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 (preprint)

Importance Studies have suggested intra-pulmonary shunts may contribute to hypoxemia in COVID-19 ARDS and may be associated with worse outcomes. Objective To evaluate the presence of right-to-left (R-L) shunts in COVID-19 and non-COVID ARDS patients using a comprehensive hypoxemia work-up for shunt etiology and associations with mortality. Design, Setting, Participants We conducted a multi-centre (4 Canadian hospitals), prospective, observational cohort study of adult critically ill, mechanically ventilated, ICU patients admitted for ARDS from both COVID-19 or non-COVID (November 16, 2020-September 1, 2021). Intervention Contrast-enhanced agitated-saline bubble studies with transthoracic echocardiography/transcranial Doppler (TTE/TCD) ± transesophageal echocardiography (TEE) assessed for the presence of R-L shunts. Main Outcomes and Measures Primary outcomes were shunt incidence and association with hospital mortality. Logistic regression analysis was used to determine association of shunt presence/absence with covariables. Results The study enrolled 226 patients (182 COVID-19 vs. 42 non-COVID). Median age was 58 years (interquartile range [IQR]: 47-67) and APACHE II scores of 30 (IQR: 21-36). In COVID-19 patients, the incidence of R-L shunt was 31/182 patients (17.0%; intra-pulmonary: 61.3%; intra-cardiac: 38.7%) versus 10/44 (22.7%) non-COVID patients. No evidence of difference was detected between the COVID-19 and non-COVID-19 shunt rates (risk difference [RD]: -5.7%, 95% CI: -18.4-7.0, p=0.38). In the COVID-19 group, hospital mortality was higher for those with R-L shunt compared to those without (54.8% vs 35.8%, RD: 19.0%, 95% CI 0.1-37.9, p=0.05). But this did not persist at 90-day mortality, nor after regression adjustments for age and illness severity. Conclusions There was no evidence of increased R-L shunt rates in COVID-19 compared to non-COVID controls. Right-to-left 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. Key Points Question Does right-to-left shunt incidence increase with COVID-19 ARDS compared to non-COVID, and is there association with shunt incidence and mortality? Findings In this prospective, observational cohort study, we showed no statistically significant difference in shunt prevalence between COVID-19 ARDS patients (17.0%) and non-COVID patients (22.7%). However, in COVID-19 patients, there was a difference in hospital mortality for those with shunt (54.8%) compared to those without shunt (35.8%), but this difference did not persist at 90-day mortality, nor after regression adjustments for age and illness severity. Meaning There was no evidence of increased R-L shunt rates in COVID-19 compared to non-COVID or historical controls. Right-to-left shunt presence was associated with increased hospital mortality for COVID-19 patients, but this did not persist for 90-day mortality or after adjustment using logistic regression.

Prone Cardiopulmonary Resuscitation: A Rapid Scoping and Expanded Grey Literature Review for the COVID-19 Pandemic (preprint)

Prone Cardiopulmonary Resuscitation: A Rapid Scoping and Expanded Grey Literature Review for the COVID-19 Pandemic Aim To rapidly identify and summarize the available science on prone resuscitation. To determine the value of undertaking a systematic review on this topic; and to identify knowledge gaps to aid future research, education and guidelines. Methods This review was guided by specific methodological framework and reporting items (PRISMA-ScR). We included studies, cases and grey literature regarding prone position and CPR/cardiac arrest. The databases searched were MEDLINE, Embase, CINAHL, Cochrane CENTRAL, Cochrane Database of Systematic Reviews, Scopus and Google Scholar. Expanded grey literature searching included internet search engine, targeted websites and social media. Results Of 453 identified studies, 24 (5%) studies met our inclusion criteria. There were four prone resuscitation-relevant studies examining: blood and tidal volumes generated by prone compressions; prone compression quality metrics on a manikin; and chest computed tomography scans for compression landmarking. Twenty case reports/series described the resuscitation of 25 prone patients. Prone compression quality was assessed by invasive blood pressure monitoring, exhaled carbon dioxide and pulse palpation. Recommended compression location was zero-to-two vertebral segments below the scapulae. Twenty of 25 cases (80%) survived prone resuscitation, although few cases reported long term outcome. Seven cases described full neurological recovery. Conclusion This scoping review did not identify sufficient evidence to justify a systematic review or modified resuscitation guidelines. It remains reasonable to initiate resuscitation in the prone position if turning the patient supine would lead to delays or risk to providers or patients. Prone resuscitation quality can be judged using end-tidal CO2, and arterial pressure tracing, with patients turned supine if insufficient. Key words CPR, prone, cardiopulmonary resuscitation, Scoping review, Resuscitation, covid-19, SARS-CoV-2