A Novel Low-Cost Ventilator for Use in a Worldwide Pandemic: The Portsmouth Ventilator

Use of a gas-operated ventilator as a noninvasive bridging respiratory therapy in critically Ill COVID-19 patients in a middle-income country

During the COVID-19 pandemic, there was a notable undersupply of respiratory support devices, especially in low- and middle-income countries. As a result, many hospitals turned to alternative respiratory therapies, including the use of gas-operated ventilators (GOV). The aim of this study was to describe the use of GOV as a noninvasive bridging respiratory therapy in critically ill COVID-19 patients and to compare clinical outcomes achieved with this device to conventional respiratory therapies. Retrospective cohort analysis of critically ill COVID-19 patients during the first local wave of the pandemic. The final analysis included 204 patients grouped according to the type of respiratory therapy received in the first 24 h, as follows: conventional oxygen therapy (COT), n = 28 (14%); GOV, n = 72 (35%); noninvasive ventilation (NIV), n = 49 (24%); invasive mechanical ventilation (IMV), n = 55 (27%). In 72, GOV served as noninvasive bridging respiratory therapy in 42 (58%) of these patients. In the other 30 patients (42%), 20 (28%) presented clinical improvement and were discharged; 10 (14%) died. In the COT and GOV groups, 68% and 39%, respectively, progressed to intubation (P ≤ 0.001). Clinical outcomes in the GOV and NIV groups were similar (no statistically significant differences). GOV was successfully used as a noninvasive bridging respiratory therapy in more than half of patients. Clinical outcomes in the GOV group were comparable to those of the NIV group. These findings support the use of GOV as an emergency, noninvasive bridging respiratory therapy in medical crises when alternative approaches to the standard of care may be justifiable.

Development and performance evaluation of a solenoid valve assisted low-cost ventilator on gas exchange and respiratory mechanics in a porcine model

INTRODUCTION

During the COVID-19 pandemic, ventilator shortages necessitated the development of new, low-cost ventilator designs. The fundamental requirements of a ventilator include precise gas delivery, rapid adjustments, durability, and user-friendliness, often achieved through solenoid valves. However, few solenoid-valve assisted low-cost ventilator (LCV) designs have been published, and gas exchange evaluation during LCV testing is lacking. This study describes the development and performance evaluation of a solenoid-valve assisted low-cost ventilator (SV-LCV) in vitro and in vivo, focusing on gas exchange and respiratory mechanics.

METHODS

The SV-LCV, a fully open ventilator device, was developed with comprehensive hardware and design documentation, utilizing solenoid valves for gas delivery regulation. Lung simulator testing calibrated tidal volumes at specified inspiratory and expiratory times, followed by in vivo testing in a porcine model to compare SV-LCV performance with a conventional ventilator.

RESULTS

The SV-LCV closely matched the control ventilator's respiratory profile and gas exchange across all test cycles. Lung simulator testing revealed direct effects of compliance and resistance changes on peak pressures and tidal volumes, with no significant changes in respiratory rate. In vivo testing demonstrated comparable gas exchange parameters between SV-LCV and conventional ventilator across all cycles. Specifically, in cycle 1, the SV-LCV showed arterial blood gas (ABG) results of pH 7.54, PCO2 34.5 mmHg, and PO2 91.7 mmHg, compared to the control ventilator's ABG of pH 7.53, PCO2 37.1 mmHg, and PO2 134 mmHg. Cycle 2 exhibited ABG results of pH 7.53, PCO2 33.6 mmHg, and PO2 84.3 mmHg for SV-LCV, and pH 7.5, PCO2 34.2 mmHg, and PO2 93.5 mmHg for the control ventilator. Similarly, cycle 3 showed ABG results of pH 7.53, PCO2 32.1 mmHg, and PO2 127 mmHg for SV-LCV, and pH 7.5, PCO2 35.5 mmHg, and PO2 91.3 mmHg for the control ventilator.

