CovHos score for predicting severe respiratory failure in COVID-19 patients presenting at the emergency department.

Hospitalization of COVID-19 patients in low-intensity wards may put patients at risk in case of clinical deterioration. We tested CovHos score in predicting severe respiratory failure (SFR) at emergency department (ED) admission. This is a monocentric observational prospective study enrolling adult COVID-19 patients admitted to the ED of IRCCS AOU di Bologna Policlinico S.Orsola in October 2020, both discharged and hospitalized. Patients were then dichotomized based on days from symptoms onset. Main outcome was the occurrence of SRF. Receiver operating characteristic (ROC) analysis was used to identify cut-off and corresponding accuracy. A CovHos cut-off of 22 yielded a sensitivity of 84.7% and specificity of 75.3% in predicting SRF (AUROC 0.856; CI 95% 0.813-0.898). In patients with symptoms onset up to 8 days, a CovHos cut-off of 22 was able to predict SRF with a sensitivity of 91.7% and a specificity of 78.6% (AUROC 0.901; CI 95% 0.861-0.941). Negative predictive value (NPV) was 97.1%. A CovHos score lower than 22, in patients with COVID-19 symptoms onset dated 8 or less days prior to the ED admittance, had a NPV of 97.1% for the development of SRF, meaning that almost none of those patients will evolve into SRF and could be therefore suitable for a lower intensity of care.

How to transform a fixed stroke alternating syringe ventricle into an adjustable elastance ventricle.

Most devices used for bench simulation of the cardiovascular system are based either on a syringe-like alternating pump or an elastic chamber inside a fluid-filled rigid box. In these devices, it is very difficult to control the ventricular elastance and simulate pathologies related to the mechanical mismatch between the ventricle and arterial load (i.e., heart failure). This work presents a possible solution to transforming a syringe-like pump with a fixed ventricle into a ventricle with variable elastance. Our proposal was tested in two steps: (1) fixing the ventricle and the aorta and changing the peripheral resistance (PHR); (2) fixing the aorta and changing the ventricular elastance and the PHR. The signals of interest were acquired to build the ventricular pressure-volume (P-V) loops describing the different physiological conditions, and the end-systolic pressure-volume relationships (ESPVRs) were calculated with linear interpolation. The results obtained show a good physiological behavior of our mock for both steps. (1) Since the ventricle is the same, the systolic pressures increase and the stroke volumes decrease with the PHR: the ESPVR, obtained by interpolating the pressure and volume values at end-systolic phases, is linear. (2) Each ventricle presents ESPVR with different slopes depending on the ventricle elastance with a very good linear behavior. In conclusion, this paper demonstrates that a fixed stroke alternating syringe ventricle can be transformed into an adjustable elastance ventricle.