Clinical characteristics of critically ill patients with COVID-19 (preprint)

ObjectiveDescribe the clinical and respiratory characteristics of critical patients with coronavirus disease 2019 (COVID-19). DesignObservational and retrospective study over 6 months. SettingIntensive care unit (ICU) of a high complexity hospital in Buenos Aires, Argentina. PatientsPatients older than 18 years with laboratory-confirmed COVID-19 by reverse transcriptase-polymerase chain reaction (RT-PCR) for SARS-CoV-2 were included in the study. Variables of interestDemographic characteristics such as sex and age, comorbidities, laboratory results, imaging results, ventilatory mechanics data, complications, and mortality were recorded. ResultsA total of 168 critically ill patients with COVID-19 were included. 66% were men with a median age of 65 years (58-75. 79.7% had at least one comorbidity. The most frequent comorbidity was arterial hypertension, affecting 52.4% of the patients. 67.9 % required invasive mechanical ventilation (MV), and no patient was treated with non-invasive ventilation. Most of the patients in MV (73.7%) required neuromuscular blockade due to severe hypoxemia. 36% of patients were ventilated in the prone position. The length of stay in the ICU was 13 days (6-24) and the mortality in the ICU was 25%. ConclusionsIn this study of critical patients infected by SARS-CoV-2 in a high-complexity hospital, the majority were comorbid elderly men, a large percentage required invasive mechanical ventilation, and ICU mortality was 25%.

MMGB/SA Consensus Estimate of the Binding Free Energy Between the Novel Coronavirus Spike Protein to the Human ACE2 Receptor (preprint)

The ability to estimate protein-protein binding free energy in a computationally efficient via a physics-based approach is beneficial to research focused on the mechanism of viruses binding to their target proteins. Implicit solvation methodology may be particularly useful in the early stages of such research, as it can offer valuable insights into the binding process, quickly. Here we evaluate the potential of the related molecular mechanics generalized Born surface area (MMGB/SA) approach to estimate the binding free energy {Delta}Gbind between the SARS-CoV-2 spike receptor-binding domain and the human ACE2 receptor. The calculations are based on a recent flavor of the generalized Born model, GBNSR6. Two estimates of {Delta}Gbind are performed: one based on standard bondi radii, and the other based on a newly developed set of atomic radii (OPT1), optimized specifically for protein-ligand binding. We take the average of the resulting two {Delta}Gbind values as the consensus estimate. For the well-studied Ras-Raf protein-protein complex, which has similar binding free energy to that of the SARS-CoV-2/ACE2 complex, the consensus {Delta}Gbind = -11.8 {+/-} 1 kcal/mol, vs. experimental -9.7 {+/-} 0.2 kcal/mol. The consensus estimates for the SARS-CoV-2/ACE2 complex is {Delta}Gbind = -9.4 {+/-} 1.5 kcal/mol, which is in near quantitative agreement with experiment (-10.6 kcal/mol). The availability of a conceptually simple MMGB/SA-based protocol for analysis of the SARS-CoV-2 /ACE2 binding may be beneficial in light of the need to move forward fast.

Tracheal aspirate with closed suction device: a modified technique developed during COVID-19 outbreak. (preprint)

BackgroundBacterial superinfection as well as ventilation associated pneumonia (VAP) are both frequent events in critical care. During COVID-19 pandemic, usual diagnostic practices such as bronchoalveolar lavage and tracheal aspirate are limited due to their associated high risk of exposure for the operator. In order to set primary focus on the protection of health care personnel, a modified tracheal aspiration (M-TA) technique is developed and used for acquiring a lower respiratory tract of microbiological samples with a closed suction device. MethodsRetrospective observational study to evaluate effectiveness of M-TA is conducted. ResultsA total of 33 M-TA samples were analyzed. In 66,6% of the cases, results led to a change in medical decision making. A 100% accuracy was achieved regarding COVID-19 diagnosis and a 56% bacterial growth-rate in cultives where VAP was suspected. No health care personnel have developed symptoms nor tested positive for COVID-19 during or after sample collection. ConclusionM-TA technique presented could be considered as a safe and effective procedure with low percentage of complications.