Browsing by Author "Sivarasu, Sudesh"

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    Open Access
    A novel cough aerosol sampling device for sputum-scarce individuals with tuberculosis
    (2025) Ismail, Ra'eesah; Sivarasu, Sudesh; Dheda, Keertan
    Introduction In 2021, there were 10.6 million tuberculosis cases worldwide, with 1.6 million deaths. Bacterial infection occurs when aerosol droplets enter the respiratory tract and travel to the lungs, causing pulmonary disease. If untreated, the disease has a 50% mortality rate. TB diagnostics require a sputum sample to conduct tests to confirm the presence of Mtb but more than 15% of patients have difficulty producing this sample. A cough aerosol sampling system (CASS) can collect aerosol droplet samples for testing when sputum sampling is not possible. These systems rely on inertial impaction whereby particles are sorted based on their diameter. Thus, CASS also offers information regarding the infectivity of the patient based on their expelled aerosol sizes. This is because smaller respiratory droplets can travel to the smallest structures of the lung and are more likely to cause infection. CASS is a useful technology in field sampling in place of sputum sampling. However current systems are bulky, heavy and not optimised for field testing in resource limited settings – which this project aims to address. Methods & Materials The methodology included designing and developing a physical prototype of a novel miniaturised cough aerosol sampling system (Mini CASS). This device was designed in subsystems, namely the impaction cascade, pump system, mask part and casing. All subsystems followed a rapid prototyping approach characterised by multiple design iterations. The impaction cascade design was guided by Marple and Liu's methodology (1976). This included testing various impaction substrates. Furthermore, it was optimised by computational fluid dynamics. The entire design was evaluated against a set of predefined needs criteria developed through identification of inadequacies in current devices. Verification testing at the Medical Devices Lab (University of Cape Town) included confirmation of the aerosol size fractionation capacity of the cascade impactor. Validation testing was conducted at the Centre for Lung Infection and Immunity (Groote Schuur Hospital) to confirm the ability of Mini CASS to collect culturable bioaerosols (M. smegmatis). Results & Discussion A partially disposable, portable and miniaturised CASS was built with a weight and size of less than 1 kg & 40 cm2 respectively. Results of in-silico and verification testing have confirmed the ability of the device to perform size fractionation with atleast a 30% efficiency per stage. The device successfully collected nebulised M. smegmatis & M. bovis. Culture confirmation of the bacteria proves this as a viable impactor with atleast 3 colony forming units on each stage, comparable to current CASS systems. Conclusion The final Mini CASS prototype exhibited favourable characteristics of being lightweight and easily portable. It fared well in tests conducted to assess viability, proving its capability to collect bioaerosol samples for culture from coughing. It exhibited the ability to fractionate aerosol samples to provide a semi-quantitative measure of infectiousness with known particle sizes and efficiencies. This proof-of-concept device shows CASS technology can be optimised for use in the clinical setting, thereby enabling it to become a more powerful sampling and research tool. The lightweight, easy to use technology has the potential for use at home or temporary sampling sites.
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    Open Access
    A structured light solution for detecting scapular dyskinesis
    (2018) Verster, Jaco; Gray, Janine; Sivarasu, Sudesh; Mutsvangwa, Tinashe
    Scapular dyskinesis is a common occurrence in overhead athletes, i.e. athletes who participate in any sport where the upper arm and shoulder is used above the athlete’s head. However, no consensus has been reached on how to evaluate scapular dyskinesis quantitatively. In this thesis, we developed a measuring tool that can be used to evaluate certain key clinical parameters specific to scapular dyskinesis. The tool employs a 3D structured light computer vision approach to create a surface map of the soft-tissue across the scapula. This surface map is then analysed using surface curvature analysis techniques to identify the key clinical parameters associated with scapular dyskinesis. The main advantage of this method is that it provides a measurement tool that may facilitate future quantitative analysis of these key parameters. This may aid with diagnosis and monitoring of the condition by allowing measurement data to be collected both before and after treatment and rehabilitation. We expect that this tool will make the monitoring of treatment effectiveness easier while contributing to diagnostic computer vision.
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    An Attempt to Improve Stance Mechanics of Trans-Tibial Amputee Gait by the Design of a Modular Ankle Joint Prosthetic
    (2018) During, Alastair B; Vicatos, George; Sivarasu, Sudesh
    Background: A-priori research shows that trans-tibial (TT) amputees display poor gait parameters when walking with low-cost ankle-foot prosthetics (here referred to as baseline AFP’s). This has drastic implications for the amputee populations in the developing world specifically, as they have limited access to advanced prosthetic technologies. Low-cost AFP’s are unable to adequately replicate natural stance mechanics, and reliance on these devices results in increased energy expenditure, osteoarthritis and lower-limb joint deterioration. Methodology: This project details the design of a novel ankle joint prosthetic (AJP) that serves as an attachment to baseline AFP’s, with the aim of facilitating better stance mechanics via the restoration of ankle joint mechanisms. The work is presented in three core sections: Part 1 explains the rationale as to why adequately replicating natural stance mechanics is an appropriate need; Part 2 presents the design of the modular low-cost AJP that utilises only simple mechanical elements; and Part 3 presents the experimental quantification of the impact the AJP has on stance mechanics of a baseline AFP (Otto Bock 1D10) in a simulation of the TT amputee walking gait cycle, via the use of three able-bodied participants and a pseudo-prosthesis. Results: The results indicate that the AJP significantly improves the stance mechanics of the baseline AFP. During forefoot rollover a stable joint moment and an increase in joint range of motion (RoM) was observed, yielding a decrease in ankle stiffness. During initial weight acceptance of early stance, an increase in joint RoM displays the restoration of controlled plantarflexion, which indicates an improved transition from heelstrike to footflat. This is a critical mechanism that facilitates stability control during weight acceptance, and the results suggest that the designed AJP is performing better in this regard than its closest functional competitor. However, equipment errors limited the ability to accurately report on ankle stiffness of this phase. Conclusions: Overall the final conclusions are that the designed AJP improves rollover shapes of the baseline AFP, eases phase transitions, and facilitates stability control and forward tibial progression. In combination with the low cost price (±50 USD), its ease of assembly and modular design, the AJP is thus a preferable option for low-income amputees in developing countries. Finally, there is significant evidence of functional and mechanical reliability, and therefore testing of the device can progress to a clinical study involving amputee participants.
