![]() Landing day symptoms from orthostatic hypotension after prolonged spaceflight can be debilitating, but severity of these symptoms can be unpredictable and highly individual. These results strongly suggest that alternative methods not dependent on pulse contour analysis are required to track cardiac function in spaceflight. This study demonstrated that pulse contour analysis of finger arterial blood pressure to estimate cardiac output failed to track the 46% increase measured by a rebreathing method. NEW & NOTEWORTHY Noninvasive assessment of cardiac function during human spaceflight is an important tool to monitor astronaut health. Future spaceflight research measuring cardiac function needs to consider this important limitation for assessing absolute values of Q̇ and stroke volume. We propose that a large increase in vascular compliance in the splanchnic circulation invalidates the model under conditions of spaceflight. Pulse contour analysis utilizes a three-element Windkessel model that incorporates parameters dependent on aortic pressure-area relationships that are assumed to represent the entire circulation. In contrast, rebreathing estimates of Q̇ increased from seated baseline (4.76 ± 0.67 l/min) to inflight (7.00 ± 1.39 l/min, significant interaction effect of method and spaceflight, P < 0.001). Heart rate was reduced in supine baseline so that there were no differences in Q̇ by Modelflow estimate between the supine (7.02 ± 1.31 l/min, means ± SD), seated (6.60 ± 1.95 l/min), or inflight (5.91 ± 1.15 l/min) conditions. By Modelflow analysis, stroke volume was greater in supine baseline than seated baseline or inflight. We compared pulse contour analysis with the Modelflow algorithm to estimates of Q̇ obtained by rebreathing during preflight baseline testing and during the final month of long-duration spaceflight in nine healthy male astronauts. The method has been compared with standard methods under a range of conditions but never before during spaceflight. I look forward to developing with you all.Pulse contour analysis of the noninvasive finger arterial pressure waveform provides a convenient means to estimate cardiac output (Q̇). I thank Andy, John, Mike, and the other great guys at SDRplay who have really done a great job with this API and making it extremely easy to use. If we all pool our experiences as we go perhaps we can enhance the knowledge base quicker through co-operation and sharing our tips and tricks or experiences. Such as setting up your build environment, x-copying to your plugin directory post build, linking libraries, debugging problems, or help with the nana control library. I just wanted to offer my assistance where I can if anyone else has the need for help. I must say using a shuttle device to control the SDRuno application is very fun indeed. ![]() The plugin is already working great with SDRuno RC 1.4 and it can control most of the functions provided by the API. It provides support for the Contour Shuttle Express, Shuttle Pro and Shuttle Pro V2. I am just now putting the finishing touches on my Contour Shuttle Plugin for SDRuno that allows native control of SDRuno. I have decided to make some of my plugin ideas in SDRuno using the great new plugin API provided by SDRplay. I have made a few plugins for other SDR software over the past while.
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