Acute Respiratory Distress Syndrome and Shunt Detection With Bubble Studies: A Systematic Review and Meta-Analysis

Abstract

Acute respiratory distress syndrome (ARDS) is a life-threatening respiratory injury with multiple physiological sequelae. Shunting of deoxygenated blood through intra-and extrapulmonary shunts may complicate ARDS management. Therefore, we conducted a systematic review to determine the prevalence of sonographically detected shunts, and their association with oxygenation and mortality in patients with ARDS.DATA SOURCES: Medical literature analysis and retrieval system online, Excerpta Medica dataBASE, Cochrane Library, and database of abstracts of reviews of effects databases on March 26, 2021. STUDY SELECTION:Articles relating to respiratory failure and sonographic shunt detection.DATA EXTRACTION: Articles were independently screened and extracted in duplicate. Data pertaining to study demographics and shunt detection were compiled for mortality and oxygenation outcomes. Risk of bias was appraised using the Joanna-Briggs Institute and the Newcastle-Ottawa Scale tools with evidence rating certainty using Grading of Recommendations Assessment, Development and Evaluation methodology.DATA SYNTHESIS: From 4,617 citations, 10 observational studies met eligibility criteria. Sonographic detection of right-to-left shunt was present in 21.8% of patients (range, 14.4-30.0%) among included studies using transthoracic, transesophageal, and transcranial bubble Doppler ultrasonographies. Shunt prevalence may be associated with increased mortality (risk ratio, 1.22; 95% CI, 1.01-1.49; p = 0.04, very low certainty evidence) with no difference in oxygenation as measured by Pao 2 :Fio 2 ratio (mean difference, -0.7; 95% CI, -18.6 to 17.2; p = 0.94, very low certainty).CONCLUSIONS: Intra-and extrapulmonary shunts are detected frequently in ARDS with ultrasound techniques. Shunts may increase mortality among patients with ARDS, but its association with oxygenation is uncertain.

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

“…We have designed an extensive protocol for ICU shunt workup, which was performed by intensivists during the pandemic, saving on personal protective equipment. We investigated different shunt types, cointerventions, and duration of mechanical ventilation plus other respiratory adjuncts, which is not routinely reported in ARDS literature (12). Our study reinforces the safety of intensivist and trainee TEE, given that there were no procedural complications (31), and our inter-relator scores highlight that ICU echocardiography and TCD is feasible and reliable (32, 33).…”

“…In this study, COVID-19 shunt rates were not significantly different compared with non-COVID ARDS. Our findings align with our recent meta-analysis (12), suggesting approximately one in five patients with ARDS had a R-L shunt. Although there was no statistical significance for intracardiac or intrapulmonary shunt types between groups, there was a signal of higher intrapulmonary shunts in COVID patients, while higher intracardiac shunt rates in non-COVID patients, which may have been exacerbated by lower lung compliance with higher plateau pressures, leading to more intracardiac shunts in non-COVID patients.…”

“…These variables were prespecified a priori. Given prior evidence of lack of association between PF ratios and shunt presence (12), this was not a variable used for adjustment.…”

“…A recent systematic review suggested an association between R-L shunts and increased mortality (12). Therefore, the purpose of our study was to compare COVID-19 ARDS and non-COVID-19 ARDS ICU patients for R-L shunt presence, shunt etiology (intrapulmonary/intracardiac), and associations with mortality.…”