An open-loop, physiological model based decision support system can reduce pressure support while acting to preserve respiratory muscle function

Purpose: To assess whether a clinical decision support system (CDSS) suggests PS and FIO ₂ maintaining appropriate breathing effort, and minimizing FIO ₂. Materials: Prospective, cross-over study in PS ventilated ICU patients. Over support (150% baseline) and under support (50% baseline) were applied by changing PS (15 patients) or PEEP (8 patients). CDSS advice was followed. Tension time index of inspiratory muscles (TTies), respiratory and metabolic variables were measured. Results: PS over support (median 8.0 to 12.0 cmH ₂O) reduced respiratory muscle activity (TTies 0.090 ± 0.028 to 0.049 ± 0.030; p <.01), and tended to increase tidal volume (VT: 8.6 ± 3.0 to 10.1 ± 2.9 ml/kg; p =.08). CDSS advice reduced PS (6.0 cmH ₂O, p =.005), increased TTies (0.076 ± 0.038, p <.01), and tended to reduce VT (8.9 ± 2.4 ml/kg, p =.08). PS under support (12.0 to 4.0 cmH ₂O) slightly increased respiratory muscle activity, (TTies to 0.120 ± 0.044; p =.007) with no significant CDSS advice. CDSS advice reduced FIO ₂ by 12–14% (p =.005), resulting in median SpO ₂ = 96% (p <.02). PEEP changes did not result in changes in physiological variables, or CDSS advice. Conclusion: The CDSS advised on low values of PS often not prohibiting extubation, while acting to preserve respiratory muscle function and preventing passive lung inflation. CDSS advice minimized FIO ₂ maintaining SpO ₂ at safe and beneficial values.