Space Ventilation Research Articles

Airflow characteristics and pollution containment effectiveness of decentralized air purifiers under longitudinal ventilation in urban tunnels

The installation of decentralized air purifiers is a solution for ventilation-constrained urban tunnels; however the interaction between the purified airflow and the tunnel ventilation airflow has rarely been revealed. In this study, the coupled flow characteristics of air purifiers in the upper space and longitudinal ventilation are numerically analyzed. The accessibility of supply air (ASA) and accessibility of contaminant source (ACS) indicators are used to evaluate the effectiveness of purified airflow and the impact of vehicle pollution sources. The effects of purifying air volume, number of purifiers, and distance between purifiers on pollution removal are revealed. The results show that the stratification of tunnel airflow results in the purified airflow acting mainly in the upper space. The increase in purifying air volume and the number of purifiers expands the dominant range of purification, however does not significantly reduce pollution in the lower space. Short-circuiting problem tends to occur when the downstream purifier extracts clean airflow from the upstream purifier. Smaller purifying air volume and greater purifier spacing help to mitigate short-circuiting, and the ACS at the downstream purifier inlet can be increased from approximately 0.3 to more than 0.5. This study provides guidance for the configuration of decentralized air purifiers.

Exercise Doppler echocardiography to detect early changes in the right ventricular-pulmonary circulation unit after pulmonary embolism

Abstract Introduction After pulmonary embolism (PE), patients frequently complain about reduced exercise capacity and dyspnea on exertion, even without pulmonary hypertension (PH). The underlying condition is often chronic thromboembolic disease, which is caused by residual pulmonary obstruction with preserved resting pulmonary haemodynamics. The symptoms are the consequences of the increased dead space ventilation, exercise-induced PH and right ventricular (RV) dysfunction. We aimed to assess the pathologic differences in the echocardiographic parameters of the RV- pulmonary circulation unit among patients with previous PE and the healthy control group. Furthermore, an objective was to compare the hemodynamic response to stress after different treatment strategies (thrombolysis vs. heparin administration). Methods 21 patients after PE (mean age 58,5±12,1 years; 53% men) have been included in the study. All of them were effectively anticoagulated for at least three months, and none had any signs of PH on echocardiography at rest. The control group included 20 healthy volunteers (mean age 56,9±11,5 years; 55% men). Each patient underwent resting and exercise stress echocardiography on a semi-recumbent bicycle ergometer according to a standardised protocol until the maximally tolerated workload. Echocardiography was performed at rest, at 50 Watt workload and during peak stress. The measurements focused on the RV's systolic function (TAPSE), the estimated pulmonary artery systolic pressure (PASP), and the Doppler measurements in the RV and left ventricular outflow tracts. Pulmonary vascular resistance (PVR) and RV-pulmonary artery coupling (RV-PA) were calculated from the echocardiographic parameters. Results The post-PE group had significantly higher PASP (39,2 ±16,6 vs. 27,7±12,5 mmHg; p<0,05) and PVR (1,5±0,4 vs. 1,1±0,3 Wood Units; p<0,05) at peak stress, than the controls. 55% of post-PE patients remained symptomatic, but there were no significant differences between the symptomatic and asymptomatic groups regarding TAPSE, PASP, RV-PA coupling and PVR. 30% of post-PE patients had thrombolysis. In the patients where thrombolysis was performed, the coupling at peak stress was significantly higher than in heparin-treated patients (1,4±0,1 vs 0,9±0,4 mm/mmHg, p<0,05). Conclusion Post-PE patients without resting PH have higher PVR and PASP than the healthy control group, even after at least 3 months of adequate therapy. Post-PE patients treated with thrombolysis may have more preserved RV-PA coupling than the heparin-treated patients.

