US-12616813-B2 - Pendelluft detection by acoustic interferometry through an endotracheal tube

Abstract

A respiratory monitoring device includes an electronic controller configured to: analyze an audio signal triggered during inspiratory and expiratory phases of a patient receiving mechanical ventilation therapy from a mechanical ventilator, the audio signal being acoustically coupled into the airway of the patient, to determine resonant frequencies of the airway; determine a shift in the resonant frequencies between the inspiratory and expiratory phases to determine a presence of pendelluft inside of a lung of the patient; and output an indication of the presence of pendelluft.

Inventors

• Rafael Wiemker
• Stefan Winter
• KIRAN HAMILTON J. DELLIMORE
• Joerg Sabczynski
• Thomas Koehler
• Cornelis Petrus HENDRIKS
• ROBERTO BUIZZA
• Jaap Roger Haartsen
• MICHAEL POLKEY
• RITA PRIORI
• Nataly Wieberneit

Assignees

• KONINKLIJKE PHILIPS N.V.

Dates

Publication Date

20260505

Application Date

20220829

Claims (16)

1. 1 . A respiratory monitoring device comprising an electronic controller configured to: analyze an audio signal triggered during inspiratory and expiratory phases of a patient receiving mechanical ventilation therapy from a mechanical ventilator, the audio signal being acoustically coupled into the airway of the patient, to determine resonant frequencies of the airway; determine a shift between a resonant frequency at the inspiratory phase and a resonant frequency at the expiratory phase; and if there is a diminishment of the shift between the resonant frequency at the inspiratory phase and the resonant frequency at the expiratory phase, output an indication of the presence of pendelluft inside a lung of the patient.
2. 2 . The device of claim 1 , wherein the electronic controller is configured to determine the shift in the resonant frequencies between the inspiratory and expiratory phases by: measuring a cross-correlation or a cross-entropy of the resonant frequencies between the inspiratory and expiratory phases.
3. 3 . The device of claim 1 , wherein the electronic controller is configured to determine the shift in the resonant frequencies between the inspiratory and expiratory phases by: implementing a trained artificial neural network (ANN) to detect and quantify the presence of pendelluft.
4. 4 . The device of claim 1 , wherein the electronic controller is further configured to: provide feedback to a user to validate a setup of the mechanical ventilator when a result of analyzing the audio signal is ambiguous or atypical.
5. 5 . The device of claim 1 , further comprising a display device, wherein the electronic controller is configured to output the indication of the presence of pendelluft by: displaying the indication of the presence of pendelluft on the display device.
6. 6 . The device of claim 1 , further comprising a loudspeaker, wherein the electronic controller is configured to: output the indication of the presence of pendelluft via the loudspeaker.
7. 7 . The device of claim 1 , wherein the mechanical ventilation therapy is delivered by an endotracheal tube (ETT), and the device further includes: an audio transducer attached to a portion of the ETT not disposed within the trachea, the audio transducer configured to generate the audio signal acoustically coupled with the ETT.
8. 8 . The device of claim 7 , further including: a microphone acoustically coupled with the ETT and configured to receive the audio signal.
9. 9 . The device of claim 1 , wherein the electronic controller is configured to analyze the audio signal to determine the resonant frequencies of the audio signal in a range of 100 Hz-5 kHz.
10. 10 . The device of claim 1 , wherein the audio signal comprises a chirp signal.
11. 11 . A respiratory therapy device, comprising: a mechanical ventilator configured to deliver mechanical ventilation therapy to a patient; and a respiratory monitoring device as set forth in claim 1 .
12. 12 . The respiratory therapy device of claim 11 , wherein the at least one electronic controller of the respiratory monitoring device is further configured to: control the mechanical ventilator to adjust one or more parameters of the mechanical ventilation therapy delivered to the patient in response to the indication of the presence of pendelluft.
13. 13 . A respiratory monitoring method, comprising, with an electronic controller: analyzing an audio signal triggered during inspiratory and expiratory phases of a patient receiving mechanical ventilation therapy from a mechanical ventilator, the audio signal being acoustically coupled into the airway of the patient, to determine resonant frequencies of the airway; determining a shift between a resonant frequency at the inspiratory phase and a resonant frequency at the expiratory phase; and if there is a diminishment of the shift between the resonant frequency at the inspiratory phase and the resonant frequency at the expiratory phase, outputting an indication of the presence of pendelluft inside of a lung of the patient.
14. 14 . The method of claim 13 , wherein determining the shift in the resonant frequencies between the inspiratory and expiratory phases includes: measuring a cross-correlation or a cross-entropy of the resonant frequencies between the inspiratory and expiratory phases.
15. 15 . The method of claim 13 , wherein determining the shift in the resonant frequencies between the inspiratory and expiratory phases includes: implementing a trained artificial neural network (ANN) to detect and quantify the presence of pendelluft.
