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Background: COVID-19 patients are related with an elevated risk for deep venous thrombosis (DVT). We evaluated the prevalence of DVT in our intubated and mechanically ventilated COVID-19+ patients at March 29th. Methods: We performed a Mono-center, investigator-initiated, observational, cross-sectional study. A total of 12 intubated COVID-19+ patients at intensive care unit (ICU) ward C3 of the Jessa Hospital, Hasselt, Belgium at March 29th were included. All patients received a prophylactic dose of low-molecular-weight heparin (LMWH). All intubated and mechanically ventilated patients were screened for the presence of DVT in femoral, popliteal, jugular and inferior caval veins with duplex ultrasound. Results: In total, 8 from all 12 intubated and ventilated COVID 19+ patients had already developed minimally one DVT. No relevant correlations could be detected. Conclusions: The prevalence of DVT in critically ill ICU patients with COVID-19 is over 60% despite adequate treatment with a prophylactic dose of LMWH. We suggest the use of graduated compression (elastic) stockings (GCS) and intermediate-dose LMWH for thrombosis prophylaxis in all COVID-19 patients. Since there were no clinical signs of DVT, we suggest to routinely screen all COVID-19 patients admitted to ICU for DVT via ultrasound. Future research should focus on the mechanisms underlying these observations.

Background and Purpose Serial ultrasonic B-mode measurements of intimal-medial thickness (IMT) of the carotid artery are commonly used as surrogates for describing atherosclerosis progression. This report describes the longitudinal reliability of IMT measurement during a multicenter clinical trial, quantifies the error attributable to differences among readers, and discusses how studies can be efficiently designed. Methods Serial B-mode measurements of carotid IMT from the 3-year Asymptomatic Carotid Artery Progression Study (ACAPS; formerly Asymptomatic Carotid Artery Plaque Study) were used to estimate the contributions to longitudinal measurement error of systematic reader effects, nonvisualization, and nonsystematic error and to describe the distribution of “true” progression rates that underlie the observed data. Variance components were estimated from random-effects models fitted to outcome measures formed by averaging IMTs from different sets of carotid artery walls. These were used to contrast the relative efficiency of study designs. Results Of the total variance of measured IMT, 11% was attributable to systematic differences among readers. Nonvisualization contributed less than 7%. Thus, the predominant source of error was unaccounted for (ie, random error or “noise,” which in our analyses included any drift, nonlinearity, and sonographer differences). For studies with measurement protocols similar to ACAPS, follow-up times of 2 years or more are desirable for describing the mean progression rates of cohorts, and of 6 years or more for categorizing progression within individuals. In 3-year studies, sample sizes as low as 237 provide 90% statistical power for detecting risk factors that have correlations with IMT progression of .50 or greater. Conclusions The ACAPS measurement protocol provided highly reliable serial IMT data. Moderate-sized multicenter studies using B-mode outcomes are feasible.

A randomly selected subset of 100 pairs of baseline and 36-month follow-up carotid B-mode ultrasound examinations from the 919 patients participating in the Asymptomatic Carotid Artery Progression Study (ACAPS) were subjected to a blinded rereading at the conclusion of the trial to assess temporal bias in the measurement of carotid artery intimal-medial thickness (IMT). The original measurements of the primary outcome variable and five secondary outcome variables at baseline and 36 months, respectively, and the 3-year change in each of these variables, were compared with those obtained from the rereadings. For the primary outcome variable, the mean value of 12 IMT measurements obtained from predefined carotid segments, the mean difference (original-rereading) and the 95% confidence interval which resulted from the rereadings were -0.005 (-0.033, 0.023) mm at baseline and -0.009 (-0.031, 0.013) mm at 36 months. The difference in the 3-year change was -0.004 (-0.038, 0.028) mm. The 95% confidence interval for the mean difference between the rereadings and the original readings for the baseline and the 36-month follow-up examinations included zero for all of the six outcome variables as was also the case for the 3-year change in each variable. The magnitude of the mean differences for these 18 variables ranged from 0.004 to 0.034 mm. Intraclass correlation coefficients between the original readings and rereadings ranged from 0.56 to 0.87 with the 3-year changes in outcome variables tending to have lower correlations and the 36-month examinations higher correlations. The carotid IMT measurement process, when combined with uniform reader training, certification and monitoring of reading performance throughout the course of the study, can avoid the temporal bias observed in other studies.