Thursday 14 April 2022

Cannabinoid hyperemesis syndrome: A 6-year audit of adult presentations to a single ED in Melbourne

I'll preface everything by stating this paper is not high science.


These authors performed a retrospective chart review on adult patients who they thought had cannabinoid hyperemesis syndrome (CHS) in their single ED in northern Melbourne.

Obviously, the diagnosis of CHS is based on clinical findings. There is no blood test for CHS and no agreed formal diagnostic criteria. So, who knows if they identified all patients with CHS or if the ones they diagnosed truly had it?

Nevertheless, there might be a few useful pieces of information… so let’s continue on our magic carpet ride.

142 patients were included. 77 were unique presentations and the rest were frequent visitors.

I’m not going to report their clinical features as this formed part of how they identified patients in the first place… kind of an incorporation bias. (Suffice to say, they were vomiting a lot.) Plus, the retrospective nature of the data means a lot of things were probably not recorded (i.e. relief from hot shower was only written down 11% of the time).

More objectively, I was interested to see that most had elevated white blood cell counts and lactates. Median WBC was 14 (IQR 11.2-16.8) and lactate was 1.95 (IQR 1.4-2.9)

These doctors also liked droperidol and the authors go on to state, “Response to droperidol (or haloperidol) as previously reported may also guide clinicians in their determination as to whether CHS should be considered.”

Arguably the best part of the paper is their proposed CHUNDER score to aid in the diagnosis of CHS. This mnemonic stands for, “Cyclical vomiting, History of regular cannabis, Under fifty years old, Normal lipase, Diagnosis of exclusion, Elevation of CRP<50, and Reduction in symptoms after droperidol.

I’m chunder struck…



Rotella J, Ferretti O, Raisi E, et al. Cannabinoid hyperemesis syndrome: A-year audit of adult presentations to an urban district hospital. 2022 Feb 23. doi: 10.1111/1742-6723.13944 [link to article]




Association of IV Contrast with Renal Function- A Regression Discontinuity Analysis

IV Contrast has been around for decades. How come we still do not know whether its causes renal damage!

Well, today is your lucky day…

These researchers conducted a randomized double-blind placebo-controlled trial of IV contrast in 2000 patients with borderline renal function to determine if there was any meaningful worsening in patient-oriented outcomes.

Just kidding!

There are limits in conducting clinical trials… the biggest of which boils down to ethics and feasibility. Sometimes, an RCT is not going to happen. So, we are stuck with observational studies which have the inherent trouble in dealing with confounding and attributing causality.

In an attempt to overcome these limitations, these researchers performed a regression discontinuity design (RDD).


The RDD relies upon the existence of a continuous variable (i.e. D-dimer) for which there is a cut-off that determines treatment or investigation. Patients on either side of the cut off have much different probabilities of investigation but probably are reasonably matched for confounding factors.

Pretty clever…

These researchers included adult patients who had a D-dimer test during an ED visit over a 5-year period in the province of Alberta, Canada. They compared the group that had elevated D-dimers vs. those that were normal. The primary outcome was long term renal function (up to six months from ED visit).


150,028 patients met inclusion criteria. Mean baseline eGFR was 86.

There was no evidence of renal damage with a change of eGFR of only 0.4 (95%CI -4.9 to 4.0) up to 6 six months later.

The authors conclude; 

“To our knowledge, this study provides the strongest evidence to date that intravenous contrast is not associated with significant kidney injury…”

This overall conclusion is correct. But... we are not worried about patients with near normal renal function to start with. We are much more interested in the cohort that has borderline function.

They tried a subgroup analysis by looking at patients with eGFR <45 but state that the analysis was hindered by missing data and small numbers. This is unfortunate.

What should we conclude?

Overall, the modern IV contrast agents probably don’t do much to kidneys. But we are not entirely sure in the cohort with more severe baseline renal impairment.


Goulden R, Rowe B, Abrahamowicz M, et al. Association of Intravenous Radiocontrast with Kidney Function. A Regression Discontinuity Analysis. JAMA Intern Med. 2021;181:767-774. [Link to article]


Saturday 9 April 2022

Rapid agitation control with ketamine in the ED: A Randomized Controlled Trial

Agitated patient tearing apart the ED...? Which IM medication do you give?

These authors from a single ED in Vancouver randomized patients to either ketamine 5mg/kg IM vs. midazolam 5mg plus haloperidol 5mg IM.

Their primary outcome was time to adequate sedation as measured on a validated agitation score.  

(They tried to blind the dose but it’s hard to blind ketamine when we all know what it looks like. Either way, this was probably only a minor source of potential bias.)


Enrolment was cut a bit short at 80 patients due to the start a supposed global pandemic.

Median time to adequate sedation was 6 minutes in the ketamine group vs. 15 minutes in those randomized to midazolam/haloperidol. 

So, ketamine is the clear winner?!?!

There are two major reasons why this conclusion is wrong.

Firstly, they compared a grizzly bear dose of ketamine to a low dose of midazolam & haloperidol. For what it is worth, I usually start with midazolam 10mg and droperidol 10mg (unless there is reason to start lower… elderly, co-morbid, etc.) Droperidol works faster than haloperidol.

Secondly, they asked the wrong research question. I care less about how quickly someone is sedated and care much more about how well it works overall.  I’m sure a dose of IM sux would work pretty quick too. Or even a bullet to the head would have an immediate calming effect (but would be associated with excess mortality.)

How often did the ketamine group require re-sedation? How well did the patients wake up? Lots of adults complain about side effects of ketamine including dysphoria to emergence phenomenon. But what could go wrong with giving an agitated patient a medication similar to PCP?

To be fair to the researchers, it is difficult to objectively measure, “how well did it work?” It's complicated and there is some subjectivity in this question. Time to sedation is much easier to measure… but just because we can measure something accurately does not necessarily mean it is important. (This kind of reminds me of the streetlight effect).

In short summary, I’m willing to believe a big slug of ketamine will cause someone to drop quickly. But is this the best thing for the patient? I doubt it.



Barbic D, Andolfatto G, Grunau, et al. Rapid Agitation Control with Ketamine in the ED- A Blinded, Randomized Controlled Trial. Ann Emerg Med. 2021;78:788-795 [link to full text article]





The erector spinae plane block for acute pain management in ED patients with rib fractures

The erector spinae plane block provides analgesia for rib fractures. It is similar to 3 in 1 blocks that we are comfortable performing for femoral neck fractures. It requires ultrasound guidance and high volume (30-40ml) of dilute anesthetic to allow the medication to spread below a fascial plane. 

For a decent video demonstrating the block, check out:

Interestingly, the block was only just described in the anesthesia literature in 2016 but it has already become quite the rage.

Why? It is simple, effective and the incidence of complications is felt to be low.

However, it looks like it hasn’t really made its way into the Emergency Department.

Enter two Canadian emergency doctors who published a case series of 9 patients. Ok… a pilot study and not great science.

The mean reduction in NRS pain scores went from about 10 to 3.5. So, it seemed to work pretty darn well. Of course, they cannot make any claims about safety, but other literature has somewhat addressed this.

The authors appropriate state that more research is needed but they “feel that the erector spinae plane block should be considered in patients with acute rib fracture pain as a method of pain control in multi-modal analgesia.”

I think this is probably a fair conclusion. We perform a multitude of blocks in the ED. With appropriate training, this can probably be added to our armamentarium.



Surdhar I, Jelic T. The erector spinae plane block for acute pain management in emergency department patients with rib fractures. Can J Emerg Med. 2022;24:50-54. [link to article]