Monitoring of the mechanical behaviour of the respiratory system during controlled mechanical ventilation

Most modern mechanical ventilators offer a multitude of graphics and numerics allowing to monitor respiratory mechanics during ongoing mechanical ventilation. The information provided by these integrated respiration monitors is first to provide the information necessary to optimise ventilator settings in an individual patient and second to document disease evolution over time or in response to therapeutic interventions. Furthermore, measuring respiratory mechanics during ventilation can allow developing automatic adaptation algorithms of ventilator settings. However, to do this either by manual or by automatic ventilator settings adjustment, a thorough understanding not only of basic respiratory mechanics during mechanical ventilation is needed but also a good understanding what graphs and numbers can tell the physician or respiratory therapist at bedside. Graphic monitoring shows graphs generated from the signals of airway pressure (as usually measured at the airway opening, e.g. endotracheal tube or face mask connection), gas flow and volume change of the respiratory system. Volume is in fact measured by the time-integral of gas flow. It must be noted also that all the measurements derived from the airway opening pressure include the resistance of the artificial airway (i.e. endotracheal tube) as part of the respiratory system resistance.