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    Aspects of the composition and origin of achondrites and mesosiderites
    (1983) Simpson, Alexander Bruce; Sivarasu, Sudesh
    [page ii missing] This investigation had as its overall aims the collection and use of both new and existing information on achondritic and mesosideritic meteorites for three main purposes: (1) to establish the relationships between the three major achondrite classes - eucrites, howardites, and diogenites - and to assess the genetic significance of these relationships; (2) to determine whether the apparent similarity between the so-called basaltic achondrites (eucrites and howardites) and the silicate portions of mesosiderites is indicative of a genetic connection; and (3) to formulate, if possible, a model for the origin of the achondrites based on all available data. The starting point for the inves~igation was defined by a critical review and systematization of relevant information scattered throughout the literature up to the end of 1973. The formation of the howardites, a range of polymict breccias with compositions that vary in a serial fashion between those of eucrites and diogenites, was investigated by a study of their petrography and by an extensive programme of electron microprobe analysis aimed at determining the extent of compositional variation present in their constituent mineral, lithic, and glassy phases. Four howardites chosen to represent the class - Bununu, Frankfort, Malvern, and Molteno - were so examined. A fifth meteorite, Binda, conventionally classed as a howardite (HEY, 1966) but later regarded as a cumulate eucrite (STOLPER, 1975a,b), was included for comparison with the howardites in the full realisation that its classification was problematical. Compositional data on 1,634 clasts in these five breccias were obtained from 2,938 microprobe analyses. The phases analyzed were pyroxene, plagioclase, olivine, silica minerals, chromite, ilmenite, meta-1,, troilite, glass,- and glassy microbreccia. University of Cape Town - xxi - A comprehensive study of inter-element relationships, particularly of those involving refractory elements, was carried out to establish the relations between the three main achondrite classes and between th~ basaltic achondrites and the silicate fractions of mesosiderites for the purpose of gaining information on the possible modes of origin of these meteorites. Additional evidence on the genesis_ of the eucrites was obtained from mathematical modelling. These studies were based on the concentrations of major, minor, and trace elements in 42 bulk analyses of achondrites and mesosiderites.· .Most of the achondrites used were previously analyzed in this labora~ory (McCARTHY, 1971; McCARTHY et al., 1972), but new analyses for 23 elements were performed by X-ray fluorescence spectrometry on five achondrite samples (Binda, Kapoeta, Molteno, and two samples.of Malvern) and on the silicate fractions of seven mesosiderites (Fmery, Estherville, .J:;owicz, Mincy, Mount Padbury, Patwar, and Va~a Muerta). The accumulated petrographic and compositional data were used to evaluate existing hypotheses of achondrite formation. These were: (1) evolution of the achondrites from a common magmatic source by igneous differentiation, diogenites being the cumula~es and eucrites the late-stage liquids produced by this process, which was followed by brecciation (e.g. DUKE and SILVER, 1967); (2) formation of the howardites by mixing, in vary~ ing proportions; of compositionally restricted diogenitic and eucritic materials and a minor chondritic component (JEROME and GOLES, 1971); and (3) genesis· of the eucrites by small degrees of low pressure partial fusion of a source region in the parent body, possibly followed by production of the more magnesian materials present in diogenites and howardites by further partial melting of the residues (STOLPER, 1977a). It was concluded that a twocomponent mixing model does not explain the observational data. The compositional bimodality of howarditic pyroxenes implicit in such a model is absent University of Cape Town - xxiii - of the mesosiderites by mixing of metal and howarditic or eucritic material. It was noted, however, that the higher content of FeO in howardites constitutes the main difference between them and the mesosideritic silicates. Recalculation of analyses after subtraction of 'excess' FeO, FeS, and P 2 o5 and Ni (assumed to be associated with the metal phase) resulted in coincidence of achondritic and mesosideritic trends in plots of major element relationships. This prompted the proposal that the source material of the achondrites - approximately represented by the average howardite - was formed from the most reduced, 'primitive' mesosiderites by oxidation of the high metal content of these mesosiderites, and that lesser degrees of oxidation produced mesosiderites with silicates compositiona~ intermediate to those of howardites and 'primitive' mesosiderites. These proposed relationships could be demonstrated, within reasonable limits of accuracy, for the major element concentrations of the 42 meteorites included in. the study but not satisfactorily for the trace elements, possibly because of their redistribution during later, depth-related metamorphism of the 'primitive' mesosiderites. It was deduced that the source material thus produced (from which the achondrites were derived) consisted of approximately 90% pyroxene (Wo5En65 ), 5% plagioclase (An94), and 5% Cr-rich spinel; this is one of the alternatives proposed by STOLPER (1977a). The composition calculated from this mode plots on the olivine-pyroxene phase boundary of the silica-olivineanorthite pseudo-ternary diagram (WALKER et al., 1972). The trend defined by the diogenites and howardites, whose more magnesian components are presumably attributable to the second stage of partial melting of the source region, also lies on this boundary. The close relationship between the calculated composition of the source material of the achondri~es, which is similar to other estimates made (e.g. DREIBUS et al., 1977), and the observed trend of University of Cape Town - xxiv - the diogenites and howardites is of significance to the genetic model presented below. Investigation of the petrography and phase chemistry of Binda showed that although some compositional variation - possibly attributable to minor fractionation - occurs in its constituent pyroxene and plagioclase and a small amount of glassy material is present, it is essentially a monomict breccia with a formational history different from the howardites. that it resembles compositionally. It is a slowly-cooled cumulate that has been subjected to brecc_iation and cataclastic action in situ, without necessarily having been part of a regolith on its parent body. It was concluded from the study of inter-element relationships that it is neither a howardite nor a cumulate eucrite. Its constant association with mesosideritic silicates in plots of these relationships, together with its depletion in trace elements and metal, suggests that it is a silicate 'clot' from a fairly highly-oxidized mesosiderite .. The model proposed on the basis of the present investigation envisages formation of the achondrites in a parent body of asteroidal dimen9 sions that accreted about 4.6 x 10 years ago from nebular material with abundances that were near-chondritic apart from depletion in volatiles. This body, for which 4 Vesta is a possible choice (CONSOLMAGNO and DRAKE, 1977), was heated by external sources and underwent primary differentiation during, or immediately following, accretion. Metal-silicate segregation was probably incomplete, and a pallasitic zone may have formed at depth in the body. It is proposed that at least the outermost parts of the body (subsequently to become outer mantle) were composed of material similar to the mesosiderites regarded as 'primitive'. Progressive oxidation of this material, possibly accompanied by segregation of metal, generated the pyroxene-rich rocks that were parental to the achondrites. Partial fusion of these source rocks University of Cape Town - xxv - pr,oduced the 'primary' eucritic melts from which Fe-rich residual liquids and complementary cumulates were formed by fractional crystallization~ this process continuing until plagioclase was exhausted from the source region. Eruption of the eucritic melts, possibly when a critical degree of partial melting had been attained, resulted in the formation of a crust in at least part of the parent body. The residues from this first stage of partial fusion constitute a series of pyroxenites ranging from the most Fe-rich diogenite hitherto reported (Yamato 75032) to the 1 normal 1 diogenites. If all plagioclase-bearing melts were removed from the source region(s), no further melting took place and only eucritic and diogenitic series were produced. If, however, some of the initial melts remained trapped in the residues, further addition of heat to the source region would have caused a second stage of partial fusion in which a range of pyroxeneplagioclase melts compositionally intermediate to the 'primary' eucrites and the new source material (residues + trapped feldspar-bearing liquids) was generated. These intermediate melts represent some of the components of howardites that were not contributed by eucrites or diogenites. Other such components ~ orthopyroxenes more magnesian than those of the diogenite series - were formed in the residues from the second stage of partial melting· after exhaustion of trapped plagioclase-bearing melt. The outermost parts of the parent body therefore presented, as a consequence of the interaction of processes of partial melting and crystallization differentiation, a wide compositional spectrum of materials for brecciation and mixing by impacting projectiles. In the regolith so formed, howardites and polymict eucrites were produced according to whether _the material incorporated in them was biased towards the orthopyroxenitic residues or towards members of the eucrite series. Intrusive impact melts were formed locally and retained inclusions of the metal of the impacting bodies. University of Cape Town ·xxvi - Lithification ' of the regolith and ejection of material from it produced the polyrnict achondritic breccias. Moncmict breccias probably represent rocks that either were fanned at depth in the crust of the parent body (e.g. residues and cumulates) or were protected by an overlying regolith deposit from all but the most violent impacts.