CONCLUSION

The SV-LCV provides similar gas exchange and respiratory mechanic profiles compared to a conventional ventilator. With a streamlined design and performance akin to commercially available ventilators, the SV-LCV presents a viable, readily available, and reliable short-term solution for overcoming ventilator supply shortages during crises.

A Comparative Study of Ex-Vivo Murine Pulmonary Mechanics Under Positive- and Negative-Pressure Ventilation

Increased ventilator use during the COVID-19 pandemic resurrected persistent questions regarding mechanical ventilation including the difference between physiological and artificial breathing induced by ventilators (i.e., positive- versus negative-pressure ventilation, PPV vs NPV). To address this controversy, we compare murine specimens subjected to PPV and NPV in ex vivo quasi-static loading and quantify pulmonary mechanics via measures of quasi-static and dynamic compliances, transpulmonary pressure, and energetics when varying inflation frequency and volume. Each investigated mechanical parameter yields instance(s) of significant variability between ventilation modes. Most notably, inflation compliance, percent relaxation, and peak pressure are found to be consistently dependent on the ventilation mode. Maximum inflation volume and frequency note varied dependencies contingent on the ventilation mode. Contradictory to limited previous clinical investigations of oxygenation and end-inspiratory measures, the mechanics-focused comprehensive findings presented here indicate lung properties are dependent on loading mode, and importantly, these dependencies differ between smaller versus larger mammalian species despite identical custom-designed PPV/NPV ventilator usage. Results indicate that past contradictory findings regarding ventilation mode comparisons in the field may be linked to the chosen animal model. Understanding the differing fundamental mechanics between PPV and NPV may provide insights for improving ventilation strategies and design to prevent associated lung injuries.

COVID-19 Lessons Learned: Response to the Anticipated Ventilator Shortage

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.

Assessment of hemodynamics, blood gases, and lung histopathology of healthy Pig model on two different mechanical ventilators

In response to COVID-19 global crisis and arising from social responsibility, efforts have been exerted to promptly research, develop and manufacture ICU ventilators locally to meet the spike in demand. This study aimed at: Evaluating the safety and performance of a newly developed mechanical ventilator; EZVent compared to a commercial ventilator regarding hemodynamics, arterial blood gases (ABG), lung inflammatory markers, and histopathology in a healthy pig model using three different ventilation modes. Methods: Eight adult male pigs were anesthetized and randomly assigned into two equal groups: Commercial vent and EZVent group, the animals of which were ventilated using a standard commercial ventilator and EZVent, respectively. On every animal, three ventilation modes were tested, each mode for 30 min: CMV-VC, CMV-PC, and CPAP-PS modes. Vital signs, ECG, Lung Mechanics (LM), and ABG were measured before ventilation and after 30 min of ventilation of each mode. After animals’ euthanasia, histological examinations of lung samples including morphometric assessment of alveolar edema, alveolar wall thickening, and the mean number of inflammatory cellular infiltrate/cm² of lung tissue were analyzed. TNF-α and Il-6 expression and localization in lung tissue were assessed by western blot and immunohistochemistry. Results: The vital signs, LM, ABG, morphometric analysis, and histopathological score during the different ventilation modes showed non-significant differences between the study groups. TNF-α and IL-6 were minimally expressed in the bronchiolar epithelium and the alveolar septa. Their increased expression level was insignificant. Conclusion: EZVent is equivalent to the commercial ventilator regarding its safety and efficacy.

PVP1-The People's Ventilator Project: A fully open, low-cost, pressure-controlled ventilator research platform compatible with adult and pediatric uses

Mechanical ventilators are safety-critical devices that help patients breathe, commonly found in hospital intensive care units (ICUs)-yet, the high costs and proprietary nature of commercial ventilators inhibit their use as an educational and research platform. We present a fully open ventilator device-The People's Ventilator: PVP1-with complete hardware and software documentation including detailed build instructions and a DIY cost of $1,700 USD. We validate PVP1 against both key performance criteria specified in the U.S. Food and Drug Administration's Emergency Use Authorization for Ventilators, and in a pediatric context against a state-of-the-art commercial ventilator. Notably, PVP1 performs well over a wide range of test conditions and performance stability is demonstrated for a minimum of 75,000 breath cycles over three days with an adult mechanical test lung. As an open project, PVP1 can enable future educational, academic, and clinical developments in the ventilator space.

