Acute respiratory distress syndrome and shunt detection with bubble studies: a systematic review and meta-analysis

Abstract

Objectives: Acute respiratory distress syndrome (ARDS) is a life-threatening respiratory injury with multiple physiological sequalae. Shunting of deoxygenated blood through intra and extra-pulmonary shunts is one consequence that may complicate ARDS management. Therefore, we conducted a systematic review to determine the prevalence of sonographically detected shunt and its association with oxygenation and mortality in patients with ARDS. Data Sources: We searched MEDLINE, EMBASE, Cochrane Library and DARE 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 Newcastle-Ottawa Scale tools with evidence rating certainty using GRADE 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%) amongst included studies using transthoracic, transesophageal and transcranial bubble Doppler sonography. 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 PaO2:FiO2 ratio (mean difference -0.7, 95% CI: -18.6 to 17.2, p=0.94, very low certainty evidence). Conclusions: Intra- and extra-pulmonary shunts are detected frequently in ARDS with ultrasound techniques. Shunts may increase mortality amongst patients with ARDS, but its association with oxygenation is uncertain. Future research should explore the role of shunt in ARDS, their association with mortality, and whether targeted precision medicine interventions can improve outcomes. PROSPERO Registration Number: CRD42021245194 (March 26, 2021)

Intra-pulmonary and intra-cardiac shunts in adult COVID-19 versus non-COVID ARDS ICU patients using echocardiography and contrast bubble studies (COVID-Shunt Study): a prospective, observational cohort study

“…In this study, COVID-19 shunt rates were not significantly different compared to non-COVID ARDS. Our findings align with the recent meta-analysis, 12 suggesting approximately ∼1 in 5 patients with ARDS had a R-L shunt. We also found an association between R-L shunts and increased hospital mortality, but this was no longer significant at 90-day mortality, or after multivariable adjustment.…”

“…We investigated different shunt types, co-interventions, 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 We performed both unadjusted and adjusted ORs analysis using multivariable logistic regression to account for known confounders (e.g age, illness severity), in keeping with STROBE and Newcastle-Ottawa score recommendations.…”

“…8,10,11 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/intra-cardiac), and associations with mortality. We utilized a comprehensive hypoxemia protocol that included contrast-enhanced TTE/transcranial Doppler (TCD) and TEE.…”