This study introduces an open-source MATLAB toolbox, LatticeWorks, that offers a versatile platform for generating and analysing lattice structures, facilitating the exploration of nonuniform, functionally graded designs. It encompasses various lattice generation methods, including single- and multi-morphology lattices, linearly graded lattices, different boundary shapes, and cell arrangements (such as cylindrical and spherical). The toolbox also features volume infill lattice generation based on a signed distance function, allowing lattice structures to be applied to arbitrary domains. Other developments include extending transition boundary shapes to cylindrical and spherical coordinates, enhancing cylindrical cell arrangement methods, and introducing tailored density lattice methods for smooth density mapping. Unlike other available packages, LatticeWorks offers inclusive and detailed implementation methods that are integrated with finite element analysis for mechanical property evaluation. The toolbox’s capabilities open new paths for designing complex lattice structures, tailored to specific functional requirements, across diverse applications

The passive material properties of skeletal muscle are key to proper force transmission, and changes to muscle microstructure can have deleterious effects on whole tissue function. However, to the best of the authors' knowledge, it is not currently possible to predict the passive material properties of skeletal muscle with microstructural measurements such as titin isoform type and/or extracellular matrix collagen content, type, or organization. The goals of this work were to 1) develop an experimental dataset at the tissue length scale of passive skeletal muscle under multiaxial loading conditions, 2) develop a biphasic microstructural model of skeletal muscle, and 3) calibrate, validate, and implement such a model. Experimental planar biaxial and semi-confined compression experiments, with intramuscular pressure measurements, were conducted. A microstructural finite element model was developed using the GIBBON toolbox based on a Voronoi-like structure and a multi-domain biphasic, anisotropic, hyper-viscoelastic constitutive approach was used to model muscle fibers and the extracellular matrix. Following model calibration and validation to experimental data (with root mean square error values ranging from 0.5 % - 21 %), a parametric study suggested that tensile properties of the muscle fibers and extracellular matrix affected anisotropic tensile stress-stretch behavior to the greatest extent, while permeability greatly affected compressive stress-stretch behavior. Some parameters, such as extracellular matrix volume fraction and muscle fiber bulk modulus, affected both tensile and compressive stress-stretch behavior. Future work to expand this model into specific impairment conditions or to simulations of whole muscle would be a benefit to the field. STATEMENT OF SIGNIFICANCE: Skeletal muscle is the primary driver of human locomotion. To better understand how healthy and impaired muscle functions towards the prevention of muscle-related impairments, we can use computational modeling. In this study, we developed a new model of the microstructure of muscle tissue that incorporates fluid, which is typically neglected in computer models of muscle tissue. Collectively, the work suggests that interactions between different tissue components, specifically muscle cells, the extracellular matrix, and fluid can collectively contribute to the mechanical behavior of muscle tissue. Our results can be used to build better computer models of muscle tissue and study specific mechanisms - such as fluid flow in muscle tissue - as ways to prevent muscle injuries such as a pressure ulcer.

This study presents a computational framework for optimising a hip implant through a functionally graded biomimetic lattice structure, designed to reduce stress shielding. The optimisation technique, inspired by an inverse bone remodelling algorithm, promotes even stress distribution by reducing density and stiffness in regions with high strain energy compared to a reference level. The resulting non-uniform density distribution showed lower density levels along the implant stem’s sides and higher density around its medial axis. This optimised material distribution was captured using mapping of a triply periodic minimal surface lattice structure on the implant, creating porous lattice surfaces within the solid structure. The porous implant’s performance was evaluated using a finite element bone remodelling algorithm, comparing its bone response to a femur with a fully solid implant model, in terms of stress distribution and mass change. Results demonstrated improved bone formation at the bone-implant interface and enhanced stress transmission to the surrounding bone.

This paper presents an open-source pipeline for simulating flow and flow-related processes in (embedded) tubular structures. Addressing a gap in computational fluid dynamics (CFD) and simulation sciences, it facilitates the transition from raw three-dimensional imaging, graph networks or computer aided design (CAD) models of tubular objects to refined, simulation-ready meshes. This transition, traditionally labour-intensive, is streamlined through a series of innovative steps that include surface mesh processing, centre-line construction, anisotropic mesh generation and volumetric meshing, leading to finite element method (FEM) simulations. The pipeline leverages a range of open-source software and libraries, notably GIBBON, FEniCS and Paraview, to provide flexibility and broad applicability across different simulation scenarios, ranging from biomedical to industrial applications. We demonstrate the versatility of our approach through five applications, including the mesh generation for soil–root systems, lung airways, microcirculation networks and portal vein networks, each originating from a different data source. Moreover, for several of these cases, we incorporate CFD simulations and strategies for 3D–1D coupling between the embedding domain and the embedded structures. Finally, we outline some future perspectives aimed at enhancing accuracy, reducing computational time and incorporating advanced modelling and boundary condition strategies to further refine the framework’s capabilities.

