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Purpose of the study Hypertension is one of the most common comorbidities in COVID-19 pneumonia. However, whether it is an independent factor on the severity and mortality of COVID-19 has not been studied. Study design In this study, 736 patients with a PCR-confirmed diagnosis of COVID-19 were included from 12 January 2020 to 25 March 2020. All patients were divided into two groups according to whether or not they were hypertensive. After propensity score matching (PSM) to remove the interference of mismatches in the baseline data, the clinical characteristics and outcomes of angiotensin II receptor blocker (ARB)/ACE inhibitors application were analysed. Results A total of 220 (29.9%) patients were hypertensive, and 516 (70.1%) patients were not hypertensive. PSM eliminated demographic and comorbidity differences between the two groups. Of all participants, 32 patients died (4.3% mortality), including 17 out of 220 in the hypertension group (7.7%) and 15 out of 516 in the non-hypertension group (2.9%). The incidence of intensive care unit (ICU) stay in the hypertension group (12.8%) was higher than in the non-hypertension group (5.3%) (p0.05). Conclusion Hypertension was an independent risk factor for the severity and mortality of patients with COVID-19. ARBs/ACE inhibitors should not be discontinued in hypertensive patients with COVID-19.

With the development of new energy resources and power electronic device technology, high voltage direct current (HVDC) transmission system based on modular multilevel converter (MMC) plays an important role in the field of power transmission because of its modularity, low loss and high power conversion efficiency. However, half bridge sub-module (HBSM) of MMC can’t clear DC fault current. In order to solve this problem, reverse blocking double sub-module (RBDSM) is proposed. The RBDSM is composed of two HBSMs in series and connected with a reverse blocking circuit in parallel. The proposed sub-module (SM) can not only operate like HBSM in normal state but also protect power devices under DC fault condition. Furthermore, it can reduce much cost than previous SM which has the ability of clearing dc fault. Finally, a two terminal model of MMC was built to verify the effectiveness of the proposed topology of SM in PSCAD/EMTDC.

Background Cough variant asthma (CVA) is one of the leading causes of chronic coughing. The main treatment is currently anti-inflammatory medication. However, the coughing may return or be aggravated and lung function may deteriorate once the anti-inflammatory treatment is stopped. The effect of Chinese herbal medicine (CHM) on chronic coughing is remarkable, but high-quality evidence supporting its effectiveness is still lacking. This trial aims to evaluate the safety and efficacy, especially the long-term efficacy, of CHM plus anti-inflammatory medications for the treatment of CVA. Methods/design A randomized placebo-controlled double-blind trial will be conducted. It will consist of a 3-month intervention followed by a 6-month follow-up period. The target sample size is 60 patients with CVA who are between 18 and 70 years old. The eligible subjects will be allocated randomly into the experimental or control group in a ratio of 1:1. Patients in the experimental group will take CHM granules (4.9 g twice daily), while patients in the control group will be given a matched placebo. An administration of salmeterol/fluticasone propionate combination for 12 weeks will be the basic therapy for the two groups. The primary outcome is the cough visual analog scales (CVAS). The secondary outcomes include quality of life, rate of symptom relapse, lung function, and blood tests. A safety assessment will also be performed during the trial. Discussion The evidence gathered by the trial will be a valuable addition to informing treatment options for patients with CVA. Trial registration http://www.chictr.org.cn, ID: ChiCTR-IOR-16009148. Registered on 3 September 2016. Electronic supplementary material The online version of this article (10.1186/s13063-018-3073-x) contains supplementary material, which is available to authorized users.