So I've been teaching my version of the scalpel-finger-bougie cric method for a few years now. I've used it on actual patient cricothyrotomies with great success. If you are not familiar with the way I teach, you can see a ton of the EMCrit cric resources here. One component of the technique that I'd been teaching is a secondary confirmation of intratracheal placement via obtaining hold-up with the bougie somewhere in the right bronchial tree. A set of comments brought up the possibility that with enough effort, a false hold-up could be obtained:
— Jason Bowman (@texprehospital) July 4, 2016
Well, that sounds less than good. So first I wrote to EM anatomy guru, Andy Neill.
From the most recent Gray’s anatomy Textbook (the big bible at the mo)“The pretracheal layer of the deep cervical fascia is very thin. It provides fascial sheaths for the thyroid gland, larynx, pharynx, trachea, oesophagus and the infrahyoid strap muscles. Superiorly, it is attached to the hyoid bone; inferiorly, it continues into the superior mediastinum along the great vessels and merges with the fibrous pericardium;”and“The retrovisceral space [this would be if you got your bougie between post trachea and oesophagus] is continuous superiorly with the retropharyngeal space. It is situated between the posterior wall of the oesophagus and the prevertebral fascia. Inferiorly, the retrovisceral space extends into the superior mediastinum. Should the prevertebral fascia merge with the connective tissue on the posterior surface of the oesophagus – usually at the level of the fourth thoracic vertebra – the retrovisceral space then has a distinct inferior boundary.”The suggestion here is that there’s a fascial plane from the pretacheal fascial space to the sup mediastinum but closed at that point and you would have to penetrate the fibrous pericardium with bougie to access the pericardial space (which i suppose you could do if you were really enthusiastic with your bougie!). You’d have to push even harder to actually penetrate the heart itself. The retrovisceal space has a clear boundary at T4 posteriorly which is still above the heart and more importantly much more posterior.Bottom line the communicating fascial planes won’t get you further than the superior mediastinum as far as i can work out.Though if you sharpened your bougie to a fine a point or used a chest drain trocar then i’m sure you could make it to the heart 😉
TLDW: It is possible, in the hands of adrenalized novices, to get a false hold-up sign with the bougie during cricothyrotomy. I no longer recommend this secondary confirmation.
Minh, before you comment, this has nothing to do with the hold-up sign during orotracheal intubation.