Shunt-mediated decompression sickness in a compressed air worker with an atrial septal defect.

We report a compressed air worker who had diffuse cutaneous decompression sickness with pain in his left shoulder and visual disturbance characteristic of migraine aura after only his third hyperbaric exposure. The maximum pressure was 253 kPa gauge with oxygen decompression using the Swanscombe Oxygen Decompression Table. He was found to have a very large right-to-left shunt across a 9 mm atrial septal defect. He had transcatheter closure of the defect but had some residual shunting with release of a Valsalva manoeuvre. Thirty-two other tunnel workers undertook the same pressure profile and activities in the same working conditions during the maintenance of a tunnel boring machine for a total of 233 similar exposures and were unaffected. As far as we are aware this is the first report of shunt-mediated decompression sickness in a hyperbaric tunnel worker in the United Kingdom and the second case reported worldwide. These cases suggest that shunt-mediated decompression sickness should be considered to be an occupational risk in modern compressed air working. A right-to-left shunt in a compressed air worker should be managed in accordance with established clinical guidance for divers.

Air Nozzle Injury: Barotrauma Resulted From an Industrial Accident.

Industrial accidents involving compressed air can lead to significant colonic injuries, ranging from minor tears to complete perforations. This study investigates a case of colonic barotrauma in a 40-year-old male oil refinery worker who suffered symptoms of lower abdominal discomfort, distension, and tenderness following the application of compressed air to his anus. Diagnostic tests, including blood count, abdominal X-ray, and ultrasonography, indicated fecal impaction, dilated bowel loops, and free gas under the diaphragm. An exploratory laparotomy revealed a 4 cm x 2 cm hole in the colon at the hepatic flexure. There were also small breaks in the mucosa at the junction of the recto-sigmoid. We surgically repaired the perforation with primary closure, metrogyl lavage, and the placement of an intra-abdominal pelvic drain. Two weeks later, the patient recovered without any complications and was discharged. This case report highlights the severe risks of non-medical compressed air exposure, as well as the critical need for immediate surgical intervention and preventive safety measures in industrial settings.

Laparoscopic Repair of Colorectal Perforations Induced by Compressed Air Pressure: A Case Report.

A compressed air nozzle has the potential to result in lethal injuries when handled inappropriately. Owing to the rarity of colorectal perforations due to barotrauma, no clear pathway to managing them has been established. We report an incident of a 33-year-old male patient who presented with tension pneumoperitoneum due to rectosigmoid perforations after being subjected to transanal compressed air insult. An emergency laparoscopic exploration with primary repair of the rectal perforation and Hartmann procedure were performed resulting in a smooth postoperative course. We hereby conclude that laparoscopy is a safe and effective approach associated with faster recovery and fewer adverse events.

Trauma dental y lesiones faciales por armas de aire comprimido: reporte de un caso / Dental trauma and facial injuries by airguns: a case report

Las armas de aire comprimido son utilizadas desde hace muchos años con distintos usos que van desde el tiro recreativo hasta el control de plagas. Las más comunes son aquellas que disparan ''balines" o esferas metálicas que pueden llegar a tener capacidad de penetrar tejidos dependiendo del tipo de carga y de la longitud del cañón. Se presenta un caso clínico de un masculino que fue agredido con un arma tipo pistola con carga de CO2 que recibió un impacto a nivel facial y sufrió laceración en piel de labio y fractura dental complicada.

Air guns have been used for many years for a variety of purposes ranging from recreational shooting to pest control. The most common are those that shoot "pellets" or metallic spheres that can penetrate tissues depending on the type of load and the length of the barrel. A clinical case is presented of a male who was assaulted with a CO2-loaded pistol-type weapon, hit at facial level, and suffered laceration of the lip's skin and complicated dental fracture.

U-Shaped Tube Based Liquid-Solid Triboelectric Nanogenerator for Harvesting Unutilized Compressed Air Energy.

Due to a lack of technologies that harvest green and sustainable energy, unutilized compressed air energy during the operation of pneumatic systems is wasted. Liquid-solid triboelectric nano-generators (L-S TENGs) have been widely used as an advanced technology with broad development prospects due to their advantages of a simple structure and long service life. Among them, liquid-solid triboelectric nanogenerators with tube structures have great potential for coupling multiple physical effects and integrating them into a single device. Herein, a U-shaped tube triboelectric nanogenerator composed of fluorinated ethylene propylene (FEP) and copper foil (UFC-TENG) is proposed to directly harvest unutilized compressed air energy. The UFC-TENG can collect unutilized compressed air energy with a stable peak voltage and current of approximately 33 V and 0.25 µA, respectively. When the alternating frequency of the liquid is 0.9 Hz, the unutilized compressed air can drive the UFC-TENG unit with an inner diameter of 12 mm, achieving a maximum output power of 3.93 µW at an external load resistance of 90 MΩ. The UFC-TENG is a novel driving method for L-S TENGs and demonstrates the promising potential of TENGs in the harvesting of unutilized compressed air energy in pneumatic systems.