Cardiopulmonary exercise testing in patients with precapillary pulmonary hypertension with an unfavorable prognosis

Aim. To compare clinical and hemodynamic parameters with survival of incident patients with idiopathic pulmonary arterial hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH) with a prognostically unfavorable pattern of cardiopulmonary exercise testing (CPET) parameters.Material and methods. The study included 48 incident cases with a verified diagnosis of IPAH (n=18) and CTEPH (n=30). All patients were examined in accordance with the European Society of Cardiology and the European Respiratory Society guidelines (2015). The inclusion criterion was the ventilatory equivalent for carbon dioxide (CO2) according to the CPET (VE/VCO2) >44, indicating an unfavorable prognosis for patients.Results. VE/VCO2 in the examined patients with IPAH and CTEPH averaged 70,6±0,8 and did not differ in the study groups. Hemodynamic parameters of patients with IPAH and CTEPH also indicated a high risk of adverse events as follows: cardiac index — 1,9±0,1 and 1,8±0,1 l/min/m2, respectively (p=0,3). Peak oxygen consumption, anaerobic threshold level, oxygen delivery to work performed were reduced in both groups. However, patients with IPAH did not have a decrease in dead space ventilation and desaturation severity during exercise was greater than in patients with CTEPH. Patients with CTEPH had better survival compared to patients with IPAH: 1 year — 89 vs 83%, 3 years — 84 vs 65%, 5 years — 73 vs 35%, 7 years — 55 vs 36%.Conclusion. Among patients with IPAH and CTEPH who have an unfavorable prognosis, patients with IPAH demonstrate a more pronounced decrease in cardiovascular and respiratory reserves, which negatively affects patient survival. CPET may be a valuable non-invasive method for death risk stratification in patients with IPAH and CTEPH.

Impact of collector aspect ratio on the energy and exergy efficiency of a louvered fin solar air heater

Solar air heaters have huge applications in renewable energy utilization segments concerning the issues of space heating, drying, and ventilation systems. Performance prediction of such systems largely depends upon the design of the collector itself. The present study has highlighted the influence of various aspect ratios of the collector on the thermal and exergy performance of louvered finned solar or air heaters. In this context, an experimental analysis has been carried out to compare the performance of LFSAH with conventional PSAH. These results show that an increase in aspect ratios enhances thermal efficiencies of heat transfer and the systems. An aspect ratio of 4:1 showed the maximum thermal efficiencies as 81.63 % for LFSAH and 68.13 % for PSAH. On the other hand, at larger mass flow rates, the exergetic efficiency of LFSAH becomes lower owing to the larger friction and exergy losses and sometimes even lower than that of PSAH. The novelties of the present study are in emphasizing the importance of aspect ratio in optimizing solar air heater design and providing relevant insight for better energy use.

Post-Pulmonary Embolism Phenotypes Described by Invasive Cardiopulmonary Exercise Testing

BackgroundPost pulmonary embolism (PE) dyspnea is common. Existing non-invasive studies have demonstrated that post PE dyspnea is associated with elevations in right ventricular afterload, dead space ventilation, and deconditioning. We aimed to use invasive cardiopulmonary exercise testing (iCPET) parameters in patients with post PE dyspnea to identify unique physiologic phenotypes. Research QuestionAre there distinct post pulmonary embolism dyspnea physiologic phenotypes described with iCPET? Study Design and MethodsPatients were enrolled at the time of acute PE and through our pulmonary hypertension and dyspnea clinic. ICPET was performed if there was high suspicion for pulmonary hypertension or if there was unexplained dyspnea. A hierarchical cluster analysis was performed to identify dyspnea phenotypes. ICPET parameters assessing pulmonary hemodynamics, ventilation, and peripheral oxygen utilization were then compared within and across each cluster and with iCPET controls against peak oxygen consumption (Peak VO2). Results173 patients were enrolled. Sixty-seven patients underwent iCPET. All patients had reductions in Peak VO2 and peak cardiac index relative to controls. Three clusters were identified. Cluster one was defined by having elevated RV afterload and impaired ventilatory efficiency. Cluster two had elevated RV afterload with reductions in respiratory mechanics. Cluster three had mild derangement in RV afterload with mild reductions in peak cardiac output. InterpretationiCPET reveals significant heterogeneity in post PE dyspnea. Three phenotypes are characterized by differences in RV afterload, ventilatory efficiency, respiratory mechanics, and peripheral oxygen utilization.