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    ASTM assessment of a novel shoulder prosthetic design: measurement of glenoid edge motion in three degrees of freedom
    (2025) Haworth, Leanne; Sivarasu, Sudesh
    The most common cause for failure of An anatomical shoulder joint prosthesis is loosening of the glenoid component, widely attributed to ‘rocking' of the component under eccentric edge loading. The American Society for Testing and Materials (ASTM) set out a standardised test to evaluate glenoid loosening, in which the glenoid is cyclically loaded (for 100,000 cycles) and the vertical displacement of the edges is measured. However, under load the glenoid edges will also deflect horizontally and with a tilting motion. Therefore, the standardised test provides limited information regarding the glenoid behaviour. To measure the complex motions of the glenoid edges, an ASTM conforming test rig was designed and then augmented with a novel edge motion measurement system. The edge motion measurement system uses LVDT sensors to track the motion of rigid blocks on the end of lever arms connected to the glenoid edges. The block's motion is converted to complex glenoid edge motion using a MATLAB algorithm based on the system geometry. The test rig and edge motion measurement system were functionally validated in preliminary tests. The augmented test rig was then used to evaluate a novel glenoid design compared to an established (5-peg cemented) control glenoid. Six samples of each design were tested, and the resultant motion vectors were statistically compared using 1-dimensional statistical parametric mapping. The design intention of the novel glenoid was to decrease the edge motion by centralising the stresses experienced using gaps in the component surface. However, the experimental results showed increased edge motion on the novel glenoid, which was statistically significant (P<0.05) in the vertical and tilting directions. Observation of overall trends in the glenoid edge motion showed that rather than rocking, a downward and outward deformation of the edges occurs (usually within 5000 cycles). This deformation was further noted to not be a permanent effect, resulting in a time-dependent relaxation of the edges out of their deformed state, which contributes to the edge motion in tension. This contribution is believed to be non-trivial with respect to the overall motion and is likely why the novel glenoid results were counter to what was expected from the FEM. Overall, the key finding from this thesis was that the deformation and strain recovery of the glenoid components played a larger role in edge motion than the expected ‘rocking' and this observation should be accounted for when developing new glenoid designs.
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    Biomechanical assessment of RTSA functional outcomes towards optimising the prosthesis configuration
    (2018) Glenday, Jonathan Daniel; Sivarasu, Sudesh; Roche, Stephen
    Reverse total shoulder arthroplasty (RTSA) alleviates pain and restores function to patients with cuff tear arthropathies or massive rotator cuff tears. The procedure uses a semi-constrained prosthesis to reverse the orientation of the glenohumeral joint, thereby altering the biomechanics of the deltoid and allowing it to restore shoulder function in the presence of an irreparably damaged rotator cuff. However, there are complications that can impact long-term success of RTSA. Adaptations to the design and placement of the prosthesis have been investigated to address these complications and this has led medical device manufacturers to develop divergent implants. This divergence, as well as previous literature regarding RTSA biomechanics, suggest that a configuration that optimises reverse shoulder functional outcomes has yet to be determined and that it can be obtained by combining multiple modifications. A biomechanical assessment framework was established to characterise reverse shoulder function and the effect of modifying prosthesis configuration. It utilised the Newcastle Shoulder Model (NSM) and a custom-made impingement detection algorithm to simulate seven standardised motions that either elevated or rotated the humerus. Four outcome measures (deltoid elongation, deltoid moment arm, joint stability and impingement-free range of motion) were evaluated for each motion. The framework took anatomical variability into consideration by performing the simulations using a subject-specific reverse shoulder cohort. Further, 36 modified configurations of the prosthesis (based on offsets to the placement of glenosphere, humeral tray and greater tuberosity) were evaluated. The effect of each of these modifiable parameters on the outcome measures was characterised as beneficial, detrimental, or negligible, in comparison to a default prosthesis configuration. Seven of the most beneficial parameters were then selected for combination and evaluated using the assessment framework. Due to an antagonistic relationship between the outcome measures, and differing functional requirements of the motions, none of the configurations were able to simultaneously maximise all outcome measures. Rather, the optimised configuration (which inferiorly translated the glenosphere and posteromedially translated the humeral tray) provided balanced, moderate improvements to majority of the outcome measures. Overall, the deltoid did not excessively elongate, and deltoid moment arms, joint stability, and impingement-free range of motion improved by 17.9%, 57.1%, and 32.1%, respectively compared to the default configuration. Subsequently, comparisons between the effect of the default and optimised configurations on muscle fatigue and micromotion at the bone-implant interface were made. Muscle fatigue was assessed by adapting the NSM, and micromotion was assessed through a finite element analysis of a subset of the reverse shoulder cohort. The optimised configuration had a beneficial impact on the time to initiate muscle fatigue by decreasing the force required by the middle deltoid to initially elevate the humerus, and it had no appreciable effect on micromotion. In summary, an optimised RTSA configuration has been presented in this thesis. For a rotator cuff deficient reverse shoulder, the proposed configuration provided balanced, moderate improvements to majority of the functional outcomes. Additionally, the configuration was able to mitigate the effect of muscle fatigue and did not affect micromotion. Future studies should look to experimentally validate these findings, determine their clinical significance, and enhance both the assessment techniques and framework.