A transtibial prosthetic interface typically comprises a compliant liner and an outer rigid socket. The preponderance of today's conventional liners are mass produced in standard sizes, and conventional socket design is labor-intensive and artisanal, lacking clear scientific rationale. This work tests the clinical efficacy of a novel, physics-based digital design framework to create custom prosthetic liner-socket interfaces. In this investigation, we hypothesize that the novel digital approach will improve comfort outcomes compared to a conventional method of liner-socket design. The digital design framework generates custom transtibial prosthetic interfaces starting from MRI or CT image scans of the residual limb. The interface design employs FEA to simulate limb deformation under load. Interfaces are fabricated for 9 limbs from 8 amputees (1 bilateral). Testing compares novel and conventional interfaces across four assessments: 5-min walking trial, thermal imaging, 90-s standing pressure trial, and an evaluation questionnaire. Outcome measures include antalgic gait criterion, skin surface pressures, skin temperature changes, and direct questionnaire feedback. Antalgic gait is compared via a repeated measures linear mixed model while the other assessments are compared via a non-parametric Wilcoxon sign-rank test. A statistically significant ([Formula: see text]) decrease in pain is demonstrated when walking on the novel interfaces compared to the conventional. Standing pressure data show a significant decrease in pressure on novel interfaces at the anterior distal tibia ([Formula: see text]), with no significant difference at other measured locations. Thermal results show no statistically significant difference related to skin temperature. Questionnaire feedback shows improved comfort on novel interfaces on posterior and medial sides while standing and the medial side while walking. Study results support the hypothesis that the novel digital approach improves comfort outcomes compared to the evaluated conventional method. The digital interface design methodology also has the potential to provide benefits in design time, repeatability, and cost.

Given its real-time capability to quantify mechanical tissue properties, ultrasound shear wave elastography holds significant promise in clinical musculoskeletal imaging. However, existing shear wave elastography methods fall short in enabling full-limb analysis of 3D anatomical structures under diverse loading conditions, and may introduce measurement bias due to sonographer-applied force on the transducer. These limitations pose numerous challenges, particularly for 3D computational biomechanical tissue modeling in areas like prosthetic socket design. In this feasibility study, a clinical linear ultrasound transducer system with integrated shear wave elastography capabilities was utilized to scan both a calibrated phantom and human limbs in a water tank imaging setup. By conducting 2D and 3D scans under varying compressive loads, this study demonstrates the feasibility of volumetric ultrasound shear wave elastography of human limbs. Our preliminary results showcase a potential method for evaluating 3D spatially varying tissue properties, offering future extensions to computational biomechanical modeling of tissue for various clinical scenarios.

The regeneration of the ruptured scapholunate interosseous ligament (SLIL) represents a clinical challenge. Here, we propose the use of a Bone-Ligament-Bone (BLB) 3D-printed polyethylene terephthalate (PET) scaffold for achieving mechanical stabilisation of the scaphoid and lunate following SLIL rupture. The BLB scaffold featured two bone compartments bridged by aligned fibres (ligament compartment) mimicking the architecture of the native tissue. The scaffold presented tensile stiffness in the range of 260 ± 38 N/mm and ultimate load of 113 ± 13 N, which would support physiological loading. A finite element analysis (FEA), using inverse finite element analysis (iFEA) for material property identification, showed an adequate fit between simulation and experimental data. The scaffold was then biofunctionalized using two different methods: injected with a Gelatin Methacryloyl solution containing human mesenchymal stem cell spheroids (hMSC) or seeded with tendon-derived stem cells (TDSC) and placed in a bioreactor to undergo cyclic deformation. The first approach demonstrated high cell viability, as cells migrated out of the spheroid and colonised the interstitial space of the scaffold. These cells adopted an elongated morphology suggesting the internal architecture of the scaffold exerted topographical guidance. The second method demonstrated the high resilience of the scaffold to cyclic deformation and the secretion of a fibroblastic related protein was enhanced by the mechanical stimulation. This process promoted the expression of relevant proteins, such as Tenomodulin (TNMD), indicating mechanical stimulation may enhance cell differentiation and be useful prior to surgical implantation. In conclusion, the PET scaffold presented several promising characteristics for the immediate mechanical stabilisation of disassociated scaphoid and lunate and, in the longer-term, the regeneration of the ruptured SLIL.

