The following is a summary of “Post-insufflation diaphragm contractions in patients receiving various modes of mechanical ventilation,” published in the September 2024 issue of Critical Care by Rodrigues et al.
Post-insufflation diaphragm contractions (PIDCs) during mechanical ventilation could be dangerous and may occur with different modes of assisted ventilation, especially with reverse-triggering.
Researchers conducted a retrospective study investigating the association between PIDCs, ventilator settings, and patient characteristics in mechanically ventilated patients with hypoxemic respiratory failure.
They collected 1-hour recordings of diaphragm electromyography (EAdi), airway pressure, and flow once daily for up to 5 days, from intubation until complete recovery of diaphragm activity or death. Each breath was classified as mandatory (without reverse triggering), reverse triggering, or patient-triggered. Reverse triggering was categorized on EAdi timing about the ventilator cycle or instances leading to breath stacking. Measurements of EAdi timing (onset, offset), peak, and neural inspiratory time (Tineuro) were taken breath-by-breath and compared to the ventilator’s expiratory time. A multivariable logistic regression model was used to explore factors independently associated with PIDCs, EAdi timing, amplitude, Tineuro, ventilator settings, and the Acute Physiology and Chronic Health Evaluation II (APACHE II).
The results showed that 47 patients (median [25%-75% IQR] age: 63 [52–77] years, BMI: 24.9 [22.9–33.7] kg/m2, 49% male, APACHE II: 21 [19–28]) contributed an average of 2 ± 1 recordings, totaling 183,962 breaths and PIDCs occurred in 74% of reverse-triggering breaths, 27% of pressure support breaths, 21% of assist-control breaths, with 5% of Neurally Adjusted Ventilatory Assist (NAVA) breaths, PIDCs were linked to a higher EAdi peak (odds ratio [OR] [95% CI] 1.01 [1.01; 1.01]), longer Tineuro (OR 37.59 [34.50; 40.98]), shorter ventilator inspiratory time (OR 0.27 [0.24; 0.30]), higher peak inspiratory flow (OR 0.22 [0.20; 0.26]), and smaller tidal volumes (OR 0.31 [0.25; 0.37]) (all P≤ 0.008). The NAVA was associated with the absence of PIDCs (OR 0.03 [0.02; 0.03]; P<0.001). Reverse triggering showed lower EAdi peaks than pressure support breaths and was associated with smaller tidal volumes and shorter set inspiratory times compared to assist-control breaths (all P< 0.05). Reverse triggering that led to breath stacking was characterized by higher peak EAdi and longer Tineuro, with smaller tidal volumes than all other reverse-triggering phenotypes (all P< 0.05).
They concluded that PIDCs and reverse triggering phenotypes were associated with modifiable factors, including ventilator settings, suggesting that proportional modes like NAVA could potentially eliminate PIDCs.
Source: ccforum.biomedcentral.com/articles/10.1186/s13054-024-05091-y
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