Monitoring diaphragmatic effort during diaphragm neurostimulation-assisted ventilation

Area of Science:

• Mechanical Ventilation
• Respiratory Physiology
• Neuromuscular Stimulation

Background:

• Diaphragm neurostimulation-assisted ventilation (DNAV) enhances cardiopulmonary function during mechanical ventilation.
• Accurate monitoring of diaphragmatic loading is crucial for effective DNAV to prevent under- or over-stimulation.

Purpose of the Study:

• To determine if the reduction in airway pressure-time product (ΔPTPaw) during diaphragm neurostimulation reliably reflects the intensity of respiratory muscle effort.
• To validate ΔPTPaw as a quantitative measure for titrating diaphragm neurostimulation.

Main Methods:

• Secondary analysis of the STIMULUS trial involving diaphragm neurostimulation titration across four levels.
• Measurement of airway, esophageal, and gastric pressures to calculate transdiaphragmatic pressure-time product (PTPdi) and respiratory muscles pressure-time product (PTPmus).
• Calculation of ΔPTPaw as the difference in airway pressure-time product between non-stimulated and stimulated breaths; statistical analysis using mixed-effects models, Bland-Altman, and ROC curves.

Main Results:

• ΔPTPaw significantly correlated with both PTPdi (R² = 0.82) and PTPmus (R² = 0.92) with good agreement.
• Increasing neurostimulation led to higher PTPdi and PTPmus, with a concurrent decrease in PTPaw.
• ΔPTPaw showed excellent discrimination for identifying inadequate and excessive diaphragmatic effort (AUROC ≥ 0.86).

Conclusions:

• The reduction in airway pressure-time product (ΔPTPaw) serves as a reliable, non-invasive indicator of diaphragm loading during DNAV.
• ΔPTPaw can effectively guide the titration of diaphragm neurostimulation in mechanically ventilated patients.