POCUS OUTCOMES AND SAFETY: A ‘NON-COCHRANY’ LITERATURE REVIEW
by Justin Bowra and Alan Giles
Part of ‘Tackling the tough topics’:The POCUS Debate NSW - 9 November 2018
The question we asked: What does the literature say about the actual efficacy and safety of POCUS? (IE actual real-world patient outcomes, rather than surrogate markers such as diagnostic accuracy)
Methods: we asked a bunch of POCUS nerds from around the world to send us copies of any literature they had on the subject. We supplemented this by looking up papers that caught our eye, but if it cost actual money to download the articles we only downloaded the abstracts.
Thanks to: Adrian Goudie and Paul Atkinson in particular for sending many of these papers, and also thanks to Frank Norman, Kylie Baker and Bob Jarman for their sage advice.
The summary (for those with short attention spans)
If used carefully by those who are properly trained, POCUS has been demonstrated to improve outcomes. (e.g. in BAT, penetrating cardiac injury, arrested patients)
If used carelessly by idiots or those without proper training, POCUS has been shown to be useless (e.g. in stable BAT, and in shocked patients) or even harmful.
Or to put it another way: ‘POCUS doesn’t kill people; doctors do!’
Now for a little more detail…
FAST in blunt abdo trauma:
Melniker’s small study showed benefit in ALL comers in ADULTS (eg decreased time to OR, fewer complications, decreased overall LOS, decreased resource use)
But often used for the wrong reasons [e.g. is there solid organ injury?] and in the wrong patients [stable BAT]
A Cochrane Review failed to show improvement in overall mortality, but confirmed lower use of CT… but this might be a bad thing considering its fairly poor accuracy for free fluid!
And just by the way, doctors tend to over-order CTs in stable adults and children who are low risk for significant traumatic injury!
It might be OK to keep performing FAST in stable BAT but only if you are doing it for the practice!
POCUS for undifferentiated shock:
A protocol that didn’t look for consolidation / B lines was demonstrated NOT to help- but be careful about the double negative! This doesn’t mean that looking for consolidation/B lines would add value!
RUSH improves diagnostic accuracy, but we didn’t find a study that translates this into effect on outcomes
Basic cardiac (2D look) in cardiac arrest:
Good news! If performed and interpreted correctly, POCUS in ALS can accurately ID patients who will NOT survive to hospital DC (= those with cardiac standstill)
Cardiac US during ALS can dangerously prolong ‘breaks’ in CPR
We have POOR interrater agreement on whether or not there’s cardiac activity!
POCUS in respiratory disease
In adult pneumonia, LUS significantly improves accuracy of ED diagnosis, but demonstrated a [non-significant] trend toward worse in-hospital and 30-day mortality, and a significant increase in downstream testing in the POCUS group: chest CTs (8.2% vs 1.9%), echocardiograms (10.1% vs 3.8%) and diagnostic thoracentesis (5.7% vs 0%).
In paediatric pneumonia, LUS (lung US) reduced the use of chest X-rays in pediatric patients with suspected pneumonia, by 38.8% (95% CI, 30.0%-48.9%). However, there was a (non-significant) increase in the number of patients diagnosed with pneumonia and treated with antibiotics with no difference in clinical outcomes. (Non-significant so it’s hard to say what this means…)
But how can POCUS hurt patients? After all, it’s non-ionising, rapid and bedside!
Below are quotes from [Crager and Hoffman editorial.But it makes sense physiologically.Annals EM 2018 .pdf
Time and resource allocation in the emergency department (ED) is a zero-sum game both on an individual provider and departmental level, so focusing on an unproven intervention at the expense of proven interventions is an obvious concern.)
Major downstream harm could result from unnecessary evaluation and treatment of incidentalomas and overdiagnosis.
Finally, in the acutely unstable patient, major false-positive and false-negative results could cause significant harm
Sonography is very operator-dependent
Finally, as a community we need to be concerned that widespread adoption of an unproven approach makes it that much harder to conduct the studies that could ultimately answer the question about whether the approach is actually valuable, and, even more important, that much harder to abandon it if and when there is evidence that it is harmful.
The last word: (this is a quote from Rory Spiegel, commenting on Laursen’s respiratory POCUS study, in ‘‘ED Hocus POCUS ... or Just a Hoax?’ -https://www.emlitofnote.com/?p=298 )
I’m sure we all have experienced firsthand the utility of bedside US and this is by no means a call to abandon our probes, but rather an acknowledgement of the possibility of subtle harms. We must keep in mind, all testing comes at a price no matter how non-invasive and radiation-free it appears. The cost in this case is information and how we choose to act on it. This would certainly not be the first time increased access to medical technology has lead to such unintended consequences.
To quote Dr Russell McLaughlin, Belfast POCUS tragic: ‘A fool with a stethoscope will be a fool with an ultrasound.’
Ultrasound will not make you smarter, or make you a better doctor or a nicer person.