Diaphragmatic ultrasonography parameters during waveform-defined double triggering asynchrony in mechanically ventilated critically ill patients

Double triggering asynchrony happens when a single inspiratory effort causes two consecutive breaths due to an extended inspiratory neural time. This is a type of patient-ventilator asynchrony (PVA). Although it can be recognized by using airway pressure and flow waveforms, it is often underdiagnosed in clinical practice. This emphasizes the need for effective bedside detection tools. This study aimed to evaluate diaphragmatic ultrasonographic changes associated with waveform-defined double triggering during assisted mechanical ventilation and after correction of asynchrony.

Twenty-eight mechanically ventilated patients were consecutively enrolled and included in the study. The median age of the population was 71 years, with a male predominance (56.3%). Most patients were non-hypertensive (71.4%), non-smokers (> 92%), and had no history of cardiac disease (89%), while 53.6% had diabetes mellitus. Overall mortality was approximately 64%. In this single cohort of mechanically ventilated patients, diaphragmatic excursion, excursion duration, thickening fraction (TF), and excursion duration/inspiratory time were significantly higher within the same individuals during waveform‑defined double triggering than after correction of asynchrony (all p < 0.001). Exploratory ROC analysis suggested that diaphragmatic parameters could distinguish asynchrony from post-correction within the same patients. Among the tested indices, diaphragm thickening fraction and excursion duration/inspiratory time ratio showed the best discriminatory performance in this specific cohort.

Diaphragmatic ultrasound parameters showed significant within-patient changes between waveform-defined double triggering and post-correction states. However, waveform interpretation lacks the physiological validation of Pes or EAdi, the established gold standards. Further studies using these reference methods are required to validate these exploratory findings and establish definitive clinical diagnostic thresholds.