When to initiate sodium bicarbonate drip in Acute Kidney Injury (AKI)?

From the Guidelines

Start a bicarbonate drip for acute kidney injury (AKI) when the patient's serum bicarbonate level falls below 22 mEq/L or when severe metabolic acidosis is present (pH < 7.2). The typical regimen is:

• Prepare a solution of 150 mEq of sodium bicarbonate in 1 L of D5W
• Start infusion at 50-100 mL/hour
• Adjust rate based on serial blood gas measurements and clinical response Monitor serum electrolytes, especially potassium and calcium, as bicarbonate therapy can lower their levels. Also, watch for signs of fluid overload. Bicarbonate therapy helps correct metabolic acidosis, which can worsen kidney function and lead to other systemic complications. It works by increasing the blood's buffering capacity, helping to normalize pH and potentially improving hemodynamics and cellular function. However, it's essential to address the underlying cause of AKI concurrently with bicarbonate therapy for optimal management, as suggested by the KDIGO guidelines 1. The use of bicarbonate in AKI patients with metabolic acidosis is also explored in a 2020 Kidney International article, which highlights the need for further research on the optimal management of fluid and electrolyte balance in AKI patients 1. Additionally, a 2013 Canadian Society of Nephrology commentary on the KDIGO guidelines notes that the optimal timing of RRT initiation in AKI patients is still a topic of debate and requires further study 1. Key considerations in AKI management include:
• Monitoring serum electrolytes and acid-base balance
• Addressing the underlying cause of AKI
• Using bicarbonate therapy to correct metabolic acidosis
• Avoiding fluid overload and monitoring for signs of complications
• Considering the use of RRT in severe cases of AKI, as recommended by the KDIGO guidelines 1.

From the FDA Drug Label

In metabolic acidosis associated with shock, therapy should be monitored by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics and cardiac rhythm. The amount of bicarbonate to be given to older children and adults over a four-to-eight-hour period is approximately 2 to 5 mEq/kg of body weight - depending upon the severity of the acidosis as judged by the lowering of total CO2 content, blood pH and clinical condition of the patient

The FDA drug label does not provide a specific indication for initiating a sodium bicarbonate drip in Acute Kidney Injury (AKI). However, it does provide guidance on the use of sodium bicarbonate in metabolic acidosis associated with shock.

• The decision to initiate sodium bicarbonate therapy should be based on the severity of the acidosis and the clinical condition of the patient.
• The initial dose is approximately 2 to 5 mEq/kg of body weight over a period of 4 to 8 hours.
• Therapy should be monitored closely by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics, and cardiac rhythm 2. However, the label does not provide specific guidance on when to initiate sodium bicarbonate drip in AKI.

From the Research

Initiation of Sodium Bicarbonate Drip in Acute Kidney Injury (AKI)

• The decision to initiate sodium bicarbonate drip in AKI should be based on the patient's underlying condition and the presence of metabolic acidosis 3.
• According to a systematic review, bicarbonate therapy may yield improvement in survival for patients with accompanying acute kidney injury, particularly those with severe metabolic acidosis (pH < 7.1 and bicarbonate < 6 mEq/L) 3.
• However, another study found no randomized controlled trial (RCT) evidence to support the use of sodium bicarbonate for people with AKI, highlighting the need for well-conducted RCTs in this area 4.
• A study on sodium bicarbonate infusion for prevention of AKI found that it does not seem to be more efficient than saline for preventing contrast-media-induced AKI, cardiac surgery-associated AKI, pigment nephropathy, or septic AKI, and may even be associated with higher rates of AKI or in-hospital mortality 5.
• The use of serum bicarbonate as a predictor of outcomes in patients with AKI has been explored, with one study finding that patients with bicarbonate outside the normal range had significantly higher mortality, and that bicarbonate <22 mmol/L was associated with a higher mortality rate 6.
• A study on the effectiveness of sodium bicarbonate infusion on mortality in septic patients with metabolic acidosis found that while it was not associated with improved outcome in the overall population, it was associated with improved survival in septic patients with AKI stage 2 or 3 and severe acidosis (pH < 7.2) 7.

Key Considerations

• The presence of severe metabolic acidosis (pH < 7.1 and bicarbonate < 6 mEq/L) may be an indication for bicarbonate therapy in patients with AKI 3.
• The use of sodium bicarbonate infusion should be evaluated further in multicenter randomized double-blind trials before being adopted into routine clinical practice 5.
• Serum bicarbonate may be a useful predictor of outcomes in patients with AKI, particularly when used in conjunction with other clinical factors 6.
• The effectiveness of sodium bicarbonate infusion may vary depending on the underlying condition and severity of acidosis, with potential benefits in septic patients with AKI stage 2 or 3 and severe acidosis 7.