Fluid and Electrolytes Flashcards
Clinical Signs - Daily Weights
(1 kg loss = 1 L fluid loss)
Clinical Signs - I & O
Urine output:
- Infants → ≥2 mL/kg/hr
- Children → 0.5-1 mL/kg/hr
Clinical Signs - Vital Signs
- Early dehydration: Tachycardia
- Late sign: Hypotension
Clinical Signs - Skin & Mucous Membranes
Turgor, dry mucosa, sunken eyes
Clinical Signs - Fontanelles
Sunken from dehydration
Clinical signs - Cap Refill
- Normal: <2 sec
- Prolonged in dehydration
Three Types of Dehydration
Isotonic
Hypotonic
Hypertonic
Isotonic Dehydration
- Equal loss of water & sodium → Normal sodium (135-145)
- Most common type
- Causes: Vomiting, diarrhea, hemorrhage
- Risk: Hypovolemic shock
Hypotonic Dehydration
- More sodium loss than water loss → Low sodium (<135)
- Fluid shifts from ECF to ICF → Worse ECF depletion
- Causes: Diuretics, excessive water intake, burns
Hypertonic Dehydration
- More water loss than sodium loss → High sodium (>145)
- Fluid shifts from ICF to ECF → Cells shrink
- Causes: Diabetes insipidus, excessive sweating, high fever
- Risk: Neurologic complications (seizures, irritability)
Mild Dehydration
<5% body loss, Normal vitals, slight thirst, moist mucous membranes, normal UO
Moderate Dehydration
6-9% body weight loss, Tachycardia, tachypnea, dry mucous membranes, decreased skin turgor, oliguria, irritable or lethargic
Severe Dehydration
> 10% body weight loss, Hypotension, very dry mucous membranes, sunken fontanelle, no tears, minimal/absent UO, lethargy, poor cap refill (>3-4 sec)
IV Maintenance Fluids (4-2-1 Rule)
- First 10 kg → 4 mL/kg/hr
- Next 10 kg → 2 mL/kg/hr
- Each kg above 20 kg → 1 mL/kg/hr
Examples:
* 8 kg child → 8 × 4 = 32 mL/hr
* 12 kg child → (10 × 4) + (2 × 2) = 44 mL/hr
* 30 kg child → (10 × 4) + (10 × 2) + (10 × 1) = 70 mL/hr
Fluid Management IV bolus (non cardiac/renal)
- Isotonic fluids (Normal Saline or Lactated Ringer’s)
- Bolus dose = 20 mL/kg over 30-60 minutes
- Avoid boluses in cardiac or renal patients
Sodium Normal Range / S/S imbalance
135-145 mmol/L
Low (hyponatremia): Confusion, seizures, weakness, nausea
High (hypernatremia): Thirst, irritability, seizures
Potassium Normal Range / S/S Imbalance
3.5-5.0 mmol/L
Low (hypokalemia): Weakness, arrhythmias
High (hyperkalemia): Peaked T waves, muscle weakness
Calcium Normal Range / S/S Imbalance
8.5-10.5 mg/dL
Low (hypocalcemia): Tetany, seizures
High (hypercalcemia): Weakness, kidney stones
Acid Base Balances
Respiratory Acidosis (CO2 retention)
Respiratory Alkalosis (Co2 Loss)
Metabolic Acidosis (Excess Acid)
Metabolic Alkalosis (Loss of Acid)
Respiratory Acidosis
(CO₂ Retention)
- Cause: Hypoventilation (asthma, respiratory failure)
- ABG: ↓ pH, ↑ CO₂
- Compensation: Kidneys retain HCO₃
Respiratory Alkalosis
(CO₂ Loss)
- Cause: Hyperventilation (anxiety, sepsis, fever)
- ABG: ↑ pH, ↓ CO₂
- Compensation: Kidneys excrete HCO₃
Metabolic Acidosis
(Excess Acid)
- Cause: DKA, diarrhea (bicarbonate loss)
= ABG: ↓ pH, ↓ HCO₃
- Compensation: Lungs hyperventilate (Kussmaul’s breathing)
Metabolic Alkalosis
(Loss of Acid)
- Cause: Vomiting, diuretics
- ABG: ↑ pH, ↑ HCO₃
- Compensation: Lungs hypoventilate
