The value of expired gas analysis is never expired.

Complications of mechanical ventilation increase with duration. Delayed weaning and premature weaning are both associated with increasing complications. In addition, adverse events and deterioration relating to the ventilator system could happen any time. Therefore, accurate monitoring of the patient’s respiratory condition and adjustment of ventilator settings are essential during mechanical ventilation.1 End-tidal CO2 (PETCO2) monitoring is useful in mechanically ventilated patients in many situations, such as intensive care and anesthesia. Although PETCO2 is not a replacement or substitute for assessing the arterial CO2 (PaCO2), PETCO2 monitoring allows continuous evaluation of alveolar ventilation, severity of pulmonary disease, and response to therapy in mechanically ventilated patients.2,3 The closed-loop knowledge-based algorithm in the SmartCare automated ventilation and weaning system (Dräger Medical, Lübeck, Germany) was originally designed to continuously adapt the ventilatory assistance during pressure support ventilation to the patient’s need, to manage a strategy of gradually decreasing the ventilatory assistance, and to indicate when the patient is able to breathe without assistance.4 As compared to a physician-controlled weaning process, the SmartCare computer-driven system reduced mechanical ventilation duration and intensive-careunit stay but did not change the re-intubation rate.5 However, I still am not convinced that SmartCare is any better than skilled clinicians. When the SmartCare system was compared to weaning managed by experienced critical care nurses, with a 1:1 nurse-to-patient ratio, there was no substantial difference in weaning duration.6