Meeting oxygen requirements of rural India: A self-contained solution.

Addressing oxygen requirements of rural India should aim at using a safe, low-cost, easily available, and replenishable source of oxygen of moderate purity. This may be possible with the provision of a self-sustaining oxygen concentrator (pressure swing adsorption with multiple molecular sieve technology) capable of delivering oxygen at high-flow rates, through a centralized distribution system to 100 or more bedded rural hospitals, with back up from an oxygen bank of 10 × 10 cylinders. This will provide a 24 × 7 supply of oxygen of acceptable purity (~93%) for the treatment of hypoxemic conditions and will enable hospitals to specifically provide for high-flow oxygen in at least 15% of the beds. It may also serve as a facility for a local refill of oxygen cylinders for emergency use within the hospital as well as to subsidiary primary health centers, subcenters, and ambulances, thereby nudging our health-care system toward self-sufficiency in oxygen generation and utilization.

Automated Home Oxygen Delivery for Patients with COPD and Respiratory Failure: A New Approach.

Long-term oxygen therapy (LTOT) has become standard care for the treatment of patients with chronic obstructive pulmonary disease (COPD) and other severe hypoxemic lung diseases. The use of new portable O2 concentrators (POC) in LTOT is being expanded. However, the issue of oxygen titration is not always properly addressed, since POCs rely on proper use by patients. The robustness of algorithms and the limited reliability of current oximetry sensors are hindering the effectiveness of new approaches to closed-loop POCs based on the feedback of blood oxygen saturation. In this study, a novel intelligent portable oxygen concentrator (iPOC) is described. The presented iPOC is capable of adjusting the O2 flow automatically by real-time classifying the intensity of a patient's physical activity (PA). It was designed with a group of patients with COPD and stable chronic respiratory failure. The technical pilot test showed a weighted accuracy of 91.1% in updating the O2 flow automatically according to medical prescriptions, and a general improvement in oxygenation compared to conventional POCs. In addition, the usability achieved was high, which indicated a significant degree of user satisfaction. This iPOC may have important benefits, including improved oxygenation, increased compliance with therapy recommendations, and the promotion of PA.

Contemporary portable oxygen concentrators and diverse breathing behaviours -- a bench comparison.

BACKGROUND: Decades of clinical research into pulsed oxygen delivery has shown variable efficacy between users, and across a user's behaviours (sleep, rest, activity). Modern portable oxygen concentrators (POCs) have been shown as effective as other oxygen delivery devices in many circumstances. However, there are concerns that they are not effective during sleep when the breathing is shallow, and at very high respiratory rates as during physical exertion. It can be challenging to examine the determinants of POC efficacy clinically due to the heterogeneity of lung function within oxygen users, the diversity of user behaviour, and measurement issues. Representative bench testing may help identify key determinants of pulsed-oxygen device efficacy. METHODS: Three contemporary devices were bench-evaluated across three simulated breathing behaviours: activity, rest, & oronasal breathing during sleep. Emphasis was placed on breathing patterns representative of oxygen users. RESULTS: All three POCs performed well during simulated breathing during exertion and at rest. Differences in triggering ability were noted for the scenario of oronasal breathing during sleep. CONCLUSIONS: The results are supportive of contemporary POC triggering abilities. The differences shown in ultimate trigger sensitivity may have relevance to oronasal breathing during sleep or other challenging scenarios for pulsed oxygen delivery, such as dominant mouth breathing during exertion or unfavourable nasal geometry.

Efficacy of a portable oxygen concentrator with pulsed delivery for treatment of hypoxemia during equine field anesthesia.