Mechanical properties of an aneurysmatic thoracic aorta are potential markers of future growth and remodelling and can help to estimate the risk of rupture. Aortic geometries obtained from routine medical imaging do not display wall stress distribution and mechanical properties. Mechanical properties for a given vessel may be determined from medical images at different physiological pressures using inverse finite element analysis. However, without considering pre-stresses, the estimation of mechanical properties will lack accuracy. In the present paper, we propose and evaluate a mechanical parameter identification technique, which recovers pre-stresses by determining the zero-pressure configuration of the aortic geometry. We first validated the method on a cylindrical geometry and subsequently applied it to a realistic aortic geometry. The verification of the assessed parameters was performed using synthetically generated reference data for both geometries. The method was able to estimate the true mechanical properties with an accuracy ranging from 98% to 99%.

The objective of this study is to evaluate the mechanical properties and energy absorption characteristics of the gyroid, dual-lattice and spinodoid structures, as biomimetic lattices, through finite element analysis and experimental characterisation. As part of the study, gyroid and dual-lattice structures at 10% volume fraction were 3D-printed using an elastic resin, and mechanically tested under uniaxial compression. Computational models were calibrated to the observed experimental data and the response of higher volume fraction structures were simulated in an explicit finite element solver. Stress-strain data of groups of lattices at different volume fractions were studied and energy absorption parameters including total energy absorbed per unit volume, energy absorption efficiency and onset of densification strain were calculated. Also, the structures were characterized into bending-dominant and stretch-dominant structures, according to their nodal connectivity and Gibson-and-Ashby’s law. The results of the study showed that the dual-lattice is capable of absorbing more energy at each volume fraction cohort. However, gyroid structures showed higher energy absorption efficiency and the onset of densification at higher strains. The spinodoid structure was found to be the poorest structure in terms of energy absorption, specifically at low volume fractions. Also, the results showed that the dual-lattice was a stretch dominated structure, while the gyroid structure was a bending dominated structure, which may be a reason that it is a better candidate for energy absorption applications.

In this study, we evaluate the performance of three algorithms as computational models of trabecular bone architecture, through systematic evaluation of morphometric, topological, and mechanical properties. Here, we consider the widely-used gyroid lattice structure, the recently-developed spinodoid structure and a structure similar to Voronoi lattices introduced here as the dual-lattice. While all computational models were calibrated to recreate the trabecular tissue volume (e.g. BV/TV), it was found that both the gyroid-and spinodoid-based structures showed substantial differences in many other morphometric and topological parameters and, in turn, showed lower effective mechanical properties compared to trabecular bone. The newly-developed dual -lattice structures better captured both morphometric parameters and mechanical properties, despite certain differences being evident their topological configuration compared to trabecular bone. Still, these computational algorithms provide useful platforms to investigate trabecular bone mechanics and for designing biomimetic structures, which could be produced through additive manufacturing for applications that include bone sub-stitutes, scaffolds and porous implants. Furthermore, the software for the creation of the structures has been added to the open source toolbox GIBBON and is therefore freely available to the community.

