Another FOAMed post on thoracotomy, surely we’ve had enough???
Well I’d tend to agree with you………. but performing a thoracotomy is one of the most stressful and time critical procedures you will do in Emergency Medicine. It also holds some real risks, mainly to the staff involved in the procedure with some alarmingly high sharps injury rates in this relatively high risk cohort of patients. Being really clear in your mind about how you will decide whether to perform a thoracotomy, should the situation rear it’s head, is vital prior to the situation arising.
And let’s be honest, although it’s a relatively infrequent event it’s an interesting topic!
Cardiac Ultrasound in Cardiac Arrest
The use of ultrasound is growing exponentially, in 2012 Blyth and colleagues performed a Systematic Review of Bedside Focused Echocardiography as Predictor of Survival in Cardiac Arrest Patients. They found ultrasound in cardiac arrest held a positive likelihood ratio for ROSC was 4.26 (95% CI = 2.63 to 6.92), and negative likelihood ratio was 0.18 (95% CI = 0.10 to 0.31). With these figures ultrasound certainly looks to add value to prognostication but doesn’t quite possess the ability to determine independently if resuscitation is futile, it’s not a binary decision maker.
A recent paper published in the Annals of Surgery looks at the utility of ultrasound to determine if thoracotomy will be futile. The paper has been discussed in EMRAP by Rob Orman and it’s well worth a listen as well.
I wanted to run through this paper as I think it’s one people will reference a lot and be quoted as a reason to game-change, if nothing else I hope this blog and podcast encourage you to go and read through the paper yourself as I’m sure everyone will have their own interpretation of the evidence.
So, it was a prospective study in the United States in 2 ED’s over a four year period from 2010-2014 of patients undergoing resuscitative thoracotomy in the ED in cardiac arrest.
These were normally either penetrating trauma patients with absent vital signs and blunt trauma patients with a loss of vital signs en route or in the resuscitation room, and in general patients who presented with this history would get a thoracotomy.
The primary outcome was the survival to discharge or organ donation. The FAST scan was performed either just prior to or during the thoracotomy and was performed by a PGY2-4 under direct faculty supervision. It’s important to note that all residents complete a 2 day, 16 hour ultrasound course in a addition to a minimum of 2 weeks training in POCUS.
Ultrasound findings were documented as adequate of inadequate with cardiac motion defined as organised, non-fibrillating contractions.
What did they find?
Well 223 cases underwent resuscitative thoracotomy during this period, with 83.9% having a FAST performed, which formed the study cohort (worth thinking that that is an average of 1 every second week per centre!).What we’re not able to know is how many patients had a FAST scan and had a decision then made not to proceed to thoracotomy
The sort of patients that we’re talking about- well the average age was was 31 (1-84) with nearly 85% being male, just over half were due to penetrating trauma and the most common mechanism was GSW. These also tended to be multiply injured patients with a concomitant head injury in nearly half of cases and multiple other areas tended to be involved as well.
22.5% of the patients undergoing thoracotomy in the ED had cardiac injury but none of these patients survived! There were 21 patients during this time period that were identified by FAST as having pericardial effusions from penetrating thoracic injuries but all were taken to the OR where 1/3 arrest ed en route.
Vital signs were lost on scene in roughly a half of patients, a quarter en route and a quarter in ED (NB the median duration of transport time was 33 minutes).
3/4 of patients received a left anterolateral thoracotomy.
Nearly a half of patients (48.7%) regained cardiac motion but only 3.2% survived and a further 1.6% of patients became organ donors.
Cardiac motion was detected in 28.9% of patients.
The sensitivity for FAST in identifying survivors or organ donators in this population was 100% (9 patients) and a specificity of 73.7%. The authors state that the negative predictive value of FAST in this context is 100%. There is no comment at all about the confidence intervals surrounding the sensitivity and specificity with this data set.
So what does this paper mean for me?
So this is where opinion is likely to be wildly split, without confidence intervals around the sensitivity and specificity I can’t get areal feel for what this small data set means, if only one patient had been deemed to have no cardiac motion but had gone onto survive then that would have slashed the sensitivity to a significantly lower value- around 90%. In this setting we’re looking for a test which has as higher sensitivity as possible, that way we can use it as a rule out test- if no cardiac motion then performing a thoracotomy becomes futile. So it is really likely that the 95% confidence intervals will have a large spread with such a small cohort of positive outcomes and it would be prudent to interpret these with a significant degree of caution.
This paper is certainly food for thought but with such a low pretest probability of survival in this patient cohort if you’re going to use USS in traumatic cardiac arrest to solely inform your practice and decide whether to proceed to thoracotomy then you’re going to need to at least wait for a paper with a larger patient population, accurately powered and with a population that reflects yours.
From personal experience I have used USS prior to the initiation of 2 thoracotomies, although I can’t be sure I’m pretty certain that irrespective of what I’d found on those 10 second scans I’d probably have proceeded to thoracotomy either way. What the images gave me was probably added confidence that performing a thoracotomy was the right thing to do, a cognitive safety blanket really.
As with almost every part of EM it’s piecing together the different parts of the puzzle that paints the picture and unfortunately it’s rare that one prognostic alone is enough.
It’d be great to hear your thoughts on the paper so please leave any comments at the bottom of the page.
Blyth, Lacey, et al. “Bedside focused echocardiography as predictor of survival in cardiac arrest patients: a systematic review.” Academic Emergency Medicine19.10 (2012): 1119-1126.
Inaba, Kenji, et al. “FAST Ultrasound Examination as a Predictor of Outcomes After Resuscitative Thoracotomy: A Prospective Evaluation.” Annals of Surgery262.3 (2015): 512-518.