Respiratory mechanics derived from signals in the ventilator circuit.

The aim of this article is to identify and interpret the data provided by modern ventilators that provide the greatest clinical help in evaluating respiratory mechanics during mechanical ventilation. In intensive care, respiratory mechanics can be assessed in dynamic conditions (no flow-interruption) or static conditions (occlusion techniques) to record compliance and resistance and to monitor pressure, flow, and volume. Real-time visualization of the pressure curve is crucial for monitoring during volume-controlled ventilation, in which pressure is the dependent variable. Analysis of the pressure curve has little clinical utility during pressure-controlled ventilation, in which the dependent variable is the flow waveform, which varies according to changes in the mechanics of the respiratory system. Pressure-volume loops and flow-volume loops provide useful information on the dynamic trends of the respiratory system compliance and resistance, respectively. Modern ventilators provide complete monitoring of respiratory system mechanics, which is our guideline for optimizing ventilatory support and avoiding complications associated with mechanical ventilation.