Thursday, 16 August 2018

Change the guidelines! An RCT of Epinephrine in Out-of-Hospital Cardiac Arrest; the PARAMEDIC2 Trial


Should we still be giving adrenalin in cardiac arrest?

Despite decades of tradition and guidelines, there has never been any good evidence showing adrenalin improves meaningful outcomes.

The PARAMEDIC2 trial was a very well conducted RCT of 8014 patients in the UK with out-of-hospital cardiac arrest. Patients were properly randomised to getting either adrenalin 1mg q3-5 minutes or matching placebo.

Primary outcome in this study was rate of survival at 30 days. But we all know the real outcome of interest is hospital discharge with a favourable neurologic outcome.

Results?

The adrenalin group had more patients with ROSC, transport to hospital and ICU resources. Rate of survival at 30 days was marginally better at 3.2% vs. 2.4%. (NNT 112)

Yes, the rates of survival were abysmal.  But remember the patients included in the study did not respond to initial resuscitative efforts (CPR and defibrillation). They were only enrolled when they got down the pathway requiring adrenalin.

But the real outcome of interest; neurologically intact survival?

No difference.

In the end, adrenalin increases resource utilization and increases survival of the neurologically devastated.

Sounds pretty bad to me. Sounds pretty bad to the consumer groups too.

Will this change the guidelines?

Old habits die hard. But there will never be a trial more definitive than this one. It would have been unethical to start this trial if the authorities (in the UK at least) were not prepared to change practice.

But adrenalin may be worse. Ask yourself; does giving a worthless treatment distract the focus from more important resuscitative efforts? This study didn't address this question but I think I know the answer.

Yes, change the guidelines!


Covering:


Paper critiqued at Emergency Tasmania 2018. Special thanks to Dr Mark Reeves, FANZCA and audience for feedback.

Image result for adrenalin vial

Tuesday, 14 August 2018

Fake News: Intraosseous vascular access is associated with lower survival and neurologic recovery among patients with out-of-hospital cardiac arrest


Prior observational studies have challenged the widely held belief that IO access is just as good as IV. This paper further explored the association between IO access and poor outcomes compared to IV.

The authors performed a secondary analysis of a large trial of patients with out-of-hospital cardiac arrest. They were able to identify patients that got IV vs. IO as their means of access.

They excluded patients who had any failed attempts at either route of vascular access or who had both performed.

The primary outcome was favourable neurologic outcome on hospital discharge (mRS <3 i.e. patients could at least walk without assistance).

Results?

13,155 were included in the analysis. 5% had IO access and 95% had IV (obviously patients were not randomised to this intervention)

For all outcomes, the IV access was far superior. 7.6% of patients with IV access had favourable neurologic outcome vs. 1.5% with IO.

This is astounding! A huge difference… let’s throw away the IO’s!!!

But there is no way this is true.

No amount of fancy statistics can make up for systematic bias and residual confounding that is present in this cohort study. There is clearly a reason why paramedics went directly to IO rather than IV. The IO group was obviously a “sicker” cohort to start with and had worse outcomes.

Not all cardiac arrest is the same. We know those with witnessed arrest, bystander CPR and shockable rhythms do better. There are also many other factors that influence outcomes.

Capturing all potential confounders in a resuscitation is problematic. When under duress, data is hard to measure accurately. In addition, there are always the unknown confounders that go unmeasured and unadjusted. No statistics can truly fix bad or absent data.

Futhermore, what was the magic medicine they used to account for this five fold increase in favorable outcomes? No drugs have really been shown to work in ALS. 

In the same context of “fake news” sometimes bad evidence is worse that no evidence at all. This study has the very unfortunate possibility to mislead and cause harm. At best, it is hypothesis generating for future prospective study.

For now, reject the fake news and keep drilling your IO’s. 

 Image result for ez-io
Paper critiqued at Emergency Tasmania 2018. Special thanks to Dr Mark Reeves, FANZCA and audience for feedback.