OBJECTIVE: Hypoxemia is common during equine field anesthesia. Our hypothesis was that oxygen therapy from a portable oxygen concentrator would increase PaO2 during field anesthesia compared with the breathing of ambient air. STUDY DESIGN: Prospective clinical study. ANIMALS: Fifteen yearling (250 - 400 kg) horses during field castration. METHODS: Horses were maintained in dorsal recumbency during anesthesia with an intravenous infusion of 2000 mg ketamine and 500 mg xylazine in 1 L of 5% guaifenesin. Arterial samples for blood gas analysis were collected immediately post-induction (PI), and at 15 and 30 minutes PI. The control group (n = 6) breathed ambient air. The treatment group (n = 9) were administered pulsed-flow oxygen (192 mL per bolus) by nasal insufflation during inspiration for 15 minutes PI, then breathed ambient air. The study was performed at 1300 m above sea level. One-way and two-way repeated-measures anova with post-hoc Bonferroni tests were used for within and between-group comparisons, respectively. Significance was set at p ≤ 0.05. RESULTS: Mean ± SD PaO2 in controls at 0, 15 and 30 minutes PI were 46 ± 7 mmHg (6.1 ± 0.9 kPa), 42 ± 9 mmHg (5.6 ± 1.1 kPa), and 48 ± 7 mmHg (6.4 ± 0.1 kPa), respectively (p = 0.4). In treatment animals, oxygen administration significantly increased PaO2 at 15 minutes PI to 60 ± 13 mmHg (8.0 ± 1.7 kPa), compared with baseline values of 46 ± 8 mmHg (6.1 ± 1 kPa) (p = 0.007), and 30 minute PI values of 48 ± 7 mmHg (6.5 ± 0.9 kPa) (p = 0.003). CONCLUSIONS: These data show that a pulsed-flow delivery of oxygen can increase PaO2 in dorsally recumbent horses during field anesthesia with ketamine-xylazine-guaifenesin. CLINICAL RELEVANCE: The portable oxygen concentrator may help combat hypoxemia during field anesthesia in horses.

Comparison of domiciliary oxygen using liquid oxygen and concentrator in northern Taiwan.

BACKGROUND/PURPOSE: Long-term oxygen therapy has become standard treatment for patients with chronic respiratory insufficiency. However, patterns of long-term home oxygen therapy have not been well studied in Taiwan. Oxygen concentrator systems are commonly used in Taiwan, but liquid oxygen delivery systems are portable and may provide advantages over the concentrator system. This study compared oxygen usage between patients from a liquid oxygen group (LOG) and an oxygen concentrator group (OCG). The authors also assessed the physiologic responses of patients with chronic obstructive pulmonary disease (COPD) to ambulatory oxygen use at home. METHODS: The study used a retrospective, cross-sectional, observational survey design. The LOG comprised 42 patients, and the OCG comprised 102 patients. We recruited participants in northern Taiwan from July 2009 to April 2010. The questionnaire instruments that were used to collect data consisted of three parts: demographic characteristics, devices used in respiratory care, and activity status with portable oxygen. Two-minute walking tests were performed on COPD patients in their homes. RESULTS: COPD was the most common diagnosis in our study, with more than 50% of patients who received oxygen long term in both groups having received this diagnosis. The LOG used oxygen for an average of 21.7 hours per day, whereas OCG averaged 15.2 hours per day (p<0.001). In the OCG, 92.2% of patients used a concentrator alone, whereas 23.8% of the LOG used liquid oxygen alone (p<0.001). The LOG patients were involved in significantly more outdoors activities (p=0.002) and reported traveling with oxygen more often (p<0.001) than the OCG patients. For patients with the same dyspnea level of COPD severity, those using liquid oxygen had a lower increase in pulse rate after the walking test, in comparison with the concentrator users. CONCLUSION: Patients in the LOG used oxygen for longer hours, went on more outings, and were more likely to travel with oxygen than patients in the OCG. Being ambulatory with liquid oxygen might enable patients with COPD to walk more effectively.

FiO2 delivered by a turbine portable ventilator with an oxygen concentrator in an Austere environment.

