The flow-pressure plot: a new look on the patient-ventilator interaction in neonatal care

Most modern neonatal ventilators have now a built-in flow sensor and, as a spin-off of their mechanical action, provide some information about lung function characteristics as compliance and resistance after computation of the flow and pressure signals. Additionally, respiratory graphics as volume-pressure and flow-volume plots can be displayed. In clinical practice, however, they are rarely used to refine the ventilator setting. A nonconventional flow-pressure plot is presented in this article, constructed from the volume or flow, and pressure outputs of a Babylog 8000 (Dräger, Lübeck, Germany). This flow-pressure diagram appears to be useful in the real-time computation of respiratory mechanics based on the Rahn's law of respiratory motion. Its major advantage, however, is the easy pattern recognition of subtle changes in infant-ventilator interaction, ie, excessive triggering, fighting against the ventilator, augmented breath, tube subobstruction. It may be useful to add the flow-pressure plot to the classical respiratory graphics allowing to monitor mechanical ventilation more accurately and to fine tune the ventilator setting accordingly.