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

BACKGROUND

Several self-assembled devices, consisting of a three-way stopcock connected to a high pressure oxygen source, have been proposed for transtracheal jet ventilation in an emergency situation. As a three-way stopcock acts as a 'flow splitter' it will, when connected to a continuous oxygen flow, never ensure total flow and pressure release through its side port. The aim of the present study was to measure the efficacy of flow and pressure release of three previously described self-assembled jet devices and one commercially available tool.

METHODS

In a laboratory setting simulating an obstructed upper airway the generated pressure at the cannula tip (PACT) during the expiration phase was measured in three self-assembled jet devices consisting of a three-way stopcock with an inner diameter of 2 mm (device A), 2.5 mm (device B), and 3 mm (device C), respectively, and in the Oxygen Flow Modulator (OFM) at oxygen flows of 6, 9, 12, and 15 l min(-1).

RESULTS

The PACT of device A at on oxygen flow of 15 l min(-1) was 71.1 (+/-0.08) cm H(2)O. At a reduced flow of 9 l min(-1) the PACT of device A was still 25.8 (+/-0.08) cm H2O. In device B and C the PACT was 35.6 (+/-0.04) and 17.6 (+/-0.04) cm H2O, respectively, at an oxygen flow of 15 l.min(-1). In contrast, the PACT in the OFM (five side holes open) was 4.4 (+/-0.02) cm H2O at the same flow.

CONCLUSION

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.