Intrapulmonary and Intracardiac Shunts in Adult COVID-19 Versus Non-COVID Acute Respiratory Distress Syndrome ICU Patients Using Echocardiography and Contrast Bubble Studies (COVID-Shunt Study): A Prospective, Observational Cohort Study

Abstract

OBJECTIVES: Studies have suggested intrapulmonary shunts may contribute to hypoxemia in COVID-19 acute respiratory distress syndrome (ARDS) with worse associated outcomes. We evaluated the presence of right-to-left (R-L) shunts in COVID-19 and non-COVID ARDS patients using a comprehensive hypoxemia workup for shunt etiology and associations with mortality. DESIGN: Prospective, observational cohort study. SETTING: Four tertiary hospitals in Edmonton, Alberta, Canada. PATIENTS: Adult critically ill, mechanically ventilated, ICU patients admitted with COVID-19 or non-COVID (November 16, 2020, to September 1, 2021). INTERVENTIONS: Agitated-saline bubble studies with transthoracic echocardiography/transcranial Doppler ± transesophageal echocardiography assessed for R-L shunts presence. MEASUREMENTS AND MAIN RESULTS: Primary outcomes were shunt frequency and association with hospital mortality. Logistic regression analysis was used for adjustment. The study enrolled 226 patients (182 COVID-19 vs 42 non-COVID). Median age was 58 years (interquartile range [IQR], 47–67 yr) and Acute Physiology and Chronic Health Evaluation II scores of 30 (IQR, 21–36). In COVID-19 patients, the frequency of R-L shunt was 31 of 182 COVID patients (17.0%) versus 10 of 44 non-COVID patients (22.7%), with no difference detected in shunt rates (risk difference [RD], –5.7%; 95% CI, –18.4 to 7.0; p = 0.38). In the COVID-19 group, hospital mortality was higher for those with R-L shunt compared with those without (54.8% vs 35.8%; RD, 19.0%; 95% CI, 0.1–37.9; p = 0.05). This did not persist at 90-day mortality nor after adjustment with regression. CONCLUSIONS: There was no evidence of increased R-L shunt rates in COVID-19 compared with non-COVID controls. R-L shunt was associated with increased in-hospital mortality for COVID-19 patients, but this did not persist at 90-day mortality or after adjusting using logistic regression.

FOT Technique Applied for Monitoring of COVID-19 Pneumonia Reveals Small Airways Involvement

“…Elastic forces decrease during the expiration, which induces the collapse of small airways by the end of expiration, especially in the dependent parts of lungs. Other different factors, such as reduced lung elasticity in emphysema, elevated bronchial muscle tone and compression from outside by swollen lung tissue, lead to a low V/Q ratio and pulmonary right-to-left shunting [ 9 , 10 ].…”

Comparing critically ill ARDS patients with COVID-19 vs. without COVID-19: A prospective, bivariate and multi-variable analysis of 690 patients

“…Several patient characteristics in COVID patients have been statistically linked to ICU admission, including senior age, male gender, and pre-existing comorbid conditions like obesity, diabetes mellitus, and kidney disease, [7][8][9][10][11][12][13] and much the same is true for ARDS in general. 14,15 However, though studies abound comparing ARDS caused by SARS-CoV-2 against other forms of ARDS, in all but a very few instances, those studies either used historical controls, [16][17][18][19][20][21][22][23][24][25][26][27][28] or very small numbers of COVID cases, 20,29 non-COVID cases, 23,[30][31][32] or both. 6,24,[33][34][35][36] The few studies that have examined concurrent samples of COVID and non-COVID ARDS cases have generally been highly case specific; for example, the large registry study published by Ruhi-Williams et al, which compared 6040 and 6382 COVID and non-COVID ARDS patients, only evaluated patients requiring extracorporeal membrane oxygenation (ECMO).…”