Performance Characteristics of a Novel 3D-Printed Bubble Intermittent Mandatory Ventilator (B-IMV) for Adult Pulmonary Support

The COVID-19 pandemic has brought attention to the need for developing effective respiratory support that can be rapidly implemented during critical surge capacity scenarios in healthcare settings. Lung support with bubble continuous positive airway pressure (B-CPAP) is a well-established therapeutic approach for supporting neonatal patients. However, the effectiveness of B-CPAP in larger pediatric and adult patients has not been addressed. Using similar principles of B-CPAP pressure generation, application of intermittent positive pressure inflations above CPAP could support gas exchange and high work of breathing levels in larger patients experiencing more severe forms of respiratory failure. This report describes the design and performance characteristics of the BubbleVent, a novel 3D-printed valve system that combined with commonly found tubes, hoses, and connectors can provide intermittent mandatory ventilation (IMV) suitable for adult mechanical ventilation without direct electrification. Testing of the BubbleVent was performed on a passive adult test lung model and compared with a critical care ventilator commonly used in tertiary care centers. The BubbleVent was shown to deliver stable PIP and PEEP levels, as well as timing control of breath delivery that was comparable with a critical care ventilator.

Design and Analysis of a Low-Cost Electronically Controlled Mobile Ventilator, Incorporating Mechanized AMBU Bag, for Patients during COVID-19 Pandemic

The outbreak of novel COVID-19 has severely and unprecedentedly affected millions of people across the globe. The painful respiratory distress caused during this disease calls for external assistance to the victims in the form of ventilation. The most common types of artificial ventilating units available at the healthcare facilities and hospitals are exorbitantly expensive to manufacture, and their number is fairly inadequate even in the so-called developed countries to cater to the burning needs of an ever-increasing number of ailing human subjects. According to available reports, without the provision of ventilation, the novel COVID-19 patients are succumbing to their ailments in a huge number of cases. This colossal problem of the availability of ventilator units can be addressed to a great extent by readily producible and cost-effective ventilating units that can be used on those suffering patients during an acute emergency and in the absence of conventional expensive ventilators at hospitals and medical care units. This paper has made an attempt to design and simulate a simple, yet effective, mechanized ventilator unit, which can be conveniently assembled without a profuse skillset and operated to resuscitate an ailing human patient. The stepper motor-controlled kinematic linkage is designed to deliver the patient with a necessitated discharge of air at optimum oxygen saturation through the AMBU bag connected in a ventilation circuit. With the associated code on MATLAB, the motor control parameters such as angular displacement and speed are deduced according to the input patient conditions (age group, tidal volume, breathing rate, etc.) and thereafter fed to the controller that drives the stepper motor. With a proposed feedback loop, the real-time static and dynamic compliance, airway resistance values can be approximately determined from the pressure variation cycle and fed to the controller unit to adjust the tidal volume as and when necessary. The simplistic yet robust design not only renders easy manufacturability by conventional and rapid prototyping techniques like 3D printing at different scales but also makes the product easily portable with minimal handling difficulty. Keeping the motto of Health for All as envisioned by the WHO, this low-cost indigenously engineered ventilator will definitely help the poor and afflicted towards their right to health and will help the medical professionals buy some time to manage the patient with acute respiratory distress syndrome (ARDS) towards recovery. Moreover, this instrument mostly includes readily available functional units having standard specifications and can be considered as standard bought-out items.

