L4-Fluid and Electrolytes

Why do infants become dehydrated much faster than adults?

• greater fluid intake/output relative to their size

• larger body surface area (more water lost through skin)

• higher metabolic rate

• immature kidneys

• greater susceptibility to insensible fluid loss

Insensible water loss is water loss that isn’t easily measured, primarily through ___________ and ___________

skin and respiration

Where is total body water located?

TBW = ICF + ECF

What are the three major locations of ECF?

Intravascular, interstitial, transcellular

__________ is the primary determinant of ECF

Na+ (sodium)

What systems control water balance?

Thirst + ADH + Aldosterone + Renin-Angiotensin System

What does ADH do?

Retains water → decreases urine output

• More ADH → kidneys retain water → less urine

• Less ADH → kidneys release water → more water

What does aldosterone do?

retains sodium (in the kidneys)

• water follows sodium

• ↑ Aldosterone → ↑ Na⁺ reabsorption → water follows sodium → ↑ blood volume/BP
  It also causes ↑ K⁺ excretion.

______________ detects changes in plasma osmolality and regulates the release of ADH to control water balance.

Hypothalamus

• ↑ Osmolality = blood too concentrated
  → Hypothalamus detects it
  → ↑ ADH
  → Kidneys retain WATER
  → Urine becomes more concentrated
  → Blood becomes more diluted

• ↓ Osmolality = blood too diluted
  → ↓ ADH
  → Kidneys release more water
  → More dilute urine

What is the key rule for osmolality?

water follows particles

• If there are lots of particles outside the cell, water gets pulled out

• If there are fewer particles outside, water moves into the cell

What happens to cells during hyponatremia?

water moves into cells → cells swell

What happens to cells during hypernatremia?

water moves out of cells → cells shrink

What are the S/S of hyponatremia?

S – Seizures
A – Abdominal cramping
L – Lethargy
T – Tendon reflexes diminished
L – Loss of appetite
O – Orthostatic hypotension
S – Shallow respirations
S – Spasms

Why can hyponatermia cause seizures?

↓Na⁺ → water enters brain cells → cerebral swelling → seizures

What are the S/S of hypernatremia?

• fatigue

• increased reflexes

• extreme thirst

• dry mouth/skin

What are the S/S of hypokalemia?

• Lethargy

• Leg cramps

• Limp muscles

• Low/shallow respirations

• Lethal dysrhythmias

• Lots of urine

• Low BP

What ECG changes occur with hypokalemia?

Flattened T waves + U waves

What are the S/S of hyperkalemia?

Muscle weakness

Urine changes — oliguria/anuria

Respiratory distress

Decreased cardiac contractility

ECG changes

Reflex changes

What ECG changes occur with hyperkalemia?

Tall, peaked T waves + widened QRS

What labs should you check with suspected hyperkalemia?

K⁺ + BUN + creatinine

What are the S/S of hypocalcemia?

Confusion
Reflexes hyperactive
Arrhythmias
Muscle spasms
Positive hyperreflexia signs
Sensation of tingling/numbness

Does hypocalcemia increase or decrease neuromuscular activity?

INCREASES it → hyperreflexia + spasms

What are manifestations of hypercalcemia?

Profound weakness

ECG changes

Absent reflexes

Kidney stones

What causes hypermagnesemia?

Excess supplementation or decreased renal function

What are manifestations of severe hypermagnesemia?

Profound lethargy + ECG changes

What are the 3 types of dehydration?

Isotonic, hypertonic, hypotonic

What is the most common type of dehydration?

Isotonic

What labs increase with isotonic dehydration?

↑ Hct

↑ BUN

↑ urine specific gravity

What defines hypertonic dehydration?

Na⁺ >145

water loss > electrolyte loss

What is the major danger of hypertonic dehydration?

Neurologic compromise/seizures

What defines hypotonic dehydration?

Na⁺ <135

electrolyte loss > water loss

What is the major danger of hypotonic dehydration?

SHOCK

What happens as dehydration becomes more severe?

• ↓ urine

• ↓ BP

• ↑ cap refill

• ↑ dry mucous membranes

• ↓ skin turgor

• ↓ weight

What is the FIRST responsibility when a dehydrated child is admitted?

WEIGH THE CHILD

What % weight loss indicates mild dehydration?

3-5%

What % weight loss indicates moderate dehydration?

6-9%

What % weight loss indicates severe dehydration?

>10%

How is mild/moderate dehydration treated?

Oral rehydration: 50–100 mL/kg over 4 hr

How much additional ORS is given for each diarrheal stool?

10mL/kg

How is moderate/severe dehydration initially treated?

Isotonic IV fluid 20 mL/kg bolus → reassess

What electrolyte should NOT be given until kidney function is verified?

Potassium (K⁺)

Why must urine output/kidney function be verified before giving potassium?

Kidneys may not eliminate K⁺ → hyperkalemia → dangerous dysrhythmias

What is the pediatric daily maintenance fluid rule?

o   First 10 kg → 100 mL/kg/day

o   11–20 kg → 1000 mL + 50 mL/kg for every kg >10

o   >20 kg → 1500 mL + 20 mL/kg for every kg >20

What does an isotonic fluid do?

Expands intravascular volume without major cellular fluid shifts

Examples of isotonic fluids?

0.9% NS + Lactated Ringer's

When are isotonic fluids commonly used?

Dehydration and shock

What does hypotonic fluid do to cells?

Water moves INTO cells → SWELL

Example of hypotonic fluid?

0.45% NS

What does hypertonic fluid do to cells?

Water moves OUT of cells → SHRINK

Example of hypertonic fluid?

3% saline

When is intraosseous (IO) access used in children?

Critically ill/shocked child when IV access is unsuccessful

How quickly should blood be started after arrival?

Within 30 minutes

How long can a blood transfusion run?

Maximum 4 hours

When is the highest-risk monitoring period during a transfusion?

First 15–20 minutes

What should the nurse do during the first 15–20 min of blood administration?

Transfuse slowly + stay with child + monitor VS/response

FIRST action for suspected transfusion reaction?

STOP THE TRANSFUSION

What is the most severe transfusion reaction?

hemolytic

What suggests a febrile transfusion reaction?

Fever + chills

What suggests an allergic transfusion reaction?

Urticaria (hives) + pruritus (itchyness) + laryngeal edema

What can cause water intoxication in an infant?

Excess water or improperly diluted infant formula

What electrolyte problem occurs with water intoxication?

Hyponatremia

Why can water intoxication cause seizures?

Excess water → ↓Na⁺ → water enters brain cells → cell swelling → seizures

What are the 3 major types of burns?

Thermal, chemical, electrical

What are typical characteristics of 1st/2nd-degree burns?

• Superficial/partial thickness

• Pink/red

• May blister

• Painful

What are typical characteristics of 3rd/4th-degree burns?

• Full thickness

• Red/tan/brown/black

• No blanching

• Little/no pain

• Severe scarring possible

Why can a 3rd-degree burn hurt LESS than a 2nd-degree burn?

Nerve endings are destroyed.

What is the priority treatment for moderate/major pediatric burns?

IV access ASAP + fluid replacement + monitor for shock

Which topical medications are listed for pediatric burns?

Bacitracin, mupirocin, Silvadene