Can 0.9% normal saline (0.9% NSS) be used as the initial fluid for an adult with hypovolemic shock?

Can 0.9% Normal Saline Be Used for Hypovolemic Shock?

Yes, 0.9% normal saline (NSS) can be used for hypovolemic shock, but balanced crystalloids (such as Ringer's Lactate or Plasmalyte) are preferred as first-line therapy to reduce mortality and adverse renal events. 1

Guideline Recommendations

The 2022 guidelines for intravenous fluid choice in critically ill patients provide a GRADE 2+ recommendation (strong agreement) that balanced crystalloids should be used rather than 0.9% NaCl as first-line fluid therapy in hemorrhagic shock to reduce mortality and adverse renal events. 1

Key Rationale for Preferring Balanced Crystalloids

• High-volume resuscitation concerns: Hemorrhagic shock often requires 5,000-10,000 mL of fluid in the first 24 hours, particularly in trauma patients. 1

• Chloride toxicity: Large volumes of chloride-rich solutions (>5,000 mL) are associated with increased mortality and postoperative hyperchloremia in patients at high hemorrhagic risk. 1

• Renal protection: The SMART study demonstrated reduced major adverse kidney events (MAKE 30: death, doubling of creatinine, or renal replacement therapy within 30 days) with balanced solutions versus 0.9% NaCl. 1

• Acid-base balance: Balanced solutions consistently provide better acid-base balance compared to 0.9% NaCl. 1

• Reduced transfusion requirements: Some studies report lower perioperative blood transfusion requirements with balanced solutions versus 0.9% NaCl. 1

Clinical Context and Nuances

When 0.9% NSS Is Acceptable

While balanced crystalloids are preferred, 0.9% NSS remains a reasonable option when:

• Limited volumes are needed: Meta-analyses show no mortality difference between 0.9% NaCl and balanced solutions when median volumes are low (approximately 1,000-1,900 mL). 1

• Balanced solutions are unavailable: 0.9% NSS is an acceptable alternative in resource-limited settings. 2

Important Caveats

• No specific RCT data: No randomized controlled trial has specifically compared balanced crystalloids to 0.9% NaCl exclusively in hemorrhagic shock patients. 1

• Colloids are not recommended: Crystalloid solutions should be preferred over colloids (hydroxyethyl starch, albumin) due to increased risks of renal failure and hemostasis disorders without mortality benefit. 1

• Hypertonic saline is not recommended: 3% or 7.5% hypertonic saline solutions do not reduce mortality (GRADE 1- recommendation) and may increase mortality in patients not requiring blood transfusion. 1, 3

Practical Algorithm for Fluid Selection

1. First-line choice: Use balanced crystalloids (Ringer's Lactate or Plasmalyte) for initial resuscitation. 1

2. If balanced crystalloids unavailable: Use 0.9% NSS, but monitor for:

   • Hyperchloremia (serum chloride elevation)
   • Metabolic acidosis (decreased bicarbonate)
   • Renal function deterioration

3. Volume considerations: The preference for balanced solutions becomes more critical when anticipated fluid requirements exceed 3,000-5,000 mL. 1

4. Avoid: Hydroxyethyl starch, albumin, and hypertonic saline as first-line agents in hemorrhagic shock. 1

Common Pitfalls

• Assuming equivalence at high volumes: While 0.9% NSS and balanced solutions may perform similarly at low volumes, the deleterious effects of 0.9% NSS become apparent with high-volume resuscitation (>5,000 mL). 1

• Ignoring acid-base status: 0.9% NSS can worsen metabolic acidosis, which is already present in shock states. 1

• Using colloids for volume expansion: Despite superior volume expansion capacity (ratio of 1.5:1 versus crystalloids), colloids do not improve mortality and increase complications. 1