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Hannon DM, Jones T, Conolly J, Judge C, Iqbal T, Shahzad A, Madden M, Kirrane F, Conneely P, Harte BH, O'Halloran M, Laffey JG. Development and assessment of the performance of a shared ventilatory system that uses clinically available components to individualize tidal volumes. BMC Anesthesiol 2023; 23:239. [PMID: 37454135 PMCID: PMC10349497 DOI: 10.1186/s12871-023-02200-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023] Open
Abstract
OBJECTIVES To develop and assess a system for shared ventilation using clinically available components to individualize tidal volumes. DESIGN Evaluation and in vitro validation study SETTING: Ventilator shortage during the SARS-CoV-2 pandemic. PARTICIPANTS The team consisted of physicians, bioengineers, computer programmers, and medical technology professionals. METHODS Using clinically available components, a system of ventilation consisting of two ventilatory limbs was assembled and connected to a ventilator. Monitors for each limb were developed using open-source software. Firstly, the effect of altering ventilator settings on tidal volumes delivered to each limb was determined. Secondly, the impact of altering the compliance and resistance of one limb on the tidal volumes delivered to both limbs was analysed. Experiments were repeated three times to determine system variability. RESULTS The system permitted accurate and reproducible titration of tidal volumes to each limb over a range of ventilator settings and simulated lung conditions. Alteration of ventilator inspiratory pressures, of respiratory rates, and I:E ratio resulted in very similar tidal volumes delivered to each limb. Alteration of compliance and resistance in one limb resulted in reproducible alterations in tidal volume to that test lung, with little change to tidal volumes in the other lung. All tidal volumes delivered were reproducible. CONCLUSIONS We demonstrate the reliability of a shared ventilation system assembled using commonly available clinical components that allows titration of individual tidal volumes. This system may be useful as a strategy of last resort for Covid-19, or other mass casualty situations, where the need for ventilators exceeds supply.
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Affiliation(s)
- David M Hannon
- Department of Anaesthesia, School of Medicine, Galway University Hospitals, University of Galway, Galway, Ireland
- Translational Medical Device Lab, University of Galway, Galway, Ireland
| | - Tim Jones
- Translational Medical Device Lab, University of Galway, Galway, Ireland
| | - Jack Conolly
- Translational Medical Device Lab, University of Galway, Galway, Ireland
| | - Conor Judge
- Translational Medical Device Lab, University of Galway, Galway, Ireland
| | - Talha Iqbal
- Smart Sensors Lab, School of Medicine, University of Galway, Galway, Ireland
| | - Atif Shahzad
- Smart Sensors Lab, School of Medicine, University of Galway, Galway, Ireland
| | - Michael Madden
- School of Computer Science, National University of Ireland Galway, Galway, Ireland
| | - Frank Kirrane
- Department of Medical Physics and Clinical Engineering, Galway University Hospitals, Galway, Ireland
| | - Peter Conneely
- Department of Medical Physics and Clinical Engineering, Galway University Hospitals, Galway, Ireland
| | - Brian H Harte
- Department of Anaesthesia, School of Medicine, Galway University Hospitals, University of Galway, Galway, Ireland
| | - Martin O'Halloran
- Translational Medical Device Lab, University of Galway, Galway, Ireland
- CÚRAM Centre for Research in Medical Devices, Biomedical Sciences Building, University of Galway, Galway, Ireland
| | - John G Laffey
- Department of Anaesthesia, School of Medicine, Galway University Hospitals, University of Galway, Galway, Ireland.
- Translational Medical Device Lab, University of Galway, Galway, Ireland.
- CÚRAM Centre for Research in Medical Devices, Biomedical Sciences Building, University of Galway, Galway, Ireland.
- School of Medicine, Clinical Sciences Institute, University of Galway, Galway, Ireland.
