Apnoeic oxygenation was associated with decreased desaturation rates during RSI in multiple Australian and New Zealand ED’s

The Australian New Zealand ED airway registry (ANZEDAR) includes 43 ED’s that prospectively submit data on patients they intubate. It has provided a wealth of information on how we manage airways.

This study looked at patients who got apnoeic oxygenation (ApOx) during RSI vs. those that did not. (ApOx was defined as patients getting up to 15L of oxygen via a nasal cannula.) They excluded patients intubated during cardiac arrest and those that got BVM or NIV during the apnoeic period.

The primary outcome was rates of desaturation to <93%.

Results

1669 (66%) patients got ApOx and 850 (33%) did not. Desaturation occurred in 10% of the ApOx group vs. 13% in the other group.

ApOx rules!!!

Maybe… maybe not…

This was not a randomized trial. As such, there could have been confounding factors or that led to the differences observed. (But to be fair, I would imagine that doctor would have been more likely to provide ApOx in those patients that they were worried might desaturate. Therefore, making the ApOx group look potentially worse. But perhaps I’m wrong…)

This was a study of registry data. Unfortunately, this data is often of poor quality. It’s possible we may have a “garbage in, garbage out” phenomenon. Intubation is often an anxiety provoking procedure where doctors get task focused. They may have not really been aware of how low the saturations dropped. Ideally, one would get the data from a research assistant who is tasked to collect accurate data at the time.

Desaturation is not really a patient-oriented outcome. Transient hypoxemia probably causes no harm in most patients. Ideally, we would look at more important outcomes involving real patient morbidity and mortality. But good luck powering such a study!

If ApOx doesn’t really change any important patient outcomes than arguably it may be one extra step that distracts us from getting the job done. In times of high stress, we need to keep our processes as simple as possible.

The debate continues…

 

Covering:

Perera A, Alkhouri H, Fogg T, et al. Apnoeic oxygenation was associated with decreased desaturation rates during rapid sequence intubation in multiple Australian and New Zealand emergency departments. Emerg Med J 2021;38:118-124. [Link to article]

The Use of Tranexamic Acid to Reduce the Need for Nasal Packing in Epistaxis (NoPAC): RCT

We all know tranexamic acid (TXA) is good for everything. It’s great for trauma, all kinds of bleeding and heck, tastes great on Weet Bix. But a lot of this enthusiasm is now being challenged by hard science.

These researchers from the UK randomized 496 patients with epistaxis (after failure of nasal compression and topical vasoconstrictor) to topical tranexamic acid or placebo.

Trial treatment was with cotton wool dental roll either soaked in 200mg tranexamic acid or sterile water. The dental roll was left in for 10 minutes and could be repeated a second time if the bleeding continued.

The primary outcome was the need for anterior nasal packing.

Results?

The mean age was about 70 and two thirds were on anticoagulants.

In the end, the rates of anterior nasal packing were about the same in both groups at 40%.

The authors conclude the that tranexamic acid is no better than placebo.

But I’m not so sure this is going to change practice to those who are tranexamic acid afficionados.

The inclusion of mostly elderly patients on anticoagulants could have diluted the results to the null hypothesis. These are a hard group to treat and, in my experience, often get nasal packing. And remember, the patients enrolled in this study had already failed compression and vasoconstrictors.

So, perhaps TXA will work better in a different population.

Many would argue that TXA is cheap and very unlikely to cause harm. But so are bedside anti-epistaxis incantations. Either one of them is possibly a waste of time and distracting from performing other measures.

Perhaps save TXA for the Weet Bix? Hmmmm….

 

Covering

Reuben A, Appelboam A, Stevens K, et al. The Use of Tranexamic Acid to Reduce the Need for Nasal Pcking in Epistaxis (NoPAC): Randomized Controlled Trial. Ann Emerg Med. 2021 Feb 18;S0196-0644(20)31461-X [Link to article]

 

 

 

Diagnostic Accuracy of the HINTS Exam in an Emergency Department: A Retrospective Chart Review

The HINTS exam for evaluation of patients with acute vestibular syndrome (AVS) has been all the rage over the past decade. Originally described in 2009, it reported phenomenal accuracy at differentiating peripheral from central causes of vertigo. However, the performance of the test has mostly been validated by neurologists and otolaryngologist.

To qualify for a HINTS exam, patients must have AVS characterized by continuous dizziness and ongoing in the ED, nystagmus, and gait unsteadiness.

This retrospective chart review looked at how often a HINTS exam was appropriately performed and the sensitivity & specificity of the test at this single ED in Ontario. The authors point out that doctors did not get any specific training on the HINTS exam prior to this review.

A total of 2,309 patients presented with a primary complaint of vertigo or dizziness. Almost 20% got a HINTS exam! However almost all (96.9%) of them were performed inappropriately as it was not clinically indicated. In addition, many patients got both a Dix-Hallpike test and a HINTS exam… which should never happen as they are “intended in mutually exclusive patient populations.” 