Surviving Critical Care: A Follow-Up Study Assessing Pulmonary Function, Cardiopulmonary Exercise Testing, and Quality of Life in COVID-19-Affected Patients

Introduction: Survivors of severe COVID-19 face complex challenges and a high degree of pulmonary sequelae. Therefore, we aim to describe their ongoing health burden. Methods: In this single-center prospective cohort study, COVID-19 ICU survivors were invited 3 and 6 months after ICU discharge. We examined pulmonary function with pulmonary function tests (PFT) and cardiopulmonary exercise testing (CPET), and we established health-related quality of life (HRQL) and health status (HS) with the EuroQol five-dimension five-level (EQ-5D-5L), the short-form health survey 12 (SF-12), and the modified British Medical Research Council dyspnea scale (mMRC) questionnaires. Results: Out of the 53 individuals screened, 23 participated in this study. Throughout both assessment points, participants maintained PFT results within range, apart from a decline in the transfer factor of the lung for carbon monoxide (TLCO). CPET showed improved fitness but persistent ventilatory deficiencies, indicated by altered dead space ventilation (VD/VT) and elevated arterial-alveoli gradient for oxygen (AaDO2). HRQL and HS remained compromised, with both physical (PCS) and mental component summary (MCS) scores significantly lower than the standardized norm population scores. Also, there was a rise in the prevalence of issues related to mobility, pain/discomfort, and anxiety/depression, and an increase in reported dyspnea. Conclusion: These results enhance our comprehension of the complex difficulties faced by COVID-19 ICU survivors. Six months post-discharge, CPET revealed the presence of ventilatory insufficiencies. Additionally, there was a decline in HRQL and HS, notably affected by mental health concerns and an increase in the level of dyspnea.

IoT-based system to detect and control natural gas leaks in residential kitchens

Natural gas is widely used in many homes for cooking, but a lack of gas leak detection has led to large fires and accidents. This article presents the design and implementation of a natural gas detection and extraction system for domestic kitchens in Lima, Peru. The ESP32 microcontroller allowed remote circuit control, resulting in a more convenient setup than the Arduino UNO microcontroller. After calibration of the sensors and their corresponding programming, three actions were established in response to different gas levels: alarm activation, space ventilation and gas extraction, and thermal shutdown. Strategic sensor placement and improved physical presentation of the system were performed to ensure accurate readings and effective deployment. The results demonstrate the proper functioning of the circuit and its ability to prevent accidents related to gas leaks. The designed system offers the advantage of remote monitoring, providing access to the user from any location. In conclusion, this project offers a comprehensive solution to prevent accidents caused by gas leaks in home kitchens. With satisfactory results in terms of operation and rapid response, the project demonstrates its effectiveness in accident prevention. This design offers a practical and accessible solution, improving security and bringing peace of mind to homes.

Adoption of Improved Buffalo Husbandry Practices in Peri-Urban Areas of Surat City, Gujarat

The present study was carried out in the peri urban areas of Surat city of Gujarat to find out the adoption of improved buffalo husbandry practices. A random sample of 50 buffalo farm owners were selected and interviewed for the interview schedule prepared about adoption of improved dairy husbandry practices in six major aspects of housing, feeding, breeding, health care, milking and calf rearing management was studied. Housing in separate located place (100%), providing proper floor space (98%) and proper height and ventilation (90%) were more adopted in housing practices. Provision of clean and fresh drinking water (100%), feeding extra ration to advance pregnant animals (64%) and feeding balance concentrate mixture on the basis of milk production (64%) were more adopted in feeding management. In adoption of breeding management, keeping watch on oestrus cycle and heat symptoms of animals (100%), artificial insemination of animals (100%) and practicing pregnancy diagnosis between 60-90 days after service (91%) were more adopted by buffalo owners. Observing animals daily for signs of sickness (100%), timely and regularly vaccination (100%) and treatment of reproductive disorders (75%) were more adopted by respondents in health care management practices. In milking and calf rearing practices, washing pails and hands before milking (100%) and regularity in milking time (100%), early solid feeding (100%) and milk feeding to calves up to three months of age (96%) were more adopted by the buffalo owners.

Lessons from the COVID-19 pandemic for ventilation and indoor air quality.

The rapid global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the beginning of 2020 presented the world with its greatest health challenge in decades. It soon became clear that governments were unprepared to respond appropriately to this crisis. National and international public health authorities were confused about the transmission routes of the virus and the control measures required to protect against it. In particular, the need to reduce the risk of infection through sufficient and effective ventilation of indoor spaces was given little attention. In this review, we discuss insights and key lessons learned from the COVID-19 pandemic regarding the role of ventilation as an effective means against airborne transmission of pathogens and, more broadly, for supporting good indoor air quality.

