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Bilodeaux J, Farooqi H, Osovskaya M, Sosa A, Wallbank A, Knudsen L, Sottile PD, Albers DJ, Smith BJ. Differential effects of two-hit models of acute and ventilator-induced lung injury on lung structure, function, and inflammation. Front Physiol 2023; 14:1217183. [PMID: 37565138 PMCID: PMC10410077 DOI: 10.3389/fphys.2023.1217183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/13/2023] [Indexed: 08/12/2023] Open
Abstract
Acute respiratory distress syndrome (ARDS) and acute lung injury have a diverse spectrum of causative factors including sepsis, aspiration of gastric contents, and near drowning. Clinical management of severe lung injury typically includes mechanical ventilation to maintain gas exchange which can lead to ventilator-induced lung injury (VILI). The cause of respiratory failure is acknowledged to affect the degree of lung inflammation, changes in lung structure, and the mechanical function of the injured lung. However, these differential effects of injury and the role of etiology in the structure-function relationship are not fully understood. To address this knowledge gap we caused lung injury with intratracheal hydrochloric acid (HCL) or endotoxin (LPS) 2 days prior to ventilation or with an injurious lavage (LAV) immediately prior to ventilation. These injury groups were then ventilated with high inspiratory pressures and positive end expiratory pressure (PEEP) = 0 cmH2O to cause VILI and model the clinical course of ARDS followed by supportive ventilation. The effects of injury were quantified using invasive lung function measurements recorded during PEEP ladders where the end-expiratory pressure was increased from 0 to 15 cm H2O and decreased back to 0 cmH2O in steps of 3 cmH2O. Design-based stereology was used to quantify the parenchymal structure of lungs air-inflated to 2, 5, and 10 cmH2O. Pro-inflammatory gene expression was measured with real-time quantitative polymerase chain reaction and alveolocapillary leak was estimated by measuring bronchoalveolar lavage protein content. The LAV group had small, stiff lungs that were recruitable at higher pressures, but did not demonstrate substantial inflammation. The LPS group showed septal swelling and high pro-inflammatory gene expression that was exacerbated by VILI. Despite widespread alveolar collapse, elastance in LPS was only modestly elevated above healthy mice (CTL) and there was no evidence of recruitability. The HCL group showed increased elastance and some recruitability, although to a lesser degree than LAV. Pro-inflammatory gene expression was elevated, but less than LPS, and the airspace dimensions were reduced. Taken together, those data highlight how different modes of injury, in combination with a 2nd hit of VILI, yield markedly different effects.
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Affiliation(s)
- Jill Bilodeaux
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
- Department of Microbiology, University of Colorado Denver/Anschutz Medical Campus, Aurora, Germany
| | - Huda Farooqi
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
| | - Maria Osovskaya
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
| | - Alexander Sosa
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
| | - Alison Wallbank
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
| | - Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Centre for Lung Research (DZL), Hannover, Germany
| | - Peter D. Sottile
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - David J. Albers
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
- Section of Informatics and Data Science, Department of Pediatrics, School of Medicine, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, United States
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, United States
- Section of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, United States
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Alsalaet J, Munahi BS, Al-Sabur R, Al-Saad M, Ali AK, Shari B A, Fadhil HA, Laftah RM, Ismael M. Laminar flowmeter for mechanical ventilator: Manufacturing challenge of Covid-19 pandemic. FLOW MEASUREMENT AND INSTRUMENTATION : FMI 2021; 82:102058. [PMID: 34611384 PMCID: PMC8484002 DOI: 10.1016/j.flowmeasinst.2021.102058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 09/13/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Abstract
The rapid and sudden attack of the covid-19 pandemic has emerged the urgent need for pulmonary resuscitation devices (ventilators). The airflow sensor is a main element in the ventilator. Sensing very low airflow rates is an essential requirement to meet the least significant bit of the analogue to digital converter included in the ventilator. This short communication describes the fabrication and test of five flow sensors using basic and the 3D printing techniques to overcome the severe challenge arising from the pandemic under strict quarantine. The principle of these five flow sensors is based on Fleisch pneumotachograph technology, which creates a pseudo-laminar flow within a bundle of capillary tubes. Amongst the five tested sensors, those fabricated by 3D printing technique were the most accurate and reliable. Results show that the 3D printed sensor of 33 trapezoidal capillary tubes and displaced pressure taps meet the requirement of sensing flowrates with less resistance to patient at exhalation and more linearity figure. The experimental data were correlated using a sophisticated MMF correlation with an R-squared factor of 0.9999 and a percentage error of 1.68%.
