Makindo Medical Notes

Related Subjects: |Respiratory Failure |Non-invasive ventilation (NIV) |Intubation and Mechanical Ventilation |Critical illness neuromuscular weakness |Haemodialysis |Dobutamine |Metabolic acidosis

0.9% Sodium Chloride (Normal Saline) is the default crystalloid solution for fluid resuscitation. It is isotonic but not physiologically “normal” as its chloride concentration is higher than plasma. Always check the BNF here before prescribing.

⚗️ Composition

• Sodium: 150 mmol/L
• Chloride: 150 mmol/L
• Osmolality: ~308 mOsm/L
• pH: ~5.0–5.5
• No glucose or buffer

📌 Indications

• Initial volume resuscitation in shock (sepsis, trauma, peri-arrest)
• Surgical patients with hypovolaemia
• When rapid intravascular expansion is needed

⚠️ Side Effects

• Large volumes (>4 L/day) → hyperchloraemic metabolic acidosis
• Acidosis may cause renal vasoconstriction → reduced urine output
• Can contribute to electrolyte disturbance (dilutional effects)

🚫 Contraindications / Cautions

• Liver disease: Risk of sodium & fluid overload
• Heart failure: May precipitate pulmonary oedema
• Prefer balanced crystalloids (e.g. Hartmann’s, Plasma-Lyte) if risk of acidosis

🌟 Teaching Pearl

Although called “normal” saline, it is not identical to plasma. High chloride → risk of acidosis, so use judiciously, especially in ICU patients. Think of it as the “workhorse” fluid, but not always the “healthiest” choice long-term.