ESA Status

CriCon meets the Vortex: by Nicholas Chrimes

Last week I had the opportunity to meet with Scott Weingart (@emcrit) in New York. One of the topics we discussed was my enthusiasm for his CriCon concept and the benefits of a staged escalation in emergency status to help overcome the psychological & practical hurdles of deciding to “cut the neck”.

CricCon

We also had a related discussion about the benefit of having “hard triggers” that give clinicians “permission” to initiate these escalations and help overcome the barriers to escalating care early enough.

While the Vortex clearly defines when performance of emergency surgical airway (ESA) is required, there is no objective point at which the it mandates initiating preparation for ESA. If optimal attempts at all three non-surgical airway (NSA) techniques have failed, the Vortex provides a clear “hard trigger” to initiate ESA but the need to begin preparing to perform an ESA in parallel with progressive failure of optimal NSA attempts is only implied (through descent into, and narrowing of, the funnel).

Fig6

If preparation for initiating ESA has not been made in advance of the decision to perform it, the delays can be surprisingly long in the context of a rapidly desaturating patient, and expose the patient to the risk of critical hypoxia in the interim. Scott suggested to me that ideally there should be a clear trigger to escalate the level of ESA preparedness.

In an attempt to achieve this I have modified the original Weingart CriCon model, condensing it down to 3 levels of preparedness. This has in part been achieved by removing CriCon 5 which is a default status and should therefore be part of the general preparation for all airway management. The remaining stages represent escalations from this during difficult airway management, with CriCon 1 & 2 (the “cutting” stages) being combined into the “GO” status. The colouring has also been reversed to provide a “traffic light” cue for performance of ESA.

ESA Status

These 3 levels of preparedness align with the 3 NSA techniques of the Vortex. A declared failure of an optimal attempt at any NSA technique mandates an escalation in ESA preparedness by the team. Sequential failure of optimal attempts at all three NSA techniques will therefore place airway management teams at “GO” status as they enter the ESA portion of the Vortex, having already prepared the necessary equipment during the “READY” and “SET” phases.

It is not the intention that this model will be included visually in the Vortex cognitive aid, for fear of cluttering it. In any case, as mentioned above, the impending need for ESA is already implied by spiralling deeper into the narrowing funnel. Instead Pete Fritz (@pzfritz) and I have agreed that as a standard part of Vortex training, when a declaration of a failed optimal attempt at any NSA technique is made, it should be accompanied by a request to escalate ESA preparedness. If this request is not made by the airway operator, then other members of the team will be empowered to make the suggestion and act upon it.

This modified CriCon model enables the escalation in ESA preparedness to be “hardwired” into the Vortex’s standardised template for difficult airway management. Using this model will hopefully better prepare clinicians, both practically & psychologically, to perform ESA in a timely manner when it is indicated. In addition, even in circumstances where ESA is ultimately not required, it should encourage this type of preparation to become routine as difficult airway scenarios deteriorate, removing some of the  self-consciousness which can form a significant barrier to even asking the team to “get out the cric kit”.

Nicholas Chrimes

(Thanks to Scott Weingart for his input into the modified CriCon model)

Mac 3 vs Mac 4: The mechanical disadvantages of a longer laryngoscope blade: By Nicholas Chrimes

Video demonstrating the mechanical disadvantages of the Mac 4 http://youtu.be/gYxwhEmYb9w

The Mac 4 is often touted as the preferred size MacIntosh blade as it avoids the need to change blades and have an extra attempt at laryngoscopy if the Mac 3 is not long enough. This short video demonstrates why, when the Mac 3 is long enough, it will give you your optimal attempt at laryngoscopy on the first go.

CVCI or CICO?: By Nicholas Chrimes

Before the advent of the laryngeal mask, the phrase “can’t intubate, can’t (face mask) ventilate” accurately described the trigger for requiring a surgical airway. More recently the term “can’t intubate, can’t oxygenate” has been popularised. Does it mean the same thing? Which term do you prefer?

My experience is that many clinicians are unclear by what is meant by the term “oxygenation”.

  • Alveolar oxygenation
  • Blood oxygenation
  • Tissue oxygenation

Whilst tissue oxygenation is clearly the ultimate goal, alveolar oxygenation is the only concept relevant to the decision to perform a surgical airway. Unfortunately alveolar oxygenation cannot be directly assessed in “real time” during an airway crisis, and indirect measures such as “ventilation” or “blood oxygenation” must be used to make a judgement about whether alveolar oxygenation is occurring. Blood oxygenation, on the other hand, can be assessed directly via pulse oximetry but factors other than airway patency (such as alveolar oxygen reserves achieved during preoxygenation and the efficiency of oxygen transfer from alveoli to pulmonary capillaries), impact on the reading seen – such that it often doesn’t correlate with airway patency and thus its relevance to decision making in a difficult airway is questionable.

Does CICO introduce a poorly defined and difficult to assess concept into time-critical decision making?

Given that the assessment of patency via any non-surgical airway technique is made by the ability to ventilate (ideally using ETCO2), was “can’t ventilate (via a facemask or laryngeal mask), can’t intubate” a better term? Ultimately isn’t the decision to proceed to surgical airway based simply on an assessment that we “can’t ventilate” – by any non-surgical airway device?

CVCI, CICO or just CV?

What are your thoughts?