Faculty Bibliography

Emergent reperfusion, most commonly with the administration of thrombolytic agents, is the recommended management approach for patients presenting with high-risk, or hemodynamically unstable pulmonary embolism. However, a subset of patients with a more catastrophic presentation, including refractory shock and impending or active cardiopulmonary arrest, may require immediate circulatory support. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) can be deployed rapidly by the well-trained team and provide systemic perfusion allowing for hemodynamic stabilization. Subsequent embolectomy or a standalone strategy allowing for thrombus autolysis may be followed with decannulation after several days. Retrospective studies and registry data suggest favorable clinical outcomes with the use of VA-ECMO as an upfront stabilization strategy even among patients presenting with cardiopulmonary arrest. In this review, we discuss the physiologic rationale, evidence base, and an approach to ECMO deployment and subsequent management strategies among select patients with high-risk pulmonary embolism.

A dysregulated immune response is associated with an excessive release of cytokines that can lead to systemic vasoplegia and vasoplegic shock with the development of multiorgan failure that is associated with an increased risk of dying. Under physiological circumstances, the endothelium and the glycocalyx are responsible for maintaining vascular tone, capillary permeability, and hemostasis, and controlling inflammation. In hyperinflammation, the endothelium and glycocalyx become damaged due to the excessive production of certain toxic proteins, along with an overwhelming release of cytokines. It has been shown in both in vitro animal experiments and in humans that extracorporeal hemoadsorption can reduce circulating levels of cytokines and may also remove toxic proteins that directly take part in endothelium and glycocalyx damage. The current review aims to summarize current knowledge, put recent findings into context, and introduce the hypothesis of "endothelial protection with hemoadsorption" in critically ill patients.

This study retrospectively examined the hemodynamic effects of passive leg raising (PLR) in mechanically ventilated patients during fluid removal before spontaneous breathing trials. In previous studies, we noticed varying cardiac responses after PLR completion, particularly in positive tests. Using a bioreactance monitor, we recorded and analyzed hemodynamic parameters, including stroke volume and cardiac index (CI), before and after PLR in post-acute ICU patients. We included 27 patients who underwent 60 PLR procedures. In preload-unresponsive patients, no significant CI changes were observed (CI_t-6 = 3.7 [2.6; 4.7] mL/min/m² vs. CI_t9 = 3.3 [2.5; 3.4] mL/min/m²; p = 0.306), while in preload-responsive patients, two distinct CI response types to PLR were identified: a transient peak with immediate return to baseline (CI_t-6 = 2.7 [2.5; 3.1] mL/min/m² vs. 3.3 [2.6; 3.8] L/min/m²; p = 0.119) and a sustained CI elevation lasting beyond the PLR maneuver (CI_t-6 = 2.8 [2.3; 2.9] L/min/m² vs. 3.3 [2.8; 3.9] ml/min/m²; p = 0.034). The latter was particularly noted when ΔCI during PLR exceeded 25%. Our findings suggest that in certain preload-responsive patients, PLR can induce a more sustained increase in CI, indicating a possible persistent hemodynamic effect. This effect could be due to a combination of autotransfusion and sympathetic activation affecting venous return and vascular tone. Further research in larger cohorts and more comprehensive hemodynamic assessments are warranted to validate these observations and elucidate the possible underlying mechanisms.The Fluid unLoading On Weaning (FLOW) study was prospectively registered under the ID NCT04496583 on 2020-07-29 at ClinicalTrials.gov.

BACKGROUND/UNASSIGNED:The cardiopulmonary exercise test (CPET) is considered a gold standard in assessing cardiorespiratory fitness (CRF) but has limited accessibility due to competency requirements and cost. Incorporating portable sensor devices into a simple bedside test of CRF could improve diagnostic and prognostic value. OBJECTIVES/UNASSIGNED:The authors sought to evaluate the association of an augmented 6-minute incremental step test (6MIST) with standard CPET. METHODS/UNASSIGNED:Master Pro) during incremental pace stationary stepping. The correlation between CPET and hemodynamic parameters from both tests was assessed using the intraclass correlation coefficient (ICC). RESULTS/UNASSIGNED:pulse (ICC = 0.71; 95% CI: 0.33-0.89), and cardiorespiratory optimal point (ICC = 0.82; 95% CI: 0.52-0.94). No significant correlation was determined between iCPET and 6MIST in measuring cardiac index at rest (ICC = 0.19; 95% CI: -0.34 to 0.63) or at peak exercise (ICC = 0.36; 95% CI: -0.17 to 0.73). CONCLUSIONS/UNASSIGNED:We demonstrate the feasibility of a novel augmented 6MIST with wearable devices for simultaneous CPET and hemodynamic assessment. 6MIST-measured CPET parameters were strongly correlated with the iCPET-derived measurements. Additional studies are needed to confirm the validity of the 6MIST compared to standard upright CPET.

