than Na (D5W, enema)
Loss of more Na than H20 (D + V with H20 replacement)
Na < 130 mmol/L
Decreased osmolality of blood
Why is D5W act as a hypotonic solution?
dextrose is quickly metabolized
S&S of hyponatremia
anorexia, headache, muscle weakness, decreased deep tendon reflexes, lethargy, confusion, coma
Seizures
Tx of hyponatremia
restricted water intake (allows kidneys to rebalance)
hypertonic saline
Causes of hypernatremia
loss of more H20 tha Na (diabetes, D + V, sweating, high solute intake)
Gain of more Na than H2O (no access to water)
Hypernatremia = >150 mmol/L
Increased osmolality (body fluids too concentrated)
SCIDS
diarrhea (all water)
Na > 170 mmol/L
S&S for hypernatremia
thirsty, decreased output
decreased LOC - confusion, lethargy, coma from shrinking of brain cells; seizures if rapid or severe; can be fatal
Tx for hypernatremia
isotonic first and then hypotonic to correct osmolality
Manifestations of dehydration
- Thready, rapid pulse
- Dry skin & mucous membranes
- Sunken fontanel
- Coolness & mottling of extremities
- decreased skin turgor
- Delayed capillary refill
- increased small vein filling time
- Dizziness, syncope
- Oliguria
- Weight loss
- Postural BP drop (older children)
What is the earliest detectable sign of dehydration?
tachycardia
followed by dry skin & mucous membranes, sunken fontanels, signs of circulatory failure
What are compensatory mechanisms for dehydration?
Interstitial fluid moves into vascular compartment to maintain blood volume in response to hemoconcentration & hypovolemia, & vasoconstriction of peripheral arterioles helps maintain pumping pressure.
Early decompensation of dehydration
Interstitial fluid moves to vascular compartment; vasoconstriction maintains pumping pressure
Late compensation of dehydration
BP falls - tissue hypoxia and metabolic acidosis
Renal compensation - ADH to conserve fluid, renin-angiotensin (vasoconstriction), aldosterone (Na retention and water conservation
Shock (from dehydration)
Tachycardia, poor perfusion (skin cool & mottled, decreased cap refill), oliguria & azotemia, low BP (late sign)
Signs of mild dehydration
up to 5% weight loss
irritable and thirsty
Signs of moderate dehydration
6-9% weight loss
Lethargic and sleepy, restless and irritable, decreased skin turgor, dry mucous membranes, urine dark, increased HR and decreased BP
Signs of severe dehydration
> 10% weight loss
Lethargic or non-responsive, decreased BP, rapid pulse, poor skin turgor, dry mucous membranes, decreased or absent urine output
Nursing care for dehydration
weight daily
I and O
LOC, pulse rate, skin turgor, mucous membranes, BP
When are increased fluid requirements needed?
Fever (add 12% per rise of 1o C)
Vomiting
Diarrhea
High-output kidney failure
Diabetes insipidus
Diabetic ketoacidosis
Burns
Shock
Tachypnea
Radiant warmer
Phototherapy (high bilirubin levels)
Post-op bowel surgery
Normal urine output
Infant and Child = 1ml/kg/hr
Adolescent = 0.5 ml/kg/hr
What is diarrhea caused by?
Caused by abnormal intestinal water & electrolyte transport
What does dehydration result in?
dehydration
electrolyte imbalances (loss of Na, Cl, K and bicarb)
Metabolic acidosis
Why are more fluid and electrolytes lost in infant with diarrhea as opposed to older child?
intestinal mucosa of infant is more permeable to water
Acute diarrhea
usually self limited to < 14 days
infants are more susceptible because their immune systems are not strong enough yet
infectious agents cause
Chronic diarrhea
> 14 days
Often caused by malabsorption causes, IBD, immunodeficiency, food allergy, lactose intolerance, radiation, motility disorders, endocrine causes, parasitic infestations
celiac, short bowel, lactose intolerance
Predisposition to diarrhea
younger the child, more likely and severe
Malnourished and immunocompromised
crowding, bad sanitation, poor facilities for food storage
First line treatment to diarrhea
oral rehydration therapy
- reabsorption of sodium and water
- reduce vomiting loss from diarrhea and illness
WANT REHYDRATION
When do you not want to use rapid IV replacement?
hypertonic dehydration
The DO NOTs with diarrhea treatment
Do not encourage po clear fluids, such as fruit juices, carbonated soft drinks, & jello
Do not drink caffeinated pop or other drinks (diuretic)
Do not give soup (high salt)
Do not use BRAT diet
Hypovolemic shock
Circulatory failure
- Tissue perfusion that is inadequate to meet metabolic demands of body
- Results in cellular dysfunction & eventual organ failure
What are the consequences to hypovolemic shock?
hypotension
tissue hypoxia
metabolic acidosis
Hypovolemic shock patho
from blood loss, plasma loss (burns), ECF loss (dehydration, diarrhea)
Three things to look at when assessing for severity of shock
- degree of tachycardia and perfusion
- LOC
- BP
Management of shock
- ventilation
- fluid administration
- improvement of pumping action of heart
A!!!
Central line
Fluid volume excess (edema) manifestations
weight gain, bounding pulse, distended neck veins (children), hepatomegaly, dyspnea, orthopnea, lung crackles, edema (interstitial overload)
Edema causes
adrenal tumours, CHF, liver cirrhosis, chronic renal failure, glucocorticoids, too much isotonic IV solutions containing Na+
What will decrease fluid requirements
CHF, SIADH, oliguric renal failure, increased ICP
Edema
abnormal accumulation of fluid & subsequent tissue expansion within the interstitial tissue & develops when a defect in the normal cardiovascular circulation or failure in lymphatic drainage to remove the increased amounts occurs.
Infant edema
often generalized; in children occurs in dependent areas of body
When do you have decreased fluid requirements?
- Heart failure
- SIADH
- Mechanical ventilation
- Post-op
- Oliguric renal failure
- Increased ICP