BACKGROUND: Management of critically ill patients in austere environments is a logistic challenge. Availability of oxygen cylinders for the mechanically ventilated patient may be difficult in such a context. A solution is to use a ventilator able to function with an oxygen concentrator. OBJECTIVES: We tested the SeQual Integra™ (SeQual, San Diego, CA) 10-OM oxygen concentrator paired with the Pulmonetic System(®) LTV 1000 ventilator (Pulmonetic Systems, Minneapolis, MN) and evaluated the delivered fraction of inspired oxygen (FiO2) across a range of minute volumes and combinations of ventilator settings. METHODS: Two LTV 1000 ventilators were tested. The ventilators were attached to a test lung and FiO2 was measured by a gas analyzer. Continuous-flow oxygen was generated by the OC from 0.5 L/min to 10 L/min and injected into the oxygen inlet port of the LTV 1000. Several combinations of ventilator settings were evaluated to determine the factors affecting the delivered FiO2. RESULTS: The LTV 1000 ventilator is a turbine ventilator that is able to deliver high FiO2 when functioning with an oxygen concentrator. However, modifications of the ventilator settings such as increase in minute ventilation affect delivered FiO2 even if oxygen flow is constant on the oxygen concentrator. CONCLUSIONS: The ability of an oxygen concentrator to deliver high FiO2 when used with a turbine ventilator makes this method of oxygen delivery a viable alternative to cylinders in austere environments when used with a turbine ventilator. However, FiO2 has to be monitored continuously because delivered FiO2 decreases when minute ventilation is increased.

Efficacy of Oxygen Treatment Using Home Oxygen Concentrators for the Treatment of Cluster Headaches: A Randomized, Crossover, Multicenter Study.

BACKGROUND AND PURPOSE: Oxygen treatment is the first-line acute treatment for cluster headaches (CHs), but this can be impeded by insurance coverage and oxygen-tank maintenance. Oxygen concentrators filter nitrogen from ambient air to produce oxygen-rich gas, and can therefore be an alternative to conventional oxygen therapy using a tank. We investigated the effectiveness and safety of using two home oxygen concentrators and compared them with using oral zolmitriptan for the acute treatment of CHs. METHODS: Forty patients with episodic CHs in an active cluster period were enrolled in this randomized, crossover, multicenter study. Two attacks during the cluster period were treated using oxygen delivered by connecting two home oxygen concentrators, whereas the other two attacks were treated using oral zolmitriptan (5 mg) in a random sequence. The primary endpoint was substantial pain reduction (0 or 1 on a five-point rating scale from 0 to 4 points) at 15 min after treatment. RESULTS: In total, 125 attacks among 32 patients were randomized and treated (63 attacks using oxygen and 62 using zolmitriptan) according to the study protocol. More attacks treated using oxygen reached the primary endpoint than did those treated using zolmitriptan (31.7% [20/63] vs. 12.9% [8/62], p=0.013). After 30 min, 57.1% of the patients who received oxygen and 38.7% who received zolmitriptan reported pain relief (p=0.082). All patients treated using oxygen reported an improvement in pain, and 61.3% preferred oxygen while only 9.7% preferred zolmitriptan. No adverse events occurred during the oxygen treatment. CONCLUSIONS: Oxygen treatment administered using two home oxygen concentrators resulted in better pain relief than oral zolmitriptan in patients with episodic CHs. Our results suggest that home oxygen concentrators are capable of efficiently supplying oxygen in a similar manner to using an oxygen tank.

A translational study evaluating a ruggedized portable oxygen concentrator versus an oxygen cylinder in simulated polytrauma intubation of swine.

