scholarly journals Use of a Single Ventilator to Support Multiple Patients: Modeling Tidal Volume Response to Heterogeneous Lung Mechanics

2020 ◽  
Author(s):  
Vitaly O. Kheyfets ◽  
Steven Lammers ◽  
Jennifer Wagner ◽  
Karsten Bartels ◽  
Bradford Smith
Keyword(s):  
New York ◽  
Computational Model ◽  
Tidal Volume ◽  
The United States ◽  
Lung Compliance ◽  
Exact Estimate ◽  
Lung Mechanics ◽  
Patient Specific ◽  
Multiple Patients ◽  
Ventilator Settings

AbstractThe COVID-19 pandemic is creating ventilator shortages in many countries that is sparking a conversation about placing multiple people on a single ventilator. However, on March 26th the American College of Chest Physicians (CHEST), along with other leading medical organizations, released a joint statement warning clinicians that attempting this technique could lead to poor outcomes and high mortality. Nevertheless, several hospitals around the United States and abroad are turning to this technique out of desperation (e.g. New York), but little data exists to guide their approach. The overall objective of this study is to utilize a computational model of mechanically ventilated lungs to assess how patient-specific lung mechanics and ventilator settings impact lung tidal volume (Vt).MethodsWe developed a single compartment computational model of four patients connected to a shared ventilator and validated it against a similar experimental study. We used this model to evaluate how patient-specific lung compliance (C) and resistance (R) would impact Vt under 5 ventilator settings of pre-set PIP, PEEP, and I:E ratio (suggested by Farkas, J.D. MD as an approach by hospitals to manage multiple patients on a single ventilator).ResultsOur computational model predicts Vt within 10% of experimental measurements. Using this model to perform a parametric study, we provide proof-of-concept for an algorithm to better match patients in different hypothetical scenarios of a single ventilator shared by more than one patient.ConclusionsAssigning patients to pre-set ventilators based on their lung mechanics could be used to overcome some of the legitimate concerns of placing multiple patients on a single ventilator. We emphasize that our results are currently based on a computational model that has not been validated against any pre-clinical/clinical data. Therefore, clinicians considering this approach should not look to our study as an exact estimate of predicted patient tidal volumes.

scholarly journals Rapid Ventilator Splitting During COVID-19 Pandemic Using 3D Printed Devices and Numerical Modeling of 200 Million Patient Specific Air Flow Scenarios

2020 ◽  
Author(s):  
Muath Bishawi ◽  
Michael Kaplan ◽  
Simbarashe Chidyagwai ◽  
Jhaymie Cappiello ◽  
Anne Cherry ◽  
...  
Keyword(s):  
Rural Communities ◽  
Computational Model ◽  
Tidal Volume ◽  
Standard Of Care ◽  
Patient Characteristics ◽  
Mobile App ◽  
Patient Specific ◽  
Wide Range ◽  
3D Printed ◽  
Ventilator Settings

Abstract There has been a pressing need for an expansion of the ventilator capacity in response to the recent COVID19 pandemic. To address this need, we present a system to enable rapid and efficacious splitting between two or more patients with varying lung compliances and tidal volume requirements. Reserved for dire situations, ventilator splitting is complex, and has been limited to patients with similar pulmonary compliances and tidal volume requirements. Here, we report a 3D printed ventilator splitter and resistor system (VSRS) that uses interchangeable airflow resistors to deliver optimal tidal volumes to patients with differing respiratory physiologies, thereby expanding the applicability of ventilator splitting to a larger patient pool. We demonstrate the capability of the VSRS using benchtop test lungs and standard-of-care ventilators, which produced data used to validate a complementary, patient-specific airflow computational model. The computational model allows clinicians to rapidly select optimal resistor sizes and predict delivered pressures and tidal volumes on-demand from different patient characteristics and ventilator settings. Due to the inherent need for rapid deployment, all simulations for the wide range of clinically-relevant patient characteristics and ventilator settings were pre-computed and compiled into an easy to use mobile app. As a result, over 200 million individual computational simulations were performed to maximize the number of scenarios for which the VSRS can provide assistance. The VSRS will help address the pressing need for increased ventilator capacity by allowing ventilator splitting to be used with patients with differing pulmonary physiologies and respiratory requirements, which will be particularly useful for developing countries and rural communities with a limited ventilator supply.