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Branson RD, Rodriquez D. COVID-19 Lessons Learned: Response to the Anticipated Ventilator Shortage. Respir Care 2023; 68:129-150. [PMID: 36566030 PMCID: PMC9993519 DOI: 10.4187/respcare.10676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Early in the COVID-19 pandemic predictions of a worldwide ventilator shortage prompted a worldwide search for solutions. The impetus for the scramble for ventilators was spurred on by inaccurate and often unrealistic predictions of ventilator requirements. Initial efforts looked simply at acquiring as many ventilators as possible from national and international sources. Ventilators from the Strategic National Stockpile were distributed to early hotspots in the Northeast and Northwest United States. In a triumph of emotion over logic, well-intended experts from other industries turned their time, talent, and treasure toward making a ventilator for the first time. Interest in shared ventilation (more than one patient per ventilator) was ignited by an ill-advised video on social media that ignored the principles of gas delivery in deference to social media notoriety. With shared ventilation, a number of groups mistook a physiologic problem for a plumbing problem. The United States government invoked the Defense Production Act to push automotive manufacturers to partner with existing ventilator manufacturers to speed production. The FDA granted emergency use authorization for "splitters" to allow shared ventilation as well as for ventilators and ancillary equipment. Rationing of ventilators was discussed in the lay press and medical literature but was never necessary in the US. Finally, planners realized that staff with expertise in providing mechanical ventilation were the most important shortage. Over 200,000 ventilators were purchased by the United States government, states, cities, health systems, and individuals. Most had little value in caring for patients with COVID-19 ARDS. This paper attempts to look at where miscalculations were made, with an eye toward what we can do better in the future.
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Affiliation(s)
- Richard D Branson
- Division of Trauma/Critical Care, Department of Surgery, University of Cincinnati, Cincinnati, Ohio.
| | - Dario Rodriquez
- Division of Trauma/Critical Care, Department of Surgery, University of Cincinnati, Cincinnati, Ohio; and Airman Biosciences Division, Airman Systems Directorate, Wright-Patterson Air Force Base, Dayton, Ohio
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3
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Hannon DM, Mistry S, Das A, Saffaran S, Laffey JG, Brook BS, Hardman JG, Bates DG. Modeling Mechanical Ventilation In Silico-Potential and Pitfalls. Semin Respir Crit Care Med 2022; 43:335-345. [PMID: 35451046 DOI: 10.1055/s-0042-1744446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Computer simulation offers a fresh approach to traditional medical research that is particularly well suited to investigating issues related to mechanical ventilation. Patients receiving mechanical ventilation are routinely monitored in great detail, providing extensive high-quality data-streams for model design and configuration. Models based on such data can incorporate very complex system dynamics that can be validated against patient responses for use as investigational surrogates. Crucially, simulation offers the potential to "look inside" the patient, allowing unimpeded access to all variables of interest. In contrast to trials on both animal models and human patients, in silico models are completely configurable and reproducible; for example, different ventilator settings can be applied to an identical virtual patient, or the same settings applied to different patients, to understand their mode of action and quantitatively compare their effectiveness. Here, we review progress on the mathematical modeling and computer simulation of human anatomy, physiology, and pathophysiology in the context of mechanical ventilation, with an emphasis on the clinical applications of this approach in various disease states. We present new results highlighting the link between model complexity and predictive capability, using data on the responses of individual patients with acute respiratory distress syndrome to changes in multiple ventilator settings. The current limitations and potential of in silico modeling are discussed from a clinical perspective, and future challenges and research directions highlighted.
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Affiliation(s)
- David M Hannon
- Anesthesia and Intensive Care Medicine, School of Medicine, NUI Galway, Ireland
| | - Sonal Mistry
- School of Engineering, University of Warwick, Coventry, United Kingdom
| | - Anup Das
- School of Engineering, University of Warwick, Coventry, United Kingdom
| | - Sina Saffaran
- Faculty of Engineering Science, University College London, London, United Kingdom
| | - John G Laffey
- Anesthesia and Intensive Care Medicine, School of Medicine, NUI Galway, Ireland
| | - Bindi S Brook
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Jonathan G Hardman
- Anesthesia and Critical Care, Injury Inflammation and Recovery Sciences, School of Medicine, University of Nottingham, Nottingham, United Kingdom.,Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom
| | - Declan G Bates
- School of Engineering, University of Warwick, Coventry, United Kingdom
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4
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Schauer SG, Naylor JF, April MD, Carius BM, Hudson IL. Analysis of the Effects of COVID-19 Mask Mandates on Hospital Resource Consumption and Mortality at the County Level. South Med J 2021; 114:597-602. [PMID: 34480194 PMCID: PMC8395971 DOI: 10.14423/smj.0000000000001294] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Coronavirus disease 2019 has continued to spread despite measures put in place to help slow the spread. It remains unclear which measures are effective. Data guiding policymakers on efficacy will help focus efforts. We found that mask orders were ineffective in slowing the spread of coronavirus disease 2019 at the county level. Supplemental digital content is available in the text. Coronavirus disease 2019 (COVID-19) threatens vulnerable patient populations, resulting in immense pressures at the local, regional, national, and international levels to contain the virus. Laboratory-based studies demonstrate that masks may offer benefit in reducing the spread of droplet-based illnesses, but few data are available to assess mask effects via executive order on a population basis. We assess the effects of a county-wide mask order on per-population mortality, intensive care unit (ICU) utilization, and ventilator utilization in Bexar County, Texas.
