The importance of flow and pressure release in emergency jet ventilation devices

Abstract

In case of complete upper airway obstruction the OFM provides sufficient flow and pressure release, whereas the self-assembled jet devices tested are inherently dangerous constructions.

A bench study of ventilation via two self‐assembled jet devices and the Oxygen Flow Modulator in simulated upper airway obstruction

“…Only flow splitters that ensure a low expiratory pressure at the catheter tip (e.g. the OFM) will allow slow exhalation through the transtracheal catheter or cannula [10,11]. In the first part of the study, high pressures at the tip of the transtracheal catheter during the expiratory phase were measured when using device A.…”

“…In a patient with an obstructed upper airway, merely connecting such a device attached to an oxygen flow of 15 l.min )1 can cause a dangerously high intrathoracic pressure [11]. In principle, due to its geometry a three-way stopcock can behave like a Venturi device.…”

A reply

“…We respectfully submit that we have correctly interpreted Xue et al's [3] time for airway topicalisation, as gleaned from Table 2 of their article clearly indicating a 'total time for airway sprays' of 24.3 (3.8) min (1% lidocaine) and 22.8 (3.5) min (2% lidocaine). We continue to believe that one of the advantages of the atomised lidocaine technique is the rapidity at which the airway can be anaesthetised (< 5 min [1,2]).…”

“…Since our publication, the authors have published at least two related articles [1,3], exploring some aspects of their original Enk Oxygen Flow Modulator (Cook Medical Inc., Bloomington, IN, USA) in combination with some aspects of our method, without mentioning our work. Yet Enk et al commented on our article from 2008 and their comment and our response were published [4,5].…”

“…We appreciate the reference to our recent article [3], but believe that Woodruff et al have misrepresented our time (> 20 min) for airway topicalisation. As the main aim of our study was to compare the safety and efficacy of 2% and 4% lidocaine to produce airway topical anaesthesia with a spray-as-you-go technique, the repeated lidocaine sprays in the airway were performed at a 3-5 min interval to provide adequate penetration of local anaesthetic into the mucosa for maximal effect, and the whole airway topicalisation protocol required 19.2-28.2 min.…”