scholarly journals Split ventilation with pressure regulators for patient-specific tidal volumes

2020 ◽  
Author(s):  
Lakshminarayan “Ram” Srinivasan ◽  
Chris A. Rishel ◽  
Barrett J. Larson ◽  
Juhwan Yoo ◽  
Ned M. Shelton
Keyword(s):  
Tidal Volume ◽  
Gas Flow ◽  
Patient Management ◽  
Patient Specific ◽  
Resource Constrained ◽  
Mechanical Ventilators ◽  
Pressure Regulator ◽  
Safety Testing ◽  
Progression Of Disease ◽  
Multiple Patients

AbstractAs a measure of last resort during the COVID-19 pandemic, single mechanical ventilators have been repurposed to support multiple patients. In existing split-ventilator configurations using FDA-approved tubing adaptors, each patient receives the same inspiratory pressure, requiring careful matching of patients to avoid barotrauma. Progression of disease may cause tidal volumes to diverge from desired targets, and routine interventions (eg. suctioning) in one patient may adversely affect other patients. To overcome these limitations, we demonstrate a split-ventilator configuration that enables individualized patient management by incorporating a commonly available pressure regulator used for gas appliances. We validate this method by achieving various combinations of tidal volume in each of two synthetic lungs using a standard ventilator machine in combination with two gas flow analyzers. With further safety testing and instrumentation, pressure regulators may represent a viable path to substantially augment the capacity for ventilation in resource-constrained settings.

scholarly journals Longitudinal assessment of the lung mechanics of very low birth weight preterm infants with and without bronchopulmonary dysplasia

2015 ◽  
Vol 133 (5) ◽  
pp. 401-407 ◽  
Author(s):  
Rosane Reis de Mello ◽  
Kátia Silveira da Silva ◽  
Anniele Medeiros Costa ◽  
José Roberto de Moraes Ramos
Keyword(s):  
Tidal Volume ◽  
Preterm Infants ◽  
Bronchopulmonary Dysplasia ◽  
Very Low Birth Weight ◽  
Statistical Tests ◽  
Pulmonary Function Tests ◽  
Invasive Mechanical Ventilation ◽  
Lung Compliance ◽  
Lung Mechanics ◽  
Longitudinal Assessment

ABSTRACT CONTEXT AND OBJECTIVE: Prematurity has been correlated with altered lung mechanics. Some infants develop lung injury as a consequence of lung immaturity, invasive mechanical ventilation and exposure to oxygen, thus resulting in bronchopulmonary dysplasia. The aim here was to compare the lung mechanics of preterm infants with and without bronchopulmonary dysplasia during the first year of life. DESIGN AND SETTING: Prospective cohort study in a tertiary-level hospital. METHODS: This study included premature infants at a public hospital who underwent two pulmonary function tests: one at discharge and the other at the corrected age of 4 to 8 months. Tidal volume, lung compliance and lung resistance were measured. Statistical tests were used for comparisons between infants with and without bronchopulmonary dysplasia. RESULTS: 102 children with mean gestational age of 29 ± 2.0 weeks were studied; 17 with bronchopulmonary dysplasia. Lung compliance (0.84 ± 0.29 versus 1.28 ± 0.46; P < 0.001) and tidal volume (6.1 ± 0.94 versus 7.2 ± 1.43; P < 0.01) at discharge were significant lower in children with bronchopulmonary dysplasia than in those without the disease, but no differences were observed at the second test (compliance: 1.53 ± 0.77 versus 1.94 ± 1.01; P = 0.12; and tidal volume: 6.9 ± 1.4 versus 7.3 ± 1.6; P = 0.42). CONCLUSION: Differences in lung mechanics were observed between infants with and without bronchopulmonary dysplasia at hospital discharge but these differences were no longer detected at the final follow-up. The lung mechanics of all the infants improved over this period of time.

scholarly journals Computational Simulation to Assess Patient Safety of Uncompensated COVID-19 Two-patient Ventilator Sharing Using the Pulse Physiology Engine

