Achieving an adequate minute volume through a 2 mm transtracheal catheter in simulated upper airway obstruction using a modified industrial ejector.

BACKGROUND

Needle cricothyrotomy and subsequent transtracheal jet ventilation (TTJV) is one of the last options to restore oxygenation while managing an airway emergency. However, in cases of complete upper airway obstruction, conventional TTJV is ineffective and dangerous. We transformed a small, industrial ejector into a simple, manual ventilator providing expiratory ventilation assistance (EVA).

METHODS

An ejector pump was modified to allow both insufflation of oxygen and jet-assisted expiration through an attached 75 mm long transtracheal catheter (TTC) with an inner diameter (ID) of 2 mm by alternately occluding and releasing the gas outlet of the ejector pump. In a lung simulator, the modified ejector pump was tested at different compliances and resistances. Inspiration and expiration times were measured and achievable minute volumes (MVs) were calculated to determine the effect of EVA.

RESULTS

The modified ejector pump shortened the expiration time and an MV up to 6.6 litre min(-1) could be achieved through a 2 mm ID TTC in a simulated obstructed airway.

CONCLUSIONS

The principle of ejector-based EVA seems promising and deserves further evaluation.