Methods and systems for monitoring resistance and work of breathing for ventilator-dependent patients

Patent metadata

Field	Value
Publication number	US-10165966-B2
Application number	US-201414197486-A
Country	US
Kind code	B2
Filing date	Mar 5, 2014
Priority date	Mar 14, 2013
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

Methods for non-invasively and accurately estimating and monitoring resistance and work of breathing parameters from airway pressure and flow sensors attached to the ventilator-dependent patient using an adaptive mathematical model are provided. These methods are based on calculations using multiple parameters derived from the above-mentioned sensors. The resistance and work of breathing parameters are important for: assessing patient status and diagnosis, appropriately selecting treatment, assessing efficacy of treatment, and properly adjusting ventilatory support.

First claim

We claim:

1. A method comprising:
(a) non-invasively measuring pressure and flow data from a breathing circuit of an intubated patient;
(b) using the pressure and flow data from step (a), determining endotracheal pressure without an end-inspiratory pause and an end-expiratory pause; and
(c) using the endotracheal pressure determined from step (b), calculating estimated real-time airway resistance (R AW ), endotracheal tube resistance (R ETT ), and total resistance (R TOT ) values, wherein the estimated R AW value is calculated based on the estimated R ETT and R TOT values, and wherein the pressure and flow data include pressure measured at a wye-piece of the breathing circuit, pressure measured at a distal end of an endotracheal tube, and airway flow within the breathing circuit, wherein the R ETT value is calculated based on a difference in tracheal airway pressure and pressure measured at the wye-piece, and dividing the difference by flow rate;
determining whether the estimated R AW value or the estimated R ETT value is outside a predetermined R AW range or R ETT range, respectively; and
determining based upon the determination of whether the estimated R AW value or the estimated R ETT value is outside the predetermined R AW range or the predetermined R ETT range, respectively i) whether to administer bronchodilator therapy, ii) whether the endotracheal tube is obstructed, iii) whether to titrate bronchodilator treatment, (iv) how to titrate bronchodilator treatment, v) whether to titrate ventilatory support, or vi) how to titrate ventilator support.

2. The method of claim 1 , wherein the pressure measurement at the distal end of the endotracheal tube is performed using an endotracheal pressure cuff.

3. The method of claim 1 , wherein step (c) includes estimating the patient expiratory time constant (τ E ) to calculate estimated real-time R AW , R ETT , and R TOT values.

4. The method of claim 1 , wherein the patient is on assisted or spontaneous ventilation.

5. The method of claim 1 , further comprising calculating physiologic tracheal pressure P trach and estimating a patient expiratory time constant (τ E ), based on the physiologic tracheal pressure P trach , prior to calculating estimated real-time airway resistance (R AW ), endotracheal tube resistance (R ETT ), and total resistance (R TOT ) values.

6. The method of claim 1 , wherein breathing gas from a ventilator is supplied to and from the patient via a ventilator flow conduit having the endotracheal tube in fluid communication with the patient, wherein the conduit and the endotracheal tube include sensors, wherein the ventilator has a display and at least one setting control for controlling the breathing gas supplied to and from the patient, and wherein determining whether to administer the bronchodilator therapy to a patient on ventilator support further comprises:
(a) sensing the pressure of the breathing gas within the ventilator conduit and generating a pressure signal representative of that pressure;
(b) measuring the flow rate of the breathing gas within the ventilator conduit and generating a flow signal representative of that flow rate;
(c) measuring the pressure at the endotracheal tube and generating an intra-tracheal pressure signal representative of that pressure; and
(d) processing the pressure, flow rate and intra-tracheal pressure signal to determine the estimated R AW value.

7. The method of claim 1 , further comprising:
causing display of a recommendation i) whether to administer the bronchodilator therapy based upon the estimated R AW value being outside of the predetermined R AW range, ii) whether to check the endotracheal tube based upon the estimated R ETT value being outside of the predetermined R ETT range, iii) whether to titrate bronchodilator treatment, (iv) how to titrate bronchodilator treatment, v) whether to titrate ventilatory support, or vi) how to titrate ventilator support.

