Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

CLIX: NETWORK CODING AND CROSS LAYER INFORMATION EXCHANGE OF WIRELESS VIDEO

Network Coding (NC) can be efficiently combined with the “physical layer broadcast ” property of wireless mediums to facilitate mutual exchange of independent information [6]. At the same time, experimental/theoretical analysis of wireless networks has shown the efficacy of cross-layer protocols that relay corrupted packets in bandwidth hungry video applications (e.g. [7]-[8]). The integration of NC-based information exchange and cross-layer (CL) protocols for wireless video is the primary theme of this work. A particular issue addressed in this paper is the impact of errors in a packet, on the performance of a network code. Thus, we identify the operating conditions under which NC, despite the presence of residue errors, is beneficial. Based on theoretical analysis and experiments using 802.11b wireless traces it is established that the combination of NC with relay of corrupted packets can perform better than (i) conventional schemes that drop all corrupted packets (ii) a scheme that deploys network coding only (iii) a scheme that only deploys a CL strategy that recovers information from corrupted packets. The proposed Cross-Layer Information-eXchange (CLIX) scheme significantly improves the performance of an H.264 based video codec for wireless networks. 1

Network-Embedded Channel Coding for Optimum Throughput of Multicast Packet Video

Abstract — Channel coding methods have played a key role in a wide range of video applications over unreliable networks. In particular, Forward Error Correction (FEC) schemes have been proposed and used successfully for packet loss recovery over the Internet, and especially for multicast applications. Traditional multicast video applications employ FEC on an end-to-end basis between the sender and the clients. However, the reliability and efficiency of end-to-end FEC-based packet video could suffer significantly over large video distribution networks. In this paper, we explore a new alternative for improving the reliability and efficiency (in terms of throughput) of packet video applications by optimum placement of few FEC codecs within large packet video distribution networks. We develop an optimization algorithm for the placement of FEC codecs within selected nodes of random packet-video networks. Based on extensive H.264 video simulations, we show that this approach provides significant improvements in video quality, both visually and in terms of PSNR values. These significant improvements are achieved while (a) maintaining a desired minimum source-video coding rate to all receiver nodes, and (b) avoiding any source-video rate shaping or complex transcoding within the network

Multi-hypothesis based Distributed Video Coding using LDPC codes

Conventional video coding paradigms are usually built on the assumption that a video stream will be encoded only once but decoded several times. Over the years, this has lead to the development of encoders, which use complex motion-estimation algorithms to reduce the size of the video bitstream. However in applications like distributed sensor networks, cell-phones etc. the encoder has a limited amount of resources available to it and cannot employ complex motion-estimation algorithms. Intracoded frames used in conventional video coding have low-complexity, however they need large bandwidth to be transmitted. This has led to the development of Wyner-Ziv video codecs [1] which are based on the principles of side-information based coding, first propounded in the 1970s by Slepian-Wolf and Wyner-Ziv in their seminal work [2] and [3] respectively. Wyner-Ziv video codecs perform intra-frame encoding at the transmitter, and inter-frame decoding at the receiver. This reduces the size of the intraframe considerably, at the cost of increasing complexity at the decoder. For video transmission using cell-phones this increased decoder complexity can be absorbed by th

INPoD: In-Network Processing over Sensor Networks based on Code Design

Abstract—In this paper, we develop a joint Network Coding (NC)-channel coding error-resilient sensor-network approach that performs In-Network Processing based on channel code Design (INPoD). INPoD represents a major development of an underlying framework for designing Code-on-Network-Graph (CNG). CNG (and hence INPoD) maps variable nodes of Low Density Parity Check (LDPC) codes onto sensor nodes, and consequently translates check equations (used in linear algebraic LDPC codes) into in-network processing. INPoD/CNG codes not only improve capacity, but are also resilient to errors in noisy environments. In absence of INPoD, basic CNG employs standard LDPC codes while assuming the underlying sensor network is capable of supporting the degree distribution dictated by these codes. In practice, however, we usually have the network topology pre-determined by the placement of the sensors, and hence we are constrained to map a code onto a given topology. In this paper, we specifically address this problem, and propose the INPoD framework, which enables the use of LDPC design tools in the design of CNG for a given sensor network topology. We formulate the design of CNG, as a convex optimization problem, which determines the best codes to be used, given the underlying network connectivity and channel conditions. Specifically, we use density evolution to design degree distributions which controls the performance of the joint NCchannel code CNG. We also give a code construction algorithm, which achieves a designed degree distribution. We show that well-designed INPoD provide gains of 1.5 to 2.5 dB, when compared with the best known erasure codes – LT codes

UTILIZING SSR INDICATIONS FOR IMPROVED VIDEO COMMUNICATION IN PRESENCE OF 802.11B RESIDUE ERRORS ⊥

Radio hardware used for the reception of 802.11b frames is capable of associating a Signal to Silence Ratio (SSR) with each received frame. If a received frame is corrupted, then these SSR indications can be used to provide robust apriori estimate of the bit error rate in the packet. In many recently proposed cross-layer protocols, for transmission of video over wireless networks, recovery of information from partially corrupted packets has shown significant utility. In this paper, based on experiments with actual 802.11b error traces, we show that the Channel State Information (CSI) provided by the SSR indications can be used to improve the error recovery performance of an FEC scheme employed in conjunction with a cross-layer protocol. H.264 based simulation are used to establish the efficacy of the proposed work for video applications; specifically for video over 802.11b WLAN. 1

Header detection to improve multimedia quality over wireless networks

Abstract—Wireless multimedia studies have revealed that forward error correction (FEC) on corrupted packets yields better bandwidth utilization and lower delay than retransmissions. To facilitate FEC-based recovery, corrupted packets should not be dropped so that maximum number of packets is relayed to a wireless receiver’s FEC decoder. Previous studies proposed to mitigate wireless packet drops by a partial checksum that ignored payload errors. Such schemes require modifications to both transmitters and receivers, and incur packet-losses due to header errors. In this paper, we introduce a receiver-based scheme which uses the history of active multimedia sessions to detect transmitted values of corrupted packet headers, thereby improving wireless multimedia throughput. Header detection is posed as the decision-theoretic problem of multihypothesis detection of known parameters in noise. Performance of the proposed scheme is evaluated using trace-driven video simulations on an 802.11b local area network. We show that header detection with application layer FEC provides significant throughput and video quality improvements over the conventional UDP/IP/802.11 protocol stack. Index Terms—Communication systems, multimedia communication, video signal processing, wireless LAN. I