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Affiliation(s)
- Steven G Schauer
- From the US Army Institute of Surgical Research and the Brooke Army Medical Center, JBSA Fort Sam Houston, Texas, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, the Madigan Army Medical Center, Joint Base Lewis McChord, Washington, the 2nd Brigade Combat Team, 4th Infantry Division, Fort Carson, Colorado, and the 121st Field Hospital, Camp Humphreys, Republic of Korea
| | - Jason F Naylor
- From the US Army Institute of Surgical Research and the Brooke Army Medical Center, JBSA Fort Sam Houston, Texas, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, the Madigan Army Medical Center, Joint Base Lewis McChord, Washington, the 2nd Brigade Combat Team, 4th Infantry Division, Fort Carson, Colorado, and the 121st Field Hospital, Camp Humphreys, Republic of Korea
| | - Michael D April
- From the US Army Institute of Surgical Research and the Brooke Army Medical Center, JBSA Fort Sam Houston, Texas, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, the Madigan Army Medical Center, Joint Base Lewis McChord, Washington, the 2nd Brigade Combat Team, 4th Infantry Division, Fort Carson, Colorado, and the 121st Field Hospital, Camp Humphreys, Republic of Korea
| | - Brandon M Carius
- From the US Army Institute of Surgical Research and the Brooke Army Medical Center, JBSA Fort Sam Houston, Texas, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, the Madigan Army Medical Center, Joint Base Lewis McChord, Washington, the 2nd Brigade Combat Team, 4th Infantry Division, Fort Carson, Colorado, and the 121st Field Hospital, Camp Humphreys, Republic of Korea
| | - Ian L Hudson
- From the US Army Institute of Surgical Research and the Brooke Army Medical Center, JBSA Fort Sam Houston, Texas, the Uniformed Services University of the Health Sciences, Bethesda, Maryland, the Madigan Army Medical Center, Joint Base Lewis McChord, Washington, the 2nd Brigade Combat Team, 4th Infantry Division, Fort Carson, Colorado, and the 121st Field Hospital, Camp Humphreys, Republic of Korea
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5
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Krause M, Henderson A, Griner D, Rissland OS, Beard J, Bartels K. A Statewide Voluntary Movement Addressing the Shortage of Medical Supplies During the COVID-19 Pandemic. Am J Public Health 2021; 111:1595-1599. [PMID: 34436929 PMCID: PMC8589063 DOI: 10.2105/ajph.2021.306364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2021] [Indexed: 11/04/2022]
Abstract
During the COVID-19 pandemic, a shortage of personal protective equipment compromised efficient patient care and provider safety. Volunteers from many different backgrounds worked to meet these demands. Additive manufacturing, laser cutting, and alternative supply chains were used to produce, test, and deliver essential equipment for health care workers and first responders. Distributed equipment included ear guards, face shields, and masks. Contingent designs were created for powered air-purifying respirator hoods, filtered air pumps, intubation shields, and N95 masks.
