Diaphragm impairment in patients admitted for severe COVID-19.

Among patients affected by the virus COVID-19, physicians have observed ventilation disorders. It is relevant to assess neurological involvement, including the role of diaphragmatic function. Its possible impairment could be related to the systemic inflammatory response and disease progression that both typify COVID-19 infection. We distinguished two groups (severe group (SG) and mild group (MG)) according to the severity of respiratory symptomatology. We performed neurophysiological and sonography studies to evaluate the diaphragmatic function. Regarding the sonography variables, we identified statistically significant differences in the right mean diaphragmatic thickness along with the expiration, showing 1.56 mm (SEM: 0.11) in the SG vs 1.92 mm (SEM: 0.19) in the MG (p = 0.042). The contractibility of both hemidiaphragms was 15% lower in the severe group, though this difference is not statistically significant. In our examination of the neurophysiological variables, in the amplitude responses, we observed a greater difference between responses from both phrenic nerves as follows: the raw differences in amplitude were 0.40 µV (SEM: 0.14) in the SG vs 0.35 µV (SEM: 0.19) in the MG and the percentage difference was 25.92% (SEM: 7.22) in the SG vs 16.28% (SEM: 4.38%) in the MG. Although diaphragmatic dysfunction is difficult to detect, our combined functional and morphological approach with phrenic electroneurograms and chest ultrasounds could improve diagnostic sensitivity. We suggest that diaphragmatic dysfunction could play a relevant role in respiratory disturbance in hospitalised patients with severe COVID-19.

Inference in epidemiological agent-based models using ensemble-based data assimilation.

To represent the complex individual interactions in the dynamics of disease spread informed by data, the coupling of an epidemiological agent-based model with the ensemble Kalman filter is proposed. The statistical inference of the propagation of a disease by means of ensemble-based data assimilation systems has been studied in previous works. The models used are mostly compartmental models representing the mean field evolution through ordinary differential equations. These techniques allow to monitor the propagation of the infections from data and to estimate several parameters of epidemiological interest. However, there are many important features which are based on the individual interactions that cannot be represented in the mean field equations, such as social network and bubbles, contact tracing, isolating individuals in risk, and social network-based distancing strategies. Agent-based models can describe contact networks at an individual level, including demographic attributes such as age, neighborhood, household, workplaces, schools, entertainment places, among others. Nevertheless, these models have several unknown parameters which are thus difficult to prescribe. In this work, we propose the use of ensemble-based data assimilation techniques to calibrate an agent-based model using daily epidemiological data. This raises the challenge of having to adapt the agent populations to incorporate the information provided by the coarse-grained data. To do this, two stochastic strategies to correct the model predictions are developed. The ensemble Kalman filter with perturbed observations is used for the joint estimation of the state and some key epidemiological parameters. We conduct experiments with an agent based-model designed for COVID-19 and assess the proposed methodology on synthetic data and on COVID-19 daily reports from Ciudad Autónoma de Buenos Aires, Argentina.

HP36: Diaphragm impairment in patients with COVID-19: A case-control study

Objective: Physicians have observed ventilation disorders in patients with COVID-19. The possible impairment of the diaphragm could be related to the systemic inflammatory response that typifies this infection. We aimed to assess the diaphragmatic function in patients with severe COVID-19. Methods: We recruited patients admitted with pneumonia and positive PCR for SARS-CoV-2, differentiating two groups according to their respiratory symptoms. The cases group consisted of 9 inpatients with moderate-severe dyspnea, pain with diaphragmatic origin or hiccup. The control group consisted of 10 inpatients who suffered from mild dyspnea. We performed phrenic nerve electroneurogram and diaphragmatic ultrasound to assess the diaphragmatic function. Results: We observed differences in the amplitude of evoked potentials, being 25.92% (SEM:7.22) in the cases group vs 19.81% (SEM:5.27) in the control group (p = 0.711). The right diaphragm thickness mean was 46.67% (SEM:8.86) in the cases group vs 62.15% (SEM:5.58) in the control group (p = 0.432), the left diaphragm thickness mean was 57.89% (SEM:15.36) in the cases group vs 73.34% (SEM:6.74) in the control group (p = 0.730), the right expiratory fraction mean was 0.53 (SEM:0.11) in the cases group vs 0.59 (SEM:0.05) in the control group (p = 0.674), and the left expiratory fraction mean was 0.58 (SEM:0.15) in the cases group vs 0.73 (SEM:0.07) in the control group (p = 0.195). Conclusion: Although diaphragmatic dysfunction is difficult to detect, our combined functional and morphological approach with electroneurograms and ultrasounds could improve diagnostic sensitivity. We suggest that diaphragmatic dysfunction could play a relevant role in respiratory failure in patients with COVID-19. [ FROM AUTHOR] Copyright of Clinical Neurophysiology is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

HP05: Diagnostic and prognostic assessment in respiratory and hemodynamic changes related to prone position in COVID-19 patients

Objective: One of the most relevant findings of COVID-19 is the respiratory damage that leads to an impairment in tissue oxygenation during the course of the disease. To study this disease's physiopathology, we have analyzed the respiratory patterns and the hemodynamic variations related to postural changes in inpatients with COVID-19. Methods: We performed a prospective study including 11 polygraph and hemodynamic studies from inpatients admitted for COVID-19 who benefited from positional changes. To assess the respiratory parameters, we conducted polygraph studies. To evaluate the hemodynamic variables, we used a thoracic electrical bioimpedance. Results: We observed a minimum oxygen saturation median of 85.00% (IQR: 7.00) in the supine position vs 91.00% (IQR: 8.00) in the prone position (p=0.173). The airflow restriction in the supine position was 2.70% (IQR: 6.55) vs 1.55% (IQR: 2.80) in the prone position (p=0.383). We observed a slight tendency to decrease in all parameters in the prone position concerning the hemodynamic variables, although they were no statistically significant. We show a decrease in vascular resistance mean in the prone position, being 18.2% vs 36.4% in the supine position (p=0.871). Conclusion: Our report shows an improvement in oxygen saturation and airflow restriction related to the placement of the patient in the prone position. Also, we observed a mild enhancement in hemodynamic variables. The data shown is relevant because early identification of the more severe cases could help anticipate the clinical progression using the therapeutic oxygen measures necessary to avoid the disease's fatal progression. [ FROM AUTHOR] Copyright of Clinical Neurophysiology is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)