| 主权项 |
1. A method for generating a signal that mirrors changes in the level of effort exerted by respiratory muscles of patients on mechanical ventilatory support (Signal), comprising:
monitoring airway pressure (Paw), rate of gas flow (F), and volume of gas flow (V) of the patient; inputting Paw, F and V data collected to a computer with said computer performing the following processes on the collected data;
calculating a composite pressure signal that mirrors changes in the level of effort exerted by respiratory muscles of patients on mechanical ventilatory support (Signal) from the relationship:
Signal=current V*Kv+current F*KF−current Paw,wherein, KF is a coefficient that converts flow into equivalent resistive pressure units and Kv is a coefficient that converts volume into equivalent elastic pressure units; said calculation begins using assumed (arbitrary) values for KF and Kv while subsequently, as more data is analysed, utilizing Patient-Specific values;calculating a Patient-Specific KF from elapsed data by determining the value that minimizes step changes in calculated Signal at the time of ventilator triggering and/or cycling-off;calculating a Patient-Specific Kv from elapsed data by steps comprising:
scanning of stored F or Paw information, and/or the time derivative thereof, during the exhalation phase of elapsed breaths and identifying instances where the trajectory of either F or Paw transiently reverses direction during said exhalation phase, thereby detecting transients;selecting two or more points within the exhalation phase that are at preselected distances away from identified transients,calculating the value of Kv required to force the values of Signal calculated at said selected points in elapsed breaths to be substantially equal when said selected value of KF is used as the flow coefficient;wherein said generated Signal is either displayed on a screen to serve the purpose of monitoring patient efforts and/or is used to control the output of the ventilator. |