ATENA-A Novel Rapidly Manufactured Medical Invasive Ventilator Designed as a Response to the COVID-19 Pandemic: Testing Protocol, Safety, and Performance Validation

Background: The urgent need for mechanical ventilators to support respiratory insufficiency due to SARS-CoV-2 led to a worldwide effort to develop low-cost, easily assembled, and locally manufactured ventilators. The ATENA ventilator project was developed in a community-based approach targeting the development, prototyping, testing, and decentralized manufacturing of a new mechanical ventilator. Objective: This article aims to demonstrate ATENA's adequate performance and safety for clinical use. Material: ATENA is a low-cost ventilator that can be rapidly manufactured, easily assembled, and locally produced anywhere in the world. It was developed following the guidelines and requirements provided by European and International Regulatory Authorities (MHRA, ISO 86201) and National Authorities (INFARMED). The device was thoroughly tested using laboratory lung simulators and animal models. Results: The device meets all the regulatory requirements for pandemic ventilators. Additionally, the pre-clinical experiences demonstrated security and adequate ventilation and oxygenation, in vivo. Conclusion: The ATENA ventilator had a good performance in required tests in laboratory scenarios and pre-clinical studies. In a pandemic context, ATENA is perfectly suited for safely treating patients in need of mechanical ventilation.

Collaborative and Structured Network for Maintenance of Mechanical Ventilators during the SARS-CoV-2 Pandemic

The SARS-CoV-2 pandemic in Brazil has grown rapidly since the first case was reported on 26 February 2020. As the pandemic has spread, the low availability of medical equipment has increased, especially mechanical ventilators. The Brazilian Unified Health System (SUS) claimed to have only 40,508 mechanical ventilators, which would be insufficient to support the Brazilian population at the pandemic peak. This lack of ventilators, especially in public hospitals, required quick, assertive, and effective actions to minimize the health crisis. This work provides an overview of the rapid deployment of a network for maintaining disused mechanical ventilators in public and private healthcare units in some regions of Brazil during the SARS-CoV-2 pandemic. Data referring to the processes of maintaining equipment, acquiring parts, and conducting national and international training were collected and analyzed. In total, 4047 ventilators were received by the maintenance sites, and 2516 ventilators were successfully repaired and returned to the healthcare units, which represents a success rate of 62.17%. The results show that the maintenance initiative directly impacted the availability and reliability of the equipment, allowing access to ventilators in the public and private health system and increasing the capacity of beds during the pandemic.

COVENT-Tester: A low-cost, open source ventilator tester

COVENT-Tester (COVID-19 VENTilator Tester) is a low-cost and open source ventilator tester developed to calibrate the output of medical ventilators, including tidal volume, inspiratory pressure, and oxygen concentration. Currently, there are several open-source ventilator testers, however, existing open-source ventilator testers are unable to measure oxygen concentration. Conversely, commercial ventilator testers with the capacity to measure tidal volume, inspiratory pressure, and oxygen concentration, are very costly. The COVENT-Tester was therefore designed to be low-cost, by using Commercial Off-The-Shelf (COTS) components, to assist the open source community for rapidly manufactured pandemic ventilators. In addition, the COVENT-Tester measurement's validation results show the tester has good accuracy.

Investigating the effect of materials and structures for negative pressure ventilators suitable for pandemic situation

The onset of the corona virus disease 2019 (COVID-19) pandemic caused shortages in mechanical ventilators (MVs) essential for the intensive care unit (ICU) in the hospitals. The increasing crisis prompted the investigation of ventilators which is low cost and offers lower health complications. Many researchers are revisiting the use of negative pressure ventilators (NPVs), due to the cost and complications of positive pressure ventilators (PPVs). This paper summarizes the evolution of the MVs, highlighting the limitations of popular positive and negative pressure ventilators and how NPV can be a cost-effective and lower health complication solution. This paper also provides a detailed investigation of the structure and material for the patient enclosure that can be used for a cost-effective NPV system using ANSYS simulations. The simulation results can confirm the selection and also help in developing a low cost while based on readily available materials. This can help the manufacturer to develop low-cost NPV and reduce the pressure on the healthcare system for any pandemic situation similar to COVID-19.