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    Design and development of a device to diagnose and treat obstructive sleep apnoea
    (2024) Philpott, Joel; Sivarasu, Sudesh
    Sleep apnoea is the repeated cessation of breathing during sleep and can result in impaired concentration, excessive unexplained sleepiness, and sleep fragmentation. Long-term effects of the condition can include hypertension, stroke and cardiovascular disease, diabetes and glucose intolerance, and obesity. Sleep apnoea is linked to a hazard ratio of 1.97, indicating that individuals with this condition face almost twice the risk of experiencing a stroke or death compared to those without sleep apnoea. It is estimated that 425 million adults between the ages of 30 and 69 have moderate to severe sleep apnoea. A study conducted in Wisconsin, America, found that 82% of men and 93% of women with moderate to severe sleep apnoea had not been diagnosed. This is likely to be even higher in low-middle-income countries like South Africa, where there is limited access to healthcare. Limited access to healthcare also affects sleep apnoea treatment. A study conducted in Latin America found that of the 880 patients diagnosed with sleep apnoea, only 55.7% started Positive Airway Pressure (PAP) therapy, as many of the study participants could not afford a basic level of treatment. This study describes the development of a device that could reduce the prevalence of undiagnosed sleep apnoea cases and improve access to treatment. The developed system makes use of standard breathing effort and pulse oximetry sensors as well as a flow sensor to provide the necessary information to conduct a home sleep test for the diagnosis of sleep apnoea, as required by the American Academy of Sleep Medicine (AASM). The diagnostic algorithm proposed by the AASM is also used to identify apnoea events and present this information to a clinician. The system also provides a basic level of Continuous Positive Airway Pressure (CPAP) treatment, the most common treatment modality used for patients with sleep apnoea. The system performance specifications are tested according to the EN ISO 80601-2-70 testing protocol for the mean static pressure, dynamic pressure accuracy, and maximum flow rate. The ISO standard does not dictate minimum performance requirements; however, the device meets most of the requirements dictated by the Association for Respiratory Technology and Physiology (ARTP), except the requirements for the dynamic pressure accuracy where the device exceeded the maximum pressure range by 1.69cmH2O. The study has demonstrated that a single device could be used to address the high prevalence of undiagnosed and untreated sleep apnoea and thereby prevent associated health risks. Using a single device for the diagnosis and treatment of the condition may also allow clinicians to monitor the efficacy of treatment and ensure that the correct pressure level of the CPAP treatment is being used. However, further development and testing would be required before the device can meet all of the minimum performance requirements. These developments include improving the pressure control and adding the ability for the device to connect to the internet.
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    Design and Development of a Lower Limb Rehabilitation Device for Spinal Cord Injury Patients
    (2021) Trusler, Matthew; Sivarasu, Sudesh; Stander, Juliette
    Introduction: Spinal cord injuries (SCI) are seen commonly in Southern Africa and can completely change the course of the affected's life. Lower limb disability is a common complication from this injury, but a patient can be rehabilitated in some cases. Research and clinical observations suggest that early mobilisation and rehabilitation leads to shorter hospital stays and better clinical outcomes. Relieving the time dedication placed onto the rehabilitation team could mean that patients receive a higher standard of care. Methods: A cyclic movement device has been designed to mimic the gait cycle that a patient is attempting to recover. The device was intended towards providing a ground reaction force simulation at the correct points of the gait cycle. The device was tested in-silico with validated skeletal models to determine joint torques and angles. In-silico testing was also utilised to determine the loads placed onto the patient by the device through its use. The force data could then be used to predict possible ground reaction forces. Results: The device allows for a gait similar trace path of the ankle, comparable to that found in the literature. The ankle has a range of motion of 3 1° as the device completes a full cycle in which the crank rotates 360 °. The hip has a range of motion of 28° and the knee 35° in this same movement. The shape of the displacements of the joints of the lower limb is comparable to that seen in researched gait patterns. However, the timing of the knee and hip joints' movements are not synchronous with that of the gait patterns. The device is validated to be sufficiently stable to use, and the motor and power components can provide the 7259N.mm of torque needed to move the model. Conclusion: The results suggest that the device has potentia l as an adjunct to rehabilitation schemes. In-silico testing showed that the device is able to simulate some of the kinetic and kinematic parameters seen in normal gait. Further work is needed to prototype the device to physically and clinically validate the device.
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    Design and Development of a Portable Multi-user Medical Grade Oxygen Concentrator
    (2024) Lowan, Vongani; Sivarasu, Sudesh; Maswime Salome
    Introduction: The COVID-19 pandemic has increased the demand for high-flow oxygen concentrators, particularly in resource-limited areas. There is a pressing need for an innovative, high-flow, multi-user oxygen concentrator using local materials to address this healthcare challenge. Methods: The study focused on creating a portable, medical-grade oxygen concentrator using the Skarstrom pressure swing adsorption cycle, incorporating a silica gel drying tank and 13X Zeolite adsorption beds. Critical parameters such as compressor output pressure, heat exchanger efficiency, systemic pressure losses, air separation duration, and peak flow rate of oxygen-enriched air were extensively analysed through experiments and simulations. Results: The concentrator achieved a 21 litres per minute flow rate with over 85% oxygen purity at 100kPa. Cost efficiency was ensured using local components. Enhancements included an orifice in the sieve beds to increase back pressure and equalisation valves to reduce cyclic duration, thus improving efficiency. An internal spacer in the sieve bed was designed to optimise airflow and oxygen production. Discussion: This device addresses the scarcity of oxygen in resource-constrained regions like sub-Saharan Africa. It aims to reduce the cost of oxygen therapy (currently R20.00-R40.00 per patient per day) and should be expanded and implemented in similar settings. Future efforts should focus on integrating advanced functionalities such as remote monitoring for operational efficacy and safety. Conclusion: This multi-user oxygen concentrator represents a significant advancement in medical technology, especially for resource-limited settings. It provides a high oxygen flow rate and concentration at an optimised cost, addressing the oxygen shortage exacerbated by the pandemic. Its innovative design utilises local materials and features that enhance efficiency, offering a cost-effective solution and a model for future healthcare technologies. Future developments should aim to extend this technology's reach, ensure adaptability, and continuously improve its features for enhanced efficacy and safety. This contributes to more equitable medical resource distribution in areas with significant resource constraints.
