Fig. 4

Representative examples of entrained and non-entrained reverse triggering. Examples of entrained and non-entrained reverse triggering. Phase angle is used to calculate the difference between the start of a patient of effort and ventilator pressurization. The breathing interval (start patient effort until a secondary patient effort) is expressed as TTOT_NEU. Subject A is showing entrained reverse triggering. During respiratory entrainment the patient is cycling between patient triggered breaths and reverse triggered breaths. The first two breaths are patient triggered and the last 2 breaths are reverse triggered. For illustrative reasons only the first 2 out of 4 entrained reverse breaths are being displayed. Despite changing phase angles (positive to negative) the breathing interval remains constant. As shown; no excessive oesophageal pressure swings or breath stacking occurs. Patient B is showing non-entrained reverse triggering. Variance in phase angle and TOT_NEU are > 15%. During the non-entrained reverse triggering event two ventilator breaths are delivered. Despite the double triggered breaths tidal volume are smaller compared to tidal volumes during patient triggered ventilation. Breath stacking resulted in an increase of 20% of delivered tidal volume