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In recent years, precise high flow oxygen therapy as a new type of oxygen therapy machine has gradually attracted people’s attention and has been widely used in hospital emergency and clinical treatment of respiratory diseases;especially in recent years, severe coronavirus disease (COVID-19) has played an important role in the treatment of patients. This paper presents a new type of precise high flow oxygen therapy machine with electromagnetic pneumatic flow valve as the core control element. A sliding mode control strategy based on the system is proposed to realize the accurate control of oxygen concentration and output flow of oxygen therapy mixture. The physical equipment of the precision high flow system is established, and its working performance is verified through the test platform. The optimization design goal of the precision high flow equipment is achieved.
ABSTRACT
Objective: To investigate the diagnostic value of serological testing and dynamic variance of serum antibody in coronavirus disease 2019 (COVID-19).
ABSTRACT
BackgroundDeep venous thrombosis (DVT) is a severe complication of the coronavirus disease 2019 (COVID-19). It may interfere with COVID-19 treatment and delay the recovery, but there is less data about the anticoagulant therapy and sex difference of VTE in patients with COVID-19. The purpose of this study is to study the prevalence, risk factors, anticoagulant therapy and sex difference of deep venous thrombosis (DVT) in patients with COVID-19.MethodsThe enrolled 121 patients were confirmed positive for COVID-19. All suspected patients with a high Caprini index (≥4) or PADUA index (≥4) received color Doppler Ultrasound (US) to screen DVT in both lower extremities. Clinical characteristics of DVT-COVID-19 patients were analyzed. Multivariate logistic regression was performed to identify risk factors related to DVT in COVID-19 patients. The distribution of DVT locations, anticoagulation therapy with sex difference, and the outcomes were also analyzed.ResultsDVT was found in 48% asymptomatic COVID-19 patients with increased PAUDA index or Caprini index by US scanning. Multivariate logistic regression determined that age, CRP and baseline D-dimer were risk factors among COVDI-19 patients. Although the most common DVT location was infrapopliteal (Class I and Class II), higher mortality in DVT-COVID-19 patients was confirmed. DVT-COVID-19 patients presented significant increases in the CRP, neutrophil count and D-dimer throughout the whole inpatient period compared to non-DVT-COVID-19 patients. Although anticoagulation therapy accelerated the recovery of lymphocytopenia condition in DVT patients, men DVT-COVID-19 patients showed higher CRP and neutrophil count vs. lymphocyte count (N/L) ratio but lower lymphocyte count compared to women DVT-COVID-19 patients. ConclusionsDVT is common in COVID-19 patients with high risk factors, especially for older age, higher CRP and baseline D-dimer populations. It is important to consider sex differences in the anticoagulant therapy among DVT-COVID-19 patients.
Subject(s)
Venous Thromboembolism , COVID-19 , Lymphopenia , Venous ThrombosisABSTRACT
Background On March 11, 2020, the World Health Organization declared its assessment of COVID-19 as a global pandemic. However, specific antiviral drugs are still unavailable, and pateints are managed by multiple complementary treatments. Methods The electronic medical records of COVID-19 patients where basic information, complete blood count, coagulation profile, inflammatory cytokines and serum biochemical indicators in 42 patients with COVID-19 (21 of whom were treated with low molecular weight heparin (LMWH), and 21 without LMWH) that were retrospectively analyzed to compare and evaluate the effect of LMWH treatment on disease progression. Findings 42 patients with COVID-19 treated at the hospital between February 1 and March 15, 2020, were selected for the study, of which 21 underwent LMWH treatment (LMWH group), and 21 did not (Control), during hospitalization. Changes in the percentage of lymphocytes in the LMWH group before and after LMWH treatment were significantly different from those in the control group (p=0.011, respectively). Changes in the levels of D-dimer and fibrinogen degradation products (FDP) in the LMWH group before and after LMWH treatment were significantly different from those in the control group (p=0.002;p=0.035). Strikingly, in the LMWH group, IL-6 levels were significantly reduced after LMWH treatment (p=0.006). Besides, the changes in IL-6 levels in the LMWH group before and after LMWH treatment were significantly different from those in the control group (p=0.031). Interpretation LMWH improves the coagulation dysfunction of COVID-19 patients and exerts anti-inflammatory effects by reducing IL-6 and increasing lymphocyte %. It appears that LMWH can be used as a potential therapeutic drug for the treatment of COVID-19, paving the way for a subsequent well-controlled clinical trial. Funding National Natural Science Foundation of China (No. 81603037 to SC) and the National Key Research and Development Plan of China(2017YFC0909900).
Subject(s)
COVID-19 , Blood Coagulation Disorders, InheritedABSTRACT
Background We aim to investigate the profile of acute antibody response in COVID-19 patients, and provide proposals for the usage of antibody test in clinical practice. Methods A multi-center cross-section study (285 patients) and a single-center follow-up study (63 patients) were performed to investigate the feature of acute antibody response to SARS-CoV-2. A cohort of 52 COVID-19 suspects and 64 close contacts were enrolled to evaluate the potentiality of the antibody test. Results The positive rate for IgG reached 100% around 20 days after symptoms onset. The median day of serocon-version for both lgG and IgM was 13 days after symptoms onset. Seroconversion of IgM occurred at the same time, or earlier, or later than that of IgG. IgG levels in 100% patients (19/19) entered a platform within 6 days after seroconversion. The criteria of IgG seroconversion and [≥] 4-fold increase in the IgG titers in sequential samples together diagnosed 82.9% (34/41) of the patients. Antibody test aided to confirm 4 patients with COVID-19 from 52 suspects who failed to be confirmed by RT-PCR and 7 patients from 148 close contacts with negative RT-PCR. Conclusion IgM and IgG should be detected simultaneously at the early phase of infection. The serological diagnosis criterion of seroconversion or [≥] 4-fold increase in the IgG titer is suitable for a majority of COVID-19 patients. Serologic test is helpful for the diagnosis of SARS-CoV-2 infection in suspects and close contacts.