Emergency transtracheal ventilation: assessment of breathing systems chosen by anaesthetists

The choice of equipment for emergency transtracheal ventilation and the time taken to assemble it were surveyed in 39 anaesthetists. Thirty seven (95%) assembled a system in a median time of 104 s (interquartile range 54 s to 120 s). Systems specially constructed from oxygen tubing and connectors took longest to put together (p < 0.05). Consultants and senior registrars performed no better than senior house officers and registrars (p > 0.05). In the second part of the study we tested four anaesthetic systems which the survey revealed might be chosen for emergency transtracheal ventilation. These were: a simple length of oxygen tubing; a T-piece system; a Bain system; a jet injector. All had the appropriate connectors. The oxygen flow was measured through a 14 G venous "transtracheal' cannula on depression of the oxygen flush device on a standard Boyle's M anaesthetic machine. The jet injector was connected to the high pressure outlet. This device delivered the highest flow, 43 l.min-1 and was the only system capable of ventilating a trachea/lung model. The T-piece system, and the one constructed from oxygen tubing, delivered flows of 12.7 and 12.0 l.min-1, respectively, whereas the Bain system delivered only 4.7 l.min-1. We conclude that, except for jet ventilation, none of the systems chosen, using equipment available in the anaesthetic room, would be likely to achieve effective CO2 elimination; at best they would provide oxygenation.