16. 16 . A respiratory monitoring device comprising an electronic controller configured to: analyze an audio signal triggered during inspiratory and expiratory phases of a patient receiving mechanical ventilation therapy from a mechanical ventilator, the audio signal being acoustically coupled into the airway of the patient, to determine resonant frequencies of the airway; determine a shift between a resonant frequency at the inspiratory phase and a resonant frequency at the expiratory phase; detect a presence of pendelluft inside of a lung of the patient as a diminishment of the shift between the resonant frequency at the inspiratory phase and the resonant frequency at the expiratory phase; and output an indication of the presence of pendelluft.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63/248,678, filed on Sep. 27, 2021, the contents of which are herein incorporated by reference. The following relates generally to the respiratory therapy arts, tracheal intubation arts, airway acoustic monitoring arts, pendelluft detection arts, and related arts. BACKGROUND Mechanical ventilation (MV) of a patient typically entails placement of an endotracheal tube (ETT) into a trachea of the patient, in a process known as tracheal intubation. The desired position of the tip of an ETT is approximately 5.0 cm (±2.0 cm) above a carina (i.e., a location where the trachea splits into the main right and left bronchus). Tracheal intubation is usually performed by an anesthesiologist or other qualified medical professional, and in a common sequence the head is moved backward to access the airway, and a laryngoscope is used to facilitate proper placement of the ETT between the vocal cords and into the trachea, without misplacement into the esophagus. Common situations where mechanical ventilation is required can include intensive care unit (ICU) cases and during major surgery. Such patients often have images (e.g., computed tomography (CT) images) obtained of the thorax before being sent to the ICU, in particular if the patient's condition is a lung-related disease (e.g., Covid-19), or trauma. An example of a condition that can lead to ventilation-induced lung injury (VILI) associated with assisted MV is the development of “pendelluft”. Pendelluft is defined as oscillatory gas movement inside the lung, for example involving the displacement of gas from a more recruited non-dependent (ND) or “faster” lung region to a less recruited dependent (D) or “slower” lung region with minimal changes in the tidal volume (TV) of the ventilator (see, e.g., Enokidani et al. Effects of ventilatory settings on pendelluft phenomenon during mechanical ventilation. Resp Care 2021; 66(1):1-10). Pendelluft may cause lung overstretching, tidal recruitment, and inflammation, due to over-inflation in the D lung region and collapse in the ND lung region. Since pendelluft develops without changes in VT of the ventilator, it is challenging for clinicians to recognize its presence via ordinary monitoring during MV. Early detection of pendelluft is important so that the treatment and/or ventilation strategies can be adjusted to ensure patient safety and better clinical outcomes. However, there is currently no widely accepted standard test to confirm the presence of pendelluft. The most commonly reported diagnostic approach relies on electrical impedance tomography (EIT) (see, e.g., Coppadoro A. et al. Occurrence of pendelluft under pressure support ventilation in patients who failed a spontaneous breathing trial: an observational study. Ann Intensive Care (2020) 10:39; Sang L. et al. Qualitative and quantitative assessment of pendelluft: a simple method based on electrical impedance tomography. Ann Transl Med 2020; 8(19):1216), although other imaging techniques are sometimes used. Pathological alterations in lungs can be observed by computed tomography (CT), magnetic resonance imaging (MM), pulmonary ultrasound, and positron emission tomography (PET). CT and MRI can provide indirect information on regional time constants, while PET can be used to capture the clearance of the tracer nitrogen-13 which can be used to calculate the pendelluft (see, e.g., Musch G, Venegas JG. Positron emission tomography imaging of regional pulmonary perfusion and ventilation. Proc Am Thorac Soc. 2005; 2(6):522-509). However, with the exception of ultrasound these non-EIT based approaches are all unsuitable for real-time, semi-continuous, diagnosis of pendelluft at the bedside. One example of an EIT-based approach for detecting pendelluft, described by Coppadoro et al., is to analyze global and regional EIT traces and ventilator waveforms, to determine if there is a phase-shift of the regional EIT signal compared to the global signal in two distinct time-periods: before and after the transition point from expiration to inspiration (To). Before T0, the lung is still expiring and tracheal airflow is directed outward; regions of interest (ROIs) inflating during expiration must gain gas from other ROIs that are deflating, indicating the pendelluft phenomenon. Conversely, after T0 tracheal airflow is directed inward, and gas lost by late-deflating ROIs must be gained from the other ROIs that are inflating, indicating the pendelluft phenomenon as well. Although EIT-based approaches are often used to detect pendelluft, they still have some drawbacks and limitations. Many approaches rely on comparing impedance-time curves from different ROIs, which is time-consuming and may miss the pendelluft depending on the division of ROIs. Another drawback is that many EIT-based techniques require an interruption of normal ventilation