Eccentric diaphragmatic contractions during mechanical ventilation in critically ill patients

Abstract

<b>Aim:</b> To investigate the prevalence of eccentric diaphragm activity in mechanically ventilated critically ill patients, including the impact of ventilation mode, type of breath (controlled or spontaneous) and asynchronies. <b>Methods:</b> Secondary analysis of a prospective observational study in critically ill patients (PMID 33430930). A 1-hour waveform of diaphragm electromyography (Edi), airway pressure and flow were collected daily from intubation until full recovery of spontaneous breathing, extubation, death or 120h. Each breath was classified as triggered by the patient, mandatory with or without reverse triggering (RT), double cycling, or double triggering. Peak Edi during the ventilator expiratory phase was used to identify eccentric diaphragm activity as a surrogate of eccentric contractions. We compared the prevalence of breaths with eccentric activity in each breath type and ventilation mode. <b>Results:</b> 52 patients were included (64±17 years, 54% male, APACHE II 23±7; 75% under mechanical ventilation due to respiratory reasons). 152 recordings were analyzed (2±1 recording day per patient; 251,687 breaths). 62% of all breaths were triggered by the patient, 34% were mandatory non-RT, 4% were RT and &lt;1% were double cycling or double triggering. Considering only recordings under assist-control, 8% of the breaths were RT and 11 out of 34 (32%) patients had ≥8% of RT. The prevalence of eccentric activity was 70% during RT and 22%, 10% and 1% for triggered breaths under assist-control, pressure support or NAVA, respectively (P&lt;0.05). <b>Conclusion:</b> Eccentric diaphragm contractions was associated with RT but also prevalent during assist-control and less during pressure support or NAVA