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 FIO2 maintaining appropriate breathing effort, and minimizing FIO2. 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 (Tiles), respiratory and metabolic variables were measured. Results: PS over support (median 8.0 to 12.0 cmH(2)O) reduced respiratory muscle activity (Tries 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(2)O, 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(2)O) slightly increased respiratory muscle activity, (Tries to 0.120 +/- 0.044; p = .007) with no significant CDSS advice. CDSS advice reduced FIO2 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 FIO2 maintaining SpO(2) at safe and beneficial values.