In Journal Club today we discussed ATOM-2, aka “Massive paracetamol overdose: an observational study of the effect of activated charcoal and increased acetylcysteine dose” Chiew A, Isbister G, Kirby K, Page C, Chan B and Buckley N Clinical Toxicology 2017
This was an observational study examining prospective and retrospective data gathered by Poisons Information Centres in NSW and Queensland.
The study looked at patients 14 years and older reporting massive paracetamol overdose (“massive” was defined by these researchers as >40g), ingested over a period of time not exceeding 8 hours. They asked the questions:
As a bit of background, charcoal used to be given to a much larger proportion of deliberate self poisoning patients than we give it to currently. Its use then fell out of favour due to concerns over aspiration-related pneumonitis and the belief that early NAC will be liver & life saving, thereby making any benefits of charcoal unnecessary. Recently however, “massive” paracetamol overdose is becoming more common and the risks of aspiration of activated charcoal have also been questioned by some researchers.
Data from 200 patients were examined, all of whom had taken more than 40g paracetamol within an 8 hour period.
The study found that patients who had activated charcoal within 4h had significantly lower paracetamol ratios than those who did not have charcoal and a lower risk of hepatotoxicity (although this is difficult to separate from the effect of NAC in those patients who received it). An increased dose of NAC (usually doubling the dose in the 3rd bag) was associated with significantly lower risk of hepatotoxicity.
Interestingly, just over 25% patients who developed hepatotoxicity had NAC commenced within 8 hours of ingestion. These patients all had paracetamol ratios greater than 2. One patient required a liver transplant despite NAC commencing within 2.5 hours. There was 1 death but it was unrelated to paracetamol.
More work needs to be done to look at the time before which charcoal is beneficial, as well as which dose of NAC is ideal and at what time.
by Josh Holden FACEM CCPU
Ever wondered why we don’t use cricoid pressure in ED? After all, compressing the oesophagus between the larynx and C5 vertebral body should stop any breakfast from coming up the wrong way quite nicely?
Check out the ultrasound video below to see the whereabouts of Jonathon Au’s foodpipe, and what might happen (other than ruining your intubation view) if you give his larynx a choke hold:
As you can see his oesophagus lies lateral to the trachea, not below it as commonly assumed.
This seems to be completely normal. Dynamic MRI studies demonstrate that application of pressure to the cricoid cartilage displaces the oesophagus laterally instead of occluding it (Smith 2003, Boet 2012). An ultrasound study demonstrated similar findings: in 60% of patients the oesophagus was lateral to the airway and cricoid pressure led to displacement rather than occlusion in all patients. (Tsung 2012). Old news then…
Journal Club Summary 21/03/2019
Today we talked about paediatric appendicitis scores, appendicitis scores and clinical decision scores and rules in general.
The article we looked at was Development and Validation of a Novel Paediatric Appendicitis Risk Calculator (pARC) Kharbanda AB, Vazquez-Benitez G, Ballard DW, et al. PEDIATRICS. 2018 Apr;141(4):e20172699. (if you would like a copy please let me know.)
In summary, this study developed a Paediatric Appendicitis Risk Calculator (pARC) using clinical findings in a cohort of normally well children presenting to ED with abdominal pain and then validated it using a separate cohort of patients, as well as comparing it to the existing Paediatric Appendicitis Score. The conclusions we reached from our discussion of the article were:
We entered into some interesting discussion around clinical decision rules, summarized below:
Any other thoughts on these issues or suggestions for Journal Club articles, please let me know.