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Author(s): Armaan F. Akbar [sup.1], Benjamin L. Shou [sup.1], Cheng-Yuan Feng [sup.1] [sup.2] [sup.3] [sup.4], David X. Zhao [sup.1] [sup.2] [sup.3] [sup.4], Bo Soo Kim [sup.3], Glenn Whitman [sup.1], Errol [...], Introduction and Methods We examined the relationship between 24-h pre- and post-cannulation arterial oxygen tension (PaO.sub.2) and arterial carbon dioxide tension (PaCO.sub.2) and subsequent acute brain injury (ABI) in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) with granular arterial blood gas (ABG) data and institutional standardized neuromonitoring. Results Eighty-nine patients underwent VV-ECMO (median age = 50, 63% male). Twenty (22%) patients experienced ABI; intracranial hemorrhage (ICH) was the most common diagnosis (n = 14, 16%). Lower post-cannulation PaO.sub.2 levels were significantly associated with ICH (66 vs. 81 mmHg, p = 0.007) and a post-cannulation PaO.sub.2 level < 70 mmHg was more frequent in these patients (71% vs. 33%, p = 0.007). PaCO.sub.2 parameters were not associated with ABI. By multivariable logistic regression, hypoxemia post-cannulation increased the odds of ICH (OR = 5.06, 95% CI:1.41-18.17; p = 0.01). Conclusion In summary, lower oxygen tension in the 24-h post-cannulation was associated with ICH development. The precise roles of peri-cannulation ABG changes deserve further investigation, as they may influence the management of VV-ECMO patients.

Estimating cell type composition of blood and tissue samples is a biological challenge relevant in both laboratory studies and clinical care. In recent years, a number of computational tools have been developed to estimate cell type abundance using gene expression data. Although these tools use a variety of approaches, they all leverage expression profiles from purified cell types to evaluate the cell type composition within samples. In this study, we compare 12 cell type quantification tools and evaluate their performance while using each of 10 separate reference profiles. Specifically, we have run each tool on over 4000 samples with known cell type proportions, spanning both immune and stromal cell types. A total of 12 of these represent in vitro synthetic mixtures and 300 represent in silico synthetic mixtures prepared using single-cell data. A final 3728 clinical samples have been collected from the Framingham cohort, for which cell populations have been quantified using electrical impedance cell counting. When tools are applied to the Framingham dataset, the tool Estimating the Proportions of Immune and Cancer cells (EPIC) produces the highest correlation, whereas Gene Expression Deconvolution Interactive Tool (GEDIT) produces the lowest error. The best tool for other datasets is varied, but CIBERSORT and GEDIT most consistently produce accurate results. We find that optimal reference depends on the tool used, and report suggested references to be used with each tool. Most tools return results within minutes, but on large datasets runtimes for CIBERSORT can exceed hours or even days. We conclude that deconvolution methods are capable of returning high-quality results, but that proper reference selection is critical.

Background: Extracorporeal membrane oxygenation (ECMO) has gained traction as a bridge to heart transplantation (HT) but remains associated with increased waitlist mortality. This study explores whether this risk is modified by underlying heart failure (HF) etiology. Methods: Using the Organ Procurement and Transplantation Network registry, we conducted a retrospective review of first‐time adult HT candidates from 2018 through 2022. Patients were categorized as "ECMO", if ECMO was utilized during the waitlisting period, or "No ECMO" otherwise. Patients were then stratified according to the following HF etiology: ischemic cardiomyopathy (CMP), dilated nonischemic CMP, restrictive CMP, hypertrophic CMP, and congenital heart disease (CHD). After baseline comparisons, waitlist mortality was characterized for ECMO and HF etiology using the Fine–Gray regression. Results: A total of 16 143 patients were identified of whom 7.0% (n = 1063) were bridged with ECMO. Compared to No ECMO patients, ECMO patients had shorter waitlist durations (46.3 vs. 185.0 days, p < 0.01) and were more likely to undergo transplantation (75.3% vs. 70.3%, p < 0.01). Outcomes analysis revealed that ECMO was associated with increased mortality risk (subdistribution hazard ratio [SHR]: 3.42, p < 0.01), a risk that persisted in all subgroups and was notably high in CHD (SHR: 4.83, p < 0.01) and hypertrophic CMP (SHR: 9.78, p < 0.01). HF etiology comparison within ECMO patients revealed increased mortality risk with CHD (SHR: 3.22, p < 0.01). Within No ECMO patients, hypertrophic CMP patients had lower mortality risk (SHR: 0.64, p = 0.03). Conclusions: The increased waitlist mortality risk with ECMO persisted after stratification by HF etiology. These findings can help decision‐making surrounding candidacy for cannulation and prognostic evaluation. [ABSTRACT FROM AUTHOR]

