From the Guidelines
Forced alkaline diuresis is indicated for enhancing the elimination of certain toxins, such as salicylates, but its use should be considered in the context of newer, more effective treatments like extracorporeal therapy, which has been shown to be more efficient in removing salicylate from the body 1. When considering the use of forced alkaline diuresis, it's crucial to understand its mechanism and application. This procedure involves administering intravenous fluids and sodium bicarbonate to alkalinize the urine, making it more effective for eliminating weak acids like salicylates (aspirin overdose), phenobarbital, and certain herbicides. The process typically involves:
- Administering intravenous fluids at 10-15 mL/kg/hr
- Adding sodium bicarbonate to achieve a urine pH of 7.5-8.5
- Supplementing with potassium (20-40 mEq/L of IV fluid) to prevent hypokalemia
- Optionally, using a loop diuretic like furosemide to enhance urine output, targeting 2-3 mL/kg/hr However, given the advancements in extracorporeal treatment techniques, as discussed in the study by the EXTRIP workgroup 1, extracorporeal treatment is recommended over forced alkaline diuresis for severe salicylate poisoning, especially when the salicylate concentration exceeds 7.2 mmol/L (100 mg/dL), due to its higher efficiency in removing the toxin and correcting acidemia. Key considerations for the use of forced alkaline diuresis include:
- Monitoring fluid status, electrolytes, and urine pH closely
- Avoiding its use in patients with renal failure, heart failure, or cerebral edema due to the risk of fluid overload
- Recognizing that while forced alkaline diuresis can be effective for certain toxins, extracorporeal treatment offers a more rapid and predictable reduction in salicylate levels, which is critical for improving outcomes in terms of morbidity and mortality 1.
From the FDA Drug Label
Sodium bicarbonate is further indicated in the treatment of certain drug intoxications, including barbiturates (where dissociation of the barbiturate-protein complex is desired), in poisoning by salicylates or methyl alcohol and in hemolytic reactions requiring alkalinization of the urine to diminish nephrotoxicity of hemoglobin and its breakdown products
- The indication for using forced alkaline diuresis for toxins is to treat certain drug intoxications, such as:
- Barbiturates
- Salicylates
- Methyl alcohol
- Forced alkaline diuresis is achieved by administering sodium bicarbonate to alkalinize the urine, which helps to:
- Dissociate the barbiturate-protein complex
- Diminish nephrotoxicity of hemoglobin and its breakdown products 2
From the Research
Indications for Forced Alkaline Diuresis
The use of forced alkaline diuresis for toxin elimination is indicated in specific cases, including:
- Salicylate poisoning: Urine alkalinization should be considered as first-line treatment for patients with moderately severe salicylate poisoning who do not meet the criteria for hemodialysis 3, 4, 5.
- 2,4-dichlorophenoxyacetic acid and mecoprop poisoning: Urine alkalinization and high urine flow should be considered in patients with severe poisoning 3.
- Methotrexate toxicity: Although urine alkalinization is employed clinically, there is limited evidence to support its use 3.
- Chlorpropamide poisoning: Supportive care, including the infusion of dextrose, is invariably adequate, and urine alkalinization is not recommended as first-line treatment 3.
- Phenobarbital poisoning: Multiple-dose activated charcoal is superior to urine alkalinization 3.
Contraindications and Complications
The use of forced alkaline diuresis may be contraindicated in certain cases, and complications can occur, including:
- Hypokalemia: The most common complication, which can be corrected by giving potassium supplements 3.
- Alkalotic tetany: Occurs occasionally, but hypocalcemia is rare 3.
- Fluid retention and biochemical disturbances: Can occur with forced diuresis regimens, but not with alkali alone 4.
Alternative Treatments
Alternative treatments, such as repeated-dose charcoal, may be effective in increasing the elimination rate of many toxins, and may be preferred over forced alkaline diuresis in some cases 6.