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Thursday, 5 July 2018

Association of Preprocedural Fasting with Outcomes of Emergency Department Sedation in Children


Many guidelines still call for patients to be properly fasted prior to ED procedural sedation. Although this is steeped in consensus and tradition, is this really beneficial?

No.

This was a planned secondary analysis of a multicentre prospective cohort study of 6183 children who received parenteral procedural sedation in one of 6 Canadian ED’s.

They compared fasted and non-fasted children with the occurrence of pulmonary aspiration, adverse events, serious adverse events and vomiting.

Results?

Most children were very healthy at baseline. 80% of the procedures were for orthopaedic reductions and laceration repairs. Two thirds of children got ketamine alone. (This is obviously a different cohort from those patients that get treated in the operating theatre.)

How many children were not properly fasted?

About 50% for solids and 5% for liquids.

In the end, there was no association between fasting and any bad outcomes. This is concordant with all of the previous studies on this subject.

Naysayers can complain about the limitations of this study; not huge enough to make definitive claims about safety, ketamine is airway protective, conducted in tertiary centres, and it was not randomised.

The excellent accompanying editorial by Steve Green (Dr Ketamine) shreds these arguments with further evidence. In addition, he emphasises many of the potential harms of fasting.

Even before this study was published, the American Collegeof Emergency Physicians (ACEP) 2014 clinical policy recommended not to delay procedures solely on fasting time.  

Outside the USA, I would imagine most of us have quietly changed our practice anyway and don’t consider fasting to be a mandatory requirement. Perhaps is time to formally change our policies.  



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Bougie vs Endotracheal Tube with Stylet for ED Intubations: an RCT


“…use of a bougie compared with an endotracheal tube + stylet resulted in significantly higher first-attempt intubation success among patients undergoing emergency endotracheal intubation.”

Should we all go bougie first?

As is often the case, the devil is in the details…

This was a single centre clinical trial randomised 757 adult patients to the two arms (bougie vs. stylet) using mostly a C-MAC Macintosh blade.

The primary outcome was first-attempt success in patients with at least one difficult airway characteristics (obesity, short neck, cervical spine immobilisation etc.)

They had a ridiculously high 96% first attempt success rate with the bougie but only an 82% with the stylet. (To put this in perspective, the first attempt success rate in the ANZEDAR registry was 84%)

Before you jump on the gum elastic bougie train, consider a few things.

This study was conducted in an ED where the tradition was to use a bougie first. They would have obviously been more comfortable with this technique and the stylet was new to them.

The vast majority of the intubations were done by less experienced PGY 2 - 4 emergency residents and fellows. Emergency medicine faculty only performed 3% of the procedures.

The incidence of hypoxemia (13% vs. 14%) did not differ between the groups. This is a more relevant patient oriented outcome. This study did not report any patient harms from the lower first-attempt success of the stylet (but to be fair, was not powered for safety).

In the end, I don’t think this study will be overly practice changing. Most clinicians will stick with what they know best. But a 96% first pass success rate is extremely high and hard to ignore.

Image result for gum elastic bougie

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Wednesday, 4 July 2018

Early application of continuous femoral nerve block for neck of femur fractures: an RCT


Many patients with neck of femur fractures get some form of a nerve block in the Emergency Department. This is most often a single injection and wears off in several hours. Would a continuous block via infusion be better?

This UK single centre trial randomised patients to standard care vs. a continuous infusion of 0.2% ropivacaine at 5ml/hour for 48 hours. The medication was delivered by perineural catheter placed by experienced anaesthesia doctors.

Included patients had to be >70 years old, without cognitive impairment, live at home and independently mobilise. Yikes! This obviously limited the number of eligible patients and made this study less feasible to undertake.

The two primary outcomes were the Cumulated Ambulation Score and Dynamic Pain Score score over three days. Whatever those are...

111 patients with fractures underwent analysis.

It is no surprise no difference was found. (Other than a secondary outcome of improved pain at rest) With these small numbers, the researchers had low statistical power and could only hope to find a big difference. In addition, there were several issues that may have drawn the conclusion to the null hypothesis.

