Accuracy of the Ventilator Automated Displayed Respiratory Mechanics in Passive and Active Breathing Conditions: A Bench Study

Daoud, Ehab; Katigbak, Reynaldo; Ottochian, Marcus

doi:10.4187/respcare.06422

Cited by 13 publications

(12 citation statements)

References 20 publications

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“…Another way of breath-to-breath automatic calculation of the dynamic respiratory mechanics (compliance, resistance, and auto-PEEP) without the need for any pause maneuvers is termed the least square fitting method, which uses regression analysis of the airway pressure, flow, and volume curves and applies it to the equation of motion (below). Those measurements are available in many new-generation ventilators [ 24 ]; however, those calculations might not be accurate in the actively breathing patient compared with the passive patient with no effort given the unknown value of the Pmus ( Table 1 , Equation 3).…”

Section: Clinical Usementioning

confidence: 99%

Go with the flow—clinical importance of flow curves during mechanical ventilation: A narrative review

2020

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Most clinicians pay attention to tidal volume and airway pressures and their curves during mechanical ventilation. On the other hand, inspiratory-expiratory flow curves also provide a plethora of information, but much less attention is paid to them. Flow curves chronologically show the velocity and direction of inspiration and expiration and are influenced by the respiratory mechanics, the patient's effort, and the mode of ventilation and its settings. When the ventilator setting does not synchronize with the patient's respiratory pattern, the patient can easily have worsening breathing effort, patient-ventilator asynchrony, which can lead to prolonged ventilator support or lung injury. The information provided by the flow curves during mechanical ventilation, such as respiratory mechanics, the patient's effort, and patient-ventilator interactions, are very helpful when adjusting the ventilator setting. If clinicians can monitor and assess the flow curves information appropriately, it can be a useful diagnostic and therapeutic tool at the bedside. There may be association between inspiratory effort and flow, and this may further guide us, especially in the weaning process and when patients are not synchronizing with the ventilator. In this review, we try to gather information about "flow" that is scattered around in the literature and textbooks in one place. We will summarize the different flow waveforms utilized in commonly used ventilator modes with their advantages and disadvantages, information gained by the flow curves (i.e., flow-time, flow-volume, and flow-pressure), how to detect and manage asynchronies, and some ideas for future uses. Flow waveforms shapes and patterns are very beneficial for the management of patients undergoing mechanical ventilatory support. Attention to those waveforms can potentially improve patient outcomes. Clinicians should be familiar with this information and how to act upon them.

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Section: Clinical Usementioning

confidence: 99%

Go with the flow—clinical importance of flow curves during mechanical ventilation: A narrative review

2020

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“…Daoud et al ( 12 ) evaluated the accuracy of the lung mechanics measurements displayed by the mechanical ventilator using the least squares method, which uses the equation of motion together with pressure, volume and flow data, to estimate lung compliance and resistance. The authors observed that these values are not reliable, especially during active breathing, as they overestimate compliance and underestimate resistance.…”

Section: Discussionmentioning

confidence: 99%

“…The authors observed that these values are not reliable, especially during active breathing, as they overestimate compliance and underestimate resistance. The use of occlusion at the end of inspiration when performing these measurements was selected because this technique is easy and fast to perform in clinical practice; ( 12 ) thus, this technique was used in all measurements performed in the present study to ensure the nonoccurrence of measurement bias.…”

Section: Discussionmentioning

confidence: 99%

Reproducibility of respiratory mechanics measurements in patients on invasive mechanical ventilation