In the end, the sensitivity & specificity of the test as performed was terrible.

What are we to conclude?

At this single ED, the HINTS exam performed poorly in untrained doctors who did the exam on the wrong patients.

They conclude that “additional training of emergency physicians may be required.” This is quite an understatement.

Of course, this study is far from perfect, but it serves as a cautionary tale.

This is not the only study suggesting a problem. A systematic review and metanalysis in 2020 concluded that “the HINTS exam, when used in isolation by emergency physicians has not been shown to be sufficiently accurate to rule out a stroke in those presenting with AVS.”

I do not think the HINTS exam is overly simple. Nor did I believe there are enough cases of vestibular stroke for an average emergency physician to develop and maintain proficiency with the exam. But perhaps I’m wrong… there are some very clever doctors who disagree with me.

Until such time we get further evidence, we should not be giddy over the HINTS exam.

 (** Addendum 28/4/2021: Please see comment section for feedback on my summary from Dr Peter Johns. He is a Canadian Emergency physician and vertigo guru. He wrote the book on vertigo... literally wrote the chapter in Tintinalli)

Covering

Dmitriew C, Regis A, Bodunde O, et al. Diagnostic Accuracy of the HINTS Exam in an Emergency Department: A Retrospective Chart Review. Acad Emerg Med 2021;28:387-393. [link to free full text]

 

 

Compression Therapy to Prevent Recurrent Cellulitis of the Leg… way to go Bruce!

We’ve all seen them…

Those big red chronic oedematous legs that we diagnose as cellulitis. We start IV antibiotics and admit. But those same legs come back to the ED again and again…

Hummm... should we be doing something to prevent recurrent cellulitis in oedematous legs?

These investigators from the Public Hospital Bruce, Canberra, conducted a single centre non-blinded RCT of patients with chronic oedema of the leg and recurrent cellulitis. Participants were randomised to leg compression therapy vs. control.

The primary outcome was recurrence of cellulitis as diagnosed by GP’s or hospital physicians and confirmed by trial assessors. There were a bunch of secondary outcomes including measuring leg volume with the use of a perometer (huh?), quality of life, adherence to intervention etc.

Shortly after starting the trial, lymphoedema therapists who were aware of the group assignments noticed a potential large treatment effect and brought it to the attention of the Human Research Ethics Committee (HREC). Stopping rules were added to the study protocol. As expected, the trial was stopped early for efficacy.

In the end, 84 patients were enrolled with 23 episodes of recurrent cellulitis. There were 6 (15%) patients with cellulitis in the compression group and 17 (40%) in the control arm.

Wow… an absolute reduction of 25% or NNT of 4. This is crazy efficacy.

(Just in case you were curious, the perometer showed a between group difference of -240ml in leg volume over time.)

Critics of this trial could justifiably point out that it was really small, stopped early, and conducted at single centre.  But perhaps the biggest limitation was the diagnosis of recurrent cellulitis is subjective and it was adjudicated by those who were unblinded- potentially leading to bias.

Either way, these results are very compelling, in line with expert opinion and should be practice changing. As ED doctors, we don’t usually focus on preventative medicine. But this intervention will have much more effect than those countless tetanus immunisations we give away.

Looks like it’s time to get on the compression train.

Covering:

Compression Therapy to Prevent Recurrent Cellulitis of the Leg. N Engl J Med. 2020;383:630-9. [link to article]

Short-Term Topical Tetracaine is Highly Efficacious for the Treatment of Pain Caused by Corneal Abrasions: A double-blind RCT

It seems to me that these researchers asked the wrong question. Most of us know that numbing up a corneal abrasion relieves pain. But the big question has always been is it safe to send patients home with topical anaesthetic. For decades, ophthalmologist have been telling us it is dangerous.  But lately, this dogma has been challenged with better quality research.

So if they didn't ask the right questions, then why was this study conducted and published in our peak emergency medicine journal?

It turns out we have never proven the efficacy of topical anaesthetics for outpatient treatment of simple corneal abrasions with an RCT. Go figure...

But, now we have.

This well conducted RCT out of a single ED in Oklahoma (yeeeehaaaaaaa!) randomised 111 patients to 2ml’s of tetracaine drops vs placebo to take home. The primary outcome was the overall NRS pain score at a 24-hour and 48-hour ED follow-up.

As expected, the tetracaine worked marvellously. Pain score was 1/10 in the tetracaine group and 8/10 in the placebo group. This is a huge difference with lots of pretty p values. The placebo group also gulped down more Vicodin than the those given tetracaine (don’t get me started…)

Unfortunately, we cannot make claims about safety with so few trial participants. A much larger study will be needed to find less common side effects. But the original studies that suggested harm are old and poor quality. It seems that the current best evidence suggests topical anaesthetics are probably safe and definitely effective for simple corneal abrasions.

