What vasopressor is most effective in patients with acidosis?

From the Guidelines

Norepinephrine is the most effective vasopressor for patients with acidosis, as it maintains its vasoconstrictive properties better than other vasopressors in acidotic conditions. In acidotic conditions, norepinephrine's effectiveness is relatively preserved compared to epinephrine or dopamine, which may have diminished effectiveness as pH decreases 1. The typical starting dose is 0.01-0.03 mcg/kg/min, titrated to a mean arterial pressure (MAP) goal of >65 mmHg, with maximum doses reaching 1-3 mcg/kg/min in severe cases.

Key Considerations

• Norepinephrine works primarily through alpha-1 adrenergic receptor stimulation, causing peripheral vasoconstriction that is relatively preserved even in acidotic environments.
• This helps maintain organ perfusion when acidosis might otherwise impair vascular responsiveness.
• When administering norepinephrine, it should be given through a central line whenever possible, and blood pressure should be monitored continuously.

Clinical Approach

• While treating the patient with vasopressors, it's crucial to simultaneously address the underlying cause of acidosis, as correcting the acidosis will improve vasopressor effectiveness and patient outcomes.
• The Surviving Sepsis Campaign guidelines support the use of norepinephrine as the first-choice vasopressor, with a grade 1B recommendation 1.

Monitoring and Titration

• Continuous monitoring of blood pressure and organ perfusion is essential when using norepinephrine in acidotic patients.
• The dose of norepinephrine should be titrated to achieve a MAP goal of >65 mmHg, while minimizing the risk of excessive vasoconstriction.

From the Research

Vasopressor Effectiveness in Acidotic Patients

• The effectiveness of vasopressors in acidotic patients is a topic of interest, with various studies investigating the impact of acidosis on the vasoactive properties of different vasopressors 2, 3, 4.
• A study published in 2014 found that severe extracellular acidosis did not significantly alter the potency and efficacy of epinephrine and norepinephrine in human isolated arteries 2.
• However, another study from 2022 suggested that lower arterial pH was independently associated with lower odds of hemodynamic response to vasopressin in patients with septic shock 4.
• The role of catecholamines, such as noradrenaline and adrenaline, in metabolic acidosis has also been investigated, with evidence suggesting that they may contribute to the development and maintenance of ketoacidosis and lactic acidosis 5.
• A study from 1997 found that epinephrine administration after cardiopulmonary bypass can precipitate the development of lactic acidosis in some patients, potentially due to its beta-mediated effects 6.

Comparison of Vasopressors

• Norepinephrine and epinephrine have been compared in terms of their effectiveness in acidotic patients, with some studies suggesting that norepinephrine may be less likely to induce lactic acidosis 6.
• Vasopressin has also been investigated as a potential vasopressor in acidotic patients, with evidence suggesting that its effectiveness may be impaired in the setting of acidemia 4.
• The choice of vasopressor in acidotic patients may depend on various factors, including the underlying cause of the acidosis, the severity of the acidosis, and the patient's individual response to different vasopressors 2, 3, 4.