Ventriculo-arterial coupling in the intensive cardiac care unit: A non-invasive prognostic parameter.

AIMS: The aim of this study was to investigate the relationship between ventriculo-arterial coupling (VAC) and in-hospital outcomes and to assess the prognostic value of VAC in critically ill patients. METHODS AND RESULTS: A total of 329 consecutive patients (mean age 66,7 ± 15.5 years, 66.9% male) admitted to the intensive cardiac care unit of the Sandro Pertini Hospital, Rome (Italy) between January 2019 and December 2019, were included in the study. All patients underwent blood pressure measurement and non-invasive, echocardiography-derived estimates of left ventricular end-systolic elastance (Ees), arterial elastance (Ea) and VAC in a single-beat determination using the iElastance© application. In-hospital events related to acute heart failure and hypoperfusion were recorded and need for invasive ventilation, intra-aortic balloon pump, renal replacement therapy and death were considered as composite. Overall, 39 patients (11,8%) experienced in-hospital complications (group C), and 290 (88,2%) did not (group NoC). Ea and VAC were found to be significantly higher in group C than in group NoC, and a trend toward decreased Ees was observed in group C. VAC was a strong and independent predictor of in-hospital clinical outcome both at univariable and multivariable analysis adjusted for comorbidities [OR (95% CI): 1.868 (1.141-3.059); P = 0.013] and hemodynamic parameters [OR (95% CI): 1674 (1018-2755); P = 0.042]. CONCLUSION: VAC might be an additional non-invasive prognosticator of outcome in critically ill patients.

Solar UV-B/A radiation is highly effective in inactivating SARS-CoV-2.

Solar UV-C photons do not reach Earth's surface, but are known to be endowed with germicidal properties that are also effective on viruses. The effect of softer UV-B and UV-A photons, which copiously reach the Earth's surface, on viruses are instead little studied, particularly on single-stranded RNA viruses. Here we combine our measurements of the action spectrum of Covid-19 in response to UV light, Solar irradiation measurements on Earth during the SARS-CoV-2 pandemics, worldwide recorded Covid-19 mortality data and our "Solar-Pump" diffusive model of epidemics to show that (a) UV-B/A photons have a powerful virucidal effect on the single-stranded RNA virus Covid-19 and that (b) the Solar radiation that reaches temperate regions of the Earth at noon during summers, is sufficient to inactivate 63% of virions in open-space concentrations (1.5 × 103 TCID50/mL, higher than typical aerosol) in less than 2 min. We conclude that the characteristic seasonality imprint displayed world-wide by the SARS-Cov-2 mortality time-series throughout the diffusion of the outbreak (with temperate regions showing clear seasonal trends and equatorial regions suffering, on average, a systematically lower mortality), might have been efficiently set by the different intensity of UV-B/A Solar radiation hitting different Earth's locations at different times of the year. Our results suggest that Solar UV-B/A play an important role in planning strategies of confinement of the epidemics, which should be worked out and set up during spring/summer months and fully implemented during low-solar-irradiation periods.

Forcing Seasonality of Influenza-like Epidemics with Daily Solar Resonance.

Seasonality of acute viral respiratory diseases is a well-known and yet not fully understood phenomenon. Several models have been proposed to explain the regularity of yearly recurring outbreaks and the phase differences observed at different latitudes on the Earth. Such models consider known internal causes, primarily the periodic emergence of new virus variants that evade the host immune response. Yet, this alone is generally unable to explain the regularity of recurrences and the observed phase differences. Here we show that seasonality of viral respiratory diseases, as well as its distribution with latitude on the Earth, can be fully explained by the virucidal properties of UV-B and UV-A solar photons through a daily, minute-scale, resonant forcing mechanism. Such an induced periodicity can last, virtually unperturbed, from tens to hundreds of cycles, and even in the presence of internal dynamics (host's loss of immunity) much slower than seasonal will, on a long period, generate seasonal oscillations.