Effect of High Flow Tracheostomy Device for weaning from Mechanical Ventilation

The weaning of long term tracheostomised ICU patients from prolonged mechanical ventilation can be difficult, challenging and at a great financial cost to the health care institution. Humidified oxygen can be delivered via a humidified t-piece at up to 15 litres a minute but this is unlikely to offer any benefit in terms of generating positive airway pressure and increasing end expiratory lung volume.The High flow tracheostomy device (HFT) allows the delivery of warmed, humidified oxygen at a prescribed fraction of inspired oxygen (FiO2) at flow rates much higher than previously allowable with other delivery systems. The use of this method of oxygen and flow delivery in weaning off mechanical ventilation is becoming more common in our ICU and there is a real need to determine if this therapy generates positive airway pressure and increases end expiratory lung volume; to quantify these changes; and also to determine if this treatment has any clinically relevant benefit which will lead to improved outcomes for these patients. Electrical Impedance Topography (EIT) is a relatively new non-invasive radiation-free imaging technique which can be used easily and safely at the bedside to provide real-time dynamic images of regional lung ventilation. Changes in end-expiratory lung impedance (EELI) as measured by EIT have been shown to have a strong linear correlation with changes in end-expiratory lung volume (EELV). Therefore, it will be possible to assess both pressure and volume simultaneously within the lung. This study aims to determine if HFT has any clinically relevant benefit in weaning patients from mechanical ventilation by assessing whether this treatment provides positive airway pressure and an increase in EELV, in addition to assessing their effects on oxygenation, respiratory rate and subjective scoring of dyspnoea