Q: 56 years old male is admitted to the ICU with an intentional overdose of Metformin. Patient is in severe refractory shock, lactic acidosis, and pH of 6.9. Preparation of dialysis started. In between, a decision was made to administer sodium bicarbonate. What should be the target PH in this case of Metformin Associated Lactic Acidosis (MALA)?
Answer: 7.1
The objective of this question is to highlight the dangers of excessive sodium bicarbonate use, especially in MALA. The recommended target arterial pH is just above 7.1 or above 7.3 in patients with severe acute kidney injury. This level of pH can be maintained until the acute toxicity resolves. The use of sodium bicarbonate in MALA is controversial, and clinicians are advised to take a bare minimum approach.
Sodium bicarbonate may induce
- Hemoglobin dissociation curve to the left
- Sodium load
- Rebound metabolic alkalosis
- Serum potassium and calcium disturbances
- Decreased myocardial contractility
- Increased CO2 production
- Reflex vasodilation after bolus injection
#toxicity
References:
1. Heaney D, Majid A, Junor B. Bicarbonate haemodialysis as a treatment of metformin overdose. Nephrol Dial Transplant 1997; 12:1046.
2. Teale KF, Devine A, Stewart H, Harper NJ. The management of metformin overdose. Anaesthesia 1998; 53:698.
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