Experimental Study: The Effect of Pore Shape, Geometrical Heterogeneity, and Flow Rate on the Repetitive Two-Phase Fluid Transport in Microfluidic Porous Media.

Geologic subsurface energy storage, such as porous-media compressed-air energy storage (PM-CAES) and underground hydrogen storage (UHS), involves the multi-phase fluid transport in structurally disordered or heterogeneous porous media (e.g., soils and rocks). Furthermore, such multi-phase fluid transport is likely to repeatedly occur due to successive fluid injections and extractions, thus, resulting in cyclic drainage-imbibition processes. To complement our preceding study, we conducted a follow-up study with microfluidic pore-network devices with a square solid shape (Type II) to further advance our understanding on the effect of the pore shape (aspect ratio, Type I: 5-6 > Type II: ~1), pore-space heterogeneity (coefficient of variation, COV = 0, 0.25, and 0.5), and flow rates (Q = 0.01 and 0.1 mL/min) on the repetitive two-phase fluid flow in general porous media. The influence of pore shape and pore-space heterogeneity were observed to be more prominent when the flow rate was low (e.g., Q = 0.01 mL/min in this study) on the examined outcomes, including the drainage and imbibition patterns, the similarity of those patterns between repeated steps, the sweep efficiency and residual saturation of the nonwetting fluid, and fluid pressure. On the other hand, a higher flow rate (e.g., Q = 0.1 mL/min in this study) appeared to outweigh those factors for the Type II structure, owing to the low aspect ratio (~1). It was also suggested that the flow morphology, sweep efficiency, residual saturation, and required pressure gradient may not severely fluctuate during the repeated drainage--imbibition processes; instead, becoming stabilized after 4-5 cycles, regardless of the aspect ratio, COV, and Q. Implications of the study results for PM-CAES and UHS are discussed as a complementary analysis at the end of this manuscript.

Analysis of Tangential Leakage Flow Characteristics of Oil-Free Scroll Expander for a Micro-Scale Compressed Air Energy Storage System.

Tangential leakage loss is the primary factor that significantly affects the output performance of oil-free scroll expanders. A scroll expander can function under different operating conditions, and the flow of tangential leakage and generation mechanism is different. This study employed computational fluid dynamics to investigate the unsteady flow characteristics of the tangential leakage flow of a scroll expander with air as the working fluid. Consequently, the effects of different radial gap sizes, rotational speeds, inlet pressures, and temperatures on the tangential leakage were discussed. The tangential leakage decreased with increases in the scroll expander rotational speed, inlet pressure, and temperature, and decreased with decrease in radial clearance. With an equal-proportional increase in radial clearance, the flow form of the gas in the first expansion and back-pressure chambers became more complicated; when the radial clearance increased from 0.2 to 0.5 mm, the volumetric efficiency of the scroll expander decreased by approximately 5.0521%. Moreover, because of the large radial clearance, the tangential leakage flow maintained a subsonic flow. Further, the tangential leakage decreased with increase in rotational speed, and when the rotational speed increased from 2000 to 5000 r/min, the volumetric efficiency increased by approximately 8.7565%.

[Systematic risk management for a planned gas shutdown in the high-care facility of a university hospital]. / Systematisches Risikomanagement für eine geplante Gasabschaltung im High-Care-Bereich eines Universitätsklinikums.