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Affiliation(s)
- Martin Krause
- Martin Krause is with the Department of Anesthesiology, University of Colorado School of Medicine, Aurora. Andrew Henderson and Daniel Griner are with Inworks Innovation Initiative, College of Engineering, Design, and Computing, University of Colorado, Denver. Olivia S. Rissland is with the Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora. Jeremy Beard is with the Center for Engagement and Innovation, IDEA Lab, Red Rocks Community College, Lakewood, CO. Karsten Bartels is with the Department of Anesthesiology, University of Nebraska Medical Center, Omaha
| | - Andrew Henderson
- Martin Krause is with the Department of Anesthesiology, University of Colorado School of Medicine, Aurora. Andrew Henderson and Daniel Griner are with Inworks Innovation Initiative, College of Engineering, Design, and Computing, University of Colorado, Denver. Olivia S. Rissland is with the Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora. Jeremy Beard is with the Center for Engagement and Innovation, IDEA Lab, Red Rocks Community College, Lakewood, CO. Karsten Bartels is with the Department of Anesthesiology, University of Nebraska Medical Center, Omaha
| | - Daniel Griner
- Martin Krause is with the Department of Anesthesiology, University of Colorado School of Medicine, Aurora. Andrew Henderson and Daniel Griner are with Inworks Innovation Initiative, College of Engineering, Design, and Computing, University of Colorado, Denver. Olivia S. Rissland is with the Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora. Jeremy Beard is with the Center for Engagement and Innovation, IDEA Lab, Red Rocks Community College, Lakewood, CO. Karsten Bartels is with the Department of Anesthesiology, University of Nebraska Medical Center, Omaha
| | - Olivia S Rissland
- Martin Krause is with the Department of Anesthesiology, University of Colorado School of Medicine, Aurora. Andrew Henderson and Daniel Griner are with Inworks Innovation Initiative, College of Engineering, Design, and Computing, University of Colorado, Denver. Olivia S. Rissland is with the Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora. Jeremy Beard is with the Center for Engagement and Innovation, IDEA Lab, Red Rocks Community College, Lakewood, CO. Karsten Bartels is with the Department of Anesthesiology, University of Nebraska Medical Center, Omaha
| | - Jeremy Beard
- Martin Krause is with the Department of Anesthesiology, University of Colorado School of Medicine, Aurora. Andrew Henderson and Daniel Griner are with Inworks Innovation Initiative, College of Engineering, Design, and Computing, University of Colorado, Denver. Olivia S. Rissland is with the Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora. Jeremy Beard is with the Center for Engagement and Innovation, IDEA Lab, Red Rocks Community College, Lakewood, CO. Karsten Bartels is with the Department of Anesthesiology, University of Nebraska Medical Center, Omaha
| | - Karsten Bartels
- Martin Krause is with the Department of Anesthesiology, University of Colorado School of Medicine, Aurora. Andrew Henderson and Daniel Griner are with Inworks Innovation Initiative, College of Engineering, Design, and Computing, University of Colorado, Denver. Olivia S. Rissland is with the Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora. Jeremy Beard is with the Center for Engagement and Innovation, IDEA Lab, Red Rocks Community College, Lakewood, CO. Karsten Bartels is with the Department of Anesthesiology, University of Nebraska Medical Center, Omaha
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Sharing Mechanical Ventilator: In Vitro Evaluation of Circuit Cross-Flows and Patient Interactions. MEMBRANES 2021; 11:membranes11070547. [PMID: 34357197 PMCID: PMC8307053 DOI: 10.3390/membranes11070547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 07/15/2021] [Accepted: 07/15/2021] [Indexed: 12/31/2022]
Abstract
During the COVID-19 pandemic, a shortage of mechanical ventilators was reported and ventilator sharing between patients was proposed as an ultimate solution. Two lung simulators were ventilated by one anesthesia machine connected through two respiratory circuits and T-pieces. Five different combinations of compliances (30–50 mL × cmH2O−1) and resistances (5–20 cmH2O × L−1 × s−1) were tested. The ventilation setting was: pressure-controlled ventilation, positive end-expiratory pressure 15 cmH2O, inspiratory pressure 10 cmH2O, respiratory rate 20 bpm. Pressures and flows from all the circuit sections have been recorded and analyzed. Simulated patients with equal compliance and resistance received similar ventilation. Compliance reduction from 50 to 30 mL × cmH2O−1 decreased the tidal volume (VT) by 32% (418 ± 49 vs. 285 ± 17 mL). The resistance increase from 5 to 20 cmH2O × L−1 × s−1 decreased VT by 22% (425 ± 69 vs. 331 ± 51 mL). The maximal alveolar pressure was lower at higher compliance and resistance values and decreased linearly with the time constant (r² = 0.80, p < 0.001). The minimum alveolar pressure ranged from 15.5 ± 0.04 to 16.57 ± 0.04 cmH2O. Cross-flows between the simulated patients have been recorded in all the tested combinations, during both the inspiratory and expiratory phases. The simultaneous ventilation of two patients with one ventilator may be unable to match individual patient’s needs and has a high risk of cross-interference.
