Purpose: Although patients with SARS-CoV-2 infection have several risk factors for ventilator-associated lower respiratory tract infections (VA-LRTI), the reported incidence of hospital-acquired infections is low. We aimed to determine the relationship between SARS-CoV-2 pneumonia, as compared to influenza pneumonia or no viral infection, and the incidence of VA-LRTI.Methods: Multicenter retrospective European cohort performed in 36 ICUs. All adult patients receiving invasive mechanical ventilation > 48 h were eligible if they had: SARS-CoV-2 pneumonia, influenza pneumonia, or no viral infection at ICU admission. VA-LRTI, including ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP), were diagnosed using clinical, radiological and quantitative microbiological criteria. All VA-LRTI were prospectively identified, and chest-X rays were analyzed by at least two physicians. Cumulative incidence of first episodes of VA-LRTI was estimated using the Kalbfleisch and Prentice method, and compared using Fine-and Gray models.Results: 1576 patients were included (568 in SARS-CoV-2, 482 in influenza, and 526 in no viral infection groups). VA-LRTI incidence was significantly higher in SARS-CoV-2 patients (287, 50.5%), as compared to influenza patients (146, 30.3%, adjusted sub hazard ratio (sHR) 1.60 (95% confidence interval (CI) 1.26 to 2.04)) or patients with no viral infection (133, 25.3%, adjusted sHR 1.7 (95% CI 1.2 to 2.39)). Gram-negative bacilli were responsible for a large proportion (82% to 89.7%) of VA-LRTI, mainly Pseudomonas aeruginosa, Enterobacter spp., and Klebsiella spp.

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A method for determining the acoustic properties of thin plates is described. Existing theoretical expressions are used to calculate transmission and reflection coefficients for sound waves striking the plates at arbitrary angles of incidence. Theory is substantiated by experimental data, and refined values for absorption coefficient and shear velocity are obtained by combining theory and experiment. Materials tested were Absonic-A, plexiglass, and polyethylene.

Background Sleep had never been assessed immediately after extubation in patients still in the ICU. However, sleep deprivation may alter respiratory function and may promote respiratory failure. We hypothesized that sleep alterations after extubation could be associated with an increased risk of post-extubation respiratory failure and reintubation. We conducted a prospective observational cohort study performed at the medical ICU of the university hospital of Poitiers in France. Patients at high-risk of extubation failure (> 65 years, with any underlying cardiac or lung disease, or intubated > 7 days) were included. Patients intubated less than 24 h, with central nervous or psychiatric disorders, continuous sedation, neuroleptic medication, or uncooperative were excluded. Sleep was assessed by complete polysomnography just following extubation including the night. The main objective was to compare sleep between patients who developed post-extubation respiratory failure or required reintubation and the others. Results Over a 3-year period, 52 patients had complete polysomnography among whom 12 (23%) developed post-extubation respiratory failure and 8 (15%) required reintubation. Among them, 10 (19%) had atypical sleep, 15 (29%) had no deep sleep, and 33 (63%) had no rapid eye movement (REM) sleep. Total sleep time was 3.2 h in median [interquartile range, 2.0–4.4] in patients who developed post-extubation respiratory failure vs. 2.0 [1.1–3.8] in those who were successfully extubated (p = 0.34). Total sleep time, and durations of deep and REM sleep stages did not differ between patients who required reintubation and the others. Reintubation rates were 21% (7/33) in patients with no REM sleep and 5% (1/19) in patients with REM sleep (difference, − 16% [95% CI − 33% to 6%]; p = 0.23). Conclusions Sleep assessment by polysomnography after extubation showed a dramatically low total, deep and REM sleep time. Sleep did not differ between patients who were successfully extubated and those who developed post-extubation respiratory failure or required reintubation.

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Background: COVID-19 may induce endovascular injury of pulmonary vessels and could be associated with increased risk of pulmonary embolism. The main objective was to compare the incidence of pulmonary embolism in patients with acute respiratory distress syndrome (ARDS) related to COVID-19 versus patients with pulmonary ARDS unrelated to COVID-19.Methods: This is an observational controlled-cohort study performed at a single center of a university teaching hospital in France. The incidence of pulmonary embolism was prospectively assessed using computed tomography pulmonary angiography (CTPA) in patients with ARDS related to COVID-19 and compared to patients from a 3-year historical cohort of patients with pulmonary ARDS unrelated to COVID-19. In patients with ARDS related to COVID-19, CTPA was performed approximately 7 days after intubation or earlier in case of respiratory or hemodynamic worsening.Results: CTPA was performed in 29 out of the 42 patients (69%) with ARDS related to COVID-19 and in 51 out of the 156 patients (33%) from the historical cohort of patients with pulmonary ARDS unrelated to COVID-19. Incidence of pulmonary embolism was 40% (17/42) in patients with ARDS related to COVID-19 and 3% (5/156) in the historical cohort (P=0.001). The proportion of patients with pulmonary embolism among all patients who had CTPA was 59% (17/29) in patients with ARDS related to COVID-19 and 10% (5/51) in the historical cohort (P=0.0001). After adjustment on the interval between ICU admission and computed tomography, COVID-19 remained independently associated with pulmonary embolism.Conclusions: Pulmonary embolism was particularly frequent in patients with ARDS related to COVID-19, thereby suggesting that CTPA should be systematically performed in these patients.

Experimental curves are presented that describe the reflected sound field from a pressure-release sinusoidal surface. The measurements were made in an 8-ft-diam, 7-ft-deep laboratory tank equipped with a dual-transducer-positioning system that is capable of positioning each transducer to any position in the tank with an accuracy of ±0.003 in. in any x, y, or z coordinate and ±0.1° in tilt and azimuth. The sinusoidal surface was machined in styrofoam sheets that were glued to a 4×4-ft tray located near the bottom of the tank. The sinusoid was cut with an amplitude of 1.5 cm and a period of 4.5 cm. The amplitudes of the reflected pulses are presented as a function of the angle of reflection for several fixed grazing angles. Amplitude data are also presented as a function of frequency for several fixed grazing angles. Zero-order or specular-reflection data are presented for incident wavelengths varying from 1 to 14 the amplitude of the sinusoidal surface. [Work supported by the U. S. Navy Bureau of Ships.]

Measurements were made to determine the reflection and transmission coefficients of several transducer window and dome materials. The coefficients were measured as a function of incident angle in the frequency range 100–500 kc/sec. The effects of the shear component as well as the absorption of both the longitudinal and shear waves are discussed. Refined values for the magnitude of the shear velocity and the absorption can be obtained by fitting the calculated values to the experimental curves. (Work supported by the U. S. Navy Bureau of Ships.]