Cannulation strategy, vasopressors, and hemolysis are important physiological factors that influence hemodynamics in extracorporeal membrane oxygenation (ECMO). We hypothesized these factors influence the discrepancy between oxygen saturation measured by pulse oximetry (Sp o 2) and arterial blood gas (Sa o 2) in patients on ECMO. We retrospectively analyzed adults (aged ≥18 years) on venoarterial or venovenous ECMO at a tertiary academic ECMO center. Sp o 2 −Sa o 2 pairs with oxygen saturation ≥70% and measured within 10 minutes were included. Occult hypoxemia was defined as Sa o 2 ≤88% with a time-matched Sp o 2 ≥92%. Adjusted linear mixed-effects modeling was used to assess the Sp o 2 −Sa o 2 discrepancy with preselected demographics and time-matched laboratory variables. Vasopressor use was quantified by vasopressor dose equivalences. Of 139 venoarterial-ECMO and 88 venovenous-ECMO patients, we examined 20,053 Sp o 2 −Sa o 2 pairs. The Sp o 2 −Sa o 2 discrepancy was greater in venovenous-ECMO (1.15%) vs venoarterial-ECMO (−0.35%, P <.001). Overall, 81 patients (35%) experienced occult hypoxemia during ECMO. Occult hypoxemia was more common in venovenous-ECMO (65%) than in venoarterial-ECMO (17%, P <.001). In linear mixed-effects modeling, Sp o 2 underestimated Sa o 2 by 9.48% in central vs peripheral venoarterial-ECMO (95% CI, −17.1% to −1.79%; P =.02). Higher vasopressor dose equivalences significantly worsened the Sp o 2 −Sa o 2 discrepancy (P <.001). In linear mixed-effects modeling, Sp o 2 overestimated Sa o 2 by 25.43% in single lumen–cannulated vs double lumen–cannulated venovenous-ECMO (95% CI, 5.27%-45.6%; P =.03). Higher vasopressor dose equivalences and lactate dehydrogenase levels significantly worsened the Sp o 2 −Sa o 2 discrepancy (P <.001). Venovenous-ECMO patients are at higher risk for occult hypoxemia compared with venoarterial-ECMO. A higher vasopressor requirement and different cannulation strategies (central venoarterial-ECMO; single-lumen venovenous-ECMO) were significant factors for clinically significant Sp o 2 −Sa o 2 discrepancy in both ECMO modes. [Display omitted] [ABSTRACT FROM AUTHOR]

Stroke is a well‐characterized complication of isolated heart and lung transplantation, but has not been described in combined heart‐lung transplantation (HLTx). We retrospectively reviewed national U.S. data to describe the incidence, risk factors, and impact of postoperative stroke in HLTx recipients. Of 871 heart‐lung recipients between 1994–2022, 35 (4.0%) experienced stroke, and the incidence increased over time, trending toward significance (p‐trend =.07). After adjustment, extracorporeal membrane oxygenation (ECMO) (Adjusted odds ratio [aOR] = 2.63, 95%CI = [1.13–6.11]) and pre‐transplant implantable defibrillator (aOR = 2.86, 95%CI = [1.20–6.81]) were independent risk factors for stroke. Postoperative stroke is common and is increasing in an era where organ allocation is driven by mechanical circulatory support (MCS) bridging. [ABSTRACT FROM AUTHOR]