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    Design and development of a sensory feedback system for transradial amputees using body powered prostheses
    (2021) Gordon-Grant, Catherine; Sivarasu, Sudesh
    Introduction Although significant advancements have been made in the realm of prosthesis design over the last two decades, amputees still reject their prostheses largely owing to the lack of sensory feedback received. The aim of this study was to develop a non-invasive sensory feedback system, including proprioceptive feedback, to work in conjunction with an existing body powered prosthesis that provides the user with increased tactile and proprioceptive awareness demonstrated in the form of improved results in an object identification and size discrimination (OISD) test, improved percieved confidence and improved response time. Materials & Methods A sensory feedback system was developed using principles of rapid prototyping and testing. The system utilises capacitive sensors to mediate detection of proximity and touch, and makes use of a flex sensor to represent the position and motion of the finger digits of the prosthesis. A vibrotactile armband on the upper arm is used to feedback the sensed information to the user. Four able-bodied, adult volunteers participated in a preliminary study to test the efficacy of the capacitive sensor-vibrating motor disc combination. Five able-bodied, adult volunteers participated in a study conducted at the Medical Devices Lab at the University of Cape Town. The study investigated whether using the designed sensory feedback system in conjunction with a body powered prosthesis improves the participant's ability to locate and discriminate the size of spheres whilst visually and aurally restricted. Results & Observations The results from the preliminary study show that all participants were able to distinguish between 3 levels of touch (proximity, light and hard touch) intensity and locate the position of the stimulation for good electrical conductors such as metal, human skin, wood and sometimes ceramic and glass materials depending on the coating. Results from the object identification test indicate that participants performed worse when no sensory feedback was provided (at an average accuracy of 0%). All participants were able to identify the objects accurately and efficiently when sensory feedback was provided at an average accuracy of 100%. Similarly, average accuracy for object discrimination improved from 58.33% with no sensory feedback to 85% with sensory feedback. Response times for both object identification tasks and size discrimination tasks also improved illustrated by a significantly negative relationship (negative gradient) in all trend lines over the period of testing. This suggests a learnability with the device: as the user becomes more cognisant of the device, the better their performance is in accuracy and response time. Confidence levels for size discrimination were highest with sensory feedback active. There was a significantly positive correlation (positive gradient) between accuracy and confidence. With no sensory feedback, confidence was on average 70% which increased to 84% with sensory feedback. Conclusions The non-invasive sensory feedback system met all design requirements successfully. Future recommendations include minor adjustments to the design to optimise its capabilities after which, the design can be revalidated and tested on transradial amputees. Future work includes performing usability studies with amputee subjects, revalidation of the design through bench testing and with amputee subjects, and evaluating the scalability and manufacturability of the design with a variety of commercially available body powered prostheses.
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    Design and development of a speculum-free digital cervical cancer screening device
    (2024) Hefer, Lehan; Sivarasu, Sudesh; Saidu, Rakiya
    Introduction Cervical cancer poses a significant global health challenge, particularly in low- and middle income countries (LMICs), where the disease remains a leading cause of cancer-related deaths among women. Despite the success of cytology-based screening programs in developed nations, implementing effective screening in resource-constrained environments has proven challenging. Visual Inspection with Acetic acid (VIA), a cost-effective alternative, has limitations due to subjective diagnosis, hindering large scale implementation. This research addresses the need for improved cervical cancer screening in LMICs through the design and development of a speculum-free digital screening device. Recognising the potential of digital technology to enhance VIA's diagnostic accuracy, the project aims to create a device that combines the simplicity and cost-effectiveness of VIA with digital advancements. This research aims to develop a speculum-free cervical cancer screening device that matches the diagnostic accuracy of the standard screening tool while enhancing usability. The objectives include the development of the device, verification guided by ISO 8600 standards for medical endoscopes and ISO 14971 risk assessment, and validation of the developed device's diagnostic performance and usability through a simulated clinical study. Materials and Methods The design and development of the cervical cancer screening device, the CerviScreen, used rapid prototyping and testing principles. Comprising five subsystems—housing, visualisation, liquid application, dilation, and decontamination—the subsystems were independently designed and subsequently integrated. The dilation subsystem, developed to enable speculum-free screening, simplifies the screening process and prioritises patient comfort. The device offers a less invasive screening procedure, providing real-time video images, controllable lights, and an acetic acid application system for cleaning the cervix and inducing the acetowhitening effect for diagnosis. The first verification phase tested the dilation subsystem's compliance with engineering specifications and selected the optimal dilation cup design. Subsequently, the complete device underwent verification using tests aligned with ISO 8600 standards and auxiliary tests done by predicate devices. The second verification phase assessed the risk of the device to identify and mitigate usability and functionality risks. Validation involved simulating a cervical cancer screening procedure using a female pelvic training model in a gynaecology clinic. This comparative study assessed the CerviScreen's diagnostic accuracy against the colposcope, with experienced gynaecologists conducting diagnoses, as well as the usability of the device. Ethics approval (Reference number: HREC REF 570/2023) was obtained for this validation study. Results and Analysis Five experienced gynaecologists from Groote Schuur Hospital participated in the study, averaging 14±7.01 years of experience. The CerviScreen and colposcope demonstrated a diagnostic accuracy of 80%, indicating comparable accuracy. Usability, measured by the System Usability Score (SUS), scored 83.75, indicating 'good' usability. Post-test feedback from the participants reflected positive perceptions regarding device usability and features. Conclusion The speculum-free digital cervical cancer screening device fulfilled all design requirements to complete an entire screening procedure. It was validated to have diagnostic accuracy equivalent to that of the standard device and good usability in the simulated screening environment. While the validation testing strength lay in utilising highly experienced gynaecologists, limitations arose from inaccuracies introduced by the simplified anatomy and pathology of the female pelvic model and cervices. Despite positive results and feedback, future testing on more accurate human anatomy is essential to establish the device's efficacy. Ongoing work involves refining specific design aspects based on input from the validation study.
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    Design and Development of a Traction Device for Semi-Automated Closed Cervical Spine Reduction Procedures
    (2021) De Villiers, Tertius; Sivarasu, Sudesh; Kruger, Nicholas
    Cervical facet dislocations are traumatic injuries which can cause severe compression to the spinal cord. This can lead to extreme adverse outcomes such as full body paralysis or loss of life. Treatment involves a closed reduction (CR) of the dislocated cervical facet joints and alignment of the spinal canal as the first step. This is the most rapid mechanism of decompressing the spinal cord and improving the neurological outcomes. This kind of injury is infrequent, with many clinicians seldom becoming well practiced in CRs, but when they do occur, these injuries require immediate urgent treatment. In addition to this, the existing equipment can be awkward to use and lacks an intuitive framework for operation. This led to the development of the collaTract, a device taking the form of a single item of equipment, able to guide a user through the performance of a CR procedure while avoiding cumbersome and heavy equipment. It is wedge shaped, with an articulating arm, connecting to a patient's skull via commonly used traction callipers. It was designed to apply force to, and alter the angle of the patient's neck allowing it to perform all operations required for a CR. The device was tested for functionality on a single cadaver, after which, a usability study was performed with ten clinicians of varying skill and experience comparing the traditional equipment of weights and a pulley to the collaTract. The device was able to perform all operations involved in a CR including, at any point, returning the neck to a neutral angle and removing the applied tension as would be the case when aborting a procedure. After the usability test, the participants rated the device excellent from a usability standpoint. Of the returned feedback all participants rated the collaTract easier to use than the current equipment and they viewed the collaTract as an improvement over the current equipment. It is important to state that the cadavers in this study had intact cervical spines with no dislocation; therefore, future studies must look into validating the collaTract device with real world spine dislocation models. In conclusion, the collaTract device can perform the functions necessary for a closed cervical reduction procedure. The device was rated by ten different clinicians of varying skill levels as excellent in terms of its usability and can be seen as a new state of the art device in treatment of cervical spine dislocations.