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Affiliation(s)
- Jaafar Alsalaet
- University of Basrah, Engineering College, Basrah, 61004, Iraq
| | - Basil Sh Munahi
- University of Basrah, Engineering College, Basrah, 61004, Iraq
| | - Raheem Al-Sabur
- University of Basrah, Engineering College, Basrah, 61004, Iraq
| | | | - Abdulbaki K Ali
- University of Basrah, Engineering College, Basrah, 61004, Iraq
| | | | | | - Rafil M Laftah
- University of Basrah, Engineering College, Basrah, 61004, Iraq
| | - Muneer Ismael
- University of Basrah, Engineering College, Basrah, 61004, Iraq
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Agrawal DK, Smith BJ, Sottile PD, Albers DJ. A Damaged-Informed Lung Ventilator Model for Ventilator Waveforms. Front Physiol 2021; 12:724046. [PMID: 34658911 PMCID: PMC8517122 DOI: 10.3389/fphys.2021.724046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 09/01/2021] [Indexed: 12/31/2022] Open
Abstract
Motivated by a desire to understand pulmonary physiology, scientists have developed physiological lung models of varying complexity. However, pathophysiology and interactions between human lungs and ventilators, e.g., ventilator-induced lung injury (VILI), present challenges for modeling efforts. This is because the real-world pressure and volume signals may be too complex for simple models to capture, and while complex models tend not to be estimable with clinical data, limiting clinical utility. To address this gap, in this manuscript we developed a new damaged-informed lung ventilator (DILV) model. This approach relies on mathematizing ventilator pressure and volume waveforms, including lung physiology, mechanical ventilation, and their interaction. The model begins with nominal waveforms and adds limited, clinically relevant, hypothesis-driven features to the waveform corresponding to pulmonary pathophysiology, patient-ventilator interaction, and ventilator settings. The DILV model parameters uniquely and reliably recapitulate these features while having enough flexibility to reproduce commonly observed variability in clinical (human) and laboratory (mouse) waveform data. We evaluate the proof-in-principle capabilities of our modeling approach by estimating 399 breaths collected for differently damaged lungs for tightly controlled measurements in mice and uncontrolled human intensive care unit data in the absence and presence of ventilator dyssynchrony. The cumulative value of mean squares error for the DILV model is, on average, ≈12 times less than the single compartment lung model for all the waveforms considered. Moreover, changes in the estimated parameters correctly correlate with known measures of lung physiology, including lung compliance as a baseline evaluation. Our long-term goal is to use the DILV model for clinical monitoring and research studies by providing high fidelity estimates of lung state and sources of VILI with an end goal of improving management of VILI and acute respiratory distress syndrome.
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Affiliation(s)
- Deepak K. Agrawal
- Department of Bioengineering, University of Colorado Denver|Anschutz Medical Campus, Aurora, CO, United States
- Section of Informatics and Data Science, Department of Pediatrics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver|Anschutz Medical Campus, Aurora, CO, United States
- Section of Pulmonary and Sleep Medicine, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Peter D. Sottile
- Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - David J. Albers
- Department of Bioengineering, University of Colorado Denver|Anschutz Medical Campus, Aurora, CO, United States
- Section of Informatics and Data Science, Department of Pediatrics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Biomedical Informatics, Columbia University, New York, NY, United States
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Bou Jawde S, Walkey AJ, Majumdar A, O'Connor GT, Smith BJ, Bates JHT, Lutchen KR, Suki B. Tracking respiratory mechanics around natural breathing rates via variable ventilation. Sci Rep 2020; 10:6722. [PMID: 32317734 PMCID: PMC7174375 DOI: 10.1038/s41598-020-63663-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/26/2020] [Indexed: 11/08/2022] Open
Abstract
Measuring respiratory resistance and elastance as a function of time, tidal volume, respiratory rate, and positive end-expiratory pressure can guide mechanical ventilation. However, current measurement techniques are limited since they are assessed intermittently at non-physiological frequencies or involve specialized equipment. To this end, we introduce ZVV, a practical approach to continuously track resistance and elastance during Variable Ventilation (VV), in which frequency and tidal volume vary from breath-to-breath. ZVV segments airway pressure and flow recordings into individual breaths, calculates resistance and elastance for each breath, bins them according to frequency or tidal volume and plots the results against bin means. ZVV's feasibility was assessed clinically in five human patients with acute lung injury, experimentally in five mice ventilated before and after lavage injury, and computationally using a viscoelastic respiratory model. ZVV provided continuous measurements in both settings, while the computational study revealed <2% estimation errors. Our findings support ZVV as a feasible technique to assess respiratory mechanics under physiological conditions. Additionally, in humans, ZVV detected a decrease in resistance and elastance with time by 12.8% and 6.2%, respectively, suggesting that VV can improve lung recruitment in some patients and can therefore potentially serve both as a dual diagnostic and therapeutic tool.
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Affiliation(s)
- Samer Bou Jawde
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Allan J Walkey
- Department of Medicine, Pulmonary, Allergy, Sleep, & Critical Care Medicine, Boston University, Boston, MA, USA
| | - Arnab Majumdar
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - George T O'Connor
- Department of Medicine, Pulmonary, Allergy, Sleep, & Critical Care Medicine, Boston University, Boston, MA, USA
| | - Bradford J Smith
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
| | - Jason H T Bates
- Pulmonary/Critical Care Division, University of Vermont, Burlington, VT, USA
| | - Kenneth R Lutchen
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, MA, USA.
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