Respiratory Physiology Under High Flow Therapy

Respiratory Physiology Measurements Under Transnasal High Flow Therapy in Patients With Tracheostoma After Long Term Ventilation

The aim of this study is to gain knowledge about effects of high flow transnasal insufflation on various breathing parameters like intratracheal pressure conditions, CO2 elimination, breathing frequency and tidal volume.

Ten patients, who are supplied with a tracheostomy stent (placeholder) for reinsertions after long term ventilation will be treated for a short time during the day with the nasal high flow system AIRVO at different flow rates (15, 30, 45L/min) to estimate possible long term implications of high flow treatment. Respiration is measured by impedance plethysmography with a calibrated belt system (Respitrace, VIASYS). Pressure and end tidal CO2 concentration is measured inside of the placeholder. The order of the high flow rates (15, 30, 45L/min) is randomized; each flow rate is measured for 15 minutes. A wash out time of ten minutes is planned after each phase. In this time the patient breathes his individual oxygen flow rate with attention to the oxygen saturation, which should not exceed 96%. Transcutaneous PCO2 and SpO2 is monitored with TOSCA during the study.

Each patient is treated with nasal high flow at different flow rates (15, 30, 45L/min). The order of flow rates is randomized. Each flow rate will be used for 15 minutes. A wash out time of ten minutes is planned after each phase, during which the patient uses his his individual oxygen flow.

The effects of high flow transnasal insufflation on intratracheal pressure conditions is measured with the Hans Rudolph Inc. pressure amplifier and continuously recorded breath by breath.

The effects of high flow transnasal insufflation on endtidal CO2 concentration is measured with the AD Instruments gas analyser and continuously recorded breath by breath.

The effects of high flow transnasal insufflation on breathing frequency and tidal volume is measured with the Viasys Respitrace calibrated belt system and continuously recorded breath by breath.

Inclusion Criteria: Patients in a stable weaning phase after long term ventilation Patients supplied with tracheostomy stent (placeholder) Patients in stable respiratory situation Exclusion Criteria: Incapable of giving consent Any other severe or acute physical illness which requires intensive medical care