Objective: The endovascular thrombectomy (EVT) procedure is the most effective treatment for large vessel occlusions (LVO) in acute ischaemic stroke. EVT is a minimally invasive procedure aiming at mechanically removing the thrombus obstructing the cerebral artery by means of a stent retriever. The cerebral arteries mostly affected by stroke are the internal carotid artery (ICA), the middle cerebral artery (MCA), and the anterior cerebral artery (ACA), which form the T-junction (Fig. 1A). The ICA is characterised by a tortuous morphology, referred to as carotid siphon, which can complicate the thrombectomy procedure during the retrieval of the stent thrombus complex. Few studies in the literature have attempted to correlate the clinical outcome of the procedure with the patient’s anatomical features.1 A finite element model of the stent retriever thrombectomy procedure, useful to this purpose, was recently developed and validated.2,3 This work aims at determining methodology to identify relations between geometric parameters of the cerebral arteries and the outcome of computational thrombectomy simulations. Methods: Cerebrovascular segmentations of 14 stroke patients with LVO were provided by the Amsterdam University Medical Center, location AMC. The centrelines of the arteries of interest, that is, ICA, MCA, and ACA, were isolated for geometric characterisation. Three global geometric parameters commonly used in the clinical setting and 27 local geometric parameters4 were collected for each patient-specific geometry with an automatic MATLAB (The MathWorks, USA) script. With the aim of investigating the impact of the vessel morphology on the procedure only, the EVT procedure was simulated for each patient with the same settings. The thrombus parameters were chosen as average values from the literature.5 The same model of TREVO ProVue stent retriever (Stryker, USA) was used in all the virtual EVT procedures, which followed the same steps: crimping of the stent inside the catheter and positioning at the thrombus location, deployment of the stent to entrap the thrombus, and retrieval of the thrombus–stent complex (Fig. 1B). The procedure has a negative outcome if the thrombus is not removed from the vessel. Results: The simulations of the EVT procedure resulted in nine successful and five unsuccessful procedures, in which the thrombus was lost in the ICA anterior bend (Fig. 1A). The outcomes were correlated with the corresponding global and local geometric parameters, singularly and pairwise, to find an index able to discriminate between different results. The best classification index resulted in a combination of local parameters, namely the radius of curvature of the ICA anterior bend (rant) and the ratio between the clot diameter and the diameter of the anterior bend in the point of maximum curvature (Dclot/Dant). It is possible to identify thresholds that correctly separate the cases with the successful and unsuccessful outcomes (Fig. 1C). Conclusion: This work proposes a methodology to investigate the influence of the complex morphology of the cerebral vasculature on the outcome of computational simulations of the EVT procedure. The Results are limited by the number of patients considered. Nonetheless, the importance of analysing local geometric parameters rather than global ones was highlighted. Acknowledgements This project received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement N° 777072. References1Ngo MT, Kwak HS, Ho CG, Koh EJ. Longitudinal study of carotid artery bifurcation geometry using magnetic resonance angiography. Vascular 2019. https://doi.org/10.1177/1708538118817666. [Epub ahead of print].2Luraghi G, Bridio S, Rodriguez Matas JF, Dubini G, Boodt N, Gijsen FJH, et al. The first virtual patient-specific thrombectomy procedure. J Biomech 2021;126:110622.3Luraghi G, Rodriguez Matas JF, Dubini G, Berti F, Bridio S, Duffy S, et al. Applicability assessment of a stent-retriever thrombectomy finite-element model. Interface Focus 2021;11:20190123.4Zhang C, Pu F, Li S, Xie S, Fan Y, Li D. Geometric classification of the carotid siphon: Association between geometry and stenoses. Surg Radiol Anat 2013;35:385–94.5Dutra BG, Tolhuisen ML, Alves HCBR, Treurniet KM, Kappelhof M, Yoo AJ, et al. Thrombus imaging characteristics and outcomes in acute ischemic stroke patients undergoing endovascular treatment. Stroke 2019;50:2057–64.

Finite element analysis (FEA) can be used to evaluate applied interface pressures and internal tissue strains for computational prosthetic socket design. This type of framework requires realistic patient-specific limb geometry and constitutive properties. In recent studies, indentations and inverse FEA with MRI-derived 3D patient geometries were used for constitutive parameter identification. However, long computational times and use of specialized equipment presents challenges for clinical, deployment. In this study, we present a novel approach for constitutive parameter identification using a combination of FEA, ultrasound indentation, and shear wave elastography. Local shear modulus measurement using elastography during an ultrasound indentation experiment has particular significance for biomechanical modeling of the residual limb since there are known regional dependencies of soft tissue properties such as varying levels of scarring and atrophy. Beyond prosthesis design, this work has broader implications to the fields of muscle health and monitoring of disease progression.