The flow regimes of two parallel-connected chambers respectively with a mechanical extractor and a buoyancy source

This research studies the ventilation flow patterns and density stratification in two parallel-connected chambers which respectively have a mechanical extractor and a localized buoyancy source. Two parallel-connected chambers are denoted as the forced and extracted chambers. The forced chamber having a continuous localized buoyancy source is located upstream, and the extracted chamber having a mechanical extractor is located downstream. Two chambers are interconnected by an internal connection opening and are connected to the exterior in a parallel manner through their own connection openings. The effects of the adjoining chamber having a mechanical extractor on the ventilation flow patterns and density stratification in the space are investigated in this study. The flow driving forces include the buoyant and inertial forces in this ventilated space. The buoyant force results from the buoyancy source, and the inertial force is due to the mechanical extractor. This research uses the theoretical analysis approach and the laboratory reduced-scale model to investigate this problem. This paper focuses on the ventilation flow patterns in the steady state and discusses different flow regimes due to the adjoining extracted chamber effect. The internal connection opening level and orientation between two chambers are discussed in this study. Three flow regimes, the small (or reduced), transition, and large (or enhanced) flow regimes, are found in two parallel-connected chambers and there is a range of critical flow rates to determine the flow regime when the internal connection opening is located in a partition wall as investigated in this research. If the internal connection opening is located in a horizontal ceiling, a clear-cut critical flow rate is expected and only two flow regimes exist. This study discusses the characteristics of different flow regimes in the space of two parallel-connected chambers. The paper presents three derived theoretical models and analogous salt-bath experimental results for three flow regimes, and comparisons between them show reasonable agreement.

Large-scale experimental study on the average temperature distribution model of fire smoke under mechanical ventilation in the flat space

Mechanical ventilation is essential to ensure the safety of persons, equipment, and structures in cruise ship fire incidents. The mass loss rate, smoke temperature, and comprehensive heat transfer coefficient during large-scale fire experiments are researched in cruise ship flat space. The results indicate that the mass loss rate of four pool fires with different sizes presents different rules in mechanical ventilation conditions compared with open conditions. In addition, the vertical distribution of temperature appears to be stratification, which aligns with the “dual-zone model”. The horizontal distribution of the temperature has a “mutation point”. With the mutation point as the boundary, the temperature drops rapidly from the fire source to the mutation point and decreases more slowly. Furthermore, the distribution model of comprehensive heat transfer coefficient and average temperature are established. The comprehensive heat transfer coefficient is in direct proportion to the 1.00 power of heat release rate and inversely in proportion to the 0.69 power of the number of mechanical ventilation. However, the average temperature is in direct proportion to the 0.52 power of heat release rate and inversely in proportion to the 1.40 power of the number of mechanical ventilation.

Heating and ventilation efficiencies of a solar chimney integrated system in a low-energy office building

Mechanical air conditioning systems have a significant share of energy consumption in the building sector. Passive solar systems, such as solar chimneys, can reduce building energy demand by supplying space heating, cooling, and ventilation, significantly decreasing greenhouse gas emissions. Therefore, this study aimed to evaluate the heating and ventilation efficiencies of a solar chimney integrated system, including a roof solar chimney coupled with an air channel, for a two-story office building in Tehran, Iran. The studied system's conditions are switchable from heating to cooling by changing the opening positions. Computational Fluid Dynamics was employed to numerically investigate the heating and ventilation efficiencies of the proposed solar system. The results confirmed that the system could be utilized for pre-heating purposes during working hours but that the building should be ventilated only for 35% of this time with an air change rate of 0.8 during the year's coldest month. The arrangement could provide thermal and ventilation comfort for the occupied space only at solar intensity and ambient temperature higher than 550 W/m2 and 10 °C, respectively. In addition, the solar system could reduce 32% of the annual heating demand (918 kWh), which is equal to a reduction of 1865 kg of CO2 emissions during working hours.