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7
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Sorg ME, Branson RD, Hatipoğlu U, Chatburn RL. Multiplex Ventilation: Solutions for Four Main Safety Problems. Respir Care 2021; 66:1074-1086. [PMID: 33906955 DOI: 10.4187/respcare.08749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The COVID-19 pandemic has led to an increased demand for mechanical ventilators and concerns of a ventilator shortage. Several groups have advocated for 1 ventilator to ventilate 2 or more patients in the event of such a shortage. However, differences in patient lung mechanics could make sharing a ventilator detrimental to both patients. Our previous study indicated failure to ventilate in 67% of simulations. The safety problems that must be solved include individual control of tidal volume (VT), individual measurement of VT, individualization of PEEP settings, and individual PEEP measurement. The purpose of this study was to evaluate potential solutions developed at our institution. METHODS Two separate lung simulators were ventilated with a modified multiplex circuit using pressure control ventilation. Parameters of the lung models used for simulations (resistance and compliance) were evidence-based from published studies. Individual circuit-modification devices were first evaluated for accuracy. Devices were an adjustable flow diverter valve, a prototype dual volume display, a PEEP valve, and a disposable PEEP display. Then the full modified multiplex circuit was assessed by ventilating 6 pairs of simulated patients with different lung models and attempting to equalize ventilation. Ventilation was considered equalized when VT and end-expiratory lung volume were within 10% for each simulation. RESULTS The adjustable flow diverter valve allowed volume adjustment to 1 patient without affecting the other. The average error of the dual volume display was -17%. The PEEP valves individualized PEEP, but the PEEP gauge error ranged from 17% to 41%. Using the multiplex circuit, ventilation was equalized regardless of differences in resistance or compliance, reversing the "failure modes" of our previous study. CONCLUSIONS The results of this simulation-based study indicate that devices for individual control and display of VT and PEEP are effective in extending the usability and potential patient safety of multiplex ventilation.
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Affiliation(s)
- Morgan E Sorg
- Cleveland Clinic, Cleveland, Ohio. Mr Branson is affiliated with the University of Cincinnati, Cincinnati, Ohio and is Editor-in-Chief of Respiratory Care.
| | - Richard D Branson
- Cleveland Clinic, Cleveland, Ohio. Mr Branson is affiliated with the University of Cincinnati, Cincinnati, Ohio and is Editor-in-Chief of Respiratory Care
| | - Umur Hatipoğlu
- Cleveland Clinic, Cleveland, Ohio. Mr Branson is affiliated with the University of Cincinnati, Cincinnati, Ohio and is Editor-in-Chief of Respiratory Care
| | - Robert L Chatburn
- Cleveland Clinic, Cleveland, Ohio. Mr Branson is affiliated with the University of Cincinnati, Cincinnati, Ohio and is Editor-in-Chief of Respiratory Care
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Abstract
COVID-19 resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in a pandemic of respiratory failure previously unencountered. Early in the pandemic, concentrated infections in high-density population cities threatened to overwhelm health systems, and ventilator shortages were predicted. An early proposed solution was the use of shared ventilation, or the use of a single ventilator to support ≥ 2 patients. Spurred by ill-conceived social media posts, the idea spread in the lay press. Prior to 2020, there were 7 publications on this topic. A year later, more than 40 publications have addressed the technical details for shared ventilation, clinical experience with shared ventilation, as well as the numerous limitations and ethics of the technique. This is a review of the literature regarding shared ventilation from peer-reviewed articles published in 2020.