Objectives: Portable oxygen concentrators (POCs) are medical devices that use filters to selectively remove nitrogen from ambient air to produce concentrated, medical-grade oxygen. This is the first study to evaluate a ruggedized POC's performance during simulated polytrauma intubation. Methods: Twenty-seven swine were intubated and anesthetized with ketamine. At T = 0, animals were extubated, received a chest wall injury, a tibia fracture, and 20% total blood volume controlled hemorrhage was initiated. At T = 10 min, the swine were pre-oxygenated using a bag-valve mask connected to one of three randomized oxygen sources: (1) a ruggedized POC, (2) a M-15 oxygen cylinder, or (3) room air (control). At T = 12 min, animals were re-intubated to simulate polytrauma intubation and connected to the test oxygen source for the remainder of the experiment. Surviving animals entered a 2-h period where partial pressure of oxygen (PaO2), oxygen saturation (SpO2), and regional oxygen saturation (rSO2) were monitored. Groups were compared using analysis of variance (ANOVA), Fisher's exact, log-rank analysis, or mixed-effects model as appropriate. Results: All animals survived except one in the POC group. Mixed-effects models revealed differences between groups with regards to PaO2 (p < 0.0001) and SpO2 (p = 0.006). Based on post hoc analysis, oxygen cylinder PaO2 was superior to both POC and control, but there were no differences between POC and control PaO2. There were statistically and clinically significant differences in SpO2 during periods of pre-oxygenation (T = 10‒12 min), intubation (T = 12‒14 min), and immediately after intubation (T = 14‒20 min). The POC battery was consumed in 43 ± 13 min. Conclusion: In our swine model, a single, ruggedized POC provided inferior amounts of oxygen supplementation compared to an oxygen cylinder and performed no better than room air.

Health and Economic Impact of Different Long-Term Oxygen Therapeutic Strategies in Patients with Chronic Respiratory Failure: A French Nationwide Health Claims Database (SNDS) Study.

INTRODUCTION: Long-term oxygen therapy (LTOT) is reported to improve survival in patients with chronic respiratory failure. We aimed to describe effectiveness, burden, and cost of illness of patients treated with portable oxygen concentrators (POC) compared to other LTOT options. METHODS: This retrospective comparative analysis included adult patients with chronic respiratory insufficiency and failure (CRF) upon a first delivery of LTOT between 2014 and 2019 and followed until December 2020, based on the French national healthcare database SNDS. Patients using POC, alone or in combination, were compared with patients using stationary concentrators alone (aSC), or compressed tanks (CTC) or liquid oxygen (LO2), matched on the basis of age, gender, comorbidities, and stationary concentrator use. RESULTS: Among 244,719 LTOT patients (mean age 75 ± 12, 48% women) included, 38% used aSC, 46% mobile oxygen in the form of LO2 (29%) and POC (18%), whereas 9% used CTC. The risk of death over the 72-month follow-up was estimated to be 13%, 15%, and 12% lower for patients in the POC group compared to aSC, CTC, and LO2, respectively. In the POC group yearly mean total costs per patient were 5% higher and 4% lower compared to aSC and CTC groups, respectively, and comparable in the LO2 group. The incremental cost-effectiveness ratio (ICER) of POC was €8895, €6288, and €13,152 per year of life gained compared to aSC, CTC, and LO2, respectively. CONCLUSION: Within the POC group, we detected an association between higher mobility (POCs autonomy higher than 5 h), improved survival, lower costs, and ICER - €6 238, compared to lower mobility POCs users.

Oxygen Therapy in COPD.

Long-term oxygen therapy (LTOT) is a mainstay treatment for patients with severe resting hypoxemia secondary to chronic respiratory conditions including COPD. The evidence for LTOT is based on two trials that are now several decades old but have been insufficiently revisited. Therefore, many questions remain about precisely which patients experience the most benefit from LTOT, as well as how to define that benefit. Most studies have examined LTOT's effect on longevity rather than its impact on quality of life. In addition, many challenges exist in training both clinicians and patients on best practices for LTOT and associated equipment. Reimbursement policies have reduced the kinds of equipment available to the LTOT patient community, presenting additional challenges. This paper will review the current evidence for LTOT in COPD, the challenges involved with providing optimal therapy, and potential avenues of modernizing this essential intervention.

A goal programming-based fuzzy best-worst method for the viable supplier selection problem: a case study.

