Episode 138: The role of sodium bicarbonate in critically ill patients

In this episode, I’ll discuss the role of sodium bicarbonate in critically ill patients.

Sodium bicarbonate is often used in critically ill patients. However, it is a treatment that is not benign.

Adverse effects

Potential adverse effects of using sodium bicarbonate include:

1. Increased production of lactate (by altering pH and interfering the feedback loop on lactate production normally created by acidemia).
2. Decreased left ventricular contractility (due to a decrease in free ionized calcium).
3. Hypernatremia.

Due to the numerous potential adverse effects, sodium bicarbonate should be judiciously used only in patients likely to benefit.

Indications for sodium bicarbonate therapy

Quinidine-induced torsades

For torsades that  is the result of quinidine, sodium bicarbonate should be administered. Alkalinizing the serum with sodium bicarbonate will decrease the amount of quinidine that is active on the heart.

Aspirin toxicity

Giving sodium bicarbonate in the setting of aspirin toxicity alkalinizes the urine, trapping ionized aspirin within the renal tubule and enhancing elimination.

Tricyclic toxicity

Serum alkalinization in the setting of tricyclic toxicity is indicated in the setting of arrhythmias or shock.

DKA and pH < 7

There is a lack of prospective randomized studies to support the use of sodium bicarbonate in severe DKA. Nonetheless in severe diabetic ketoacidosis with pH less than 7, sodium bicarbonate can be used to prevent the decrease in myocardial contractility that accompanies severe acidosis. When the pH rises above 7, sodium bicarbonate therapy can be stopped.

Hyperkalemia

Sodium bicarbonate administration will not have an effect on potassium levels until several hours of a bicarb infusion have elapsed. After 4-6 hours, if the patient with hyperkalemia also had metabolic acidosis, the serum potassium will decrease by just over 0.5 mEq/L. That is not enough to make a difference for a patient with severe hyperkalemia. I think sodium bicarbonate’s only role would be as an adjunct to insulin+dextrose in a patient with concomitant metabolic acidosis.

Circumstances where sodium bicarbonate has little/no effect

Coagulopathy

Coagulation parameters are worsened in the setting of acidosis. Unfortunately, correction of the pH with sodium bicarbonate does not seem to be enough to reverse the adverse effects of acidemia coagulation.

Respiratory acidosis with inadequate ventilation

In the setting of acidosis and inadequate ventilation, administering sodium bicarbonate will have no effect on blood pH. To recap: -HCO3 accepts a hydrogen ion to become H2CO3, and is further broken down into H2O and CO2. The removal of CO2 by adequate ventilation allows more -HCO3 to accept more hydrogen ions and raise the pH. The elevated PCO2 that results from inadequate ventilation puts a stop to the generation of H2O and CO2 that normally results from -HCO3 administration.

Cardiac arrest

A recent review of literature and ACLS guidelines concluded:

Although many studies have shown little/no benefit and perhaps harm from administration of sodium bicarbonate (SB) for rapid correction of acidemia accompanying cardiac arrest, and the latest ACLS guidelines published by the AHA do not recommend routine administration, SB is still used as part of resuscitation in cardiac arrest. Additional research is needed to elucidate further the effects of SB on organ function, on the likelihood of ROSC and on survival in patients resuscitated from cardiac arrest. An objective reappraisal of the use of SB or other buffer agents and perhaps on an appropriate “therapeutic window” for use of SB in cardiac arrest patients is warranted.

If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.

<– Previous Post                    Next Post –>