Vanderbilt Internal Medicine Residency Podcast · Jared Freitas and Terra Swanson

S6: E6 The Basics about Bicarb!

May 12, 2023·22 min·2 clips

One amp of bicarb has an osmolarity of 2000 miliosmoles, higher than hypertonic saline.

This episode of the Vanderbilt Internal Medicine Residency Podcast focuses on the clinical use of sodium bicarbonate in hospital medicine. Hosts Dr. Tara Swanson and Dr. Jared, both residents interested in pulmonary and critical care, examine the evidence behind common bicarbonate practices. They structure the discussion around when bicarbonate is clearly indicated, when evidence is lacking, and the potential risks of its administration. Dr. Swanson explains the two common formulations: a concentrated 8.4% ampule used in codes and a more isotonic 1.3% solution often mixed in intravenous fluids. The hosts review the physiological harms of acidemia, including reduced cardiac contractility, decreased vasopressor effectiveness, and increased risk of arrhythmias. Clear indications for bicarbonate include non-anion gap metabolic acidosis from conditions like diarrhea or renal tubular acidosis, and specific drug overdoses like tricyclic antidepressants or salicylates. For hyperkalemia, they note bicarbonate is only effective if the patient is also acidotic. A significant portion examines "gray zone" uses, starting with diabetic ketoacidosis, where systematic reviews show no benefit and a potential increased risk of cerebral edema. They reference the 2018 French BICAR-ICU trial, which studied patients with severe acidemia and found no mortality benefit from bicarbonate overall. However, a subgroup of patients with acute kidney injury saw a reduced need for renal replacement therapy, with the number needed to treat to prevent one dialysis event being six. For pure lactic acidosis, such as in septic shock, the evidence does not support routine bicarbonate use. The hosts note bicarbonate was removed from the standard ACLS cardiac arrest algorithm due to potential harms like intracellular acidosis and hyperosmolarity. A key insight is that bicarbonate generates carbon dioxide upon administration, which can worsen acidosis if a patient cannot increase ventilation. They conclude that treatment should always target the underlying cause of acidosis first, with bicarbonate serving as a temporizing measure in specific deficiencies. The tone is educational and conversational, resembling two colleagues reviewing literature to inform their clinical practice. The style is direct, with hosts referencing specific trials, guidelines, and physiological mechanisms to support their points. This episode is ideal for medical trainees, residents, and hospitalists seeking a evidence-based refresher on managing metabolic acidosis and hyperkalemia. Listeners interested in critical care nephrology or sepsis management will find the trial data particularly relevant. Those looking for broad patient stories or non-medical content should skip this technically focused discussion.

As heard by us

A practical reset on when bicarbonate helps, when it buys time, and when the underlying cause still has to do the heavy lifting.

It takes sodium bicarbonate through a careful bedside check, moving from physiology to the practical question of when it helps and when it only buys time. The discussion keeps the focus where it belongs: treat the underlying cause, while bicarbonate may briefly raise pH.

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A practical reset on when bicarbonate helps, and when it does not.

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