(1156) Characterization of Reverse Triggering in an Intensive Care Unit in Guadalajara, Mexico

Introduction: Awareness of ventilatory dyssynchronies and their influence on the outcomes is increasing. Reverse trigger (RT) has been associated with increased lung stress, excessive tidal volume and diaphragmatic damage. The evidence supporting interventions to avoid RT is based on case reports. The aim of this study was to characterize the phenotypes of RT.

Methods: Observational, prospective, single-center study, included patients undergoing invasive ventilation for >24 h with RT identified in ventilator waveforms. Cases were confirmed by off-line analysis of waveforms, including esophageal manometry. The primary objective was to determine the most common phenotype of RT. The incidence, most common entrainment pattern, and the associated sedation levels were also evaluated.

Results: From July 2022 to March 2023, 83 patients with mechanical ventilation (MV) for more than 24h were admitted, and 20 patients with RT were identified. Most patients were ventilated using volume-controlled mode. The most common phenotype was early reverse trigger with early relaxation, a 1:1 entrainment pattern in most patients. Four patients experienced double trigger. The RT was resolved by switching to spontaneous mode in 18 patients for a median of 30 minutes until resolution, while 2 patients required neuromuscular blockade due to severe work shifting. Change from volume to pressure-controlled ventilation didn't resolve RT in any case. The median esophageal swing pressure during RT was 6.8 cmH2O; the highest values found in patients with ARDS (14 cmH2O). Days of mechanical ventilation were similar in patients with and without reverse triggering (4.2 days vs. 3.7 days, respectively; p=0.43). All patients had deep sedation levels (RASS -5) at the moment of RT identification.

Conclusions: Reverse trigger is common and often goes unnoticed, potentially leading to the loss of lung protection, perpetuating lung injury, and even causing diaphragmatic damage, especially in patients with ARDS. We found that all patients had a deep sedation level, highlighting the importance of using the minimum sedative dose and allow spontaneous breaths as early as possible. It is hypothesized that the presence of RT might be associated with a shorter duration of MV; however, further clinical studies are required to validate this hypothesis.