Synchrony between end of ventilator cycles and end of patient efforts during assisted ventilation

Abstract

Automatic ongoing adjustment of the cycling-off time of ventilator inflation phase during assisted ventilation in accordance with true respiratory rate of a patient. Electrical signals are generated corresponding to the gas flow exchanged between patient and ventilator (flow) and/or to airway pressure (P) and the true respiratory rate of the patient (patient RR) is determined on an ongoing basis from the flow and/or P. The current average cycle duration of patient respiratory efforts (current patient T) is estimated from patient RR. A current desirable duration of the inhalation phase (desirable T) is calculated from the product of current patient Ta T/Tratio chosen to be in the physiological range, usually 0.25 to 0.50. The ventilator phase is caused to terminate in accordance with the desirable T.