When Brigham postdoctoral researcher Shriya Srinivasan, PhD, heard about physicians splitting ventilators in a dangerous attempt to help multiple patients under dire circumstances, she knew she had to help. Srinivasan, who received her PhD in medical engineering and medical physics through the Harvard-MIT Health Sciences and Technology program, had recently joined Giovanni Traverso’s lab at the Brigham. As a biomedical bioengineer, Srinivasan looks for opportunities to help solve medical challenges through engineering. Previously, she had been working on bionic limbs and an innovative amputation procedure. Now, she and her colleagues are focusing their attention on ventilators and the safety issues of splitting these life-saving devices across multiple patients.
“When I heard about the safety issues around splitting ventilators, I thought that this was a problem that could be addressed through biomedical engineering,” said Srinivasan, who has a primary appointment in the Division of Gastroenterology, Hepatology and Endoscopy at the Brigham. “This is a critical time when physicians and biomedical engineers need to come together and harness their creativity collectively to devise solutions for the pressing needs at hand. I’m honored to play whatever small role I can.”
Desperate Times, Desperate Measures
The COVID-19 pandemic has created a surge in ventilator demand that threatens to overwhelm or has already overwhelmed health care systems. Ventilators are needed for patients with severe COVID-19 who have developed pneumonia and acute respiratory distress syndrome (ARDS). In settings where the number of patients in need of ventilators has outpaced the availability of equipment, clinicians have split one ventilator among multiple people — a decision that multiple medical studies have issued a joint statement advising against, even under calamitous circumstances, due to major safety concerns.
Given the limited availability of ventilators but the rising numbers of COVID-19 patients, a team of investigators led by experts from the Brigham has developed a new approach that uses readily-available parts to modify ventilators so that a single machine can provide personalized support for two or more patients. The team’s design and results of its benchtop and animal testing to date are published in Science Translational Medicine. Accompanying protocols and resources for the clinical community are available on the team’s web site.
“We recognize the extreme times we are experiencing and hope that our developments can provide ventilatory support to multiple patients in a way that mitigates infectious concerns, as well having the capacity to support patients with potentially significantly different ventilatory needs all connected to the same ventilator,” said Giovanni Traverso, MD, PhD, a gastroenterologist at the Brigham and the senior author of the study.
Srinivasan and colleagues refer to their approach as the Individualized System for Augmenting Ventilator Efficacy (iSAVE), the name of which emphasizes the importance of individualized care. Srinivasan likens the problem of splitting a single ventilator to multiple patients to plumbing. Just as a kitchen sink and bathroom shower need different amounts of water pressure and water volume, patients on ventilators also have different requirements for volume and pressure control. As one patient’s requirements change — either because their condition improves or deteriorates — it can impact the pressure and volume available to other patients on the same ventilator. With the current ventilation splitting methods, clinicians would not be able to customize support for patients or rebalance ventilation when one patient improves or deteriorates, leading to potentially dangerous ventilation conditions. The iSAVE adds a series of valves and flow regulators that can help maintain individualized settings for each patient.
The system also includes safety features — one-way valves to prevent backflow and cross-contamination, pressure-release valves to release excess pressure, filters for expired gas to prevent pathogens from being released into the room and infecting health care workers and more.
The team has conducted benchtop testing of the iSAVE, simulating the needs of two different patients sharing a single ventilator. They have also performed ventilation using a porcine model, which has lung capacity similar to humans, to test splitting a ventilator between two subjects. The authors have tested the iSAVE on a range of ventilators to make sure the approach is generalizable.
Meeting a Clinical Need
Srinivasan and Traverso worked closely with Rebecca Baron, MD, a physician in the Brigham’s Division of Pulmonary and Critical Care Medicine, who provided a clinical perspective on the ventilator shortage and needs of clinical staff.
“It’s a privilege to work with such talented engineers to try to solve the ventilator shortage problem that will directly impact our ability to try to save people from this virus,” said Baron who is a co-author of the Science Translational Medicine paper. “The ability to augment the ventilator supply in a manner that is readily available, safe for the patients and retains individual control of the ventilator settings for each patient is a critical addition to our armamentarium of tools to fight this pandemic.”
Srinivasan explains that one of the advantages to the iSAVE is that the parts it requires are already available in many hospitals. For hospitals in low-resource settings, parts are likely available in hardware stores and could be adapted and sterilized for clinical use. With a total cost less than $25, the iSAVE could serve as a component of emergency kits that hospitals have on hand in case of future surges.
“This approach is rapidly deployable because it uses off-the-shelf components that are familiar to those working in hospitals,” she said.
Proceeding with Caution
The authors caution that the iSAVE approach is not a standard of care and should be considered only in the direst settings where shortages of patient ventilators threaten lives. With further testing and validation, implementation may be classified under the Emergency Use Authorization issued by Food and Drug Administration for ventilators for use in healthcare settings to support patients during the Coronavirus Disease 2019 pandemic. The techniques and approaches described in their article do not represent a recommendation or alteration in the recommended use of any device that was used in this demonstration and study. The use of any technique described by the authors is subject to the clinical judgement of the physicians caring for individual patients.
This work was supported in part by the Massachusetts Consortium on Pathogen Readiness (MassCPR) and the Massachusetts Life Sciences Center. The work was further supported in part by in kind services from Philips, and discretionary funds from the Department of Mechanical Engineering at MIT and at the Brigham. Two co-authors serve as employees for Philips North America, a maker of Healthcare devices and monitoring solutions including patient ventilators. Baron is part of an Advisory Board for Merck. Complete details of all relationships for profit and not for profit for Traverso can be found here. Complete details for co-author Robert Langer can be found here.