What is the calculation for intravenous (IV) fluid administration in a patient requiring fluid resuscitation, considering their individual needs and underlying conditions such as sepsis or burns?

IV Fluid Calculation and Administration

Initial Fluid Resuscitation Calculations

For most critically ill patients requiring fluid resuscitation, use balanced crystalloids (Ringer's Lactate or Plasmalyte) as first-line therapy, with initial boluses of 30 mL/kg for adults with sepsis or 20 mL/kg for children, titrated to clinical endpoints including mean arterial pressure ≥65 mmHg, urine output ≥0.5 mL/kg/h, and lactate clearance. 1

Standard Resuscitation Formulas by Clinical Scenario

Sepsis/Septic Shock (Adults):

• Initial bolus: 30 mL/kg of balanced crystalloid within first 3 hours 2
• Some patients may require several liters during first 24-48 hours 2
• Target endpoints: MAP ≥65 mmHg, urine output ≥0.5 mL/kg/h, improved mental status and peripheral perfusion 2

Sepsis/Septic Shock (Children):

• Initial bolus: 20 mL/kg of balanced crystalloid 2
• May require up to 110 mL/kg during early resuscitation 2
• Critical caveat: In children with profound anemia and severe sepsis (particularly malaria), administer fluid boluses cautiously and consider blood transfusion instead 2

Severe Burns (Adults):

• Modified Parkland formula: 2-4 mL/kg/%TBSA over first 24 hours 2
• Give half of calculated volume in first 8 hours post-burn, remaining half over next 16 hours 2
• Target urine output: 0.5-1 mL/kg/h 2, 3
• Adjust infusion rate based on clinical response to avoid both under-resuscitation and "fluid creep" 2

Severe Burns (Children):

• Calculate daily basal requirement using Holliday-Segar 4-2-1 rule, then add modified Parkland formula (3-4 mL/kg/%TBSA) 2
• Total fluid intake approximately 6 mL/kg/%TBSA over first 48 hours 2
• For burns 10-20% TBSA, consider reducing total fluid intake to decrease hospital stay and grafting needs 2

Fluid Type Selection Algorithm

Primary Choice - Balanced Crystalloids:

• Ringer's Lactate or Plasmalyte reduce 30-day mortality (OR 0.84,95% CI 0.74-0.95) and major adverse kidney events compared to normal saline 1
• Use for sepsis, emergency surgery, hemorrhagic shock, and general resuscitation 1

When to Avoid Normal Saline:

• Limit to maximum 1-1.5 L due to hyperchloremic metabolic acidosis risk 1, 4
• Large volumes (>5000 mL) associated with increased mortality 1
• Never use for large volume resuscitation 1

When to Add Albumin:

• Burns: Consider when plasma albumin <2.5 g/dL (target 2.5 ± 0.5 g/dL, oncotic pressure 20 mmHg) 2, 5
• Sepsis with cirrhosis: Albumin shows higher shock reversal rates and 1-week survival versus normal saline 1
• Hypoproteinemia: Adults 50-75 g/day, children 25 g/day; infuse no faster than 2 mL/min to prevent circulatory overload 5

Special Populations:

Traumatic Brain Injury/Intracranial Hypertension:

• Use hypertonic saline (3% NaCl) for refractory intracranial hypertension, target sodium 140-150 mEq/L 4
• Avoid hypotonic solutions including Ringer's Lactate in acute brain injury 4
• Maintain cerebral perfusion pressure 60-70 mmHg 4

Heart Failure:

• Use balanced crystalloids with careful volume monitoring 1
• Employ point-of-care ultrasound to assess cardiac function and IVC preload 1
• Monitor stroke volume variation with fluid boluses 1

Titration and Monitoring Parameters

Stop or Interrupt Fluid Resuscitation When:

• No improvement in tissue perfusion with volume loading 2
• Development of pulmonary crepitations (indicates overload or cardiac dysfunction) 2
• Positive fluid balance on Day 3 in burns (associated with longer mechanical ventilation) 2

Hourly Monitoring Requirements:

• Urine output (target 0.5-1 mL/kg/h for adults, adjust for children) 2, 3
• Mean arterial pressure (≥65 mmHg for adults, ≥70 mmHg for some guidelines) 2
• Heart rate (≥10% reduction indicates positive response) 2
• Lactate clearance 3
• Mental status and peripheral perfusion 2

Advanced Monitoring When Available:

• Echocardiography for cardiac function and volume status 2, 1
• Cardiac output monitoring 2
• Central venous pressure (though not as reliable as dynamic parameters) 2
• Transpulmonary thermodilution in children with >30% TBSA burns 2

Four Phases of Fluid Therapy

Phase 1 - Resuscitation (0-6 hours):

• Aggressive fluid administration to restore perfusion 6
• Achieve hemodynamic endpoints within 6 hours 2

Phase 2 - Optimization (6-24 hours):

• Continue fluid based on ongoing assessment 6
• Adjust rates to clinical response 2

Phase 3 - Stabilization (24-72 hours):

• Minimize further fluid accumulation 6
• Aim for zero or negative fluid balance 7

Phase 4 - Evacuation/De-resuscitation (>72 hours):

• Active fluid removal if fluid overload present (>10% weight gain) 7, 6
• Fluid overload independently predicts mortality 7

Critical Pitfalls to Avoid

• Never give routine maintenance fluids to patients on oral intake - leads to fluid creep and overload 7
• Never use hydroxyethyl starches - associated with renal failure and no mortality benefit 1
• Never delay balanced crystalloids until ICU admission - benefits greatest when started in emergency department 1
• Never assume all patients need continuous IV fluids - fluids are drugs requiring specific indications 7
• Never ignore signs of fluid overload - 10% cumulative positive balance predicts worse outcomes 7