ABSTRACT
ImportanceStudies have suggested intra-pulmonary shunts may contribute to hypoxemia in COVID-19 ARDS and may be associated with worse outcomes. ObjectiveTo 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, ParticipantsWe 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). InterventionContrast-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 MeasuresPrimary outcomes were shunt incidence and association with hospital mortality. Logistic regression analysis was used to determine association of shunt presence/absence with covariables. ResultsThe 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. ConclusionsThere 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 QuestionDoes right-to-left shunt incidence increase with COVID-19 ARDS compared to non-COVID, and is there association with shunt incidence and mortality? FindingsIn 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. MeaningThere 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.
ABSTRACT
The primary survey assessment is a cornerstone of resuscitation processes. The name itself implies that it is the first step in resuscitation. In this article, we argue that in an organized resuscitation the primary survey must be preceded by a series of steps to optimize safety and performance and set the stage for the execution of expert team behavior. Even in the most time critical situations, an effective team will optimize the environment, perform self-assessments of personal readiness and participate in a preemptive team brief. We call these processes the ‘zero point survey’ as it precedes the primary survey. This paper explains the rationale for the zero point survey and describes a structured approach designed to be suitable for all resuscitation situations.