Since the COVID-19 outbreak has led to drastic changes in the business environment, researchers attempt to introduce new approaches to improve the capability and flexibility of the industries. In this regard, recently, the concept of the viable supply chain, which tried to incorporate the leagile, resiliency, sustainability, and digitalization aspects into the post-pandemic supply chain, has been introduced by researchers. However, the literature shows that there is lack of study that investigated the viable supplier selection problem, as one of the crucial branches of viable supply chain management. Therefore, to cover this gap, the current work aims to develop a decision-making framework to investigated the viable supplier selection problem. In this regard, owing to the crucial role of the oxygen concentrator device during the COVID-19 outbreak, this research selects the mentioned product as a case study. After determining the indicators and alternatives of the research problem, a novel method named goal programming-based fuzzy best-worst method (GP-FBWM) is proposed to compute the indicators' weights. Then, the potential alternatives are prioritized employing the Fuzzy Vlse Kriterijumsk Optimizacija Kompromisno Resenje method. In general, the main contributions and novelties of the present research are to incorporate the elements of the viability concepts in the supplier selection problem for the medical devices industry and to develop an efficient method GP-FBWM to measure the importance of the criteria. Then, the developed method is implemented and the obtained results are analyzed. Finally, managerial and theoretical implications are provided. Supplementary Information: The online version contains supplementary material available at 10.1007/s00500-022-07572-0.

COVOX: Providing oxygen during the COVID-19 health emergency.

We introduce an autonomous oxygen concentrator that was designed in Peru to fight the oxygen shortage produced worldwide as a consequence of the COVID-19 pandemic. Oxygen concentrators represent a suitable and favorable option for administering this gas at the patient's bedside in developing countries, especially when cylinders and tubed systems are unavailable or when access to them is restricted by lack of accessories, inadequate power supply, or shortage of qualified personnel. Our system uses a pressure swing adsorption technique to provide oxygen to patients at a flow rate of up to 15 l/min ± 1,5 l/min and a concentration of 93 % ± 3 %, offering robustness, safety and functionality. The quality measurements obtained from the validation process demonstrate repeatability and accuracy. The complete design files are provided in the source file repository to facilitate oxygen concentrator production in low and middle income countries, where access to oxygen is still a major problem even after the pandemic. Oxygen is part of the World Health Organization Model List of Essential Medicines and is perhaps the only medicine that has no substitute. This device can provide a reliable supply of oxygen for critically ill patients and improve their chances of survival.

Evaluation of Over-the-Counter Portable Oxygen Concentrators Utilizing a Metabolic Simulator.

BACKGROUND: Supplemental oxygen is designed to raise alveolar PO2 to facilitate diffusion into arterial blood. Oxygen is generally delivered by nasal cannula either by continuous or pulsatile flow. Battery-powered portable oxygen concentrators (POCs) facilitate ambulation in patients experiencing exertional hypoxemia. In the United States, the Food and Drug Administration (FDA) clears these devices to be sold by physician prescription. Recently, however, lower-cost devices described as POCs have been advertised by online retailers. These devices lack FDA clearance and are obtained over the counter (OTC) without prescription. This study determined whether a selected group of OTC POCs have oxygen delivery characteristics suitable for use by hypoxemic patients. METHODS: A metabolic simulator, capable of simulating a range of metabolic rates and minute ventilations, determined effects of oxygen supplementation delivered by a variety of devices on alveolar PO2 . Devices tested included 3 OTC POCs, an FDA-cleared POC, and continuous-flow oxygen from a compressed oxygen cylinder. End-tidal PETO2 , a surrogate of alveolar PO2 , was determined at each of each device's flow settings at 3 metabolic rates. RESULTS: Continuous-flow tank oxygen yielded a linear PETO2 increase as flow increased, with progressively lower slope of increase for higher metabolic rate. The prescription POC device yielded similar PETO2 elevations, though with somewhat smaller elevations in pulse-dose operation. One OTC POC was only technically portable (no on-board battery); it provided only modest PETO2 elevation that failed to increase as flow setting was incremented. A second OTC POC produced only minimal PETO2 elevation. A third OTC POC, a pulsed-dose device, produced meaningful PETO2 increases, though not as great as the prescription device. CONCLUSIONS: Only one of 3 OTC POCs tested was potentially of use by patients requiring ambulatory oxygen. Physicians and respiratory therapists should inform patients requiring portable oxygen that OTC devices may not meet their oxygenation requirements.

