Hospital respiratory support apparatus
The recent impact of COVID-19 in Italy has caused regional shortages of key equipment, including masks and hoods for non-invasive ventilation in CPAP/PEEP respiratory support. Crucially, venturi valves, key components of such respiratory support equipment [3] proved difficult to reproduce or substitute in the setting of these shortages. While venturi valve design is subject to copyright and patent covers, certain emergencies resulting in life-or-death decisions may justify full use regardless of intellectual property, in the appropriate clinical setting. This critical demand has resulted in the 3D printing community of physicians and engineers at a local Italian startup Isinnova successfully developing methods for manufacturing these valves to bolster local supply [4]. Additional methods of bolstering local ventilator supply include the use of a single ventilator for multiple patients with a 3D printed ventilator splitter. Fortunately, the US FDA does not object to the creation and use of certain devices such as the T-connector that meet specifications described in the instructions provided to the FDA for use in placing more than one patient on mechanical ventilation when the number of patients who need invasive mechanical ventilation exceeds the supply of available ventilators and the usual medical standards of care have been changed to crisis care in the interest of preserving life. The FDA's "no objection" policy in this regard applies during the duration of the declared COVID-19 emergency.
Access to such models is still limited for many local 3D printing community members and will require close collaboration between companies and hospitals to ensure adequate manufacturing approaches and appropriate clinical use. The reverse-engineered 3D printable model of the Isinnova valve is not widely available at the time of writing, with the authors maintaining the position that such resources should be adequately evaluated and used only when such equipment is not available from the original manufacturers. Ongoing efforts by the engineers at Isinnova are focusing on developing creative adaptations of existing products for respiratory support, for example by adapting a snorkelling mask into a non-invasive ventilator [5]. Most recently, non-adjustable venturi valve designs were developed and made available by the GrabCAD user Filip Kober [6]. These valve designs achieve specific levels of inspired oxygen (FiO2) at set rates of supplemental oxygen supply (Fig. 2). Model porosity may inadvertently alter intended FiO2 levels, requiring the use of printing technologies that ensure airtight parts.
Automated ventilators with flow-driven, pressure-controlled respiratory support systems featuring safety valves, spontaneous respiration valves, and flexible membranes present an ongoing open source design challenge with some promising results, including the Illinois RapidVent design. While sourcing ventilators and ventilator parts from existing manufacturers is the clearly preferred option when feasible, the supply of these crucial devices is inadequate in many areas. A solution currently being applied to this challenge in Europe and the United States is the creation of 3D printed ventilator splitters and adjustable flow control valves, such as the no2covid-ONE valve, to be able to adapt a single ventilator for use with multiple patients who have different oxygen requirements [7]. We anticipate new creative solutions for such increasingly complex challenges from emerging international open source design efforts such as the Montreal General Hospital Foundation Code Life Ventilator Challenge [8] as the COVID-19 health crisis emerges.