Methods and apparatus for the sytematic control of ventilatory support in the presence of respiratory insufficiency

摘要

A method and apparatus for providing ventilatory assistance to a spontaneously breathing patient An error signal (56) is computed that is the difference between a function of respiratory airflow (54) over a period of time and a target value (52). Using a servo loop, air is delivered to the patient at a pressure that is a function of the error signal, the phase of the current breathing cycle, and a loop gain that varies depending on the magnitude of the error signal. The loop gain increases with the magnitude of the error signal, and the gain is greater for error signals below a ventilation target than for error signals above the ventilation target value. The target value (52) is an alveolar ventilation that takes into account the patient's physiologic dead space.

主权项

1. Apparatus for providing ventilatory pressure support to a patient comprising
a control mechanism configured to:
obtain a first ventilation measure with a first speed of response and a second ventilation measure with a second speed of response, the first speed of response being faster than the second speed of response, the ventilation measures being derived from respiratory flow of the patient, the second ventilation measure derived by low pass filtering;derive a first calculated error being a function of a target ventilation value and the first ventilation measure, and a second calculated error being a function of the target ventilation value and the second ventilation measure, andcalculate a control response based on the first calculated error and the second calculated error, wherein said control response is increasingly dependent on the first calculated error and less dependent on the second calculated error, as the first ventilation measure becomes increasingly less than said target ventilation value; and a ventilator responsive to said control response for controlling the level of pressure of air delivered to said patient.