How to correct severe acidosis with a pH of 7.2?

Management of Severe Acidosis with pH of 7.2

For severe acidosis with pH of 7.2, bicarbonate therapy is recommended only if the pH falls below 7.0, while the primary approach should be treating the underlying cause and providing appropriate supportive care based on the type of acidosis. 1

Initial Assessment and Classification

1. Determine the type of acidosis:

   • Respiratory acidosis: Elevated PaCO₂ (>46 mmHg)
   • Metabolic acidosis: Decreased bicarbonate (<15 mEq/L)
   • Mixed acidosis: Both respiratory and metabolic components

2. For metabolic acidosis, calculate anion gap to further classify:

   • High anion gap: Lactic acidosis, diabetic ketoacidosis, toxins, renal failure
   • Normal anion gap: Diarrhea, renal tubular acidosis, early renal failure

Treatment Algorithm Based on Acidosis Type

Respiratory Acidosis (pH 7.2)

• Primary intervention: Improve ventilation
  • Non-invasive ventilation (NIV) is recommended for COPD patients with acute respiratory acidosis 1
  • Target pH 7.2-7.4 (permissive hypercapnia acceptable if inspiratory airway pressure >30 cmH₂O) 1
  • Use tidal volumes of 6-8 mL/kg with respiratory rate 10-15 breaths/min for obstructive disease 1
  • Consider intubation if NIV fails or if patient has severe acidosis with respiratory distress 1

Metabolic Acidosis (pH 7.2)

• Primary intervention: Treat underlying cause

  • Diabetic ketoacidosis: Insulin therapy and fluid resuscitation
  • Lactic acidosis: Improve tissue perfusion and oxygenation
  • Toxic ingestion: Remove toxin (e.g., salicylate poisoning may require extracorporeal treatment) 1

• Fluid management:

  • Use isotonic balanced crystalloid solutions at 15-20 mL/kg/hour initially, then adjust to 4-14 mL/kg/hour based on hydration status 2
  • Avoid normal saline which may worsen hyperchloremic metabolic acidosis 2

Bicarbonate Therapy Considerations

• Do not administer bicarbonate if pH ≥ 7.0 1

• For pH < 7.0:

  • Adult dosing: 1-2 mEq/kg initially, can be repeated based on arterial pH monitoring 3
  • Pediatric dosing: 1-2 mEq/kg sodium bicarbonate over 1 hour if pH remains < 7.0 after initial hydration 1

• Cautions with bicarbonate therapy:

  • May cause paradoxical worsening of intracellular acidosis
  • Can lead to hypernatremia and fluid overload
  • May decrease ionized calcium
  • Can cause overshoot alkalosis if administered too rapidly 3

Special Considerations

Diabetic Ketoacidosis (DKA)

• DKA is considered resolved when glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, and venous pH >7.3 2
• Add dextrose when glucose reaches 250-300 mg/dL to prevent hypoglycemia 2
• Continuous monitoring of electrolytes every 2-4 hours during treatment 2

Severe Acidemia in Critical Care

• In patients with metabolic acidosis and septic shock, time from admission to initiation of source control surgery is critical (survival rate 0% when >6 hours) 1
• For patients with pH < 7.15 and catecholamine-resistant hypotension, alkalinizing agents may be needed 1

Extracorporeal Treatments

• Consider extracorporeal treatment for salicylate poisoning if pH ≤ 7.20 1
• Novel approaches such as extracorporeal chloride removal may be considered in research settings for refractory acidosis 4

Monitoring During Treatment

• Arterial blood gases every 30-60 minutes until stabilization
• Continuous cardiac monitoring for arrhythmias
• Electrolytes, especially potassium, calcium, and phosphate
• Signs of fluid overload: jugular venous distention, pulmonary crackles, peripheral edema
• Mental status changes

Common Pitfalls to Avoid

• Overaggressive bicarbonate administration leading to alkalosis
• Failure to identify and treat the underlying cause
• Neglecting ventilatory support in mixed acidosis
• Ignoring electrolyte abnormalities during treatment
• Rapid correction of chronic acidosis which may lead to metabolic alkalosis

Remember that treating the underlying cause of acidosis is paramount, and bicarbonate therapy should be reserved for severe acidosis with pH < 7.0, as it has not been shown to improve outcomes in less severe cases.