Development of in-silico models of patient-specific cerebral artery networks presents several significant technical challenges: (i) The resolution and smoothness of medical CT images are much lower than the required element/cell length for FEA/CFD/FSI models; (ii) contact between vessels, and indeed self contact of high tortuosity vessel segments are not clearly identifiable from medical CT images. Commercial model construction software does not provide customised solutions for such technical challenges, with the result that accurate, efficient and automated development of patient-specific models of the cerebral vessels is not facilitated. This paper presents the development of a customised and highly automated platform for the generation of high resolution patient-specific FEA/CFD/FSI models from clinical images. This platform is used to perform the first fluid-structure-interaction patient-specific analysis of blood flow and artery deformation of an occluded cerebral vessel. Results demonstrate that in addition to flow disruption, clot occlusion significantly alters the geometry and strain distribution in the vessel network, with the blocked M2 segment undergoing axial elongation. The new computational approach presented in this study can be further developed as a clinical diagnostic tool and as a platform for thrombectomy device design.

Treatment of acute ischemic stroke has been recently improved with the introduction of endovascular mechanical thrombectomy, a minimally invasive procedure able to remove a clot using aspiration devices and/or stent-retrievers. Despite the promising and encouraging results, improvements to the procedure and to the stent design are the focus of the recent efforts. Computational studies can pave the road to these improvements, providing their ability to describe and accurately reproduce a real procedure. A patient with ischemic stroke due to intracranial large vessel occlusion was selected and after the creation of the cerebral vasculature from computed tomography images and a histologic analysis to determine the clot composition, the entire thrombectomy procedure was virtually replicated. As in the real situation, the computational replica showed that two attempts were necessary to remove the clot, as a result of the position of the stent retriever with respect to the clot. Furthermore, the results indicated that clot fragmentation did not occur as the deformations were mainly in a compressive state without the possibility for clot cracks to propagate. The accurate representation of the procedure can be used as an important step for operative optimization planning and future improvements of stent designs.

Mechanical thrombectomy can be significantly affected by the mechanical properties of the occluding thrombus. In this study, we provide the first characterisation of the volumetric behaviour of blood clots. We propose a new hyperelastic model for the volumetric and isochoric deformation of clot. We demonstrate that the proposed model provides significant improvements over established models in terms of accurate prediction of nonlinear stress-strain and volumetric behaviours of clots with low and high red blood cell compositions. We perform a rigorous investigation of the factors that govern clot occlusion of a tapered vessel. The motivation for such an analysis is twofold: (i) the role of clot composition on the in vivo occlusion location is an open clinical question that has significant implications for thrombectomy procedures; (ii) in vitro measurement of occlusion location in an engineered tapered tube can be used as a quick and simple methodology to assess the mechanical properties/compositions of clots. Simulations demonstrate that both isochoric and volumetric behaviours of clots are key determinants of clot lodgement location, in addition to clot-vessel friction. The proposed formulation is shown to provide accurate predictions of in vitro measurement of clot occlusion location in a silicone tapered vessel, in addition to accurately predicting the deformed shape of the clot.

Rupture of the scapholunate interosseous ligament can cause the dissociation of scaphoid and lunate bones, resulting in impaired wrist function. Current treatments (e.g., tendon-based surgical reconstruction, screw-based fixation, fusion, or carpectomy) may restore wrist stability, but do not address regeneration of the ruptured ligament, and may result in wrist functional limitations and osteoarthritis. Recently a novel multiphasic bone-ligament-bone scaffold was proposed, which aims to reconstruct the ruptured ligament, and which can be 3D-printed using medical-grade polycaprolactone. This scaffold is composed of a central ligament-scaffold section and features a bone attachment terminal at either end. Since the ligament-scaffold is the primary load bearing structure during physiological wrist motion, its geometry, mechanical properties, and the surgical placement of the scaffold are critical for performance optimisation. This study presents a patient-specific computational biomechanical evaluation of the effect of scaffold length, and positioning of the bone attachment sites. Through segmentation and image processing of medical image data for natural wrist motion, detailed 3D geometries as well as patient-specific physiological wrist motion could be derived. This data formed the input for detailed finite element analysis, enabling computational of scaffold stress and strain distributions, which are key predictors of scaffold structural integrity. The computational analysis demonstrated that longer scaffolds present reduced peak scaffold stresses and a more homogeneous stress state compared to shorter scaffolds. Furthermore, it was found that scaffolds attached at proximal sites experience lower stresses than those attached at distal sites. However, scaffold length, rather than bone terminal location, most strongly influences peak stress. For each scaffold terminal placement configuration, a basic metric was computed indicative of bone fracture risk. This metric was the minimum distance from the bone surface to the internal scaffold bone terminal. Analysis of this minimum bone thickness data confirmed further optimisation of terminal locations is warranted.