A heuristic-based hybrid algorithm to configure a sustainable supply chain network for medical devices considering information-sharing systems.

In today's hyper-competitive marketplace, the crucial role of the sustainability concept has been highlighted more. Hence, managers' attention has been attracted to the concept of sustainable supply chains. On the other hand, after the COVID-19 outbreak, the importance of medical devices and their demand has drastically enhanced, which has led to shifting the attention of researchers toward this industry. In this regard, based on the importance of the mentioned points, the current study configures a sustainable supply chain network for the medical devices industry. In this way, given the crucial role of the oxygen concentrator during the COVID-19 outbreak, the present study investigates the supply chain of the mentioned goods as a case study. Also, this research develops an efficient hybrid solution method based on goal programming, a heuristic algorithm, and the simulated annealing algorithm to solve the suggested model. Eventually, sensitivity analysis is conducted to examine the influence of the crucial parameters of the model on the outputs, and managerial insights are provided. According to the achieved results, the suggested model and the developed hybrid method demonstrate a good performance which shows their efficiency.

The Use of Portable Oxygen Concentrators in Low-Resource Settings: A Systematic Review.

INTRODUCTION: Portable oxygen concentrators (POCs) are medical devices that use physical means to separate oxygen from the atmosphere to produce concentrated, medical-grade gas. Providing oxygen to low-resources environments, such as austere locations, military combat zones, rural Emergency Medical Services (EMS), and during disasters, becomes expensive and logistically intensive. Recent advances in separation technology have promoted the development of POC systems ruggedized for austere use. This review provides a comprehensive summary of the available data regarding POCs in these challenge environments. METHODS: PubMed, Google Scholar, and the Defense Technical Information Center were searched from inception to November 2021. Articles addressing the use of POCs in low-resource settings were selected. Three authors were independently involved in the search, review, and synthesis of the articles. Evidence was graded using Oxford Centre for Evidence-Based Medicine guidelines. RESULTS: The initial search identified 349 articles, of which 40 articles were included in the review. A total of 724 study subjects were associated with the included articles. There were no Level I systematic reviews or randomized controlled trials. DISCUSSION: Generally, POCs are a low-cost, light-weight tool that may fill gaps in austere, military, veterinary, EMS, and disaster medicine. They are cost-effective in low-resource areas, such as rural and high-altitude hospitals in developing nations, despite relatively high capital costs associated with initial equipment purchase. Implementation of POC in low-resource locations is limited primarily on access to electricity but can otherwise operate for thousands of hours without maintenance. They provide a unique advantage in combat operations as there is no risk of explosive if oxygen tanks are struck by high-velocity projectiles. Despite their deployment throughout the battlespace, there were no manuscripts identified during the review involving the efficacy of POCs for combat casualties or clinical outcomes in combat. Veterinary medicine and animal studies have provided the most robust data on the physiological effectiveness of POCs. The success of POCs during the coronavirus disease 2019 (COVID-19) pandemic highlights the potential for POCs during future mass-casualty events. There is emerging technology available that combines a larger oxygen concentrator with a compressor system capable of refilling small oxygen cylinders, which could transform the delivery of oxygen in austere environments if ruggedized and miniaturized. Future clinical research is needed to quantify the clinical efficacy of POCs in low-resource settings.

Evaluation of an innovative low flow oxygen blender system for global access.