2020 ◽  
Author(s):  
Jeffrey B. Webb ◽  
Aaron Bray ◽  
Philip K. Asare ◽  
Rachel B. Clipp ◽  
Yatin B. Mehta ◽  
...  
Keyword(s):  
Patient Outcome ◽  
Mechanical Ventilation ◽  
Oxygen Saturation ◽  
Saturation Index ◽  
Computational Simulation ◽  
Lung Compliance ◽  
Arterial Oxygen ◽  
Single Patient ◽  
Multiple Patients ◽  
Ventilator Settings

AbstractBackgroundThe COVID-19 pandemic is stretching medical resources internationally, including creating ventilator short-ages that complicate clinical and ethical situations. The possibility of needing to ventilate multiple patients with a single ventilator raises patient health and safety concerns. This simulation study explores patient compatibility and ventilator settings during multi-patient ventilation without the use of flow compensating resistances.MethodsA whole-body computational physiology model was used to simulate each patient on a ventilator. The primary model of a single patient with a dedicated ventilator was augmented to model two patients sharing a single ventilator. A range of ventilator settings and patient characteristics were simulated for paired patients. In addition to mechanical ventilation parameters, the full physiological simulation provides estimates of additional values for oxyhemoglobin saturation, arterial oxygen tension, and other patient parameters.FindingsThese simulations show patient outcome during multi-patient ventilation is most closely correlated to lung compliance, oxygenation index, oxygen saturation index, and endtidal carbon dioxide of individual patients. The simulated patient outcome metrics were satisfactory when the lung compliance difference between two patients was less than 12 cmH2O/mL, and the oxygen saturation index difference was less than 2 mmHg.InterpretationIn resource-limited regions of the world, the COVID-19 pandemic will result in equipment shortages. While single-patient ventilation is preferable, if unavailable, these simulations provide a conceptual framework for clinical patient selection guidelines if ventilator sharing is the only available alternative.FundingKitware employees were internally supported by Kitware. Bucknell and Geisinger participants contributed their time.Research in ContextEvidence before this studyIf numbers of patients requiring mechanical ventilation exceed the number of available ventilators in a surge, shared branched ventilator circuits have been proposed for sharing one ventilator by multiple patients. Only rudimentary laboratory or clinical studies have been reported. Testing over expected ranges of lung-chest wall compliance has not been found. Few clinical experiences of mechanical ventilation parameters employed for COVID-19 patients have been reported.Added value of this studyThe number of possible combinations of ventilation and physiological parameters is very large. Time and resource constraints do not permit conventional research. Computational simulation provides rapid sensitivity evaluation of several factors over a wide range of hypothetical ventilation conditions. Envelopes of evaluated parameters may provide reasonably estimated safety boundaries for clinicians compelled in an emergency surge to employ a poorly characterized practice. A previously well-vetted computational model for ventilation of a single patient by a dedicated ventilator has been modified to model the sharing of a single ventilator by two or more patients. Only pairings of two equally sized 70 kg patients are modeled in this report. These simulations provide estimates of effects on ventilation and blood oxygenation by clinically measurable values using conceivable mismatched patient lung compliance and oxygenation (diffusion and shunt).Implications of all the available evidenceThese estimates are for pressure mode ventilation using a single ventilator shared by branched breathing apparatus for paired patients. Individual patient flow restriction to compensate for compliance mismatch is not considered. Reasonable though arbitrary bounds of acceptable parameters may guide clinicians when determining pairings of patients with different physiological characteristics. Further laboratory testing and clinical experience will be needed to determine the validity or utility of these assessments. Different simulations will be needed for flow-compensated branches, more than two patients, and unmatched body habitus.

scholarly journals Uptake and Utilization of the Management of Anticoagulation in the Periprocedural Period App: Longitudinal Analysis (Preprint)

2018 ◽  
Author(s):  
Alex C Spyropoulos ◽  
Anne Myrka ◽  
Darren M Triller ◽  
Stephen Ragan ◽  
Collin York ◽  
...  
Keyword(s):  
New York ◽  
New York State ◽  
Bleeding Risk ◽  
The United States ◽  
Mobile App ◽  
Clinical Impact ◽  
Rapid Expansion ◽  
Patient Specific ◽  
Medical Evidence ◽  
Thromboembolic Risk