End-tidal-to-arterial PCO2 ratio as a prognostic value in mechanically ventilated patients at respiratory intensive care unit

Background Dead space refers to the part of each tidal volume that does not contribute to gas exchange. It serves as an indicator of lung function efficiency. Aim To evaluate the end-tidal-to-arterial PCO2 ratio and Acute Physiological and Chronic Health Assessment (APACHE IV) scoring system as prognostic values in mechanically ventilated patients at the respiratory intensive care unit (ICU). Patients and methods This prospective cohort research was done on 40 mechanically ventilated patients due to different respiratory causes who were admitted at the respiratory ICU at Ain Shams University hospitals. Results This study found that decreasing end tidal PCO2 (PETCO2)/arterial carbon dioxide (PaCO2) is associated with higher mortality amongst mechanically ventilated cases in respiratory ICU. A significant negative association between APACHE IV score and end-tidal to arterial PCO2 ratio following 1 h and after 24 h of mechanical ventilation. APACHE IV score showed a significant relation with mortality, being higher in survivors than nonsurvivors. Conclusion PETCO2/PaCO2 is a relevant prognostic value that reflects dead space ventilation among mechanically ventilated patients in respiratory ICU. APACHE IV score is a good mortality predictor in respiratory ICU.

The Influence of Climatic and Geographical Conditions on the Volume and Spatial Solutions of Shopping and Entertainment Centers of the Republic of the Congo

The article examines the main climatic and geographic conditions of the Republic of Congo. It was revealed that design in the Republic of Congo is carried out in a warm and humid climate. Based on examples of analyzed construction experience in humid climates, the author made proposals for architectural techniques for organizing the space of shopping and entertainment centers at three hierarchical levels. At the urban planning level, the author proposed organizing the landscape of streets and park areas in such a way as to organize the natural drainage of water from the surface and from the upper balls of the soil. At the level of building formation, techniques are associated with organizing the collection of rainwater through the shaping of the building. The possibilities of protecting retail spaces from rain using canopies are also considered. At the spatial level, it is proposed to drain the swampy area on the territory of the shopping and entertainment center by creating canals. It is proposed to design public areas of shopping centers in such a way that public areas, using their shape, can collect surface water from rain. Further research by the author will be aimed at creating volumetric-spatial methods for organizing shopping center buildings, taking into account the warm, humid climate of the region. Also, further research will be aimed at studying the ventilation of internal open spaces of shopping and entertainment centers. These studies are aimed at creating comfortable urban hygienic conditions within the boundaries of public centers, which should become shopping and entertainment centers.

Study of the use of wallpaper to mitigate radon exhalation from building materials in indoor spaces

Radon gas is known to exhale from the ground and can enter and accumulate inside buildings. Many countries set radon limit concentrations and propose mitigation techniques applied in the outdoors to prevent radon from entering buildings. However, radon can also exhale from building materials, e.g. cement, bricks, marble or tiles, contributing high concentrations indoors. Space ventilation is the most used technique to reduce the indoor radon concentration to safe limits, but sometimes, it is not enough. In these cases, it is necessary to apply alternative techniques. This work exposes a prevention technique to reduce radon concentration in indoor spaces that come from building materials or from the subsoil diffusing through basement walls, based on the use of wallpapers. The use of wallpapers is a common decorative technique in homes and buildings, which is compatible with interior finishes and is simple to apply, easily accessible, commercially available and inexpensive. Different commercial wallpapers were selected with a cellulosic and polymeric base and vinylic, cellulosic, latex or non-woven coating material. Configurations of single and double layers of wallpaper and a triple configuration by adding an intermediate layer of aluminium film have been tested. Tests to determine the reduction of radon concentration were performed, and diffusion coefficient and diffusion length were calculated following an adaptation of ISO/TS 11665–13 standard. Radon reduction of 90%, low-medium radon resistance and a diffusion coefficient around 10−11 m2/s were reached for single-layer configuration, and up to 98% of radon reduction, medium radon resistance and diffusion coefficient of 10−12 m2/s with double-layer configuration for dense non-porous base wallpapers with vinylic and non-woven coatings. Adding an aluminium foil intermediate in the double configuration improves the results of all wallpapers tested regarding radon reduction concentration, radon resistance, diffusion length and diffusion coefficient. Moreover, for the dense non-porous base made of non-woven fabric with a vinyl coating layer wallpaper, the diffusion length is shorter than the thickness of the sample in this configuration so the amount of penetrating radon will be reduced by the decay of radon in the wallpaper. Therefore, most radon would disintegrate along the sample and the concentration in the interior space would be lower. These results open a new alternative to protect indoor spaces from radon that access through walls or building materials based on a simple, easy and low-cost technique.