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    Design and development of an adaptive external bone fracture fixation system
    (2019) Herbert, Christopher; Sivarasu, Sudesh
    External fixation is a surgical treatment primarily utilised for long bone fracture stabilisation. External fixation, through either pin or wire insertion, is done by constraining bone fragments and providing support to the injury via external scaffolding built across the fracture., but it can also be used to solve both traumatic and congenital bony deformities. Certain devices, particularly the Ilizarov Ring Fixator, can employ external bone fixation to create a biomechanical environment to gradually correct deformities (comprised of: translation, rotation and angulation). A typical application for deformity correction is the fixation of lower leg fractures, particularly tibial fractures, which have been recognised as the most common incident in long bone fractures. External ring fixators have become more developed; manufactured from sophisticated materials; or designed to incorporate computational support, to achieve accurate correction, however these factors have created limitations regarding their accessibility, complexity and ease in application. In addition, standard systems are not as versatile or correctively exact as required to prove their cost of use, creating reluctance as well as added bias towards the more developed devices. Threedimensional and multi-planar deformity correction has become major factors for current devices, yet the feasibility to use such expensive and complex devices may not be beneficial for all parties. External Fixation Systems are considered operationally expensive. Standard systems still utilise expensive and cumbersome setups, while developed devices require computational consultation and extensive training. With such complex procedural actions required to facilitate multi-planar correction, most devices utilise computational support, which in turn minimizes the clinician’s control. The current study aims to design a light-weight Adaptive External Bone Fracture Fixation System that can offer definite treatment and full clinical control over the injury. The system is to be able to stabilise and offer correction of planar bony deformities via controlled shape change. The functional verification of the device was limited to (according to the scope) stress testing. The proposed device consists of hinge systems capable of allowing for full assembly expansion to permit quick installation for various injury structures or states. In addition, the design possesses longitudinal elements that can offer both rapid and finite lengthening (with lock-and-switch) to offer both rapid and gradual system shape change, improving the control over the injury fixation. The device stress testing had revealed limited capabilities in providing enough scaffolding stability for a certain directional stress condition. To determine the quality of its structural integrity, the device was loaded under direct compressive and tensile load. The strain generated was measured and analysed using a Load-Deformation Curve. The device could support tension close to [3.5 kN], equivalent to standard models, whilst unable to support compression for loads close to [1.2 kN]. The conclusive points that were made had detailed that it was limited by its structural integrity, however the design was evaluated as functionally versatile as and should be further developed. Future recommendations proposed include the addition of constrained joints; improved locking capabilities; implementation of failure modes for hinges and lastly improved structural integrity by using sophisticated materials to further validate the skeletal structure of the fixation system.
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    Design and Development of an Autoinjector Tracking Device to Integrate with Emergency Service
    (2024) Maqungu, Qhamani; Sivarasu, Sudesh
    Anaphylaxis is a life-threatening allergic reaction that requires treatment by prompt injection of epinephrine typically via epinephrine autoinjectors (EAI). An immediate visit to the emergency room (ER) to avoid possible relapse is necessary. Studies have shown that the effectiveness of epinephrine decreases with the prolonged delay of injection after symptoms onset. Many patients get hospitalised or die due to delayed epinephrine injection or unavailability of the EAI devices when it is mostly needed. Some of the reasons for unavailability at the incident site is usually associated with patients forgetting to carry their EAI. Some patients hesitated to administer epinephrine, resulting to a relapse hours later and while some did not seek further monitoring from a trained clinician after administering epinephrine. This study aimed at designing and developing an EAI tracking device to send reminder notifications to patients when they are located ten meters away from their EAI, and to alert emergency medical services (EMS) via SMS, containing location, when the patient is experiencing anaphylaxis. Using Impulse Biomedical's EAI ZibiPen device as a use case, a Bluetooth low energy (BLE) tracking device named GuardAin, was developed and linked to an Android mobile phone application. A pilot case-based study aimed at validating the accuracy of the notification alert algorithm in threedimensional directions was conducted at the Impulse Biomedical offices in the Western Cape. The test conditions were phone in hand and phone in pocket. The distance algorithm was validated using a ttest. The location accuracy from the emergency alert SMS was validated and compared to Google Maps. A total of 80 notification alert tracking tests were conducted. Forty tests were conducted for the horizontal direction test resulting in the detection of ten meters with an average of 10.7 meters. Forty vertical tests resulted in poor detection of a ten-meter distance. However, consistency in detecting three meters was observed with an average of 3.3 meters. The 3.3 meters was the average floor height in the building. Eight locations were selected as the choice of emergency trigger locations. The emergency alert locations were accurately detected within a 50-meter radius. The algorithm was found to be fairly accurate in detecting 10 meters and could serve as a reliable reminder for EAI adherence. However, walking pace determined how far past ten meters the notifications were sent. SMS emergency alerts were found useful to detect EAI usage and accurately relaying patient location to EMS and other emergency contacts. Future works include investigating the usability of the reminder system, and practicality of the emergency services alert system. Additionally, the tracking algorithm to be validated with different Android mobile devices.
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    Design and development of an automated MDI delivery system with breath detection for use with oxygen therapy
    (2024) Eyasim, Muhammad Arshad; Sivarasu, Sudesh
    Introduction: Metered Dose Inhalers (MDI) are pressurised canisters that contain a bronchodilator medication used to treat obstructive lung disease symptoms. The medication is delivered to the lungs' airways by simultaneously actuating the MDI and inhaling, and the medication's effectiveness depends on optimal actuation-inhalation coordination. With the emergence of Covid-19, the use of MDI has increased among ventilated patients with Chronic Obstructive Pulmonary Disease or Asthma. This emphasised the difficulty with actuation-inhalation coordination, in which a nurse must remain by the bedside to monitor inhalation, time the actuations, and synchronise the actuations with inhalation, which is inaccurate because it more often falls outside the desired range of 0.2 s, resulting in lower drug effectiveness. To address the inaccurate actuation inhalation coordination and the limited number of Intensive Care Unit (ICU) resources, a need was identified for a device that can be used outside of ICU settings and can automatically deliver bronchodilator medications using MDIs. Methods: An automated MDI delivery system with breath detection was designed and developed. The device comprises of an actuation mechanism, a breath detection system, and a user interface. A cam and servo mechanism actuates the canister, the breath detection system detects inhalation with a pressure and flow rate sensor, and the user interface (UI) consists of a display and a rotary encoder. The device was tested using a continuous positive airway pressure device and a breathing simulator to validate the accuracy of the breath detection system, the accuracy of the actuation mechanism, and the device's operation. The device was then validated against the existing manual solution by comparing the delay between the actuation and the inhalation signal to determine the effectiveness of the developed device. Results: The developed device includes all the required functionalities and an intuitive UI. The device, however, is quite large and not impact-resistant; the noise during actuation can be disturbing, and it can only be used with canisters that do not require shaking before actuation. The device detects inhalation 0.11 s before the inhalation signal, and the servo actuates the canister in 0.25 s. This time difference of 0.14 s allows the medication to be delivered within the desired time after the onset of inhalation. Based on the user input settings, the device also operates as intended and the interval between actuations is the required 15 s. The automated test also shows a constant delay time of 0.14 s between the actuation and onset of inhalation, compared to the delays in the manual test, which vary and are mostly outside of the acceptable range. Conclusion: The results show that the device works as intended and is more effective than the existing manual solution by providing an automated and improved solution for bronchodilator therapy, thus increasing the medication delivery's effectiveness. Future recommendations are made to improve the device's design, and future work includes further validating the device's effectiveness.
