Secondary respiratory early and late infections in mechanically ventilated patients with COVID-19.

BACKGROUND: Patients with COVID-19 receiving mechanical ventilation may become aggravated with a secondary respiratory infection. The aim of this study was to describe secondary respiratory infections, their predictive factors, and outcomes in patients with COVID-19 requiring mechanical ventilation. METHODS: A cohort study was carried out in a single tertiary hospital in Santiago, Chile, from 1st June to 31st July 2020. All patients with COVID-19 admitted to the intensive care unit that required mechanical ventilation were included. RESULTS: A total of 175 patients were enrolled, of which 71 (40.6%) developed at least one secondary respiratory infection during follow-up. Early and late secondary infections were diagnosed in 1.7% and 31.4% respectively. Within late secondary infections, 88% were bacterial, 10% were fungal, and 2% were of viral origin. One-third of isolated bacteria were multidrug-resistant. Bivariate analysis showed that the history of corticosteroids used before admission and the use of dexamethasone during hospitalization were associated with a higher risk of secondary infections (p = 0.041 and p = 0.019 respectively). Multivariate analysis showed that for each additional day of mechanical ventilation, the risk of secondary infection increases 1.1 times (adOR = 1.07; 95% CI 1.02-1.13, p = 0.008) CONCLUSIONS: Patients with COVID-19 admitted to the intensive care unit and requiring mechanical ventilation had a high rate of secondary infections during their hospital stay. The number of days on MV was a risk factor for acquiring secondary respiratory infections.

A new angular velocity observer for attitude tracking of spacecraft.

This paper proposes a new angular velocity observer for attitude tracking of spacecraft based on contraction analysis. The observer is designed in the inertial reference frame via estimating the inertial angular momentum to avoid the square term of the angular velocity when the spacecraft dynamics is expressed in the body frame. It employs a continuous angular-velocity dependent innovation term generated by means of a simple first-order linear filter, instead of a discontinuous attitude-dependent innovation term commonly used in angular velocity observer designs, resulting in a smooth behavior. The global exponential convergence is achieved. Moreover, when combined with the exponentially convergent tracking controller devised in this paper, it gives an overall system with exponential stability relying on a separation property. Finally, a switching function with hysteresis is introduced to stabilize the closest equilibrium in the configuration space, achieving the global exponential stability. Numerical simulations are included to illustrate the performance of the proposed observer in the closed loop, comparison with similar results, and robustness verification under inertia parameter uncertainties and noisy measurements.

Intubation timing as determinant of outcome in patients with acute respiratory distress syndrome by SARS-CoV-2 infection.

PURPOSE: To determine whether time-to-intubation was associated with higher ICU mortality in patients with COVID-19 on mechanical ventilation due to respiratory insufficiency. MATERIALS AND METHODS: We conducted an observational, prospective, single-center study of patients with confirmed SARS-CoV-2 infection hospitalized with moderate to severe ARDS, connected to mechanical ventilation in the ICU between March 17 and July 31, 2020. We examined their general and clinical characteristics. Time-to-intubation was the time from hospital admission to endotracheal intubation. RESULTS: We included 183 consecutive patients; 28% were female, and median age was 62 years old. Eighty-eight patients (48%) were intubated before 48 h (early) and ninety-five (52%) after 48 h (late). Patients intubated early had similar admission PaO2/FiO2 ratio (123 vs 99; p = 0.179) but were younger (59 vs 64; p = 0.013) and had higher body mass index (30 vs 28; p = 0.006) compared to patients intubated late. Mortality was higher in patients intubated late (18% versus 43%), with admission PaO2/FiO2 ratio < 100 mmHg (OR 5.2; p = 0.011), of older age (OR 1.1; p = 0.001), and with previous use of ACE inhibitors (OR 4.8; p = 0.026). CONCLUSIONS: In COVID-19 patients, late intubation, Pafi <100, older age, and previous ACE inhibitors use were associated with increased ICU mortality.

Avaliação histopatológica dos efeitos colaterais do uso intraestromal de biguanida em córnea de coelhos / Histopathological assessment of side effects of the use of corneal intrastromal biguanide in rabbits

OBJETIVO: Observar os efeitos da injeção intraestromal de biguanida a 0,02%, 0,1% e 0,5% em córnea de coelhos. MÉTODOS: Experimento prospectivo duplo cego. Foram utilizados 8 coelhos, identificados aleatoreamente e divididos em 4 grupos de 2 coelhos cada, ocorrendo a administração intraestromal de 0,2ml do fármaco na córnea do olho direito. O primeiro grupo recebeu biguanida na concentração de 0,02%, o segundo grupo a 0,1%, o terceiro a 0,5% e o quarto grupo (controle) recebeu a injeção de placebo - Soro Fisiológico 0,9%. Um dos coelhos de cada grupo foi sacrificado no terceiro dia e o outro no décimo dia após a injeção da droga e tiveram os olhos direitos enucleados e submetidos a exame histopatológico. RESULTADOS: Os coelhos que receberam placebo e biguanida a 0,02% apresentaram tanto no terceiro quanto no décimo dia da aplicação, reação inflamatória muito discreta. O coelho sacrificado no terceiro dia após a injeção da droga a 0,1% apresentou infiltrado inflamatório discreto com neutrófilos e eosinófilos, porém no décimo dia houve necrose estromal, vascularização e infiltrado intenso. O terceiro grupo apresentou necrose estromal, infiltrado moderado de leucócitos e atrofia endotelial com leucócitos na câmara anterior ao terceiro dia, evoluindo com necrose estromal extensa, infiltrado moderado e atrofia endotelial e epitelial no décimo dia. CONCLUSÃO: A biguanida quando utilizada via estromal nas concentrações de 0,1% e 0,5% pode causar efeitos indesejáveis na córnea de coelho, o que nos desperta para a necessidade de estudos posteriores com amostra maior para a confirmação dos achados.

PURPOSE: Observe the effects of corneal intrastromal injection of biguanide at 0.02%, 0.1% and 0.5% in rabbits' eyes. METHODS: Doble blind prospective study. 8 rabbits were used, randomly identified and divided into 4 groups, with 2 rabbits each, with the administration of 0.2 ml of the drug via intrastromal, in the right eye. The first group received biguanide at a concentration of 0.02%, the second one at 0.1%, the third at 0.5% and the fourth group (control) was given a placebo injection - saline solution at 0.9%. One rabbit from each group was sacrificed on the third day and the remaining rabbits on the tenth day after the drug injection and had its right eyes enucleated and submitted to histopathological analysis. RESULTS: The rabbits that received placebo and biguanide at 0.02% presented, both on the third and the tenth day of the application, mild inflammation response. The rabbit sacrificed on the third day after the drug injection at 0.1% presented mild inflammatory infiltrate with neutrophils and eosinophils, although on the tenth day there was stromal necrosis, vascularization and intense infiltrate. The third group presented stromal necrosis, moderate infiltrate of leukocytes and endothelial atrophy with leukocytes in the anterior chamber on the third day, developing extensive stromal necrosis, moderate infiltrate and endothelial and epithelial atrophy on the t enth day. CONCLUSION: Biguanide when used at concentrations of 0.1% and 0.5% may cause adverse reactions in the rabbit's cornea, which arouses the necessity of further studies with a larger sample to confirm the findings.