Perioperative use of high flow nasal cannula

High flow nasal cannula (HFNC) is an innovative oxygen therapy system that has gained increasing popularity in recent decades, particularly in the field of critical care medicine. The device provides a more constant and higher FiO2, generates low levels of PEEP, reduces dead space ventilation, and conditions the inspired gas, which collectively results in a reduction in work of breathing (WOB) and improved patient comfort. While the application of HFNC in critically ill patients is well-established and supported by a large body of evidence, studies of HFNC during the perioperative period are limited. However, the working mechanisms of HFNC align with physiological demands across various anesthetic processes. Consequently, this system could potentially serve as an alternative oxygen delivery system for surgical patients during perioperative care. In this article, we summarize the working principles and the effects provided by HFNC, review its implementation during the perioperative period, and discuss the current evidence regarding its use.

Prognostic value of biohybrid screening results for assessing cancer risk using the example of lung cancer

Introduction. One of the leading places in the structure of socially significant diseases in the Russian Federation is occupied by malignant neoplasms, among which cancer of the trachea, bronchi and lung occupies the first place in terms of prevalence. Screening for lung cancer is not carried out at the federal level in Russia; recommended screening measures include questionnaires to identify risk factors for the development of the disease (including occupational) and the formation of dispensary observation groups. The study aims to assess the prognostic value of a new method of biohybrid screening of lung cancer by exhaled air. Materials and methods. Scientists conducted a study at the National Medical Research Center of Oncology of the Ministry of Health, Russian Federation, with the participation of 24 conditionally healthy volunteers and 5 patients diagnosed with lung cancer in the early stages of the disease. The design of the study is simultaneous (on-line) with blinding; experts estimated the risk of systematic errors at 10 points on the QUADAS scale. The authors examined exhaled air samples on a gas analyzer (biohybrid detector) of the BGS-APK 02SZZ model, in which the sensor were animals — gray domesticated rats (Rattus norvegicus) with microelectrode matrices implanted into the olfactory bulb, and which were in the internal (ventilated) space of the analyzer in a state of drug anesthesia. The conclusion about the presence or absence of a risk of lung cancer was formed by an artificial neural network of the analyzer, at the input of which bioelectric signals from each microelectrode were received, which were preprocessed using a system for recording the focal activity of the olfactory analyzer. The specialists confirmed the presence or absence of a risk of lung cancer by a reference method, according to computed tomography of the chest in accordance with the Lung Imaging Reporting and Data System (LungRADS™). Results. During the study, experts determined the effectiveness indicators of the method of biohybrid lung cancer screening by exhaled air: sensitivity (64%), specificity (87%), prognosticality of negative and positive conclusions about the presence/absence of disease risk (82% and 72%, respectively). Conclusion. The safety, efficiency and throughput of the investigated method, together with the reproducibility of the analyzer's conclusions, meet the criteria of practicability to ensure the first (population-based) stage of lung cancer screening.

SCARLET (Supplemental Citicoline Administration to Reduce Lung injury Efficacy Trial): study protocol for a single-site, double-blinded, placebo-controlled, and randomized Phase 1/2 trial of i.v. citicoline (CDP-choline) in hospitalized SARS CoV-2-infected patients with hypoxemic acute respiratory failure

BackgroundThe SARS CoV-2 pandemic has resulted in more than 1.1 million deaths in the USA alone. Therapeutic options for critically ill patients with COVID-19 are limited. Prior studies showed that post-infection treatment of influenza A virus-infected mice with the liponucleotide CDP-choline, which is an essential precursor for de novo phosphatidylcholine synthesis, improved gas exchange and reduced pulmonary inflammation without altering viral replication. In unpublished studies, we found that treatment of SARS CoV-2-infected K18-hACE2-transgenic mice with CDP-choline prevented development of hypoxemia. We hypothesize that administration of citicoline (the pharmaceutical form of CDP-choline) will be safe in hospitalized SARS CoV-2-infected patients with hypoxemic acute respiratory failure (HARF) and that we will obtain preliminary evidence of clinical benefit to support a larger Phase 3 trial using one or more citicoline doses.MethodsWe will conduct a single-site, double-blinded, placebo-controlled, and randomized Phase 1/2 dose-ranging and safety study of Somazina® citicoline solution for injection in consented adults of any sex, gender, age, or ethnicity hospitalized for SARS CoV-2-associated HARF. The trial is named “SCARLET” (Supplemental Citicoline Administration to Reduce Lung injury Efficacy Trial). We hypothesize that SCARLET will show that i.v. citicoline is safe at one or more of three doses (0.5, 2.5, or 5 mg/kg, every 12 h for 5 days) in hospitalized SARS CoV-2-infected patients with HARF (20 per dose) and provide preliminary evidence that i.v. citicoline improves pulmonary outcomes in this population. The primary efficacy outcome will be the SpO2:FiO2 ratio on study day 3. Exploratory outcomes include Sequential Organ Failure Assessment (SOFA) scores, dead space ventilation index, and lung compliance. Citicoline effects on a panel of COVID-relevant lung and blood biomarkers will also be determined.DiscussionCiticoline has many characteristics that would be advantageous to any candidate COVID-19 therapeutic, including safety, low-cost, favorable chemical characteristics, and potentially pathogen-agnostic efficacy. Successful demonstration that citicoline is beneficial in severely ill patients with SARS CoV-2-induced HARF could transform management of severely ill COVID patients.Trial registrationThe trial was registered at www.clinicaltrials.gov on 5/31/2023 (NCT05881135).Trial statusCurrently enrolling.