Background: Safe and effective oxygen delivery methods are not available for the majority of infants and young children globally. A novel oxygen blender system was designed to accurately deliver concentration-controlled, oxygen-enriched air to hypoxemic children up to age five. The system does not require compressed medical air, is compatible with both oxygen tanks and oxygen concentrators, and is low cost. This is the first study that tested the performance of the innovative oxygen blender system. Methods: The performance of the oxygen blender system was assessed in vitro based on delivered oxygen levels and flow rates with an oxygen tank, an oxygen tank using a nasal occlusion model, and an oxygen concentrator. Results: The measured %O2 of the performance test was within ± 5% of full scale (FS) of the target value across all flows and all nasal cannulas. Occlusion testing demonstrated that 50% occlusion did not significantly affect the system outputs. The oxygen blender system was shown to be compatible with both oxygen tanks and oxygen concentrators. Conclusions: The novel oxygen blender system accurately controls oxygen concentrations and blended air flow rates, and is compatible with both oxygen tanks and oxygen concentrators. This innovation may be an opportunity for improved infant and child oxygen treatment worldwide.

3D-printed activated charcoal inlet filters for oxygen concentrators: A circular economy approach.

As of May 2021, the current COVID-19 pandemic is still plaguing the world, challenging all the countries and their health systems, globally. In this context, conditions typical of low-resource settings surfaced also in high-resource ones (e.g., the lack of essential medical equipment, of resources etc.), while exacerbating in the already resource-scarce settings, because of COVID-19. This is the case of oxygen concentrators that are one of the first-line medical devices for treating COVID-19 patients. Since the beginning of 2020, their demand has been rapidly growing worldwide, aggravating the situation for low-resource settings, where the availability of devices providing oxygen-enriched air was already scarce. In fact, due to their delicacy, the lack of spare parts and of an appropriate health technology management system, oxygen concentrators can often be found broken or not working properly in these settings. The underlying problems have deep roots. The current regulatory frameworks and standards, which are set by high-income countries, are too stringent, and do not take into account the limited resources of poorer settings. Thus, they are often inapplicable in such settings. One of the main issues affecting the oxygen concentrators, is that related to the filters, which are designed to filter out dust, particles, bacteria, and to be used in medical locations complying with international standards (e.g., the air filtration level in a surgical theatre in Italy is at 99.97%). When used in low-resource settings, which do not comply with these standards and face several challenges (e.g., dust), these filters have a much-reduced lifespan. For these reasons, this paper aims to present the redesign of the inlet filter of an oxygen concentrator, which is used to prevent gross particles to enter the device. The redesign is based on a reverse engineering approach, and on the use of 3D-printing along with activated charcoal. After testing the filtration efficiency with a particle counter, the filter design has been refined through several iterations. The final prototype performs particularly well when filtering particles above 1 µm (with a filtration efficiency of 64.2%), and still has a satisfactory performance with any particle size over 0.3 µm (with a filtration efficiency of 38.8%). Following the United Nations Sustainable Development Goals, this project aims to empower local communities, and start a positive trend of self-sustained supply chain of simple spare parts for medical devices, leveraging on frugal engineering, 3D-printing, locally produced activated charcoal, and circular economy.

Subject Preferences and Psychological Implications of Portable Oxygen Concentrator Versus Compressed Oxygen Cylinder in Chronic Lung Disease.

