Background: Consensus guidelines recommend that dopamine or norepinephrine be the first-choice vasopressor for patients in shock. Dopamine may increase splanchnic and renal perfusion more than norepinephrine, but observational studies have reported that it is also associated with a greater risk of death. The true benefits of these agents compared with each other are unknown. De Backer and colleagues conducted a multicenter, randomized, double-blind trial to determine if using norepinephrine instead of dopamine could reduce the death rate among patients in shock.

The Study: The authors enrolled 1,679 adult patients in shock (i.e., signs of tissue hypoperfusion despite hydration, with a mean arterial pressure less than 70 mm Hg or systolic blood pressure remaining below 100 mm Hg) who received dopamine or norepinephrine. If hypotension persisted with the maximal drug dosage (20 mcg per kg per minute for dopamine or 0.19 mcg per kg per minute for norepinephrine), open-label norepinephrine was added.

Patients were excluded for serious arrhythmias (e.g., rapid atrial fibrillation [more than 160 beats per minute]) or if they had already received a vasopressor for more than four hours during the current episode of shock. The primary end point was the rate of death at 28 days. Secondary end points included the rates of death in the intensive care unit and in the hospital, and the duration of stay in the intensive care unit.

Results: Septic shock (62.2 percent) was the most common etiology, followed by cardiogenic shock (16.7 percent) and hypovolemic shock (15.7 percent). Baseline characteristics were similar between groups, as were initial mean arterial pressure and the mean time to achieve a mean arterial pressure of 65 mm Hg.

Overall mortality rates were similar; however, subgroup analysis found that dopamine was associated with a higher risk of death in patients with cardiogenic shock. Arrhythmias were nearly twice as common in the dopamine group compared with the norepinephrine group (24.1 versus 12.4 percent), with atrial fibrillation being the most common arrhythmia with either agent. There was nearly a fourfold greater discontinuation rate with dopamine because of severe arrhythmias, compared with norepinephrine (6.1 versus 1.6 percent).

Conclusion: The authors conclude that although there is no overall difference in the rate of death between patients treated with dopamine or norepinephrine, dopamine is associated with more arrhythmias and increased mortality among patients with cardiogenic shock.