AIMS/OBJECTIVE:Among patients with acute pulmonary embolism (PE) undergoing mechanical thrombectomy, the cardiac index (CI) is frequently reduced even among those without a clinically apparent shock. The purpose of this study is to describe the mixed venous-to-arterial carbon dioxide gradient (CO2 gap), a surrogate of perfusion adequacy, among patients with acute PE undergoing mechanical thrombectomy. METHODS AND RESULTS/RESULTS:This was a single-centre retrospective study of consecutive patients with PE undergoing mechanical thrombectomy and simultaneous pulmonary artery catheterization over a 3-year period. Of 107 patients, 97 had simultaneous mixed venous and arterial blood gas measurements available. The CO2 gap was elevated (>6 mmHg) in 51% of the cohort and in 49% of patients with intermediate-risk PE. A reduced CI (≤2.2 L/min/m2) was associated with an increased odds [odds ratio = 7.9; 95% confidence interval (CI) 3.49-18.1, P < 0.001] for an elevated CO2 gap. There was an inverse relationship between the CI and the CO2 gap. For every 1 L/min/m2 decrease in the CI, the CO2 gap increased by 1.3 mmHg (P = 0.001). Among patients with an elevated baseline CO2 gap >6 mmHg, thrombectomy improved the CO2 gap, CI, and mixed venous oxygen saturation. When the CO2 gap was dichotomized above and below 6, there was no difference in the in-hospital mortality rate (9 vs. 0%; P = 0.10; hazard ratio: 1.24; 95% CI 0.97-1.60; P = 0.085). CONCLUSION/CONCLUSIONS:Among patients with acute PE undergoing mechanical thrombectomy, the CO2 gap is abnormal in nearly 50% of patients and inversely related to the CI. Further studies should examine the relationship between markers of perfusion and outcomes in this population to refine risk stratification.

A positive fluid balance may evolve to fluid overload and associate with organ dysfunctions, weaning difficulties, and increased mortality in ICU patients. We explored whether individualized fluid management, assessing fluid responsiveness via a passive leg-raising maneuver (PLR) before a spontaneous breathing trial (SBT), is associated with less extubation failure in ventilated patients with a high fluid balance admitted to the ICU after liver transplantation (LT). We recruited 15 LT patients in 2023. Their postoperative fluid balance was +4476 {3697, 5722} mL. PLR maneuvers were conducted upon ICU admission (T1) and pre SBT (T2). Cardiac index (CI) changes were recorded before and after each SBT (T3). Seven patients were fluid-responsive at T1, and twelve were responsive at T2. No significant differences occurred in hemodynamic, respiratory, and perfusion parameters between the fluid-responsive and fluid-unresponsive patients at any time. Fluid-responsive patients at T1 and T2 increased their CI during SBT from 3.1 {2.8, 3.7} to 3.7 {3.4, 4.1} mL/min/m² (p = 0.045). All fluid-responsive patients at T2 were extubated after the SBTs and consolidated extubation. Two out of three of the fluid-unresponsive patients experienced weaning difficulties. We concluded that fluid-responsive patients post LT may start weaning earlier and achieve successful extubation despite a high postoperative fluid balance. This highlights the profound impact of personalized assessments of cardiovascular state on critical surgical patients.

BACKGROUND:Reliable predictors of outcomes in venoarterial extracorporeal membrane oxygenation (VA-ECMO) therapy are limited. While elevated lactate levels over time have been linked to outcomes in cardiogenic shock (CS), their significance in VA-ECMO-treated patients remains inconclusive. METHODS:We conducted a post hoc analysis of data from the HYPO-ECMO trial, which compared normothermia to moderate hypothermia in CS patients supported by VA-ECMO. We examined daily lactate levels collected over a week to assess their correlation with 30-day mortality. RESULTS:Among the 318 out of 334 patients (95%) with baseline lactate measurements, 66 had normal levels (< 2.2 mmol/l, 21%). No difference was found in lactate course between moderate hypothermia and normothermia groups. Lactate levels were consistently higher in non-survivors at each time point (p = 0.0002). Baseline hyperlactatemia was associated with an increased risk of death (Hazard Ratio [HR]: 1.85 (1.12-3.05), p = 0.016). When considering all time points, lactate levels during the ICU stay were significantly and gradually associated with a higher risk of death (p < 0.0001). In the overall population, a decrease in lactate levels was not linked to 30-day mortality. However, patients with baseline hyperlactatemia exhibited a more significant decrease in lactate levels from day one to seven (p < 0.0001). In this group, survivors had a significantly greater decrease in lactate levels at day 1 compared to non-survivors (63% (48-77) versus 57% (21-75), p = 0.026). Patients experiencing a secondary increase in lactate (24%) had a worse prognosis (Hazard Ratio: 1.78 (1.21-2.61), p = 0.004), regardless of both baseline lactate levels and the occurrence of severe ischemic adverse events (intestinal and/or limb ischemia). CONCLUSIONS:The consistent and significant association between lactate levels, whether assessed at baseline or during ICU treatment, and the risk of mortality underscores the pivotal prognostic relevance of lactate levels in patients with CS undergoing VA-ECMO therapy. The study findings provide some novel insights, regarding the trend profile and the relevance of a second peak during the 7 day period after ECMO start. Trial Registration identifier NCT02754193 registered on 2016-04-12.