What is the preferred choice between crystalloids (e.g. 0.9% saline or lactated Ringer's solution) and colloids (e.g. albumin) for fluid resuscitation?

Crystalloids vs. Colloids for Fluid Resuscitation

Crystalloids should be used as the first-choice fluid for initial resuscitation in most clinical scenarios requiring volume expansion, with balanced crystalloids generally preferred over normal saline. 1, 2, 3

General Recommendation for Fluid Choice

• Isotonic crystalloids are recommended as the initial resuscitation fluid for patients with hypovolemic shock 1
• The Society of Critical Care Medicine recommends crystalloids as the first-choice fluid for initial resuscitation in septic shock 2
• European Society of Intensive Care Medicine conditionally recommends using crystalloids rather than albumin in critically ill patients in general (moderate certainty of evidence) 3
• Crystalloids have small molecules, are inexpensive, easy to use, and provide immediate fluid resuscitation, though they may increase edema 4

Specific Crystalloid Selection

• Balanced crystalloids (e.g., lactated Ringer's) are conditionally recommended over isotonic saline in critically ill patients in general (low certainty of evidence) 3
• Normal saline use is associated with hyperchloremic metabolic acidosis and increased risk of acute kidney injury compared to balanced salt solutions 5
• For patients with traumatic brain injury, isotonic saline is conditionally recommended over balanced crystalloids (very low certainty of evidence) 3

Special Circumstances for Colloid Consideration

• Albumin may be considered when patients require substantial amounts of crystalloids, but should not be first-line therapy 2
• For patients with cirrhosis, albumin is conditionally recommended over crystalloids (very low certainty of evidence) 3
• According to the FDA label for albumin, it may be indicated in specific situations such as:
  • Hypoproteinemia with or without edema 6
  • Adult Respiratory Distress Syndrome when clinical signs are those of hypoproteinemia with fluid volume overload 6
  • Acute liver failure 6

Evidence Against Colloids

• Meta-analyses show no mortality benefit of colloids over crystalloids in critically ill patients 4
• Hydroxyethyl starches appear to increase mortality and kidney injury in critically ill patients and are no longer indicated 7
• Starches probably slightly increase the need for blood transfusion (RR 1.19) and renal replacement therapy (RR 1.30) compared to crystalloids (moderate-certainty evidence) 4
• Dutch Pediatric Society guidelines found several meta-analyses showing excess mortality in albumin-treated groups compared with crystalloid-treated groups 1

Practical Approach to Fluid Resuscitation

• Administer at least 30 mL/kg of IV crystalloid within the first 3 hours for patients with septic shock 8, 2
• Continue fluid administration using a challenge technique, giving additional fluids as long as hemodynamic parameters improve 2
• Dynamic measures of fluid responsiveness are preferred over static measures when available 2
• Monitor for signs of fluid overload, such as pulmonary crackles, increased jugular venous pressure, and worsening respiratory function 8

Pitfalls to Avoid

• Avoid fluid overresuscitation, which can delay organ recovery, prolong ICU stay, and increase mortality 2
• Do not rely solely on static measures like central venous pressure to guide fluid therapy 2
• Remember that the standard 30 mL/kg fluid recommendation may need modification based on individual patient characteristics, particularly cardiac function 2
• For patients with low ejection fraction, consider smaller fluid boluses with frequent reassessment rather than the standard 30 mL/kg 2

In summary, crystalloids remain the first-choice fluid for resuscitation in most clinical scenarios, with balanced solutions generally preferred over normal saline except in specific conditions like traumatic brain injury. Colloids should be reserved for special circumstances, with albumin being the preferred colloid when indicated.