A decision support system for suggesting ventilator settings: retrospective evaluation in cardiac surgery patients ventilated in the ICU.

Selecting appropriate ventilator settings decreases the risk of ventilator-induced lung injury. A decision support system (DSS) has been developed based on physiological models, which can advise on setting of tidal volume (Vt), respiratory frequency (f) and fraction of inspired oxygen (FiO2). The aim of this study is to assess the feasibility of the DSS by comparing its advice with the values used in clinical practice. Data from 20 patients following uncomplicated coronary artery bypass grafting (CABG) with cardiopulmonary bypass was used to test the DSS. Ventilator settings suggested by the DSS were compared to the settings selected by the clinician. When compared to the clinician the DSS suggested: lowering FiO2 (by median 7%, range 2-17%) at high SpO2 and increasing FiO2 (by median 2%, range 1-5%) at low SpO2; lowering ventilation volume (by median 0.57 l min(-1), range 0.2-1.1 l min(-1)) at high pHa and increasing ventilation volume (by median 0.4 l min(-1), range 0.1-0.9 l min(-1)) at low pHa. Suggested changes in ventilation volume were such that simulated values of PIP were < or = 22.9 cmH2O and respiratory frequency < or = 18 breaths min(-1). In all cases, computer suggested values of FiO2, Vt or f were consistent with maintaining sufficient oxygenation, normalising pH and obtaining low values of PIP.