What is the best course of action for a patient with type 2 diabetes (T2D) and suspected appendicitis who developed metabolic acidosis with a decreased bicarbonate level and increased chloride level after receiving normal saline (0.9% sodium chloride solution)?

Hyperchloremic Metabolic Acidosis from Normal Saline - Immediate Management

Switch immediately from normal saline to a balanced crystalloid solution (Ringer's Lactate or Plasmalyte) to halt progression of the hyperchloremic metabolic acidosis. 1

Understanding What Happened

Your patient developed iatrogenic hyperchloremic metabolic acidosis from the normal saline administration. 2, 1 Here's the mechanism:

• Normal saline contains 154 mEq/L of chloride (supraphysiologic compared to plasma ~103 mEq/L) 1
• The chloride load decreased the strong ion difference (SID), directly lowering pH and bicarbonate 1
• The rising chloride (103→108) with falling bicarbonate (17→13) and stable anion gap (15) confirms this is non-anion gap metabolic acidosis from excessive chloride 2, 3
• This is not diabetic ketoacidosis—the anion gap would be >12 and rising in DKA 2

Immediate Actions

1. Stop All Chloride-Rich Fluids Now

• Discontinue 0.9% normal saline immediately 1
• Even switching to 0.45% saline won't help—it still contains 77 mEq/L chloride, which is supraphysiologic 1

2. Switch to Balanced Crystalloids

• Use Ringer's Lactate or Plasmalyte as first-line fluid 1
• These contain physiologic chloride concentrations and buffers that help correct acidosis 1
• Continue at maintenance rates appropriate for the patient's volume status 2

3. Add Potassium to IV Fluids

• Include 20-30 mEq/L of potassium in maintenance fluids 2, 1
• Use 2/3 KCl and 1/3 KPO4 for optimal replacement 2, 1
• Monitor serum potassium closely as acidosis correction causes intracellular potassium shift 1

Monitoring Parameters

Check the following labs in 4-6 hours:

• Arterial or venous blood gas (pH, bicarbonate) 3
• Serum electrolytes with calculated anion gap 1, 3
• Serum chloride specifically 1
• Renal function (BUN/creatinine) 1

What About the Appendicitis?

This patient still needs surgical evaluation for suspected appendicitis. The metabolic acidosis will improve with:

• Balanced crystalloid resuscitation 1
• Definitive treatment of the appendicitis (surgery) 2
• The acidosis itself should not delay necessary surgery 2

Critical Pitfall to Avoid

Do not give sodium bicarbonate for hyperchloremic acidosis. 1 This is a chloride-driven acidosis that resolves by:

1. Stopping the chloride load (no more normal saline) 1
2. Allowing renal excretion of excess chloride 1
3. Using balanced fluids that don't worsen the problem 1

Bicarbonate therapy is only considered for severe metabolic acidosis (pH <7.2 with bicarbonate <12 mEq/L) from other causes, not hyperchloremic acidosis. 1

Expected Timeline

• Bicarbonate should begin rising within 6-12 hours of switching to balanced crystalloids 1
• Chloride should trend downward as kidneys excrete the excess load 1
• If bicarbonate doesn't improve, reassess for other causes of acidosis (ongoing sepsis, bowel ischemia from appendicitis, etc.) 3

Key Takeaway for Future Cases

Balanced crystalloids should be the default resuscitation fluid for all patients, not normal saline. 1 Normal saline should be limited to a maximum of 1-1.5 L when used at all. 1 This prevents the exact complication your patient experienced—iatrogenic hyperchloremic metabolic acidosis that complicates clinical assessment and potentially worsens outcomes. 2, 1, 4