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    Design and Development of an Open-Source ADL-Compliant Prosthetic Arm for Transradial Amputees
    (2021) Timm, Lara; Sivarasu, Sudesh
    Transradial amputation is traumatic – leading to the amputee having a limited ability to perform activities of daily living (ADLs). Below-elbow prostheses are prescribed. The high cost associated with prostheses results in many amputees in low-to-middleincome countries relying on government subsidised devices, which are cosmetic rather than functional, or none at all. Open-source prostheses have the potential to increase the accessibility of functional prosthetic arms, but at present are not optimised to assist the dominant hand in performing bimanual ADLs. The aim of this study is thus to design and experimentally validate an open-source prosthetic arm that is functionally optimised for the performance of ADLs in the unilateral transradial amputee population. The ADL arm is functional open-source below-elbow prosthesis. This device is bodypowered; featuring a hand terminal device with thumb abduction and adduction, and wrist pronation and supination functionality. Elbow flexion of the residual limb is used to actuate the terminal device. The prosthesis requires no existing prosthetic hardware; and the majority of parts can be 3D printed. The ADL arm is designed to reliably perform the grasps required by the non-dominant hand in two-handed ADL activities. Device validation includes functional and simulated-use components. The functional assessment uses the Anthropomorphic Hand Assessment Protocol (AHAP); while the simulated-use assessment involves a practical ADL verification, and a usability assessment using healthy volunteer participants. The AHAP gives as result a grasping ability score (GAS) and partial GAS for ten grasp types associated with ADLs. The GAS represents the percentage of healthy limb function achievable by the prosthesis. The overall GAS of the ADL arm is found to be 68 %. The ADL arm achieved a partial GAS of greater than 75 % for four of five bimanual ADL grasps. A major design flaw resulted in a partial GAS of 33.3 % for the lateral pinch grasp type. The performance in this grasp, as well as others, would be greatly improved by the inclusion of a mechanism to lock the distal joint of the digits in extension during grasp. In this way, the hand would be better able to apply force to an object with the pads of the digits. Simulated-use validation of the ADL arm is performed on healthy participants using the designed bypass socket. The ADL assessment involves the completion of 86 ADL and instrumental ADL tasks; scored using the designed self-report questionnaire. The participant could perform all but seven tasks independently, and the perceived difficulty for tasks requiring the prosthesis was low overall. Seven healthy volunteers are used to assess the system usability. Participants performed a number of tasks and then completed the system usability scale (SUS). The perceived usability of the device is found to increase with increased device familiarity, yielding an overall score of 84.29. This result indicates that participants found the experience with the device to be ‘good' overall. In conclusion, the ADL arm is functionally competent and has proven its ability to assist in the performance of ADLs in a simulated-use environment; using healthy participants. A number of design modifications are recommended to overcome the limitations of the current design, which should be tested in the transradial amputee population to corroborate the results obtained in this study.
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    Design and Development Towards a Novel Prosthesis for Total Shoulder Arthroplasty to Reduce Aseptic Glenoid Loosening
    (2018) Dey, Roopam; Sivarasu, Sudesh; Roche, Stephen
    Total shoulder arthroplasty (TSA) is the most common surgical solution, that helps in restoring the structural and functional integrity of a diseased glenohumeral (GH) joint with intact rotator-cuff. A 300% increase in the usage of TSA has been observed since 2007, along with 2.5% increase in revision rate. Aseptic glenoid loosening accounts for 37% of postsurgical failures in TSA. Eccentric loading of the prosthetic glenoid cup, leading to the “rocking horse” effect, is one of the prevalent causes of aseptic glenoid loosening. Current anatomical total shoulder prosthesis (ATSP) geometry does not consider all the GH morphometric features, for example the elliptical shape of the humeral head. Moreover, the morphometric studies leading to the initial ATSP design did not consider the GH morphology of any sub-Saharan population. Hence, there exists a gap in understanding of the implications of certain morphometric features on the functionality of a post-TSA GH joint. This thesis had two primary aims to address this gap in knowledge. Firstly, to study the GH morphometric variations between cohorts representing native European (Swiss) and native sub-Saharan (South African) populations. Secondly, to develop anatomically inspired ATSP design concepts and test them using biomechanical and finite element (FE) models, insilico, under standardised testing protocols. The morphometric analysis suggested that an average Swiss humeral head radius of curvature was larger (P<0.05) than the average South African humeral head. By comparing the biological head sizes, across both the populations, with the dimensions of the commercially available humeral heads, it can be inferred that suitable humeral prostheses are currently not available for individuals with head sizes >28mm or <19mm. Considering both the populations, the inherent shape of an average humeral head was found to be elliptical. The thickest region of the head was found to lie in the posterior region and not at the geometric center. Hertzian contact theory was applied to calculate the GH stresses produced by symmetric and asymmetric elliptical heads. Higher concentric stresses (P<0.001), within the acceptable limit for polyethylene, were observed to be imparted by the asymmetric heads. Population-specific musculoskeletal models were developed to study the post-TSA kinematic variation. When an identical range of motion (RoM) was performed by these models, population-specific variation in muscle moment arms was observed. The novel glenoid designs were not found to alter the post-surgical kinematics. FE models of the biradial, compartmental and pear-shaped glenoid implant designs were subjected to compressive and shear loading according to the American Society for Testing and Materials (ASTM). Using the bi-radial the glenoid cup, with thickened posterior-superior surface, anatomically relevant force distribution patterns could be replicated. Compartmentalising the glenoid prosthesis into concentric and eccentric regions with the gaps, proved to be highly beneficial. When compared to a commercially available glenoid prosthesis, the compartmental prosthesis was able to contain the GH forces to the concentric region for longer, delaying the eccentric loading and therefore potentially reducing the “rocking horse” effect. In the light of the above observations, two conclusions can be drawn from this thesis. Firstly, it would be beneficial if population-specific ATSP were made available for natives of certain geographic locations. Secondly, glenoid prosthesis designs could be compartmentalised to contain the GH joint forces within the concentric regions of the cup which might aid in the reduction of post-TSA complications.
