Background The Doppler-derived renal resistive index (RRI) is emerging as a promising bedside tool for assessing renal perfusion and risk of developing acute kidney injury in critically ill patients. It is not known what level of ultrasonography competence is needed to obtain reliable RRI values. Objective The aim of this study was to evaluate the feasibility of RRI measurements by an intermediate and novice sonographer in a volunteer population. Methods After a focused teaching session, an intermediate (resident), novice (medical student) and expert sonographer performed RRI measurements in 23 volunteers consecutively and blinded to the results of one another. Intraclass correlation coefficients and Bland–Altman plots were used to evaluate interobserver reliability, bias and precision. Results Both non-experts were able to obtain RRI values in all volunteers. Median RRI in the population measured by the expert was 0.58 (interquartile range 0.52–0.62). The intraclass correlation coefficient was 0.96 (95% confidence interval 0.90–0.98) for the intermediate and expert, and 0.85 (95% confidence interval 0.69–0.94) for the novice and expert. In relation to the measurements of the expert, both non-experts showed negligible bias (mean difference 0.002 [95% confidence interval − 0.005 to 0.009, p = 0.597] between intermediate and expert, mean difference 0.002 [95% confidence interval − 0.011 to 0.015, p = 0.752] between novice and expert) and clinically acceptable precision (95% limits of agreement − 0.031 to 0.035 for the intermediate, 95% limits of agreement − 0.056 to 0.060 for the novice). Conclusions RRI measurements by both an intermediate and novice sonographer in a volunteer population were reliable, accurate and precise after a brief course. RRI is easy to learn and feasible within the scope of point-of-care ultrasound.

Background Renal resistive index (RRI) is a promising tool for the assessment of acute kidney injury (AKI) in critically ill patients in general, but its role and association to AKI among patients with Coronavirus disease 2019 (COVID-19) is not known. Objective The aim of this study was to describe the pattern of RRI in relation to AKI in patients with COVID-19 treated in the intensive care unit. Methods In this observational cohort study, RRI was measured in COVID-19 patients in six intensive care units at two sites of a Swedish University Hospital. AKI was defined by the creatinine criteria in the Kidney Disease Improving Global Outcomes classification. We investigated the association between RRI and AKI diagnosis, different AKI stages and urine output. Results RRI was measured in 51 patients, of which 23 patients (45%) had AKI at the time of measurement. Median RRI in patients with AKI was 0.80 (IQR 0.71–0.85) compared to 0.72 (IQR 0.67–0.78) in patients without AKI (p = 0.004). Compared to patients without AKI, RRI was higher in patients with AKI stage 3 (median 0.83, IQR 0.71–0.85, p = 0.006) but not in patients with AKI stage 1 (median 0.76, IQR 0.71–0.83, p = 0.347) or AKI stage 2 (median 0.79, min/max 0.79/0.80, n = 2, p = 0.134). RRI was higher in patients with an ongoing AKI episode compared to patients who never developed AKI (median 0.72, IQR 0.69–0.78, p = 0.015) or patients who developed AKI but had recovered at the time of measurement (median 0.68, IQR 0.67–0.81, p = 0.021). Oliguric patients had higher RRI (median 0.84, IQR 0.83–0.85) compared to non-oliguric patients (median 0.74, IQR 0.69–0.81) (p = 0.009). After multivariable adjustment, RRI was independently associated with AKI (OR for 0.01 increments of RRI 1.22, 95% CI 1.07–1.41). Conclusions Critically ill COVID-19 patients with AKI have higher RRI compared to those without AKI, and elevated RRI may have a role in identifying severe and oliguric AKI at the bedside in these patients.

Thrombosis and bleeding after implementation of an intermediate-dose prophylactic anticoagulation protocol in intensive care unit (ICU) patients with coronavirus disease 2019 (COVID-19): a multicenter screening study Background: Venous thromboembolism (VTE) is common among critically ill patients with COVID-19. Information regarding VTE prevalence and bleeding complications after implementation of intermediate-dose prophylactic anticoagulation in such patients is, however, limited. Methods: We performed a prospective, observational study in 6 ICUs in 2 university-affiliated teaching hospitals in Sweden. After implementation of an intermediate-dose prophylactic anticoagulation protocol, we performed ultrasound screening for proximal lower-extremity deep vein thrombosis (DVT) and collected routine computed tomography pulmonary angiography exam results. Results: A total of 100 COVID-19 patients were included from June 21, 2020, through February 18, 2021. During a median follow-up of 120 (IQR, 89-134) days, we found VTE in 37 patients with the majority (78.4%) being diagnosed after ICU arrival. Overall, 20 patients had proximal lower-extremity DVT with 95% being detected on ultrasound screening; 22 patients had pulmonary vascular thrombosis; and 4 patients had venous thrombosis at other sites. A total of 6 patients had both proximal lower-extremity DVT and pulmonary vascular thrombosis. On univariate logistic regression analysis of 14 baseline characteristics, only pre-existing heart failure was associated with VTE (OR 4.67, 95% CI 1.13-19.34). Major and non-major bleeding occurred in 10 and 18 patients, respectively. Conclusions: In our cohort of ICU patients with COVID-19, we observed a high prevalence of VTE and bleeding complications after implementation of intermediate-dose anticoagulation. In approximately half of patients, VTE was identified on screening ultrasound.

Background: Renal resistive index (RRI) is a promising tool for prediction of acute kidney injury (AKI) in critically ill patients but is not described among patients with Coronavirus disease 2019 (COVID-19). The aim of this study was to describe the pattern of RRI in relation to AKI in patients with COVID-19 treated in the intensive care unit.Methods: In this observational cohort study, RRI was measured in COVID-19 patients in six ICUs at two sites of a Swedish University Hospital. AKI was defined by the creatinine criteria in the Kidney Disease Improving Global Outcome classification. We investigated the association between RRI and AKI diagnosis, different AKI stages and urine output.Results: RRI was measured in 51 patients, of which 23 patients (45%) had AKI at the time of measurement. Median RRI in patients with AKI was 0.80 (IQR 0.71-0.85) compared to 0.72 (IQR 0.67-0.78) in patients without AKI (p=0.004). Compared to patients without AKI, RRI was higher in patients with AKI stage 3 (median 0.83, IQR 0.71-0.85, p=0.006) but not in patients with AKI stage 1 (median 0.76, IQR 0.71-0.83, p=0.347) or AKI stage 2 (median 0.79, min/max 0.79/0.80, n=2, p=0.134). RRI was higher in patients with an ongoing AKI episode compared to patients who never developed AKI (median 0.72, IQR 0.69-0.78, p=0.015) or patients who developed AKI but had recovered at the time of measurement (median 0.68, IQR 0.67-0.81, p=0.021). Oliguric patients had higher RRI (median 0.84, IQR 0.83-0.85) compared to non-oliguric patients (median 0.74, IQR 0.69-0.81) (p=0.009).Conclusions: Critically ill COVID-19 patients with AKI have higher RRI compared to those without AKI, and elevated RRI may have a role in identifying severe and oliguric AKI in these patients.