Emergency Fluid Management

Overview – Emergency Fluid Management

Emergency fluid management is a cornerstone of resuscitation in critically unwell patients. It involves rapid assessment and correction of fluid deficits due to dehydration, bleeding, or third-space losses. A solid understanding of fluid compartments, fluid types, and clinical indications is essential for any emergency or acute care practitioner.

Indications for Fluid Therapy

• Dehydration
• Fluid loss (e.g. vomiting, diarrhoea, burns)
• Blood loss
• Third spacing (e.g. pancreatitis, sepsis, trauma)

Goals of Fluid Replacement

• Correct pre-existing deficits
• Replace ongoing physiological losses (urine, sweat)
• Compensate for third-space losses
• Restore volume following bleeding

Types of Intravenous Fluids

Crystalloids

• Normal Saline (0.9% NaCl)
  • Isotonic
  • Preferred for general extracellular replacement
  • Risks: Dilutional anaemia, oedema in CHF
• Dextrose (e.g. 4% Dextrose + 0.5% NaCl)
  • Becomes hypotonic after glucose metabolism
  • Used in hypoglycaemia or hypernatremia
• Hartmann’s / Lactated Ringer’s
  • Contains sodium, chloride, potassium, calcium, lactate
  • Buffers acidosis and supports trauma, burn or surgical patients
• Cheap, widely available, effective for most resuscitation scenarios

Colloids

• Albumin 4% / 20%
  • Indicated in liver disease, burns, sepsis, or hypoalbuminaemia
  • Maintains oncotic pressure
• Polygeline (e.g. Haemaccel)
  • Gelatin-based
  • Used for GI fluid loss (vomiting, diarrhoea)
• Not suitable for routine resuscitation
• More expensive than crystalloids

Blood Products

• Whole Blood
  • RBCs, plasma, WBCs, clotting factors, platelets
• Packed RBCs
  • Increases oxygen-carrying capacity
• Fresh Frozen Plasma (FFP)
  • Provides clotting factors and plasma proteins

Fluid Compartments & Distribution

• Intravascular: 5L
• Interstitial: 10L
• Intracellular: 30L

1/3 Rule: Only ~300mL of each 1L crystalloid stays in the IV space
→ Blood loss of 1L requires 3L of crystalloids

Key Rules & Formulas

“35–45 Rule”

• Na⁺: 135–145 mmol/L
• K⁺: 3.5–5.0 mmol/L
• pH: 7.35–7.45

“4–2–1 Rule” for Maintenance Fluids

• 4 mL/kg/hr for first 10 kg
• 2 mL/kg/hr for next 10 kg
• 1 mL/kg/hr for each kg >20 kg
• Example:
  • 60 kg patient = 100 mL/hr
  • 80 kg patient = 120 mL/hr

Fluid Resuscitation Principles

• Crystalloids:
  • Distributed in extracellular fluid
  • ~25% remains intravascular
  • Not suitable for raising BP in shock alone
• Colloids:
  • Stay within vasculature
  • Smaller volume needed (e.g. 500 mL colloid ≈ 2L crystalloid)
• Glucose:
  • Rapidly metabolised → fluid shifts intracellularly
  • Not appropriate for volume resuscitation
• Blood:
  • Best for blood loss
  • Risks: immunological reactions, infections
  • Not to be replaced with glucose-containing fluids

Blood Transfusion Basics

ABO Blood Groups

Rh Factor

• Rh-D positive: No anti-D antibodies
• Rh-D negative: Anti-D antibodies present

Universal Donor & Recipient

• Donor: O-negative
• Recipient: AB-positive

Blood Matching

• Group-Specific Blood: ABO + Rh matched only (takes ~20 min)
• Cross-Matched Blood: Full antibody screening (takes ~1 hr)

In Emergencies

• Use O-negative blood if type unknown and delay is unsafe

Practical Considerations

• Propofol and neuromuscular blockers may cause hypotension via ↓ PVR and venous pooling
• Anuria = Think obstruction, not hypovolaemia
• Be aware of fluid overload risks in heart failure, renal failure, or hypoalbuminaemia

Summary – Emergency Fluid Management

This emergency fluid management guide explains how to effectively assess and replace fluid losses in acute settings using crystalloids, colloids, and blood products. Proper selection and dosing are key to restoring haemodynamic stability. For a broader context, see our Emergency Medicine Overview page.