What are the different types of intravenous (IV) fluids, and when should they be used, at what rate, and when should they be stopped?

Types of IV Fluids, Indications, Administration Rates, and Discontinuation Guidelines

Balanced crystalloids should be the first-line choice for most fluid resuscitation scenarios due to their superior safety profile compared to other options. 1

Types of IV Fluids

Crystalloids

1. Normal Saline (0.9% NaCl)

   • Composition: 154 mmol/L sodium, 154 mmol/L chloride
   • Osmolarity: 308 mOsm/L
   • Cautions: Can cause hyperchloremic metabolic acidosis with large volumes 1
   • Cost: Inexpensive

2. Balanced Crystalloids

   • Ringer's Lactate
     • Composition: Sodium, potassium, calcium, chloride, and lactate
     • Osmolarity: 273 mOsm/L
   • Plasmalyte
     • Composition: Sodium, potassium, magnesium, chloride (98 mmol/L), acetate
     • Osmolarity: 295 mOsm/L
     • No calcium content - compatible with blood transfusions 1
   • Isofundine
     • Composition: Sodium, potassium, magnesium, calcium (2.5 mmol/L), chloride (127 mmol/L), acetate, malate
     • Osmolarity: 309 mOsm/L 1

Colloids

1. Albumin (5% or 25%)

   • Oncotic effect: 20 mL of 25% albumin draws approximately 70 mL of fluid from extravascular tissues into circulation within 15 minutes 2
   • Indications: Hypoproteinemic states, plasma volume expansion, severe hemolytic disease in neonates, acute liver failure 2
   • Cautions: Expensive, risk of infection transmission (though extremely low) 2

2. Synthetic Colloids (e.g., hydroxyethyl starch)

   • Cautions: Associated with increased mortality and renal failure in critically ill patients 1, 3

Clinical Indications and Selection

Trauma and Hemorrhagic Shock

• First-line: Balanced crystalloids (Plasmalyte preferred) 4, 1
• Rate: For aggressive resuscitation in hemorrhagic shock, fluid administration at >10 mL/kg/hour or >500 mL/hour for the first 12-24 hours 4
• Volume: For non-aggressive approach, <10 mL/kg/hour or <500 mL/hour 4
• Monitoring: Rate of infusion is the best predictor for patients requiring immediate surgical intervention 5

Sepsis and Septic Shock

• First-line: Balanced crystalloids 4, 1
• Rate: Initial fluid bolus within first hour of recognizing sepsis 4
• Monitoring: Achieve hemodynamic endpoints within 6 hours of recognizing sepsis 4
• Volume: After initial resuscitation, targeted fluid minimization guided by assessments of fluid responsiveness may be beneficial 6

Pediatric Resuscitation

• First-line: Balanced crystalloids
• Rate: For shock, fluid bolus of 20 mL/kg over 5-20 minutes, may repeat based on reassessment 4
• Volume: Up to 110 mL/kg may be required in children with septic shock during early resuscitation 4
• Caution: In children with profound anemia and severe sepsis, particularly due to malaria, fluid boluses must be administered cautiously, and blood transfusion should be considered 4

Acute Pancreatitis

• First-line: Balanced crystalloids (Lactated Ringer's solution) 4
• Rate:
  • Aggressive approach: >10 mL/kg/hour or fluid bolus 20 mL/kg for 2 hours, then 2-3 mL/kg/hour in first 24 hours 4
  • Non-aggressive approach: <10 mL/kg/hour or fluid bolus 10 mL/kg for 2 hours, then 1.5 mL/kg/hour in first 24 hours 4

Administration Rates

Initial Resuscitation

• Shock states: 10-20 mL/kg in first hour, reassess and repeat if needed 4
• Moderate fluid requirements: 5-10 mL/kg/hour
• Maintenance: 1-3 mL/kg/hour based on clinical status

Rate Adjustment Based on Response

• Positive response: 10% increase in systolic/mean arterial blood pressure, 10% reduction of heart rate, improvement of mental state, peripheral perfusion, and/or urine output 4
• Moderate infusion rate should be considered to allow identification of the patient's response to initial fluid resuscitation 5

When to Stop or Reduce IV Fluids

1. No improvement in tissue perfusion in response to volume loading 4
2. Development of crepitations indicating fluid overload or impaired cardiac function 4
3. Signs of fluid overload:
   • Rapid weight gain
   • Incident ascites
   • Jugular vein engorgement
   • Pulmonary/peripheral edema 4
4. After achieving hemodynamic targets:
   • Normalized blood pressure
   • Heart rate within normal range
   • Adequate urine output (>0.5 mL/kg/hour)
   • Improved mental status
   • Normalized lactate levels

Monitoring During Fluid Administration

• Vital signs: Heart rate, blood pressure, respiratory rate
• Urine output: Target >0.5 mL/kg/hour
• Clinical examination: Mental status, peripheral perfusion, capillary refill
• Laboratory parameters: Hematocrit, BUN, creatinine, lactate
• For critically ill patients: Consider more advanced monitoring (central venous pressure, echocardiography)

Pitfalls and Caveats

1. Avoid excessive fluid administration after initial resuscitation as it is associated with adverse outcomes in critically ill patients 3, 6

2. Never use sterile water as a diluent for albumin as it can cause severe hemolysis and acute renal failure 2

3. Avoid synthetic colloids (particularly starch-based solutions) in critically ill patients due to increased risk of mortality and renal failure 1, 3

4. Avoid normal saline in large volumes due to risk of hyperchloremic metabolic acidosis 1, 7

5. Do not begin administration more than 4 hours after the container has been entered 2

6. Albumin should not be used in patients with severe traumatic brain injury due to association with increased mortality 3