VENTILATOR CONTROL SYSTEM UTILIZING A MID-FREQUENCY VENTILATION PATTERN

• US 20100300445A1
• Filed: 05/19/2010
• Published: 12/02/2010
• Est. Priority Date: 05/19/2009
• Status: Active Grant

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Mireles-Cabodevila, Eduardo, Chatburn, Robert L.
• Granted Patent: US 8,550,077 B2
• Time in Patent Office: Days
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0063 Compressors
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2205/3561 local, e.g. within room or hospital
• CPC Class Codes: A61M 2205/3584 using modem, internet or bluetooth
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/202 partial carbon oxide pressure, e.g. partial dioxide pressure (P-CO2)
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/30 Blood pressure A61M2230/04 takes precedence
• CPC Class Codes: A61M 2230/42 Rate
• CPC Class Codes: A61M 2230/43 Composition of exhalation
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)

Abstract

Systems and methods are provided for providing ventilation to a patient. An air source is configured to provide pressurized air to a patient through a patient circuit according to a ventilation pattern. At least one sensor is configured to monitor a corresponding physiologic property of the patient. A ventilator control system is configured to calculate an alveolar ventilation value from the monitored physiologic property of the patient, determine at least an optimal frequency for the ventilation pattern from the calculated alveolar ventilation value, and update the ventilation pattern according to the determined optimal frequency.

Claims

1. A method for controlling a mechanical ventilator to provide mid-frequency mandatory ventilation to a patient comprising:

providing mandatory ventilation to a patient according to a ventilation pattern;

monitoring an alveolar ventilation of the patient;

determining one of an optimal frequency, an optimal duty cycle, and an optimal positive end expiratory pressure for the mechanical ventilator according to the alveolar ventilation of the patient; and

updating the ventilation pattern of the mechanical ventilator to include the determined one of the optimal frequency, the optimal duty cycle, and the optimal positive end expiratory pressure.

2. The method of claim 1, wherein determining one of the optimal frequency, the optimal duty cycle, and the optimal positive end expiratory pressure for the mechanical ventilator according to the monitored alveolar ventilation comprises determining an optimal frequency for the mechanical ventilator according to the monitored alveolar ventilation, the method further comprising determining the optimal duty cycle, given the determined optimal frequency, for the mechanical ventilator from the monitored alveolar ventilation.

3. The method of claim 2, further comprising determining the optimal positive end expiratory pressure, given the determined optimal frequency and optimal duty cycle, for the mechanical ventilator from the monitored alveolar ventilation.

4. The method of claim 3, further comprising monitoring at least one hemodynamic property of the patient and utilizing a baseline value for the positive end expiratory pressure if the hemodynamics of the patient become unstable.

5. The method of claim 2, wherein determining an optimal frequency for the mechanical ventilator according to the monitored alveolar ventilation comprises determining a frequency for the mechanical ventilator that provides a maximum alveolar ventilation that is less than a threshold value.

6. The method of claim 5, wherein a tidal volume provided by the respirator is reduced when the monitored alveolar ventilation exceeds the threshold value.

7. The method of claim 1, wherein monitoring an alveolar ventilation of the patient comprises monitoring each of an end tidal concentration of carbon dioxide and tidal volume of air exhaled by the patient, monitoring a concentration of carbon dioxide in arterial blood of the patient, and calculating a minute alveolar ventilation from the monitored tidal volume, end tidal concentration of carbon dioxide, and the concentration of carbon dioxide in the arterial blood of the patient.

8. A medical ventilator system, comprising:

an air source configured to provide pressurized air to a patient through a patient circuit according to a ventilation pattern;

at least one sensor configured to monitor a corresponding physiologic property of the patient; and

a ventilator control system configured to calculate an alveolar ventilation value from the monitored physiologic property of the patient, determine at least an optimal frequency for the ventilation pattern from the calculated alveolar ventilation value, and update the ventilation pattern according to the determined optimal frequency.

9. The system of claim 8, the at least one sensor comprising a return air sensor configured to receive air exhaled by the patient and measure a tidal volume and a concentration of carbon dioxide of the returned air.

10. The system of claim 9, the ventilator control system comprising a parameter calculation component configured to calculate a minute alveolar ventilation from the measured tidal volume and concentration of carbon dioxide.

11. The system of claim 8, the ventilator control system comprising an adaptive rule based optimization system configured to alter a frequency associated with the ventilator and adjust the frequency according to feedback from the at least one sensor until a termination condition is achieved.

12. The system of claim 11, the at least one sensor comprising a hemodynamic sensor configured to monitor a hemodynamic parameter associated with the patient, the adaptive rule based optimization system being responsive to the hemodynamic sensor such that a termination condition is achieved if the hemodynamic property deviates from a prescribed range.

13. The system of claim 8, the ventilator control system being configured to determine an optimal duty cycle for the ventilation pattern from the calculated alveolar ventilation value.

14. The system of claim 8, the ventilator control system being configured to determine an optimal positive end expiratory pressure for the ventilation pattern from the calculated alveolar ventilation value.

15. A computer readable medium storing computer executable instructions for controlling a mechanical ventilator to provide mid-frequency mandatory ventilation to a patient, such that, upon execution in a computer processor, the executable instructions are configured to perform a iterative method comprising the steps of:

instructing the mechanical ventilator to provide mandatory ventilation to a patient according to a ventilation pattern;

monitoring the feedback value representing an alveolar ventilation of the patient; and

adjusting a duty cycle of the ventilation pattern according to the feedback value;

wherein the iterative method is continued until a termination event is detected, such that a plurality of adjusted duty cycles and associated feedback values are collected.

16. The computer readable medium of claim 15, the executable instructions being configured to, upon the termination event, select an optimal duty cycle from the plurality of adjusted duty cycles according to the associated feedback values and update the ventilation pattern of the mechanical ventilator such that the patient continues to receive mandatory ventilation at the selected optimal duty cycle.

17. The computer readable medium of claim 15, the iterative method further comprising adjusting a frequency of the ventilation pattern according to the feedback value, such that a plurality of adjusted frequencies and associated feedback values are collected, the executable instructions being configured to, upon the termination event, select an optimal frequency from the plurality of adjusted frequencies according to the associated feedback values and update the ventilation pattern of the mechanical ventilator such that the patient continues to receive mandatory ventilation at the selected optimal frequency.

18. The computer readable medium of claim 15, the iterative method further comprising adjusting a positive end expiratory pressure of the ventilation pattern according to the feedback value, such that a plurality of adjusted positive end expiratory pressures and associated feedback values are collected, the executable instructions being configured to, upon the termination event, select an optimal positive end expiratory pressure from the plurality of adjusted positive end expiratory pressures according to the associated feedback values and update the ventilation pattern of the mechanical ventilator such that the patient continues to receive mandatory ventilation at the selected optimal end expiratory pressure.

19. The computer readable medium of claim 15, wherein adjusting a duty cycle of the ventilation pattern according to a feedback value during the iterative method comprises decreasing the duty cycle of the ventilation pattern by a predetermined amount until the feedback value indicates no increase in alveolar ventilation.

20. The computer readable medium of claim 19, wherein adjusting a duty cycle of the ventilation pattern according to a feedback value during the iterative method further comprises returning the duty cycle to a baseline value and increasing the duty cycle of the ventilation pattern by a predetermined amount until the feedback value indicates no increase in alveolar ventilation.