Arterial lines for shock: harms exceed benefits (EVERDAC trial)

Does this remove yet another brick in the wall of critical care dogma?

Continuous measurement of blood pressure by arterial catheters has been a cornerstone of shock management since the birth of critical care. Directed by clinical guidelines and generations of tradition, clinicians insert arterial lines into millions of patients each year in ICUs around the world.

Arterial catheters’ utility for patients in shock on vasopressors has always seemed so obvious that it didn’t need to be tested.

Then it was.

The EVERDAC Trial

At ICUs at nine French hospitals between 2018 and 2022, 1,010 adults in shock were randomized to an invasive or noninvasive strategy for blood pressure measurement.

Almost all were non-surgical patients in MICUs, with shock associated with sepsis (~54%), cardiogenic/post-arrest (~20%), and a mix of other etiologies.

They were sick. Two-thirds were receiving mechanical ventilation at randomization, and almost 90% were receiving vasopressors, usually at moderate or greater doses (>30 mcg/min of norepinephrine, on average).

Almost all the patients randomized to invasive management received arterial catheters (98%), although so did 15% of those in the noninvasive group (for various prespecified reasons; see below).

Instead of ABGs, central venous blood gases were drawn whenever possible, and an app converted the results to the most likely ABG values.

Results

After 28 days, numerically fewer patients had died in the noninvasively managed group (34% vs 37%). This did not demonstrate superiority of the noninvasive strategy (P=0.20), but easily met the trial’s criteria for “noninferiority,” with a virtual certainty (99.4% chance) that mortality was not increased more than an absolute 5% by a noninvasive strategy (P=0.006).

• Organ failure and the use of renal replacement therapy were similar between groups, as was death before 90 days.

• Patients with arterial catheters did not require fewer vasopressors.

• They did not analyze or report the correlation between invasive and noninvasive BP readings.

• The patients receiving arterial catheters had three adjudicated catheter-related bloodstream infections, vs. one in the noninvasive arm.

So, reading the top-line results, the takeaway appears clear: arterial lines are not nearly as important as they have traditionally been believed to be, and most patients with shock (even if severe) can be well-managed without an arterial catheter.

As always, there’s a bit more to the story than that, though.

Shock on >100 μg/min of norepinephrine managed with a BP cuff(?!)

Like us, you might have to read this twice to believe it: arterial catheterization was forbidden for patients in the noninvasive arm of EVERDAC even while they received extremely high doses of vasopressors—up to 1.25 μg/kg/min of total combined norepinephrine and epinephrine infusions (by U.S. dosing conventions).