A quasi-realistic computational model development and flow field study of the human upper and central airways.

The impact of drug delivery and particulate matter exposure on the human respiratory tract is influenced by various anatomical and physiological factors, particularly the structure of the respiratory tract and its fluid dynamics. This study employs computational fluid dynamics (CFD) to investigate airflow in two 3D models of the human air conducting zone. The first model uses a combination of CT-scan images and geometrical data from human cadaver to extract the upper and central airways down to the ninth generation, while the second model develops the lung airways from the first Carina to the end of the ninth generation using Kitaoka's deterministic algorithm. The study examines the differences in geometrical characteristics, airflow rates, velocity, Reynolds number, and pressure drops of both models in the inhalation and exhalation phases for different lobes and generations of the airways. From trachea to the ninth generation, the average air flowrates and Reynolds numbers exponentially decay in both models during inhalation and exhalation. The steady drop is the case for the average air velocity in Kitaoka's model, while that experiences a maximum in the 3rd or 4th generation in the quasi-realistic model. Besides, it is shown that the flow field remains laminar in the upper and central airways up to the total flow rate of 15 l/min. The results of this work can contribute to the understanding of flow behavior in upper respiratory tract.

Evaluating the efficacy and safety of rivaroxaban as a warfarin alternative in chronic thromboembolic pulmonary hypertension patients undergoing pulmonary endarterectomy: A randomized clinical trial.

BACKGROUND AND AIM: Chronic thromboembolic pulmonary hypertension (CTEPH) is caused by the obstruction of the main pulmonary artery due to thrombosis and vascular remodeling. Regarding the need for anticoagulant therapy in CTEPH patients, this study aimed to compare rivaroxaban with warfarin in terms of its efficacy and safety in patients undergoing endarterectomy surgery. METHODS: The study was a parallel clinical trial in patients who underwent endarterectomy following CTEPH. A total of 96 patients were randomly selected and assigned to two groups: warfarin-treated (control) and rivaroxaban-treated (intervention). Patients were clinically assessed for re-thrombosis, re-admission, bleeding, and mortality in the first, third, and sixth months after surgery. RESULTS: There was no significant difference in the occurrence of thrombosis between the two groups within the first, third-, and sixth-months post-surgery (p=0.52, 1, 0.38 respectively). Moreover, the mortality rate (p=0.9), bleeding rate (p=0.06), and re-admission rate (p=0.15) showed no significant differences between the two groups. CONCLUSION: Rivaroxaban may be as effective as warfarin in treating CTEPH patients after endarterectomy in the short term and can be used as an anticoagulant in these patients. However, studies with long-term follow-ups are needed to consolidate the strategy of treating these patients with rivaroxaban.

Combined Therapy of Ciclosporin Plus Favipiravir in the Management of Patients with Severe COVID-19, not Responding to Dexamethasone: A non-Controlled Prospective Trial.

BACKGROUND: Regarding the COVID-19 pandemic, potential therapeutic agents are being evaluated almost every day. Ciclosporin, a calcineurin inhibitor, is characterized by beneficial antiviral and immunomodulatory effects. The present study aimed to evaluate the efficacy of ciclosporin in managing COVID-19. METHODS: This study was a prospective non-controlled clinical trial carried out on 20 patients. Confirmed COVID-19 patients received two doses of ciclosporin (10 mg/kg and 5 mg/kg injections) 24 h apart. Mortality rate and the lengths of intensive care unit (ICU) and hospital stays were assessed for all 20 patients. RESULTS: The mortality rate and the need for mechanical ventilation were calculated as 50%. The percentage of ICU admission was 70%. The lengths of ICU and hospital stays were 8.13 ± 6.81 and 14.25 ± 8.55 days, respectively. The levels of ferritin and white blood cells were significantly higher after injecting the second dose of ciclosporin. Seven patients (35%) had radiologically improved lungs after ciclosporin therapy. CONCLUSION: It seems that the protocol of two doses of ciclosporin in combination with favipiravir does not have favorable effects among COVID-19 patients that do not respond to dexamethasone. Controlled trials are needed to confirm the results.

Evaluation of adalimumab effects in managing severe cases of COVID-19: A randomized controlled trial.

