Non-invasive estimation of hemodynamic parameters during mechanical ventilation

A ventilation system for non-invasive determination of a hemodynamic parameter of a mechanically ventilated subject based on a point in time (thb) of a heartbeat of the subject and an arrival point in time (tarr_pulm, tarr_sys) at which a blood pressure pulse caused by the heartbeat reaches a point of arrival in a circulatory system of the subject, the ventilation system comprising:

• a breathing apparatus mechanically ventilating the subject;
• at least one pressure sensor measuring a respiratory pressure and/or at least one flow sensor measuring a respiratory flow;
• a blood oxygen sensor;
• and
• a computer determining the hemodynamic parameter,
• wherein the computer is configured to:
• estimate a time window for a heartbeat based on data obtained from the blood oxygen sensor;
• determine, within the time window, the point in time (thb) of the heartbeat from a change in the measured respiratory pressure and/or the respiratory flow resulting from a physical impact of the heart on the lungs of the subject during the heartbeat;
• determine:
• a pulmonary pulse transit time, PTTpulm, for the blood pressure pulse based on the point in time of the heartbeat (thb) and a point in time of arrival (tarr_pulm) of the blood pressure pulse to the lungs of the subject;
• and/or
• a systemic pulse transit time, PTTsys, for the blood pressure pulse based on the point in time of the heartbeat (thb) and a point in time of arrival (tarr_sys) of the blood pressure pulse to a point of arrival in the systemic circulatory system of the subject;
• and
• determine the hemodynamic parameter based on PTTpulm and/or PTTsys.