But don’t be surprised if your local ophthalmologists disagree… it's hard to teach an old dog(ma) new tricks. 

 

Covering:

Shipman S, Painter K, Keuchel M, et al. Short-Term Tetracaine is Highly Efficacious for the Treatment of Pain Caused by Corneal Abrasions: A Double-Blind, Randomized Clinical Trial. Ann Emerg Med. 2020 Oct 27;S0196-0644(20)30739-3.    doi: 10.1016/j.annemergmed.2020.08.036 [link to article]

 

 

Early Rhythm-Control Therapy in Patients with Atrial Fibrillation

Rate vs. rhythm control of atrial fibrillation has been a perennial question.

These investigators sough to determine if patients with “early atrial fibrillation” (<1 year since diagnosis) and cardiovascular conditions had better outcomes with rhythm control.

The was a behemoth study and worthy of publication in the NEJM.

2789 patients in 135 centres in 11 different countries in Europe were randomised to either rhythm control (antiarrhythmic drugs, ablation, & cardioversion) vs. usual care (mostly rate control but occasionally rhythm control to manage AF related symptoms.)

One primary outcome was a composite of death from cardiovascular cause, hospitalisation for heart failure and/or ACS. The other primary outcome was nights spent in hospital. There were lots of secondary and safety outcomes.

After a median 5 year per patient follow up time, the trial was stopped early due to efficacy at the 3^rd interim analysis. There was an absolute decrease of 1.1 events per 100 person years for the first primary outcome. This may not seem like much of a treatment effect, but there are a lot of people out there with AF.

No study is perfect, and this one has some limitations. There were reasonably narrow inclusion criteria which limit generalisability. It probably excluded most symptomatic patients as they would not have been candidates to be randomised to “usual care.” In the manuscript, there is an entire column of author conflicts of interest- in small font no less! Cardiologist love to cosy up to industry….

Either way, this study will change the guidelines. And in speaking with my local electrophysiologist, this study has already changed practice. Cardiologists are pushing suitable patients with new AF towards a rhythm control strategy with antiarrhythmics and more ablations are being performed.

Of course, emergency physicians are not likely to prescribe antiarrhymics and certainly won’t do ablations (unless you want a friendly visit from a regulatory body). But it is good for us to know the overall strategy and we will be asked to be more aggressive with early rhythm control.

Covering:

Kirchhof P, Camm AJ, Goette A, et al. Early Rhythm-Control Therapy in Patients with Atrial Fibrillation. N Engl J Med. 2020;383:1305-16. [link to article]

Testicular Workup for Ischemia and Suspected Torsion in Pediatric Patients and Resource Utilisation: Everybody do the TWIST?

 

The TWIST score is a "validated" clinical decision instrument to aid in the diagnosis of acute testicular torsion.

TWIST sore?

Yes, I’ve never heard of it either… and I will probably forget about it very soon.

The TWIST score (0-7) is calculated by the presence of testicular swelling (2 points), hard testes (2 points), nausea/vomiting (1 point), high riding testes (1 point), and absent cremasteric reflex (1 point). Based on the score, patients can be stratified into high, intermediate, or low risk. I’ll spare you further details…

These authors sought to apply the TWIST score to a group of patients by performing a retrospective medical record review. They were looking at potentially decreasing formal ultrasound use, decreasing ED length of stay and ischemic time. (Methods for their chart review are absent however…)

Results?

77 patients were identified by ICD-10 codes. All 9 high risk patients had torsion. And it was absent in the 57 low risk patients. The authors claim the score could have reduced the need for ultrasound 75% of the time and reduced ischemia time.

Sounds great, but there are major problems with this study.

Retrospectively collected data is usually poor quality. The authors assumed data not recorded indicated absence of findings. Of course, this is nuts (sorry).

Regardless of prior studies, I don’t believe the TWIST score has face validity. The most important features in diagnosis of torsion are the appropriate age (usually adolescent) and the history. Sudden severe pain with vomiting and potentially a high-riding testicle is all you need. These patients should not be getting ultrasounds… just an immediate referral to the appropriate surgeon. A hard & swollen testicle is very common in orchitis and I can’t believe it wound be discriminatory. 

Of course, a clinical decision instrument should improve upon what we do already. These scores must be compared to clinician gestalt before being adopted. Otherwise we don’t know if they will underperform and cause harm.

Regardless of what Cubby Checker says, please don’t do the TWIST.

 

Covering:

Roberts CE, Ricks WA, Roy JD, et al. Testicular Workup for Ischemia and Suspected Torsion in Pediatric Patients and Resourse Utilization. J Surg Res. 2021;257:406-411. [link to article]