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The Speed of Sound

No Benefit of POCUS for Shock (but Keep Using It)

Butts, Christine, MD

doi: 10.1097/01.EEM.0000552786.49703.4a
The Speed of Sound

Dr. Butts is the director of the division of emergency ultrasound and a clinical associate professor of emergency medicine at Louisiana State University at New Orleans. Follow her on Twitter @EMNSpeedofSound, and read her past columns at http://bit.ly/EMN-SpeedofSound.

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It was a bombshell: A recent study found no difference in any outcomes between undifferentiated shock patients who did and did not receive ultrasound.

This multicenter study evaluated the use of point-of-care ultrasound (POCUS) in adults who presented with a systolic blood pressure less than 100 mm Hg or a shock index greater than 1. (Ann Emerg Med 2018;72[4]:478; http://bit.ly/2OnZFEy.)

There were quite a few exclusion criteria, which appear to have been intended to exclude patients with known causes of hypotension (history of trauma, for example). Patients were randomized to a group that utilized the established POCUS RUSH protocol to evaluate hypotension and direct care or to a group receiving standard, non-ultrasound directed care. The primary outcome of the study was survival at 30 days or to hospital discharge. They also looked at secondary outcomes such as length of stay, ICU admission, and use of inotropes.

Certainly, the study design had a number of methodological issues. The initial proposal was powered for 400 patients, but only 270 were enrolled. The study was halted early due to slow enrollment and the futility of continuing, as decided by their ethical board. But were there really that few patients over four years? Would it have made a difference if they had met their initial goal?

The study design required patients in the POCUS arm to have their first ultrasound within 60 minutes of initial assessment. The physicians performing the scan were not blinded; is it possible that they were influenced by their clinical gestalt prior to the ultrasound? Most of the patients in this study had non-cardiogenic shock, specifically sepsis. Short of identifying an obvious source (hot gallbladder, big abscess), the mortality benefit of POCUS in these patients seems a bit murkier and likely less important than other factors, such as early antibiotic administration.

Hopefully, additional validation will add to the findings of this study and clear up these issues. This study made me think of a bigger question, however: What do we expect from bedside ultrasound? Sometimes I am surprised by what I find when I put the probe on a patient's abdomen, but most of the time I know what I'm looking for. That's the role of my history, physical exam, experience, and clinical judgment.

I use POCUS to confirm my thoughts and to look for the really bad things. If bedside ultrasound really is the stethoscope of the 21st century, as so many have suggested, perhaps we should use it as such. I'm not aware of any randomized, controlled trials that show an increased survival rate when I listen to my patient's heart, but I'm going to do it anyway because it adds to my overall understanding and every now and then points me in a different direction.

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More about Kurdistan

The map used with Dr. Butts' column last month demonstrated the region in which the Kurdish people and culture are the majority. The term Kurdistan referred to the semi-autonomous region of Iraqi Kurdistan, located within northern Iraq.

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