Júnior¹,

Silva²,

Santos

et al. 2020

Revista Brasileira De Terapia Intensiva

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Objective To evaluate the intra- and interexaminer reproducibility of measurements of the resistance and static and dynamic compliance of the respiratory system in patients on mechanical ventilation. Methods This was an analytical study conducted with individuals aged ≥ 18 years who were on invasive mechanical ventilation and had no clinical diagnosis of respiratory system disease and/or chest abnormality. Three measurements of respiratory mechanics were performed with a 1-minute interval between them. The first and third measurements were performed by examiner A, the second by examiner B. The values for the resistance and static and dynamic compliance of the respiratory system were compared using the intraclass correlation coefficient. Results A total of 198 measurements of respiratory mechanics were performed for 66 patients on mechanical ventilation. The patients had a mean age of 52.6 ± 18.6 years and a mean body mass index of 21.6 ± 2.1kg/m 2 ; a surgical profile (61.5%) and female sex (53.8%) were predominant. Mean values were obtained for the three measurements of respiratory system resistance (A1: 15.7 ± 6.8cmH 2 O/L/s; B1: 15.7 ± 6.4cmH 2 O/L/s and A2: 15.9 ± 6.2cmH 2 O/L/s), respiratory system static compliance (A1: 42.1 ± 13.7mL/cmH 2 O; B1: 42.4 ± 14.6mL/cmH 2 O and A2: 42.2 ± 14.5mL/cmH 2 O) and respiratory system dynamic compliance (A1: 21.3 ± 7.3mL/cmH 2 O; B1: 21.4 ± 7.5mL/cmH 2 O and A2: 21.3 ± 6.2mL/cmH 2 O). The intraclass correlation coefficient was also calculated for respiratory system resistance (R = 0.882 and p = 0.001; R = 0.949 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.932 and p = 0.001 - intraexaminer); respiratory system static compliance (R = 0.951 and p = 0.001; R = 0.958 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.965 and p = 0.001 - intraexaminer) and respiratory system dynamic compliance (R = 0.957 and p = 0.001; R = 0.946 and p = 0.001 - interexaminer A1 versus B and B versus A2, respectively; R = 0.926 and p = 0.001 - intraexaminer). Conclusion The measurements of resistance and static and dynamic compliance of the respiratory system show good intra- and interexaminer reproducibility for ventilated patients.

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“…To mimic representative ICU patients [ 9 ], the performance of the device was tested using the ASL 5000 lung model (Ingmar Medical, Pittsburgh, PA, USA). Standard ventilator circuits (Intersurgical ® , ntersurgical Ltd., Berkshire, UK) and heat-and-moisture exchangers (HEPA Light Isogard ® , Gibeck, Gibeck® Iso-Gard HEPA light, Teleflex Inc., Morrisville, NC, USA) were used.…”

Section: Evaluation Protocolmentioning

confidence: 99%

The eSpiro Ventilator: An Open-Source Response to a Worldwide Pandemic

Terzi

Rastello

Déhan

et al. 2021

JCM

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Objective: To address the issue of ventilator shortages, our group (eSpiro Network) developed a freely replicable, open-source hardware ventilator. Design: We performed a bench study. Setting: Dedicated research room as part of an ICU affiliated to a university hospital. Subjects: We set the lung model with three conditions of resistance and linear compliance for mimicking different respiratory mechanics of representative intensive care unit (ICU) patients. Interventions: The performance of the device was tested using the ASL5000 lung model. Measurements and Main Results: Twenty-seven conditions were tested. All the measurements fell within the ±10% limits for the tidal volume (VT). The volume error was influenced by the mechanical condition (p = 5.9 × 10−15) and the PEEP level (P = 1.1 × 10−12) but the clinical significance of this finding is likely meaningless (maximum −34 mL in the error). The PEEP error was not influenced by the mechanical condition (p = 0.25). Our experimental results demonstrate that the eSpiro ventilator is reliable to deliver VT and PEEP accurately in various respiratory mechanics conditions. Conclusions: We report a low-cost, easy-to-build ventilator, which is reliable to deliver VT and PEEP in passive invasive mechanical ventilation.

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Accuracy of the Ventilator Automated Displayed Respiratory Mechanics in Passive and Active Breathing Conditions: A Bench Study

Cited by 13 publications

References 20 publications

Go with the flow—clinical importance of flow curves during mechanical ventilation: A narrative review

Go with the flow—clinical importance of flow curves during mechanical ventilation: A narrative review

Reproducibility of respiratory mechanics measurements in patients on invasive mechanical ventilation

The eSpiro Ventilator: An Open-Source Response to a Worldwide Pandemic

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