Many questions remain; did they use the right dose, did they do the correct block, were the primary outcome scores appropriate & relevant, etc.

In the end, the jury is still out. Despite the negative conclusion, the research question really remains unanswered. If there was a longer delay to theatre, one would hope a continuous infusion would be better than standard care… but who knows, there still is clinical equipois

 Image result for neck of femur fracture

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Monday, 7 May 2018

Aromatherapy for nausea? Inhaled isopropyl alcohol vs oral ondansetron for nausea in the ED; an RCT



A patient with nausea presents to your ED...

A busy triage nurse to hands a patient an isopropyl alcohol pad and says, “sniff on this.” 

Nausea magically disappears.

Believe it or not, this is not a new concept. The use of aromatherapy to reduce post-operative nausea & vomiting has been studied for decades. But it has only just just recently popped its head (nose?) into the ED.

This was a very well conducted RCT that enrolled 122 young adults with a chief complaint of nausea & vomiting >3 on a numerical rating scale. They excluded patients who had already got IV cannulation and prior antiemetic therapy.

They were randomised to one of three arms:
  • Inhaled isopropyl alcohol alone (with oral placebo)
  • Ondansetron alone (with inhaled saline placebo)
  • Both inhaled isopropyl alcohol and ondansetron

They were told to sniff on the isopropyl alcohol pad as much as they like and could get a new/fresh one about every 10 minutes.

The primary outcome was reduction in nausea as measured on a visual analog scale (VAS) at 30 minutes.

Results?

Both arms using isopropyl alcohol had reductions in nausea by about 30mm. The ondansetron alone arm only had reduction by 9mm. This was statistically significant and the authors made the expected conclusions.

Despite elegant methods, this study did have some important limitations.
  • It is difficult to blind alcohol. (but you can get blind with alcohol… sorry). This could have introduced bias.
  • Persistence and duration of effect is difficult to gage. What about the repeat customer who states, “you’re not going to try to get me to sniff on that alcohol pad again?”
  • These were low risk patients who didn’t need IV’s.
  • Small studies reporting large treatment effect are often disproven

In the discussion, the authors state the mechanism of action remains unclear but could be “related to olfactory distraction.” Perhaps a nausea voodoo dance would have met with the same effect? Who knows…

What should we conclude?

Inhaled isopropyl alcohol might help some low risk patients in the ED with nausea. It is very unlikely to cause harm. But I still like the idea of a voodoo macarena.


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Sunday, 6 May 2018

Unsuspected Critical Illness Among ED Patients Presenting for Acute Alcohol Intoxication


During my ED training, I was taught the maxim; nobody is ever "just drunk." Of course, this was meant to emphasize caution in recklessly labelling patients as such. Some may have subdurals, infections or other bad illness.

These authors attempted to quantify the proportion of patients who were thought to be just drunk but who ended up requiring critical care resources. In addition, they sought to find clinical features that might be associated with the need for these resources.

Enter Minneapolis, Minnesota. (Evidently, a lot of people resort to drinking here.) Their ED has a “dedicated intoxication unit” where these presumed low risk patients are grouped.

Over five years, they put over 35,000 patients through this area. One patient was readmitted 227 times!

Of these low risk patients, what proportion of them ended up requiring critical care resources?

1%

Abnormal vital signs, hypoglycaemia and parenteral sedation were associated with this outcome. This has face validity i.e. makes sense.

However, this study had substantial limitations.

It was a retrospective review of EHR data which we know to be rather unreliable. It also rested on subjectivity in the definition of their study population and other assumptions.

At best the 1% estimate is a ballpark figure.

But the accuracy doesn’t matter. The overall message has not changed; a small proportion of patients who you suspect to be “just drunk” will really have something bad. Pay attention to vital signs and overall be cautious.

Where have I heard this before?


Covering:

Klein LR, Cole JB, Driver BE, et al. Unsuspected CriticalIllness Among Emergency Department Patients Presenting for Acute AlcoholIntoxication. Ann Emerg Med 2018;71:279-288.
Image result for just drunk