BACKGROUND Anticoagulants are major contributors to preventable adverse drug events, and their optimal management in the periprocedural period is particularly challenging. Traditional methods of disseminating clinical guidelines and tools cannot keep pace with the rapid expansion of available therapeutic agents, approved indications for use, and published medical evidence, so a mobile app, Management of Anticoagulation in the Periprocedural Period (MAPPP), was developed and disseminated to provide clinicians with guidance that reflects the most current medical evidence. OBJECTIVE The objective of this study was to assess the global, national, and state-level acquisition of a mobile app since its initial release and characterize individual episodes of use based on drug selection, procedural bleeding risk, and patient thromboembolic risk. METHODS Data were extracted from a mobile app usage tracker (Google Analytics) to characterize new users and completed episodes temporally (by calendar quarter) and geographically (globally, nationally, and in the targeted US state of New York) for the period between April 1, 2016 and September 30, 2017. RESULTS The app was acquired by 2866 new users in the measurement period, and the users completed nearly 10,000 individual episodes of use. Acquisition and utilization spanned 51 countries globally, predominantly in the United States and particularly in New York State. Warfarin and rivaroxaban were the most frequently selected drugs, and completed episodes most frequently included the selection of high bleeding risk (4888/9963, 49.06%) and high thromboembolic risk categories (4500/9963, 45.17%). CONCLUSIONS The MAPPP app is a successful means of disseminating current guidance on periprocedural anticoagulant use, as indicated by broad global uptake and upward trends in utilization. Limitations in access to provider and patient-specific data preclude objective evaluation of the clinical impact of the app. An ongoing study incorporating app logic into electronic health record systems at participant health systems will provide a more definitive evaluation of the clinical impact of the app logic.

Volume-Guaranteed Ventilation

2003 ◽  
Vol 22 (2) ◽  
pp. 17-21 ◽  
Author(s):  
Cheryl Riley ◽  
Jobeth Pilcher
Keyword(s):  
Lung Injury ◽  
Tidal Volume ◽  
Lung Compliance ◽  
Respiratory Drive ◽  
Limited Time ◽  
Careful Attention ◽  
Primary Mode ◽  
Ventilator Induced Lung Injury ◽  
New Strategies ◽  
Ventilator Settings

Pressure-limited, time-cycled ventilation has been the primary mode of ventilation for neonates for several decades. But the realization that volume rather than pressure causes ventilator-induced lung injury has led to the development of new strategies for ventilation. Volume guarantee is a mode of ventilation that automatically adjusts the inspiratory pressure to achieve a set tidal volume according to changes in lung compliance or resistance or the patient’s respiratory drive. Volume-guaranteed ventilation delivers a specific, preset volume of gas, and inspiration ends when it has been delivered. This mode of ventilation requires careful attention to the infant and to ventilator settings.

Gerald H. Thayer's ornithological work in St Vincent and the Grenadines, Lesser Antilles

2018 ◽  
Vol 45 (1) ◽  
pp. 21-39 ◽  
Author(s):  
James W. Wiley
Keyword(s):  
New York ◽  
New York City ◽  
West Indies ◽  
The United States ◽  
Lesser Antilles ◽  
American Museum ◽  
The West ◽  
Comparative Zoology ◽  
North And South America ◽  
North And South

Gerald Handerson Thayer (1883–1939) was an artist, writer and naturalist who worked in North and South America, Europe and the West Indies. In the Lesser Antilles, Thayer made substantial contributions to the knowledge and conservation of birds in St Vincent and the Grenadines. Thayer observed and collected birds throughout much of St Vincent and on many of the Grenadines from January 1924 through to December 1925. Although he produced a preliminary manuscript containing interesting distributional notes and which is an early record of the region's ornithology, Thayer never published the results of his work in the islands. Some 413 bird and bird egg specimens have survived from his work in St Vincent and the Grenadines and are now housed in the American Museum of Natural History (New York City) and the Museum of Comparative Zoology (Cambridge, Massachusetts). Four hundred and fifty eight specimens of birds and eggs collected by Gerald and his father, Abbott, from other countries are held in museums in the United States.

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