BACKGROUND: In the course of building extension works at Dresden University Hospital, it was necessary to shut down the central medical gas supply in a building with 3 intensive care wards with 22 beds, an operating theater tract with 5 operating rooms and 6 normal wards each with 28 beds during ongoing services. Thus, for the construction phase there was a need to establish an interim decentralized gas supply with zero failure tolerance for the affected functional units . METHODS: Following established procedures for possible risk and failure analysis, a project group was set up by the hospital's emergency and disaster management officer to develop a project plan, a needs assessment and a communication plan. RESULTS: A variety of risk factors were systematically identified for which appropriate countermeasures needed to be designed. The needs assessment over 4 h based on physiological parameters for the maximum available 22 ventilator beds resulted in 26,000 l of oxygen and 26,000 l of compressed air. A total of 7 supply points were each equipped with two 50l cylinders for both oxygen and compressed air, with a total availability of 175,000 l of each of the 2 gases. Another eight cylinders each were held in reserve. The project was carried out on a Saturday without an elective surgery program, so that the operating rooms concerned could be closed. The timing was chosen so that double staffing of intensive care personnel was available during the afternoon shift change. In advance, as many of the patients on mechanical ventilation as possible were transferred within the hospital; however, nine of the mechanically ventilated patients had to remain. The technical intervention in the gas supply lasted only 2 h without affecting the patient's condition. During the 2­h interim supply, 16,500 l of compressed air and 8000 l of oxygen were consumed on the high-care wards. The calculated hourly consumption per ventilated patient was 917 l of air (15 l/min) and 444 l of oxygen (7 l/min). The quantity framework based on empirical values from intensive care medicine was significantly lower. This was more than compensated for by the 10-fold stocking of gas and the predictably lower number of ventilated patients than the maximum occupancy used as a basis. CONCLUSION: For technical interventions in high-risk areas, careful planning and execution in an effective team is required. Established procedures of project management and risk assessment help to avoid errors.

A case of transanal barotrauma by high-pressure compressed air leading to transverse colon perforation with extensive colon serosal tear.

INTRODUCTION AND IMPORTANCE: Compressed air is used to apply paint, wash vehicles or machines, and remove water droplets after washing the precision instrument. Barotrauma due to high-pressure compressed air is extremely rare. CASE PRESENTATION: We report a case of transverse colon perforation caused by a compressed air gun in a 20-year-old male. He used a compressed air machine to dust after work, and a coworker inserted compressed air transanally as a joke. Although he returned home once, he consulted a former hospital with worsening abdominal pain. Radiography and computed tomography (CT) revealed a massive amount of free air. The patient was admitted to our hospital. The patient underwent emergency surgery. Transverse colon perforation with extensive serosal tears and massive air bubbles inside the omental bursa were observed. Double-barrel colostomy using transverse colon perforation point for decompression and diverting the stoma at the ileum end was performed with serosal tear repair and abdominal cleaning drainage. Four months after the surgery, the patient underwent colostomy and diverting stoma closure. CLINICAL DISCUSSION: The management of colon injury due to compressed air has two aspects: tension pneumoperitoneum and colon injury. The initial management of tension pneumoperitoneum is converted to open pneumoperitoneum and early emergency operation for colon injury is recommended as soon as full-thickness perforation is diagnosed. CONCLUSION: Transanal high-pressure compressed air can cause lethal situations, and we encountered a similar case that required surgical intervention.

Periarticular calcifications containing giant pseudo-crystals of francolite in skeletal fluorosis from 1,1-difluoroethane "huffing".

Inhalant use disorder is a psychiatric condition characterized by repeated deliberate inhalation from among a broad range of household and industrial chemical products with the intention of producing psychoactive effects. In addition to acute intoxication, prolonged inhalation of fluorinated compounds can cause skeletal fluorosis (SF). We report a young woman referred for hypophosphatasemia and carrying a heterozygous ALPL gene variant (c.457T>C, p.Trp153Arg) associated with hypophosphatasia, the heritable metabolic bone disease featuring impaired skeletal mineralization, who instead suffered from SF. Manifestations of her SF included recurrent articular pain, axial osteosclerosis, elevated bone mineral density, maxillary exostoses, and multifocal periarticular calcifications. SF was suspected when a long history was discovered of 'huffing' a computer cleaner containing 1,1-difluoroethane. Investigation revealed markedly elevated serum and urine levels of F-. Histopathology and imaging techniques including backscattered electron mode scanning electron microscopy, X-ray microtomography, energy dispersive and wavelength dispersive X-ray emission microanalysis, and polarized light microscopy revealed that her periarticular calcifications were dystrophic deposition of giant pseudo-crystals of francolite, a carbonate-rich fluorapatite. Identifying unusual circumstances of F- exposure is key for diagnosing non-endemic SF. Increased awareness of the disorder can be lifesaving.

Advanced Exergy Analysis of Adiabatic Underwater Compressed Air Energy Storage System.

