Parameters of high-frequency jet ventilation using a mechanical lung model.

High frequency jet ventilationis a mechanical lung ventilation method which uses a relatively high flow usually through an open system. This work examined the effect of high-frequency jet ventilation on respiratory parameters of an intubated patient simulated using a high-frequency jet ventilator attached to a ventilation monitor for measurements of ventilation parameters. The series of experiments altered specific parameters each time (respiratory rate, inspiratory-expiratory (I:E) ratio, and inspiratory pressure), under different lung compliances. A reduction of minute ventilation was observed alongside a rise in respiratory rate, with low airway pressures over the entire range of lung compliances. In addition, an I:E ratio of 2:1 to 1:1; and the tidal and minute volumes were directly related to the inspiratory pressure over all compliance settings. To conclude, the respiratory mechanics in high-frequency jet ventilation are very different from those of conventional rate ventilation in a lung model. Further studies on patients and/or a biological model are needed to investigate pCO2 and end-tidal carbon-dioxide during high-frequency jet ventilation.

Percutaneous Dilatational Tracheostomy Using Tube Exchanger.

We describe a modified technique for percutaneous dilatational tracheostomy using a 15F tube exchanger or Eschmann catheter. A retrospective review of 1180 procedures using this modified technique demonstrated it to be effective with a failure rate of only 0.25% (3 patients). Moreover, it provides an additional safeguard with the ability to rapidly reintroduce the endotracheal tube into the trachea guided by the exchange catheter in the event of accidental extubation during the procedure. This technique needs no additional special devices or equipment (eg, a bronchoscope). However, a prospective study is needed to better define its complication rate.