OBJECTIVES: Acute respiratory distress syndrome (ARDS) is associated with high ventilation-perfusion heterogeneity and dead-space ventilation. However, whether the degree of dead-space ventilation is associated with outcomes is uncertain. In this systematic review and meta-analysis, we evaluated the ability of dead-space ventilation measures to predict mortality in patients with ARDS. DATA SOURCES: MEDLINE, CENTRAL, and Google Scholar from inception to November 2022. STUDY SELECTION: Studies including adults with ARDS reporting a dead-space ventilation index and mortality. DATA EXTRACTION: Two reviewers independently identified eligible studies and extracted data. We calculated pooled effect estimates using a random effects model for both adjusted and unadjusted results. The quality and strength of evidence were assessed using the Quality in Prognostic Studies and Grading of Recommendations, Assessment, Development, and Evaluation, respectively. DATA SYNTHESIS: We included 28 studies in our review, 21 of which were included in our meta-analysis. All studies had a low risk of bias. A high pulmonary dead-space fraction was associated with increased mortality (odds ratio [OR], 3.52; 95% CI, 2.22–5.58; p < 0.001; I 2 = 84%). After adjusting for other confounding variables, every 0.05 increase in pulmonary-dead space fraction was associated with an increased odds of death (OR, 1.23; 95% CI, 1.13–1.34; p < 0.001; I 2 = 57%). A high ventilatory ratio was also associated with increased mortality (OR, 1.55; 95% CI, 1.33–1.80; p < 0.001; I 2 = 48%). This association was independent of common confounding variables (OR, 1.33; 95% CI, 1.12–1.58; p = 0.001; I 2 = 66%). CONCLUSIONS: Dead-space ventilation indices were independently associated with mortality in adults with ARDS. These indices could be incorporated into clinical trials and used to identify patients who could benefit from early institution of adjunctive therapies. The cut-offs identified in this study should be prospectively validated.

Background: Cardiac Magnetic Resonance (CMR) imaging is increasingly utilised to assess the aetiology and severity of cardiomyopathies. Non-ischaemic cardiomyopathy (NICM) is a heterogeneous condition, with varying clinical and demographic factors influencing outcome. This study assesses differences in clinical outcomes in European compared with M aori and Pacific NICM patients undergoing CMR in South Auckland.Method: CMR reports from Counties Manukau District Health Board region (2005 -2019) were analysed from an ANZACS-QI linked CMR database. 536 patients with a diagnosis of NICM were identified and linked ethnicity data recorded. 498 patients were grouped according to European (n = 231) vs M aori and Pacific ethnicity (n = 267). Clinical, biochemical, imaging and demographic data was collected from electronic medical records. The primary end point was combined all cause mortality and readmission rate for decompensated heart failure.Results: M aori and Pacific patients were younger (52.3 +/-11.6 vs 57.2 +/-14.6 years, p,0.001), had higher Body Mass Index (36.7 kg/m 2 vs 29.5 kg/m 2 , p,0.001), and weight (105.3kg vs 87.4kg, p,0.001). CMR markers of left ventricular (LV) volumes (p=0.95), LV ejection fraction (p=0.14), and presence of myocardial fibrosis (p=0.13) were similar between the two groups. Implantable Cardiac Defibrillator, and Cardiac Resynchronisation Therapy implantation rates were similar (p=0.58). The primary combined outcome of readmission for decompensated heart failure and all cause mortality was significantly higher in M aori and Pacific patients (96 vs 48, p,0.001).Conclusion: M aori and Pacific patients with NICM have worse clinical outcomes than European patients, despite similar disease severity on CMR.

NSTEMI patients, not STEMI and UA patients, which needs to be further investigated.