BACKGROUND: COVID-19, which is a disease caused by the SARS-CoV-2 virus, has spread around the world since late 2019. Studies have found associations between the rising levels of TNF-α and severe COVID-19 cases. Hence, TNF-α blocking can possibly be a favorable intervention in modifying COVID-19. To this end, in order to manage pneumonia caused by COVID-19, adalimumab may potentially be considered as a potential therapeutic agent. The present study aimed to investigate the potential therapeutic role of adalimumab in treating COVID-19 cases in combination therapy with remdesivir and dexamethasone. METHODS: Among the 68 patients who were included in the current randomized controlled trial, 34 were assigned to the adalimumab group and the remaining 34 were assigned to the control group. Adalimumab at a dose of 40 mg, subcutaneous for once, was used for the intervention group. Both the intervention and control groups received remdesivir, dexamethasone, and supportive care. The data gathered to make comparisons of the groups included demographic information, the rate of mortality, mechanical ventilation requirement, length of stay in hospital and Intensive Care Unit (ICU), and imaging findings. RESULTS: There was no significant difference between the two groups in the terms of mortality rate (P-value = 1) and mechanical ventilation requirement (P-value = 1). The length of hospital and ICU stay as well as radiologic changes were not affected either (P-value = 1, 0.27, and 0.53, respectively). CONCLUSIONS: Our findings did not support the use of adalimumab in combination with remdesivir and dexamethasone in the treatment of severe COVID-19 cases.

No clinical benefit of high dose corticosteroid administration in patients with COVID-19: A preliminary report of a randomized clinical trial.

The aim of this study was to evaluate the clinical effects of dexamethasone administration in patients with mild to moderate acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19). The study included 50 patients who were randomly assigned to the dexamethasone group or control group. Dexamethasone was administered at a dose of 20 mg/day from day 1-5 and then at 10 mg/day from day 6-10. The need for invasive mechanical ventilation, death rate, duration of clinical improvement, length of hospital stay, and radiological changes in the computed tomography scan were assessed. The results revealed that 92% and 96% of patients in the dexamethasone and control groups, respectively, required noninvasive ventilation (P = 0.500). Among them, 52% and 44% of patients in the dexamethasone and control groups, respectively, required invasive mechanical ventilation (P = 0.389). At the end of the study, 64% of patients in the dexamethasone group and 60% of patients in the control group died (P = 0.500); the remaining patients were discharged from the hospital during the 28-day follow-up period. The median length of hospital stay was 11 days in the dexamethasone group and 6 days in the control group (P = 0.036) and the median length of hospital stay was 7 days in the dexamethasone group and 3 days in the control group (P < 0.001). No significant differences were observed in the other outcomes. This study showed that corticosteroid administration had no clinical benefit in patients with COVID-19-induced mild to moderate ARDS.

Favipiravir Effects on the Control of Clinical Symptoms of Hospitalized COVID-19 Cases: An Experience with Iranian Formulated Dosage Form.

Coronavirus disease -19 (COVID-19) pandemic, caused by SARS-CoV-2, has gradually spread worldwide, becoming a major public health event. This situation requires designing a novel antiviral agent against the SARS-CoV-2; however, this is time-consuming and the use of repurposed medicines may be promising. One such medicine is favipiravir, primarily introduced as an anti-influenza agent in east world. The aim of this study was to evaluate the efficacy and safety of favipiravir in comparison with lopinavir-ritonavir in SARS-CoV-2 infection. In this randomized clinical trial, 62 patients were recruited. These patients had bilateral pulmonary infiltration with peripheral oxygen saturation lower than 93%. The median time from symptoms onset to intervention initiation was seven days. Favipiravir was not available in the Iranian pharmaceutical market, and it was decided to formulate it at the research laboratory of School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran. The patients received favipiravir tablet at a dose of 1600 mg orally twice a day for day one and then 600 mg orally twice a day for days 2 to 6. In the second group, the patients received lopinavir-ritonavir combination tablet at a dose of 200/50 mg twice a day for seven days. Fever, cough, and dyspnea were improved significantly in favipiravir group in comparison with lopinavir-ritonavir group on days four and five. Mortality rate and ICU stay in both groups were similar, and there was no significant difference in this regard (P = 0.463 and P = 0.286, respectively). Chest X-ray improvement also was not significantly different between the two groups. Adverse drug reactions occurred in both groups, and impaired liver enzymes were the most frequent adverse effect. In conclusion, early administration of oral favipiravir may reduce the duration of clinical signs and symptoms in patients with COVID-19 and hospitalization period. The mortality rate also should be investigated in future clinical trials.

Evaluating the effects of Intravenous Immunoglobulin (IVIg) on the management of severe COVID-19 cases: A randomized controlled trial.