Experimental and Theoretical Investigation of Longitudinal Temperature Attenuation and Smoke Movement in Urban Utility Tunnel Fires

The urban utility tunnel is an indispensable part of modern engineering construction. However, the fire risk cannot be ignored due to the narrow space and limited ventilation of the utility tunnel. A study of smoke filling is performed in a 1/8-scaled utility tunnel (25 m × 0.5 m × 0.45 m). Five heat release rates (5, 10, 15, 20 and 25 kW) and four positions of fire sources are used for tests. The initial position of the one-dimensional smoke movement of strong plume is determined. Based on the traditional model, the longitudinal temperature attenuation model of tunnel smoke is established with consideration of radiation and convection heat losses. The theoretical value of the longitudinal temperature rise of smoke is in good agreement with the experimental value. A one-dimensional spreading velocity model is established that coincides well with the experimental value, and the relative error is less than 20%. The spreading velocity of smoke is increased by the heat release rate. The velocity of the smoke spreading at the near end is smaller than that at the center, due to the long spreading route. The current conclusions disclosed in this study provide important guidance for the ventilation design of utility tunnels for fire smoke scenarios.

Apneustic anesthesia ventilation improves pulmonary function in anesthetized bottlenose dolphins (Tursiops truncatus).

Use of mechanical ventilation during general anesthesia is a necessary practice in the anesthetization of small cetaceans as spontaneous ventilation fails to provide adequate gas exchange. Currently available methods of ventilation do not account for the intermittent breathing strategy of representative species within this infraorder of fully aquatic mammals and may have a significant effect on cardiac and respiratory physiology. To understand the impact of mechanical ventilation on cardiopulmonary function in one small species of cetacean, the bottlenose dolphin (Tursiops truncatus), we compared controlled mechanical ventilation (CMV) to a novel ventilation method known as apneustic anesthesia ventilation (AAV). AAV simulates the normal inspiratory breath-hold pattern of dolphins. Ten anesthetic procedures (dental procedure, n = 9; bronchoscopy, n = 2) were performed on nine dolphins (age range: 10-42 years; mean = 32 years; median = 37 years; female = 3, 40%; male = 6, 60%). In a cross-over study design, dolphins were instrumented and randomly assigned to AAV or CMV as the initial mode of ventilation, then switched to the alternate mode. Baseline cardiopulmonary data were collected and again after 30 min on each mode of ventilation. Cardiac index, stroke volume index, systemic vascular resistance, alveolar dead space, alveolar-arterial oxygen tension gradient, arterial oxygen content, oxygen delivery index, and dynamic respiratory system compliance index were calculated at each of the four time points. During AAV, dolphins had higher arterial oxygen tension, higher mean airway pressure, reduced alveolar dead space ventilation and lower alveolar-arterial oxygen difference. Cardiovascular performance was not statistically different between the two modes. Our study suggests AAV, which more closely resembles the conscious intermittent respiratory pattern phenotype of dolphins, improves ventilation and pulmonary function in the anesthetized dolphin. Future studies should evaluate the cardiopulmonary effects of neutral buoyancy and cardiopulmonary sparing drug protocols to reduce the need for hemodynamic support of current protocols.