Lung ultrasonography performed by nephrologist: COVID-19 as an opportunity to reveal ultrasound's full potential and usefulness in the dialysis room.

Background: Interest in point-of-care ultrasound (POCUS) and lung ultrasound (LUS) is growing in the nephrology and dialysis field, and the number of nephrologists skilled in what is proving to be the "5th pillar of bedside physical examination" is increasing. Patients on hemodialysis (HD) are at high risk of contracting severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) and developing coronavirus disease 2019 (COVID-19) serious complications. Despite this, to our knowledge there are no studies to date that show the role of LUS in this setting, while there are many in the emergency room, where LUS proved to be an important tool, providing risk stratification and guiding management strategies and resource allocation. Therefore, it is not clear whether the usefulness and cut-offs of LUS highlighted in studies in the general population are reliable in dialysis, or whether variations, precautions and adjustments to this specific situation are necessary. Methods: This was a 1-year monocentric prospective observational cohort study of 56 HD patients with COVID-19. Patients underwent a monitoring protocol that included at first evaluation bedside LUS, using a 12-scan scoring system, by the same nephrologist. All data were prospectively and systematically collected. Outcomes. hospitalization rate, combined outcome [non-invasive ventilation (NIV + death)], mortality. Descriptive variables are presented as medians (interquartile range), or percentage. Univariate and multivariate analysis, as well as Kaplan-Meier (K-M) survival curves, were carried out. Results: Median age was 78 years, 90% had at least one comorbidity (46% diabetics), 55% were hospitalized and 23% deaths. Median duration of disease was 23 days (14-34). A LUS score ≥11 represented a 13-fold risk of hospitalization, a 16.5-fold risk of combined outcome (NIV + death) vs risk factors such as age [odds ratio (OR) 1.6], diabetes (OR 1.2), male sex (OR 1.3) and obesity (OR 1.25), and a 7.7-fold risk of mortality. In the logistic regression, LUS score ≥11 is associated with the combined outcome with a hazard ratio (HR) of 6.1 vs inflammations indices such as CRP ≥9 mg/dL (HR 5.5) and interleukin-6 (IL-6) ≥62 pg/mL (HR 5.4). In K-M curves, survival drops significantly with LUS score above 11. Conclusions: In our experience of COVID-19 HD patients, LUS appeared to be an effective and easy tool, predicting the need for NIV and mortality better than "classic" known COVID-19 risk factors such as age, diabetes, male sex and obesity, and even better than inflammations indices such as CRP and IL-6. These results are consistent with those of the studies in the emergency room setting, but with a lower LUS score cut-off (11 vs 16-18). This is probably due to the higher global frailty and peculiarity of HD population, and emphasizes how nephrologists should themselves use LUS and POCUS as a part of their everyday clinical practice, adapting it to the peculiarity of the HD ward.