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Affiliation(s)
- Richard D Branson
- Department of Surgery, Division of Trauma & Critical Care, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, Ohio.
| | - Dario Rodriquez
- Division of Trauma/Critical Care, Department of Surgery, University of Cincinnati, Cincinnati, Ohio
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Garcia Eijo PM, D’Adamo J, Bianchetti A, Duriez T, Cabaleiro JM, Irrazabal C, Otero P, Artana G. Exhalatory dynamic interactions between patients connected to a shared ventilation device. PLoS One 2021; 16:e0250672. [PMID: 33945551 PMCID: PMC8096090 DOI: 10.1371/journal.pone.0250672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 04/08/2021] [Indexed: 11/23/2022] Open
Abstract
In this work a shared pressure-controlled ventilation device for two patients is considered. By the use of different valves incorporated to the circuit, the device enables the restriction of possible cross contamination and the individualization of tidal volumes, driving pressures, and positive end expiratory pressure PEEP. Possible interactions in the expiratory dynamics of different pairs of patients are evaluated in terms of the characteristic exhalatory times. These characteristic times can not be easily established using simple linear lumped element models. For this purpose, a 1D model using the Hydraulic and Mechanical libraries in Matlab Simulink was developed. In this sense, experiments accompany this study to validate the model and characterize the different valves of the circuit. Our results show that connecting two patients in parallel to a ventilator always resulted in delays of time during the exhalation. The size of this effect depends on different parameters associated with the patients, the circuit and the ventilator. The dynamics of the exhalation of both patients is determined by the ratios between patients exhalatory resistances, compliances, driving pressures and PEEPs. Adverse effects on exhalations became less noticeable when respiratory parameters of both patients were similar, flow resistances of valves added to the circuit were negligible, and when the ventilator exhalatory valve resistance was also negligible. The asymmetries of driving pressures, compliances or resistances exacerbated the possibility of auto-PEEP and the increase in relaxation times became greater in one patient than in the other. In contrast, exhalatory dynamics were less sensitive to the ratio of PEEP imposed to the patients.
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Affiliation(s)
- Pedro M. Garcia Eijo
- Laboratorio de Fluidodinámica, Facultad de Ingeniería, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Juan D’Adamo
- Laboratorio de Fluidodinámica, Facultad de Ingeniería, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Arturo Bianchetti
- Laboratorio de Fluidodinámica, Facultad de Ingeniería, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Thomas Duriez
- Laboratorio de Fluidodinámica, Facultad de Ingeniería, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Juan M. Cabaleiro
- Laboratorio de Fluidodinámica, Facultad de Ingeniería, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
| | - Célica Irrazabal
- División Terapia Intensiva del Hospital de Clínicas, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pablo Otero
- Cátedra de Anestesiología y Algiología, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Guillermo Artana
- Laboratorio de Fluidodinámica, Facultad de Ingeniería, Universidad de Buenos Aires-CONICET, Buenos Aires, Argentina
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Korsós A, Peták F, Südy R, Schranc Á, Fodor GH, Babik B. Use of capnography to verify emergency ventilator sharing in the COVID-19 era. Respir Physiol Neurobiol 2021; 285:103611. [PMID: 33359758 PMCID: PMC7832691 DOI: 10.1016/j.resp.2020.103611] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/10/2020] [Accepted: 12/21/2020] [Indexed: 01/29/2023]
Abstract
Exacerbation of COVID-19 pandemic may lead to acute shortage of ventilators, which may require shared use of ventilator as a lifesaving concept. Two model lungs were ventilated with one ventilator to i) test the adequacy of individual tidal volumes via capnography, ii) assess cross-breathing between lungs, and iii) offer a simulation-based algorithm for ensuring equal tidal volumes. Ventilation asymmetry was induced by placing rubber band around one model lung, and the uneven distribution of tidal volumes (VT) was counterbalanced by elevating airflow resistance (HR) contralaterally. VT, end-tidal CO2 concentration (ETCO2), and peak inspiratory pressure (Ppi) were measured. Unilateral LC reduced VT and elevated ETCO2 on the affected side. Under HR, VT and ETCO2 were re-equilibrated. In conclusion, capnography serves as simple, bedside method for controlling the adequacy of split ventilation in each patient. No collateral gas flow was observed between the two lungs with different time constants. Ventilator sharing may play a role in emergency situations.
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Affiliation(s)
- Anita Korsós
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, H 6725, Szeged, Hungary
| | - Ferenc Peták
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi Fasor, H 6720, Szeged, Hungary.
| | - Roberta Südy
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, H 6725, Szeged, Hungary
| | - Álmos Schranc
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi Fasor, H 6720, Szeged, Hungary
| | - Gergely H Fodor
- Department of Medical Physics and Informatics, University of Szeged, 9 Koranyi Fasor, H 6720, Szeged, Hungary
| | - Barna Babik
- Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis Street, H 6725, Szeged, Hungary
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