Why cricoid pressure doesn’t work (probably)

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 2003Boet 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…

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Paediatric Appendicitis Risk Calculator

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:

  • The description of the methodology was confusing and we did not feel we would be able to replicate it based on what was described in the article (one of the “acid tests” for an article.)
  • The article did not tell us what the components of the calculator they derived actually were! This is probably the biggest frustration with this article. It states: “The pARC is not intuitive and requires sophisticated calculations… The pARC can be easily programmed and integrated within the electronic health record.” Not terribly useful to staff outside of the hospitals the author plans to implement his calculator in!

We entered into some interesting discussion around clinical decision rules, summarized below:

  • Most clinical decision rules (think PECARN/CHALICE/HEART…. almost anything) condense findings on history and examination that we would all obtain during a routine assessment into a list and allocate a quantitative value to the presence or absence of those findings.
  • Most clinical decision rules are too hard to remember in full. Yes you can plug them into an app but still….
  • We usually know who has appendicitis (or a severe head injury, or ischaemic chest pain) after performing an adequate clinical assessment.
  • Possibly more importantly, we usually know who doesn’t have these conditions after assessing them.
  • The difficult patients are:
    • The “maybes” ie the intermediate scoring patients
      • Many clinical decision rules are NOT useful for this intermediate group of patients.
  • So if clinical decision rules confirm what we already know and don’t help us when we don’t know, do they have any use at all?
    • Potentially.
      • They are sometimes helpful to convey information to other teams
        • Eg convincing the surgeon they have appendicitis because they score highly on the Alvarado/PAS score
      • They can be useful in rationalizing imaging and investigations
        • Eg deciding NOT to image low risk patients (and in some cases, eg high risk appendicitis patients if admission & OT is more appropriate)
    • They can be useful for developing a standardised guideline for conditions in which there is a large variation in practice within and between departments (ie calculate score then admit/investigate/discharge based on score)
  • They can be useful in reassuring ourselves when our gut feeling is “this is not appendicitis” that a patient is, in fact, low risk and ok to go home!

Any other thoughts on these issues or suggestions for Journal Club articles, please let me know.

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Ultrasound Case 2

Click here for US Case 2

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Ultrasound Case 1

Click here for US Case 1

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Education Session: Shock

Knowledge Review Quiz here

Cases we discussed are here

PEA

Causes of elevated LACTATES

Venue Ultrasound : Auto VTI Demo

Femoral vs radial arterial lines, and non-invasive vs invasive BP measurement (PulmCrit): http://emcrit.org/pulmcrit/a-line/

Other references:

1. Perner A, Cecconi M, Cronhjort M, Darmon M, Jakob SM, Pettilä V, et al. Expert statement for the management of hypovolemia in sepsis. Intensive Care Med. 2018 Apr 25;44(6):791–8.

2. Marik PE. Fluid Responsiveness and the Six Guiding Principles of Fluid Resuscitation. Critical Care Medicine. 2016 Oct;44(10):1920–2.

3. Dynamic LVOTO: https://echo.anesthesia.med.utah.edu/dynamic-obstruction/

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Education Session: Ambu aScope

ascope

Here is the pre-reading for the Education Session on the Ambu aScope.

Objectives for the session:

1. Indications for endoscopic airway instrumentation

(1) looking at airways (eg. burns, FBs, stridor)

(2) awake fibreoptic intubation

(3) intubation through a supraglottic device following failed intubation

2. Discussion of recent cases

3. Patient preparation

4. Airway local anaesthetic topicalisation

5. Environment preparation

6. Use of the aScope

Device familiarisation

The aView Monitor:

One of the consultants got intubated by his registrars. It shows the challenge of topicalisation in a non-sedated patient who has not received an antisialogogue:

Further comments and reflection by the intubatee are documented here

The retrieval service (Greater Sydney Area HEMS) has been using the aScope for several years and has some useful aides-memoire and checklists available below.

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Articles of interest

Alpha-blockers in renal colic (rebel em)

Challenging patients (dftb)

”Expectations in the trauma bay”

Calcaneus fractures (core em)

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