Tracheal sound parameters of respiratory cycle phases show differences between flow-limited and normal breathing during sleep

2010 ◽  
Vol 31 (3) ◽  
pp. 427-438 ◽  
Author(s):  
A Kulkas ◽  
E Huupponen ◽  
J Virkkala ◽  
A Saastamoinen ◽  
E Rauhala ◽  
...  
Keyword(s):  
Respiratory Cycle ◽  
Normal Breathing ◽  
Tracheal Sound

scholarly journals Using the Entropy of Tracheal Sounds to Detect Apnea during Sedation in Healthy Nonobese Volunteers

2013 ◽  
Vol 118 (6) ◽  
pp. 1341-1349 ◽  
Author(s):  
Lu Yu ◽  
Chien-Kun Ting ◽  
Bryce E. Hill ◽  
Joseph A. Orr ◽  
Lara M. Brewer ◽  
...  
Keyword(s):  
Flow Rate ◽  
Secondary Analysis ◽  
Acoustic Method ◽  
Central Apnea ◽  
Robust Method ◽  
Normal Breathing ◽  
Respiratory Flow ◽  
Tracheal Sound ◽  
Tracheal Sounds ◽  
Estimate Flow

Abstract Background: Undetected apnea can lead to severe hypoxia, bradycardia, and cardiac arrest. Tracheal sounds entropy has been proved to be a robust method for estimating respiratory flow, thus maybe a more reliable way to detect obstructive and central apnea during sedation. Methods: A secondary analysis of a previous pharmacodynamics study was conducted. Twenty volunteers received propofol and remifentinal until they became unresponsive to the insertion of a bougie into the esophagus. Respiratory flow rate and tracheal sounds were recorded using a pneumotachometer and a microphone. The logarithm of the tracheal sound Shannon entropy (Log-E) was calculated to estimate flow rate. An adaptive Log-E threshold was used to distinguish between the presence of normal breath and apnea. Apnea detected from tracheal sounds was compared to the apnea detected from respiratory flow rate. Results: The volunteers stopped breathing for 15 s or longer (apnea) 322 times during the 12.9-h study. Apnea was correctly detected 310 times from both the tracheal sounds and the respiratory flow. Periods of apnea were not detected by the tracheal sounds 12 times. The absence of tracheal sounds was falsely detected as apnea 89 times. Normal breathing was detected correctly 1,196 times. The acoustic method detected obstructive and central apnea in sedated volunteers with 95% sensitivity and 92% specificity. Conclusions: We found that the entropy of the acoustic signal from a microphone placed over the trachea may reliably provide an early warning of the onset of obstructive and central apnea in volunteers under sedation.

Intelligent methods for identifying respiratory cycle phases from tracheal sound signal during sleep

2009 ◽  
Vol 39 (11) ◽  
pp. 1000-1005 ◽  
Author(s):  
A. Kulkas ◽  
E. Huupponen ◽  
J. Virkkala ◽  
M. Tenhunen ◽  
A. Saastamoinen ◽  
...  
Keyword(s):  
Sound Signal ◽  
Respiratory Cycle ◽  
Tracheal Sound ◽  
Intelligent Methods

scholarly journals Modeling of aerosol transmission of airborne pathogens in ICU rooms of COVID-19 patients with acute respiratory failure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cyril Crawford ◽  
Emmanuel Vanoli ◽  
Baptiste Decorde ◽  
Maxime Lancelot ◽  
Camille Duprat ◽  
...  
Keyword(s):  
Ventilation System ◽  
Medical Personnel ◽  
Airborne Particles ◽  
Proof Of Concept ◽  
Dynamics Model ◽  
Treatment Unit ◽  
Normal Breathing ◽  
Air Flows ◽  
Boltzmann Method ◽  
Number Of Particles

AbstractThe COVID-19 pandemic has generated many concerns about cross-contamination risks, particularly in hospital settings and Intensive Care Units (ICU). Virus-laden aerosols produced by infected patients can propagate throughout ventilated rooms and put medical personnel entering them at risk. Experimental results found with a schlieren optical method have shown that the air flows generated by a cough and normal breathing were modified by the oxygenation technique used, especially when using High Flow Nasal Canulae, increasing the shedding of potentially infectious airborne particles. This study also uses a 3D Computational Fluid Dynamics model based on a Lattice Boltzmann Method to simulate the air flows as well as the movement of numerous airborne particles produced by a patient’s cough within an ICU room under negative pressure. The effects of different mitigation scenarii on the amount of aerosols potentially containing SARS-CoV-2 that are extracted through the ventilation system are investigated. Numerical results indicate that adequate bed orientation and additional air treatment unit positioning can increase by 40% the number of particles extracted and decrease by 25% the amount of particles deposited on surfaces 45s after shedding. This approach could help lay the grounds for a more comprehensive way to tackle contamination risks in hospitals, as the model can be seen as a proof of concept and be adapted to any room configuration.

scholarly journals Impact of artificial airway resistances on regional ventilation distribution during airway closure

2020 ◽  
Vol 6 (3) ◽  
pp. 32-35
Author(s):  
Melanie März ◽  
Sarah Howe ◽  
Bernhard Laufer ◽  
Knut Moeller ◽  
Sabine Krueger-Ziolek
Keyword(s):  
Pulmonary Function ◽  
Airway Resistance ◽  
Airway Closure ◽  
Ventilation Distribution ◽  
Regional Ventilation ◽  
Impedance Tomography ◽  
Artificial Airway ◽  
Normal Breathing ◽  
Airway Obstructions ◽  
Forced Breathing

