SMART Trigger versus Flow and Pressure trigger performance during auto-PEEP

Background Intrinsic positive end-expiratory pressure (auto-PEEP) is a common problem in mechanically ventilated patients, which can lead to adverse effects on patients comfort, hemodynamics, lung mechanics and gas exchange. Triggering systems play a crucial role in the delivery of mechanical ventilation, and advancements in smart triggering technology aim to optimize patient-ventilator synchrony. This bench study aims to compare the performance of the novel SMART Trigger to traditional pressure and flow triggers in the context of auto-PEEP. Methods A lung model simulating severe obstructive pattern with high compliance (80 ml/cmH2O) and high resistance 30 cmH2O/L/s was connected to the Panther 5 ventilator (Origin Medical, California, USA). The mode was set at Volume Controlled with a tidal volume of 700 ml and mandatory breath per min (BPM) of 10/min and Inspiratory time of 2 seconds to intentionally create auto-PEEP. Simulated spontaneous breaths set at 20 BPM with increasing muscle pressure (Pmus) from -1 to maximum of -25 or till full trigger of all breaths. Three different triggering systems were evaluated: SMART Trigger (ST sensitivity 1 to 7), pressure trigger (-1 cmH2O), and flow trigger (1 l/min). The range of auto-PEEP levels induced increased incrementally with the increase in the respiratory rate ranging from 3 cmH2O for 10 BPM, 8 for 15 BPM, to 13 for 20 BPM. The following parameters were assessed for each triggering system: trigger sensitivity (defined as the number of breaths triggered above the mandatory breaths), and the trigger response time (time it takes from the beginning of muscle effort to the initiation of the breath. Results 100% of the breaths were triggered at Pmus (cmH2O) of -15 in the pressure trigger, -25 in flow trigger, -3 for ST1, -9 for ST2, -10 for ST3, -10 for ST4, -12 for ST5, -18 for ST 6, and -22 for ST 7. Trigger time (msec) for flow was 0.135 ± 0.02, for pressure 0.141 ± 0.04, for ST 1-4: 0.076 ± 0.03, for ST 5-7: 0.104 ± 0.04. Multivariate analysis of variance test showed significant difference between the time to trigger P <0.001. Conclusion This bench study highlights the potential advantages of SMART Trigger technology over conventional pressure and flow triggers during auto-PEEP. The SMART Trigger enhanced sensitivity and rapid response might contribute to improved patient-ventilator synchrony. Further research and clinical studies are warranted to validate these findings and explore the impact of smart trigger technology on patient outcomes in real-world scenarios. Keywords: SMART Trigger, Auto-PEEP, Trigger time