BACKGROUND: Oxygen therapy represents the elective therapy to improve the quality of life for patients with chronic respiratory diseases like COPD and interstitial lung disease. Lightweight portable oxygen concentrators (POCs) are a valid alternative to traditional systems such as portable compressed oxygen cylinders. However, patient preference and the possible psychological implications related to the use of both devices have been poorly assessed. We sought to evaluate patient preference between the ambulatory oxygen systems (ie, a POC or a small cylinder) for patients with COPD and interstitial lung disease experiencing exertional desaturation in a rehabilitation setting. Furthermore, the use of one device in comparison with the other was related to specific mechanical characteristics and related to perceived quality of life, anxiety, and depressive symptoms. METHODS: 30 subjects with COPD and interstitial lung disease, who demonstrated exertional desaturation on room air during 6-min walk test (6MWT), were recruited. Each subject performed 2 6MWTs, in random order: one breathing oxygen via a POC and one with a portable compressed oxygen cylinder. Both devices were set up to ensure oxyhemoglobin saturation between 92% and 95% during the 6MWTs. All subjects completed a questionnaire assessing anxiety, depression, and quality of life. Each device was randomly assigned to each subject for 1 week, and then replaced with the other in the following week. At the end of the trial period, all subjects completed a questionnaire evaluating several aspects of the oxygen therapy devices. RESULTS: There were no significant differences in oxygen saturation or the mean distances achieved during the 6MWTs between the 2 portable oxygen devices. The subjects expressed greater preference for the POC (73.3%), basing their choice mainly on ease of transport and lower weight. Subjects' age also correlated with preferences: younger subjects were more negatively focused on the weight of the portable compressed oxygen cylinder, whereas older subjects considered the POC easier to manage. No significant differences in preferences were present between COPD and interstitial lung disease. CONCLUSIONS: The POC and the portable compressed oxygen cylinder performed in a comparable manner during 6MWT for subjects with COPD and interstitial lung disease and exertional desaturation. Subjects preferred the POC because it was associated with better mobility.

Experimental design of a "Snap-on" and standalone single-bed oxygen concentrator for medical applications.

A novel single-bed, "Snap-on" and standalone, medical oxygen concentrator design based on a rapid pressure swing adsorption process was investigated for continuous oxygen supply. The Snap-on concentrator design is easy to hook up to an existing compressed air source, and the unit can then be readily used to produce oxygen for medical applications. It is easily transportable and compared to a traditional oxygen concentrator with its dedicated compressor, the Snap-on concentrator is particularly relevant for the oxygen therapy needs of a larger number of patients in situations such as COVID-19. A commercially available LiLSX zeolite was used for the separation of oxygen from compressed ambient air. The experiments were performed at different feed air pressures using a constant supply of house air in the lab. Further, the device performance was also analyzed using a standalone medium size air compressor. The minimum bed size factor obtained with compressed house air was 100 lb/tons per day contained (TPDc) O2 at a cycle time of 7 s, whereas the minimum bed size factor obtained with a medium size air compressor weighing about 12 lbs was 210 lb/TPDc O2 at a cycle time of 14.5 s under the same feed pressures of 3.1 bar at an oxygen product purity of 90%. The product oxygen flow rate was nearly double for the same amount of adsorbent when using house air for the Snap-on design. The primary reason for this significantly higher oxygen production was the substantially higher and stable air throughput capacity of a typical house air compressor that enabled rapid cycling of the process at near-constant feed pressure compared to a medium size compressor used in a medical oxygen concentrator. The oxygen recovery was approximately 34% for both cases. Thus, the Snap-on oxygen concentrator was found to be easier to build and it delivered more oxygen for medical use compared to standalone units in locations where a constant supply of compressed feed air is available. This is typically the case in facilities such as hospitals, military medical camps and cruise ships. Further, the Snap-on design offers other benefits such as ease of transportation, higher reliability and lower weight.

Ventilators are not the answer in Africa.

The treatment of severely ill coronavirus disease 2019 (COVID-19) patients has brought the worldwide shortage of oxygen and ventilator-related resources to public attention. Ventilators are considered as the vital equipment needed to manage these patients, who account for 3% - 5% of patients with Covid-19. Most patients need oxygen and supportive therapy. In Africa, the shortage of oxygen is even more severe and needs equipment that is simpler to use than a ventilator. Different models of generating oxygen locally at hospitals, including at provincial and district levels, are required. In some countries, hospitals have established small oxygen production plants to supply themselves and neighbouring hospitals. Oxygen concentrators have also been explored but require dependable power supply and are influenced by local factors such as ambient temperature and humidity. By attaching a reservoir tank, the effect of short power outages or high demands can be smoothed over. The local and regional energy unleashed in the citizens to respond to the COVID-19 pandemic should now be directed towards developing appropriate infrastructure for oxygen and critical care. This infrastructure is education and technology intensive, requiring investment in these areas.