Leak-compensated proportional assist ventilation

• US 8,448,641 B2
• Filed: 08/02/2012
• Issued: 05/28/2013
• Est. Priority Date: 03/20/2009
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Jafari, Mehdi M., Jimenez, Rhomere S., Upham, Gail F., Aviano, Jeffrey K.
• Primary Examiner(s): Anderson, Lynne
• Assistant Examiner(s): PHILIPS, BRADLEY H
• Application Number:
  US13/565,595
• Publication Number:
  US 20120304997A1
• Time in Patent Office: 299 Days
• Field of Search: 128/200.24, 128/204.18, 12820421-20423
• US Class Current: 128/204.21
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0057 Pumps therefor
• CPC Class Codes: A61M 16/0063 Compressors
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 16/04 Tracheal tubes catheters in general A61M25/00
• CPC Class Codes: A61M 16/0666 Nasal cannulas or tubing devices for improving normal breathing through the nose A61F5/08; nose filters A62B23/06; outside holding devices A61M25/02
• CPC Class Codes: A61M 16/0816 Joints or connectors
• CPC Class Codes: A61M 16/0875 Connecting tubes
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0033 electrical
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2230/46 Resistance or compliance of the lungs

Abstract

This disclosure describes systems and methods for compensating for leakage when during delivery of gas from a medical ventilator in a proportional assist mode to a patient. The technology described herein includes systems and methods to compensate the delivery of PA ventilation for leakage in the patient circuit by using leak-compensated lung flows as well as leak-compensated respiratory mechanics parameters (lung compliance and lung resistance) estimated in a manner that compensates for elastic and inelastic leaks from the ventilation system.

Claims

1. A pressure support system comprising:

a pressure generating system adapted to generate a flow of breathing gas;

a ventilation tubing system including a patient interface device for connecting the pressure generating system to a patient;

one or more sensors operatively coupled to the pressure generating system or the ventilation tubing system, each sensor capable of generating an output indicative of a pressure of the breathing gas;

a leak estimation module that identifies leakage in the ventilation tubing system;

a respiratory mechanics calculation module that generates a leak-compensated lung compliance and a leak-compensated lung resistance based on the leakage and at least one output indicative of a pressure of the breathing gas; and

a proportional assistance ventilation module that causes the pressure generating system to provide ventilation to the patient based on patient effort and a support setting, wherein the patient effort is determined from the leakage, the leak-compensated lung compliance and the leak-compensated lung resistance.

2. The system of claim 1 wherein the respiratory mechanics module is a static respiratory mechanics module that uses a static respiratory mechanics model to determine a leak-compensated static lung compliance and a leak-compensated static lung resistance based on a leak-compensated lung flow and an output of at least one sensor.

3. The system of claim 1 wherein the respiratory mechanics module is a dynamic respiratory mechanics module that uses a dynamic respiratory mechanics model to determine at least one of a leak-compensated dynamic lung compliance and a leak-compensated dynamic lung resistance based on the leak-compensated lung flow and an output of at least one sensor.

4. The system of claim 1 wherein the leak estimation module further identifies an inelastic leakage in the ventilation tubing system and wherein the compensation module further generates the leak-compensated lung flow based on the inelastic leakage.

5. The system of claim 4 further comprising:

a pressure monitoring module that monitors at least one output of the one or more sensors and provides data indicative of the pressure of the breathing gas to the leak estimation module.

6. A controller for a medical ventilator comprising:

a microprocessor;

a module that compensates calculations of lung compliance and lung resistance based on an instantaneous elastic leakage of breathing gas from a variable orifice and an instantaneous inelastic leakage of breathing gas from a fixed orifice of a ventilation tubing system; and

a pressure generating module controlled by the microprocessor that provides proportional assist ventilation based on the compensated lung compliance and lung resistance.

7. The controller of claim 6 further comprising:

a leak estimation module that identifies the instantaneous inelastic leakage from the associated ventilation tubing system and the instantaneous elastic leakage from the associated ventilation tubing system.