BACKGROUND: The newly discovered coronavirus has turned into coronavirus disease 2019 (COVID-19) pandemic and it rages at an unprecedented rate. Considering the findings of previous studies on the use of Intravenous Immunoglobulin (IVIg) for treating severe H1N1 infection and the satisfying results for reducing viral load and mortality, this study aimed to investigate the potential usefulness of IVIg for the management of severe cases. METHODS: In this randomized controlled trial, 84 patients were included: 52 in the IVIg group and 32 in the control group. The intervention group received IVIg at a dose of 400 mg/kg, IV, daily for three days. Both groups received hydroxychloroquine, lopinavir/ritonavir and supportive care. The demographic data, mortality rate, the need for mechanical ventilation, length of stay in hospital and in Intensive Care Unit (ICU), and imaging findings were recorded and compared in terms of the mentioned factors. RESULTS: The mean time from admission to IVIg initiation was 3.84 ± 3.35 days. There was no significant difference between the two groups in terms of mortality rate (P-value = 0.8) and the need for mechanical ventilation (P-value = 0.39). The length of hospital stay was significantly lower for the control group than that of the intervention group (P-value = 0.003). There was a significant positive relationship between the time from hospital admission to IVIg initiation and the length of stay in the hospital and ICU among the survivors (P-value < 0.001 and =0.01, respectively). CONCLUSIONS: Our findings did not support the use of IVIg in combination with hydroxychloroquine and lopinavir/ritonavir in treatment of severe COVID-19 cases.

Promising effects of tocilizumab in COVID-19: A non-controlled, prospective clinical trial.

BACKGROUND: The clinical presentation of SARS-CoV-2 infection ranges from mild symptoms to severe complications, including acute respiratory distress syndrome. In this syndrome, inflammatory cytokines are released after activation of the inflammatory cascade, with the predominant role of interleukin (IL)-6. The aim of this study was to evaluate the effects of tocilizumab, as an IL-6 antagonist, in patients with severe or critical SARS-CoV-2 infection. METHODS: In this prospective clinical trial, 76 patients with severe or critical SARS-CoV-2 infection were evaluated for eligibility, and ultimately, 42 patients were included. Tocilizumab was administered at a dose of 400 mg as a single dose via intravenous infusion. Primary outcomes included changes in oxygenation support, need for invasive mechanical ventilation, and death. Secondary outcomes included radiological changes in the lungs, IL-6 plasma levels, C-reactive protein levels, and adverse drug reactions. The data were analyzed using SPSS software. RESULTS: Of the 42 included patients, 20 (48%) patients presented the severe infection stage and 22 (52%) were in the critical stage. The median age of patients was 56 years, and the median IL-6 level was 28.55 pg/mL. After tocilizumab administration, only 6 patients (14%) required invasive ventilation. Additionally, 35 patients (83.33%) showed clinical improvement. By day 28, a total of 7 patients died (6 patients in the critical stage and 1 patient in the severe stage). Neurological adverse effects were observed in 3 patients. CONCLUSIONS: Based on the current results, tocilizumab may be a promising agent for patients with severe or critical SARS-CoV-2 infection, if promptly initiated during the severe stage.

Thermal Hysteresis and Seeding of Twisted Fibers Formed by Achiral Discotic Particles.

In this paper, molecular dynamics simulations of simple disc-shaped particles are used to investigate the free self-assembly of defect-free fibers. Depending on the choice of particle shape and interaction strength, the formed fibers are reproducibly either straight or, for reasons of packing efficiency, spontaneously chiral. As they grow radially, increasing stresses cause chiral fibers to untwist either continuously or via morphological rearrangement. It is also found that, due to the kinetics of fiber initiation, the isotropic solution has to be significantly supercooled before aggregation takes place. As a result, the thermal hysteresis of one formed fiber extends to 13.9% of the formation temperature. In the presence of a three-thread seed cluster of 15 particles, however, monotonic fiber growth is observed 9.3% above the normal formation temperature. Thus, as in many experimental systems, it is the kinetic pathway, rather than the thermodynamic stability of the final assembly, that dominates the observed behavior.

Computer simulations of pressure and velocity fields in a human upper airway during sneezing.

In this paper, the airflow field including the velocity, pressure and turbulence intensity distributions during sneezing of a female subject was simulated using a computational fluid dynamics model of realistic upper airways including both oral and nasal cavities. The effects of variation of reaction of the subject during sneezing were also investigated. That is, the impacts of holding the nose or closing the mouth during sneezing on the pressure and velocity distributions were studied. Few works have studied the sneeze and therefore different aspects of this phenomenon have remained unknown. To cover more possibilities about the inlet condition of trachea in different sneeze scenarios, it was assumed that the suppressed sneeze happens with either the same inlet pressure or the same flow rate as the normal sneeze. The simulation results showed that during a normal sneeze, the pressure in the trachea reaches about 7000Pa, which is much higher than the pressure level of about 200Pa during the high activity exhalation. In addition, the results showed that, suppressing the sneeze by holding the nose or mouth leads to a noticeable increase in pressure difference in the tract. This increase was about 5 to 24 times of that during a normal sneeze. This significant rise in the pressure can justify some reported damage due to suppressing a sneeze.