8. The method of claim 1 , further comprising:
providing a visual or audio alarm in response to i) determining that the bronchodilator therapy is to be administered, ii) that the endotracheal tube is obstructed, iii) determining to titrate bronchodilator treatment, (iv) how to titrate bronchodilator treatment, v) determining to titrate ventilatory support, or vi) how to titrate ventilator support.

9. The method of claim 1 , wherein breathing gas from a ventilator is supplied to and from the patient via a ventilator flow conduit having the endotracheal tube in fluid communication with the patient, wherein the conduit and the endotracheal tube include sensors, wherein the ventilator has a display and at least one setting control for controlling the breathing gas supplied to and from the patient, and wherein determining whether the endotracheal tube of an intubated patient on ventilator support is obstructed further comprises:
(a) sensing the pressure of the breathing gas within the ventilator conduit and generating a pressure signal representative of that pressure;
(b) measuring the flow rate of the breathing gas within the ventilator conduit and generating a flow signal representative of that flow rate;
(c) measuring the pressure at the endotracheal tube and generating an intra-tracheal pressure signal representative of that pressure; and
(d) processing the pressure, flow and intra-tracheal pressure signal to determine the estimated R ETT value.

10. A system comprising:
a ventilator conduit having an endotracheal tube, wherein the conduit and the endotracheal tube include sensors;
a user interface, one or more processors, and one or more non-transitory computer-readable media having computer-useable instructions embodied thereon that, when executed, causes the one or more processors of the system to:
(a) non-invasively measuring pressure and flow data from a breathing circuit of an intubated patient;
(b) using the pressure and flow data from step (a), determining endotracheal pressure without an end-inspiratory pause and an end-expiratory pause; and
(c) using the endotracheal pressure determined from step (b), calculating estimated real-time airway resistance (R AW ), endotracheal tube resistance (R ETT ), and total resistance (R TOT ) values, wherein the estimated R AW value is calculated based on the estimated R ETT and R TOT values, and wherein the pressure and flow data include pressure measured at a wye-piece of the breathing circuit, pressure measured at a distal end of the endotracheal tube, and airway flow within the breathing circuit, wherein the R ETT value is calculated based on a difference in tracheal airway pressure and pressure measured at the wye-piece, and dividing the difference by flow rate;

determine whether the estimated R AW value or the estimated R ETT value is outside a R AW range or R ETT range, respectively; and
determine based upon the determination of whether the estimated R AW value or the estimated R ETT value is outside the predetermined R AW range or the R ETT range, respectively i) whether to administer bronchodilator therapy, ii) whether the endotracheal tube is obstructed, iii) whether to titrate bronchodilator treatment, (iv) how to titrate bronchodilator treatment, v) whether to titrate ventilatory support, or vi) how to titrate ventilator support.

11. The system of claim 10 , wherein the pressure measurement at the distal end of the endotracheal tube is performed using an endotracheal pressure cuff.

12. The system of claim 10 , wherein step (c) includes estimating the patient expiratory time constant (τ E ) to calculate estimated real-time R AW , R ETT , and R TOT values.

13. The system of claim 10 , where

Assignees

• Univ Florida
• Convergent Eng Inc
• Univ Florida

Inventors

• Banner Michael J
• Euliano Neil Russell
• Gabrielli Andrea
• Al-Rawas Nawar Nazar Yousif

Classifications

• A61B5/087

  Measuring breath flow · CPC title

• A61M16/026

  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 title

• A61B5/085 Primary

  Measuring impedance of respiratory organs or lung elasticity · CPC title

• A61M16/0883

  Circuit type · CPC title

• A61B5/4836

  Diagnosis combined with treatment in closed-loop systems or methods (A61B5/0036 takes precedence) · CPC title