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    Design and in vivo verification of a stress radiography device towards it's suitability for multi-ligament laxity measurements
    (2017) Beukes, Giancarlo; Sivarasu, Sudesh
    The human knee is a hinge joint, primarily facilitating locomotion. Knee joint instability, due to ligament injuries, is a result of direct or indirect trauma, non-anatomical stresses during pivoting movements about the knee, imbalanced landing during jumping and rapid deceleration during high intensity locomotion. Biomechanical indications of an unstable knee joint include decreased joint integrity, hyperlaxity, abrupt locking and catching combined with clicking noises during locomotion. Approximately, two hundred and fifty thousand ACL injuries occur in the United States of America annually. Current diagnostic procedures are subjective according to the clinician's experience. This potentially leads to misdiagnosis of the injury and improper treatment. Non-invasive diagnostic techniques make use of manual methods, MRI and laxity measurement devices (e.g. arthrometers and stress radiography devices). Laxity measurement devices (the focus of this study) determine ligament health by measuring their elasticity and stiffness. Directional tibial and fibular bone translation is induced by applying an external load to the joint. The bone translation is measured in relation to the load applied, which denotes ligament laxity. The Laxmeter is a novel, cost effective and radiolucent multi-ligament laxity measurement stress radiography device. This device facilitates the measurement of MCL and LCL laxity at multiple degrees of knee joint flexion, however, it lacks the essential means to perform the laxity measurement technique. The current study aims to redesign the Laxmeter to perform ACL, PCL, MCL and LCL laxity measurement procedures at multiple fixed degrees of knee joint flexion. The in vitro functional verification of the device was limited to (according to scope) a single cadaver trial; to validate functionality, structural integrity, usability as well as demonstrate the Laxmeter concept prior to a prospective full clinical trial. The redesigned Laxmeter Prototype consists of a load applicator capable of applying a 250N load to various aspects of the proximal lower leg, to induce bone translation for laxity measurements. The load applicator is designed to integrate with the ergonomic patient support structure, the later potentially improving reproducibility and accuracy of the laxity measurement results. The cadaver trial demonstrated the device's capability of measuring the laxity of the ACL, MCL and LCL at predetermined knee flexion angles. To measure the ligament laxity, equal loads were applied to both proximal lower limbs independently. The bilateral average displacement of the tibia with respect to the femur for each ligament was noted. In the case of the ACL, the Laxmeter measured an average laxity of 3.07mm at 30° knee flexion and a load of 150N. The average laxities for the MCL and LCL at 30° knee flexion and 150N were 1.11mm and 2.02mm. The trial yielded preclinical results that were comparable with existing clinical and healthy cadaver based studies (using similar techniques), and suggests that the Laxmeter is capable of measuring the laxity of the ACL, MCL and LCL at various degrees of knee flexion. PCL laxity measurements could not be performed due to compromised structural integrity, which was essential to make the Laxmeter portable and lightweight. Future recommendations for the device include rotational ankle fixation; improved overall limb fixation; improved structural integrity to allow for PCL laxity measurements as well as further preclinical (functional) verification procedures prior to a full clinical trial.
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    Design of a Novel Video-Assisted Tube Over Tube Rigid Bronchoscope for the Removal of Foreign Bodies from the Bronchi Following Aspiration
    (2022) McEwan, Sarah Ann; Sivarasu, Sudesh; Myburgh, Adriaan
    Foreign body aspiration (FBA) is a prevalent occurrence in the paediatric population. FBA is when a foreign body (FB) is inhaled accidentally into the airways. The location of the FB may differ according to each patient, but in most cases, the FB is found in the right bronchial tree. FBA symptoms are often misdiagnosed, resulting in late discovery of the obstruction. There is an increase in difficulty to remove a FB, dependent on how long it remains within the airway. This poses a greater risk to the patient, fatality or other serious long-term complications. Currently, FBs are removed using a bronchoscope in conjunction with a pair of forceps. The two types of bronchoscopes used currently are the flexible and rigid bronchoscopes. The rigid scope is preferred for FB removal due to better control and clear visuals of the air way and an array of forceps ends. The costly flexible scope is more difficult to use and is used in cases where radiological findings of a FB are inconclusive. During insertion of the scope, no ventilation is supplied to the patient, posing a high risk of hypoxia. Both instruments require considerable skill and extensive training, limiting the procedure applicability. The difficulty experienced when handling the current instruments and the high risk of hypoxia are motivations for a product redesign. Therefore, this study aims to design and develop a novel video-assisted tube-over-tube rigid bronchoscope to remove foreign bodies from the airways following aspiration, whilst providing constant ventilation and visualisation of the airway. The redesign compromises of several subsystems: the rigid bronchoscope (and attached camera), ventilation connector tube and an uncuffed endotracheal tube (ETT). These subsystems were designed to ensure constant ventilation throughout the insertion of the bronchoscope, whilst providing real-time imaging of the airways. The design incorporated a guiding mechanism to increase the usability further. A testing protocol was performed on a Laerdal airway management trainer using the designed device, named the ‘Re-Aspire' device and its competitor, the Karl Storz rigid bronchoscope. The testing participants were a group of anaesthesiologists who have had prior training in bronchoscopy, but do not practise the procedure. A common FB was placed inside the airway of the trainer, and both scopes were used to retrieve it. The facilitator timed the procedure and observed the participants. Post testing, each participant was interviewed about the functionality of each device and completed a system usability scale. A total of 34 attempts of FB removal was recorded for the rigid bronchoscope compared to 14 attempts for the Re-Aspire device. As hypothesised, the estimated average hypoxic time was more than double for the rigid bronchoscope compared to that of the Re-Aspire device. According to the system usability scale, the Re-Aspire device resulted in a higher average system usability score. These results demonstrated that the Re Aspire device has a higher perceived ease of use and system satisfaction according to the user's perspective. Therefore, achieving all the stated testing hypotheses. However, the design of the device can be improved to increase the usability and efficacy further.
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    Design of a wireless ureteropyeloscope
    (2015) Ncube, Mkhokheli; Sivarasu, Sudesh; Lazarus, John
    Ureteroscopy is a form of endoscopy that concerns itself with the urinary system. Flexible ureteropyeloscopes are instruments used to access the urinary system for diagnostic and therapeutic procedures. An average ureteropyeloscope requires a repair for every 3 to 13 hours of use, or alternatively 6 to 15 procedures. Therefore, there is a need to increase the durability of the ureteropyeloscope to lower the frequency of repairs required. In addition, the number of cables in the workspace needs to be reduced for improved handling by the clinician. The present study details the design of an ureteropyeloscope, which is modelled after currently existing instruments. Current endoscopes use fibre-optics for lighting area of interest as well as image acquisition. However, the ureteropyeloscope discussed was developed with a camera at the distal end of the insertion tube as its image acquisition system. The images captured were transmitted to a monitor for viewing via a wireless transmission module. The ureteropyeloscope discussed in the study was aimed at increasing the durability of the deflection unit of the ureteropyeloscope, with primary component made of nitinol, and reducing the number of cables around the workstation by using wireless means to transmit images from image acquisition system to monitor.