AbstractElectrical impedance tomography (EIT), a noninvasive and radiation-free imaging technique can be used in pulmonary function monitoring for determining regional ventilation distribution within the lung. Gold standard in pulmonary function monitoring is spirometry/body plethysmography, a method using forced breathing maneuvers to obtain global lung function parameters. However, this method is heavily dependent on the cooperation of the patients. Within this observational study, a method under normal breathing was tested with 5 healthy volunteers, which provides regional information about ventilation distribution. The occlusion method Rocc, a method for determining airway resistance, was used to create a short-term airway closure. Regional ventilation during the airway closure was examined with EIT. Simultaneously four different artificial airway resistances were used to simulate airway obstructions. Results show that EIT in combination with the ROcc method is suitable for the detection of regional differences in ventilation during airway closure for all four artificial airway resistances. Although the sum of relative impedances at the end of the shutter maneuver are smaller (nearly -0.100 AU) for the airway resistances Ø 12.5 mm, Ø 10.5 mm and Ø 9.5 mm than for the smallest one with Ø 30.0 mm (~ -0.070 AU), the changes in impedance from the start to the end of the shutter maneuver differs only slightly between the four artificial airway resistances. All impedance changes are in the range of 0.100 to 0.130 AU. The combination of EIT and the ROcc method provides not only global parameters such as airway resistance under normal breathing conditions, but also results of regional ventilation, which could enable the identification of areas affected by airway obstructions. However, the obtained results indicate that EIT might be a useful tool in the diagnosis and follow-up of obstructive lung diseases.

Relative tidal volume and respiratory airflow estimation using tracheal sound and movement during sleep

2021 ◽  
Author(s):  
Nasim Montazeri Ghahjaverestan ◽  
Muammar M. Kabir ◽  
Shumit Saha ◽  
Bojan Gavrilovic ◽  
Kaiyin Zhu ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Tracheal Sound ◽  
Respiratory Airflow

scholarly journals Diagnostic characteristics of 11 formulae for calculating corrected flow time as measured by a wearable Doppler patch

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Jon-Émile S. Kenny ◽  
Igor Barjaktarevic ◽  
David C. Mackenzie ◽  
Andrew M. Eibl ◽  
Matthew Parrotta ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Sensitivity And Specificity ◽  
Doppler Ultrasound ◽  
Flow Time ◽  
Cardiac Preload ◽  
Respiratory Cycle ◽  
Quiet Breathing ◽  
Diagnostic Characteristics ◽  
Corrected Flow Time ◽  
Corrected Flow

Abstract Background Change of the corrected flow time (Ftc) is a surrogate for tracking stroke volume (SV) in the intensive care unit. Multiple Ftc equations have been proposed; many have not had their diagnostic characteristics for detecting SV change reported. Further, little is known about the inherent Ftc variability induced by the respiratory cycle. Materials and methods Using a wearable Doppler ultrasound patch, we studied the clinical performance of 11 Ftc equations to detect a 10% change in SV measured by non-invasive pulse contour analysis; 26 healthy volunteers performed a standardized cardiac preload modifying maneuver. Results One hundred changes in cardiac preload and 3890 carotid beats were analyzed. Most of the 11 Ftc equations studied had similar diagnostic attributes. Wodeys’ and Chambers’ formulae had identical results; a 2% change in Ftc detected a 10% change in SV with a sensitivity and specificity of 96% and 93%, respectively. Similarly, a 3% change in Ftc calculated by Bazett’s formula displayed a sensitivity and specificity of 91% and 93%. FtcWodey had 100% concordance and an R2 of 0.75 with change in SV; these values were 99%, 0.76 and 98%, 0.71 for FtcChambers and FtcBazetts, respectively. As an exploratory analysis, we studied 3335 carotid beats for the dispersion of Ftc during quiet breathing using the equations of Wodey and Bazett. The coefficient of variation of Ftc during quiet breathing for these formulae were 0.06 and 0.07, respectively. Conclusions Most of the 11 different equations used to calculate carotid artery Ftc from a wearable Doppler ultrasound patch had similar thresholds and abilities to detect SV change in healthy volunteers. Variation in Ftc induced by the respiratory cycle is important; measuring a clinically significant change in Ftc with statistical confidence requires a large sample of beats.

Detection Latency of Added Loads to Breathing

1982 ◽  
Vol 63 (1) ◽  
pp. 11-15 ◽  
Author(s):  
J. G. W. Burdon ◽  
K. J. Killian ◽  
E. J. M. Campbell
Keyword(s):  
Peak Inspiratory Pressure ◽  
Normal Subjects ◽  
Reciprocal Relationship ◽  
Respiratory Cycle ◽  
Curvilinear Relationship ◽  
Similar Relationship ◽  
Detection Latency ◽  
Mechanical Information ◽  
Resistive Loads ◽  
Comparable Magnitude

1. Detection latency of a range of added elastic (0·95–4·50 kPa/l) and resistive (0·73–3·29 kPa l−1 s) loads to breathing were measured in five normal subjects. Detection latency was defined as the time from the onset of the breath to detection of the load. 2. Detection latency followed a curvilinear relationship when plotted as a function of the magnitude of the added loads. A similar relationship was found with both elastic and resistive loads although detection latencies to added elastances were longer than for added resistances. 3. When the added load was expressed in terms of comparable magnitude (peak inspiratory pressure) detection latencies for added elastances were found to be consistently longer than for added resistive loads. 4. These studies show that the detection latency to added inspiratory loads follows a reciprocal relationship, that detection latencies for elastic and resistive loads are clearly different and suggest that these loads are detected during the respiratory cycle at a time when the mechanical information regarding muscular pressure is greatest.

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