Medical devices, such as silicone-based prostheses designed for soft tissue implantation, often induce a suboptimal foreign-body response which results in a hardened avascular fibrotic capsule around the device, often leading to patient discomfort or implant failure. Here, it is proposed that additive manufacturing techniques can be used to deposit durable coatings with multiscale porosity on soft tissue implant surfaces to promote optimal tissue integration. Specifically, the "liquid rope coil effect", is exploited via direct ink writing, to create a controlled macro open-pore architecture, including over highly curved surfaces, while adapting atomizing spray deposition of a silicone ink to create a microporous texture. The potential to tailor the degree of tissue integration and vascularization using these fabrication techniques is demonstrated through subdermal and submuscular implantation studies in rodent and porcine models respectively, illustrating the implant coating's potential applications in both traditional soft tissue prosthetics and active drug-eluting devices.

The aim of this work is to propose a methodology for identifying relationships between morphological features of the cerebral vasculature and the outcome of in silico simulations of thrombectomy, the mechanical treatment for acute ischemic stroke. Fourteen patient-specific cerebral vasculature segmentations were collected and used for geometric characterization of the intracranial arteries mostly affected by large vessel occlusions, i.e., internal carotid artery (ICA), middle cerebral artery (MCA) and anterior cerebral artery (ACA). First, a set of global parameters was created, including the geometrical information commonly provided in the clinical context, namely the total length, the average diameter and the tortuosity (length over head-tail distance) of the intracranial ICA. Then, a more exhaustive geometrical analysis was performed to collect a set of local parameters . A total of 27 parameters was measured from each patient-specific vascular configuration. Fourteen virtual thrombectomy simulations were performed with a blood clot with the same length and composition placed in the middle of the MCA. The model of TREVO ProVue stent-retriever was used for all the simulations. Results from simulations produced five unsuccessful outcomes, i.e., the clot was not removed from the vessels. The geometric parameters of the successful and unsuccessful simulations were compared to find relations between the vascular geometry and the outcome. None of the global parameters alone or combined proved able to discriminate between positive and negative outcome, while a combination of local parameters allowed to correctly identify the successful from the unsuccessful simulations. Although these results are limited by the number of patients considered, this study indicates a promising methodology to relate patient-specific geometry to virtual thrombectomy outcome, which might eventually guide decision making in the treatment of acute ischemic stroke.

Materials such as elastomeric foams, lattices, and cellular solids are capable of undergoing large elastic volume changes. Although many hyperelastic constitutive formulations have been proposed for deviatoric (shape changing) behaviour, few variations exist for large deformation volumetric behaviour. The first section of this paper presents a critical analysis of current volumetric hyperelastic models and highlights their limitations for large volumetric strains. In the second section of the paper we propose three novel volumetric strain energy density functions, which: (1) are valid for large volumetric deformations, (2) offer separate control of the volumetric strain stiffening behaviour during shrinkage (volume reduction) and expansion (volume increase), and (3) provide precise control of non-monotonic volumetric strain stiffening. To illustrate the ability of the novel formulations to capture complex volumetric material behaviour they are fitted and compared to a range of published experimental data.

The COVID-19 pandemic is a public health emergency of unprecedented scale. The surge in clinical cases of patients with severe respiratory illness has overwhelmed the traditional capacity of healthcare systems worldwide. Continuous Positive Airway Pressure (CPAP) delivered through Non-Invasive Ventilation (NIV) has been shown to be useful in caring for patients with COVID-19. In particular patients with early stage milder acute hypoxemic respiratory failure can benefit from NIV CPAP therapy, though there is an acknowledged risk of COVID-19 aerosolization with traditional circuit use. Furthermore, given the surge in clinical care demand, there is an acute global shortage of ventilators, including NIV devices and therefore innovative methods are needed to increase NIV capacity and ameliorate infectious aerosolization. This paper outlines an emergency use modified dual NIV CPAP Circuit that uses a 3D printed splitter designed to work with traditional international NIV CPAP tubing standards and a 3D printed respiratory face mask knuckle to allow for distal expiratory breath exhalation through a viral filter rather than through an open to air proximal valve, which is the traditional NIV CPAP configuration. We expect that this work will increase global NIV CPAP capacity and ameliorate aerosolization of COVID-19 in patients undergoing therapy in an emergency scenario.