Rapid development in the renewable energy sector require energy storage facilities. Currently, pumped storage power plants provide the most large-scale storage in the world. Another option for large-scale system storage is compressed air energy storage (CAES). This paper discusses a particular case of CAES-an adiabatic underwater energy storage system based on compressed air-and its evaluation using advanced exergy analysis. The energy storage system is charged during the valleys of load and discharged at peaks. The model was built using Aspen HYSYS software. Advanced exergy analysis revealed interactions between system components and the potential for improving both system components individually and the system as a whole. The most significant reduction in exergy destruction can be achieved with heat exchangers. The round-trip efficiency of this system is 64.1% and 87.9% for real and unavoidable operation conditions, respectively.

A Needle-Free Jet Injection System for Controlled Release and Repeated Biopharmaceutical Delivery.

Swift vaccination is necessary as a response to disease outbreaks and pandemics; otherwise, the species under attack is at risk of a high fatality rate or even mass extinction. Statistics suggest that at least 16 billion injections are administered worldwide every year. Such a high rate of needle/syringe injection administration worldwide is alarming due to the risk of needle-stick injuries, disease spread due to cross-contamination and the reuse of needles, and the misuse of needles. In addition, there are production, handling, and disposal costs. Needle phobia is an additional issue faced by many recipients of injections with needles. In addition to a detailed literature review highlighting the need for needle-free injection systems, a compressed air-driven needle-free jet injection system with a hydro-pneumatic mechanism was designed and developed by employing an axiomatic design approach. The proposed injection system has higher flexibility, uninterrupted force generation, and provides the possibility of delivering repeated injections at different tissue depths from the dermis to the muscle (depending on the drug delivery requirements) by controlling the inlet compressed air pressure. The designed needle-free jet injector consists of two primary circuits: the pneumatic and the hydraulic circuit. The pneumatic circuit is responsible for driving, pressurizing, and repeatability. The hydraulic circuit precisely injects and contains the liquid jet, allowing us to control the volume of the liquid jet at elevated pressure by offering flexibility in the dose volume per injection. Finally, in this paper we report on the successful design and working model of an air-driven needle-free jet injector for 0.2-0.5 mL drug delivery by ex vivo experimental validation.

Cutting Oxygen Production-Related Greenhouse Gas Emissions by Improved Compression Heat Management in a Cryogenic Air Separation Unit.

Oxygen production in cryogenic air separation units is related to a significant carbon footprint and its supply in the medicinal sphere became critical during the recent COVID-19 crisis. An improved unit design was proposed, utilizing a part of waste heat produced during air pre-cooling and intercooling via absorption coolers, to reduce power consumption. Variable ambient air humidity impact on compressed air dryers' regeneration was also considered. A steady-state process simulation of a model 500 t h-1 inlet cryogenic air separation unit was performed in Aspen Plus® V11. Comparison of a model without and with absorption coolers yielded an achievable reduction in power consumption for air compression and air dryer regeneration by 6 to 9% (23 to 33 GWh year-1) and a favorable simple payback period of 4 to 10 years, both depending on air pressure loss in additional heat exchangers to be installed. The resulting specific oxygen production decrease amounted to EUR 2-4.2 t-1. Emissions of major gaseous pollutants from power production were both calculated by an in-house developed thermal power plant model and adopted from literature. A power consumption cut was translated into the following annual greenhouse gas emission reduction: CO2 16 to 30 kilotons, CO 0.3 to 2.3 tons, SOx 4.7 to 187 tons and NOx 11 to 56 tons, depending on applied fossil fuel-based emission factors. Considering a more renewable energy sources-containing energy mix, annual greenhouse gas emissions decreased by 50 to over 80%, varying for individual pollutants.

Effect of Defocused Nanosecond Laser Paint Removal on Mild Steel Substrate in Ambient Atmosphere.

The obvious advantages of laser paint removal technology make it a viable alternative to traditional paint removal methods. Infrared nanosecond laser was used to remove paint from car body. The microstructure, composition, surface roughness, hardness and ablative products of the samples were analyzed. The effect of the process combination of laser defocus distance and ambient atmosphere (ambient air, compressed air and inert atmosphere) on the substrate damage and the paint removal effectiveness was explored, and the related mechanism was discussed. Defocus not only changed the fluence of laser spot but also increased the spot diameter. The effect of defocused laser paint removal on the paint and substrate was caused by the superposition of these two factors. The results show that the laser with defocus distance of +4 mm effectively removed the paint in inert atmosphere and has the least adverse effect on the substrate. The content of C element and organic components on the substrate surface was the lowest, and its surface roughness and hardness was very close to the uncoated substrate. Focused laser paint removal in ambient air caused the most serious damage to the substrate. Its surface microhardness increased by 11 HV, and the influence depth reached 37 µm. The mechanism of laser paint removal without auxiliary gas is the superposition of laser plasma effect, laser gasification effect and thermal stress effect. In open atmosphere (compressed air and inert atmosphere), the mechanism of laser paint removal is laser gasification effect and thermal stress effect. This research can provide practical references and theoretical basis for the large-scale industrial application of low/non-damage laser paint removal technology.

