The long-term clinical management and evolution of a cohort of critical COVID-19 survivors have not been described in detail. We report a prospective observational study of COVID-19 patients admitted ...to the ICU between March and August 2020. The follow-up in a post-COVID consultation comprised symptoms, pulmonary function tests, the 6-minute walking test (6MWT), and chest computed tomography (CT). Additionally, questionnaires to evaluate the prevalence of post-COVID-19 syndrome were administered at 1 year. A total of 181 patients were admitted to the ICU during the study period. They were middle-aged (median IQR of 61 52;67) and male (66.9%), with a median ICU stay of 9 (5–24.2) days. 20% died in the hospital, and 39 were not able to be included. A cohort of 105 patients initiated the follow-up. At 1 year, 32.2% persisted with respiratory alterations and needed to continue the follow-up. Ten percent still had moderate/severe lung diffusion (DLCO) involvement (<60%), and 53.7% had a fibrotic pattern on CT. Moreover, patients had a mean (SD) number of symptoms of 5.7 ± 4.6, and 61.3% met the criteria for post-COVID syndrome at 1 year. During the follow-up, 46 patients were discharged, and 16 were transferred to other consultations. Other conditions, such as emphysema (21.6%), COPD (8.2%), severe neurocognitive disorders (4.1%), and lung cancer (1%) were identified. A high use of health care resources is observed in the first year. In conclusion, one-third of critically ill COVID-19 patients need to continue follow-up beyond 1 year, due to abnormalities on DLCO, chest CT, or persistent symptoms.
We used electron spin resonance (ESR) to analyze several kinds of single‐walled carbon nanotubes (SWNTs) synthesized by different methods. We observed that ESR is a sensitive probe that can be used ...to observe major differences between samples of carbon nanotubes (CNTs), in relation to their proportion of magnetic catalysts, impurities or defects. We analyzed the ESR spectra of CNTs in the usual way, by three overlapping lines. We then, implemented a function to fit the spectra, which gave us the intensity, line width (ΔHPP), and resonance line position (g factor) of each component line. The asymmetric line, which is assigned to the conduction electrons, could be used as a fingerprint of CNT purity. However, this asymmetric line is not always observed, since the three ESR lines often overlap, particularly when there is a large amount of paramagnetic ions. We studied the ESR spectra for different samples and estimated their purity by comparing the resulting parameters with data obtained by Raman spectroscopy on the same samples.
Studies of electron spin resonance (ESR) are reported on several types of single‐walled carbon nanotubes (SWCNTs) synthesized by different methods. We work both with the obtained samples, which ...contained randomly distributed semiconducting and metallic SWCNTs, and with selected 99% semiconducting or metallic SWCNTs. Our aim is to use ESR spectroscopy in order to assess the quality of carbon nanotubes. We analyze the temperature dependence of ESR spectra in the range 4–300 K and report the temperature dependence of the linewidth, the intensity and the asymmetry factor (I+/I−) of the ESR lines. The ESR response from the arc discharge SWCNTs produced using non‐magnetic Pt/Rh catalyst and from the selected semiconducting tubes exhibits an asymmetric line with an intensity that remains almost constant with decreasing temperature, showing a constant linewidth of about 2.9 mT. For selected bucky paper (BP) metallic or semiconducting carbon nanotubes, we also study the ESR signal according to the BP parallel or perpendicular orientation to the magnetic field. The g‐factor and the asymmetry factor show a clear anisotropy.
We evaluated whether the time between first respiratory support and intubation of patients receiving invasive mechanical ventilation (IMV) due to COVID-19 was associated with mortality or pulmonary ...sequelae.
Prospective cohort of critical COVID-19 patients on IMV. Patients were classified as early intubation if they were intubated within the first 48 h from the first respiratory support or delayed intubation if they were intubated later. Surviving patients were evaluated after hospital discharge.
We included 205 patients (140 with early IMV and 65 with delayed IMV). The median p
;p
age was 63 56.0; 70.0 years, and 74.1% were male. The survival analysis showed a significant increase in the risk of mortality in the delayed group with an adjusted hazard ratio (HR) of 2.45 (95% CI 1.29-4.65). The continuous predictor time to IMV showed a nonlinear association with the risk of in-hospital mortality. A multivariate mortality model showed that delay of IMV was a factor associated with mortality (HR of 2.40; 95% CI 1.42-4.1). During follow-up, patients in the delayed group showed a worse DLCO (mean difference of - 10.77 (95% CI - 18.40 to - 3.15), with a greater number of affected lobes (+ 1.51 95% CI 0.89-2.13) and a greater TSS (+ 4.35 95% CI 2.41-6.27) in the chest CT scan.
Among critically ill patients with COVID-19 who required IMV, the delay in intubation from the first respiratory support was associated with an increase in hospital mortality and worse pulmonary sequelae during follow-up.
More than 20% of hospitalized patients with COVID-19 demonstrate ARDS requiring ICU admission. The long-term respiratory sequelae in such patients remain unclear.
What are the major long-term ...pulmonary sequelae in critical patients who survive COVID-19?
Consecutive patients with COVID-19 requiring ICU admission were recruited and evaluated 3 months after hospitalization discharge. The follow-up comprised symptom and quality of life, anxiety and depression questionnaires, pulmonary function tests, exercise test (6-min walking test 6MWT), and chest CT imaging.
One hundred twenty-five patients admitted to the ICU with ARDS secondary to COVID-19 were recruited between March and June 2020. At the 3-month follow-up, 62 patients were available for pulmonary evaluation. The most frequent symptoms were dyspnea (46.7%) and cough (34.4%). Eighty-two percent of patients showed a lung diffusing capacity of less than 80%. The median distance in the 6MWT was 400 m (interquartile range, 362-440 m). CT scans showed abnormal results in 70.2% of patients, demonstrating reticular lesions in 49.1% and fibrotic patterns in 21.1%. Patients with more severe alterations on chest CT scan showed worse pulmonary function and presented more degrees of desaturation in the 6MWT. Factors associated with the severity of lung damage on chest CT scan were age and length of invasive mechanical ventilation during the ICU stay.
Three months after hospital discharge, pulmonary structural abnormalities and functional impairment are highly prevalent in patients with ARDS secondary to COVID-19 who required an ICU stay. Pulmonary evaluation should be considered for all critical COVID-19 survivors 3 months after discharge.
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Regular and distance-regular characterizations of general graphs are well-known. In particular, the spectral excess theorem states that a connected graph Γ is distance-regular if and only if its ...spectral excess (a number that can be computed from the spectrum) equals the average excess (the mean of the numbers of vertices at extremal distance from every vertex). The aim of this paper is to derive new characterizations of regularity and distance-regularity for the more restricted family of bipartite graphs. In this case, some characterizations of (bi)regular bipartite graphs are given in terms of the mean degrees in every partite set and the Hoffman polynomial. Moreover, it is shown that the conditions for having distance-regularity in such graphs can be relaxed when compared with general graphs. Finally, a new version of the spectral excess theorem for bipartite graphs is presented.
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