Colorectal barotrauma following compressed air spray to the perineum.

Colorectal injuries caused by high-pressure air compressors are rare and reported especially among industrial workers. They may appear because of intended or accidental injury. In the present paper, we report a case of colorectal injuries due to air insufflation from a distance towards the anus with the clothes on, as a means of a practical joke. The patient presented one day after the trauma to the Emergency Department with complaints of severe abdominal pain and vomiting. On examination, he had signs of peritonitis. A computed tomography (CT) scan did not show any perforation. Emergency laparotomy was performed with the suspicion of pneumatic pressure-induced lesions. A total resection of the colon was made with enterostomy. The pathologic examination of the resected piece revealed multiple gangrenous areas without perforation associated to signs of peritonitis. Follow up was uneventful. A reversal of the enterostomy was scheduled.

Water-Spray-Cooled Quasi-Isothermal Compression Method: Water-Spray Flow Improvement.

Water-spray-cooled quasi-isothermal compressed air energy storage aims to avoid heat energy losses from advanced adiabatic compressed-air energy storage (AA-CAES). The compression efficiency increases with injection water spray. However, the energy-generated water spray cannot be ignored. As the air pressure increases, the work done by the piston and the work converted into heat rise gradually in the compression process. Accordingly, the flow rate of the water needed for heat transfer is not a constant with respect to time. To match the rising compression heat, a time sequence of water-spray flow rate is constructed, and the algorithm is designed. Real-time water-spray flow rate is calculated according to the difference between the compression power and heat-transfer power. Compared with the uniform flow rate of water spray, energy consumption from the improved flow rate is reduced.

Spinal cord decompression sickness in an inside attendant after a standard hyperbaric oxygen treatment session.

Medical personnel in hyperbaric treatment centres are at occupational risk for decompression sickness (DCS) while attending patients inside the multiplace hyperbaric chamber (MHC). A 51-year-old male hyperbaric physician, also an experienced diver, was working as an inside attendant during a standard hyperbaric oxygen therapy (HBOT) session (70 minutes at 253.3 kPa [2.5 atmospheres absolute, 15 metres' seawater equivalent]) in a large walk-in MHC. Within 10 minutes after the end of the session, symptoms of spinal DCS occurred. Recompression started within 90 minutes with an infusion of lignocaine and hydration. All neurological symptoms resolved within 10 minutes breathing 100% oxygen at 283.6 kPa (2.8 atmospheres absolute) and a standard US Navy Treatment Table 6 was completed. He returned to regular hyperbaric work after four weeks of avoiding hyperbaric exposures. Transoesophageal echocardiography with a bubble study was performed 18 months after the event without any sign of a persistent (patent) foramen ovale. Any hyperbaric exposure, even within no-decompression limits, is an essential occupational risk for decompression sickness in internal hyperbaric attendants, especially considering the additional risk factors typical for medical personnel (age, dehydration, tiredness, non-optimal physical capabilities and frequent problems with the lower back).

Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load.

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

Technical feasibility of a pneumatically driven vehicle.

In this work, the technical feasibility of an all-air vehicle is investigated. A test rig has been built for this purpose in order to assess the proposed system experimentally. The operating pressures selected are deliberately low to mitigate the heat generated/dissipated during charging and discharging of the air cylinders driving an air motor, respectively. The experimental setup consists of three cylinders charged up to 5 bar and operated via solenoid valves to control the discharge of the cylinders via a programmable logic controller. The operating modes vary according to the expected load demand on the vehicle during startup and also during cruise. The three cylinders are discharged in tandem if the demand calls for high power density, then they are operated sequentially to augment the operational range of the vehicle. A simple sprocket-chain mechanism is used for its simplicity in this proof-of-concept stage to better understand the parameters pertinent to vehicle operation, which will later be replaced by a continuously variable transmission (CVT) gear. The results show a great potential for such mode of transport, especially for vast locales, such as a hospital, golf course or a university campus, with top velocities estimated to be around 14 km/h velocities and driven sprocket powers of 0.7 hp. Other combinations of drive gear ratio and cylinder discharge sequences result in a wide range of output power and maximum speed possibilities.