Anaerobic Lactate Production Is Associated With Decreased Microcirculatory Blood Flow and Decreased Mitochondrial Respiration Following Cardiovascular Surgery With Cardiopulmonary Bypass.

OBJECTIVES: Quantify the relationship between perioperative anaerobic lactate production, microcirculatory blood flow, and mitochondrial respiration in patients after cardiovascular surgery with cardiopulmonary bypass. DESIGN: Serial measurements of lactate-pyruvate ratio (LPR), microcirculatory blood flow, plasma tricarboxylic acid cycle cycle intermediates, and mitochondrial respiration were compared between patients with a normal peak lactate (≤ 2 mmol/L) and a high peak lactate (≥ 4 mmol/L) in the first 6 hours after surgery. Regression analysis was performed to quantify the relationship between clinically relevant hemodynamic variables, lactate, LPR, and microcirculatory blood flow. SETTING: This was a single-center, prospective observational study conducted in an academic cardiovascular ICU. PATIENTS: One hundred thirty-two patients undergoing elective cardiovascular surgery with cardiopulmonary bypass. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients with a high postoperative lactate were found to have a higher LPR compared with patients with a normal postoperative lactate (14.4 ± 2.5 vs. 11.7 ± 3.4; p = 0.005). Linear regression analysis found a significant, negative relationship between LPR and microcirculatory flow index (r = -0.225; ß = -0.037; p = 0.001 and proportion of perfused vessels: r = -0.17; ß = -0.468; p = 0.009). There was not a significant relationship between absolute plasma lactate and microcirculation variables. Last, mitochondrial complex I and complex II oxidative phosphorylation were reduced in patients with high postoperative lactate levels compared with patients with normal lactate (22.6 ± 6.2 vs. 14.5 ± 7.4 pmol O2/s/106 cells; p = 0.002). CONCLUSIONS: Increased anaerobic lactate production, estimated by LPR, has a negative relationship with microcirculatory blood flow after cardiovascular surgery. This relationship does not persist when measuring lactate alone. In addition, decreased mitochondrial respiration is associated with increased lactate after cardiovascular surgery. These findings suggest that high lactate levels after cardiovascular surgery, even in the setting of normal hemodynamics, are not simply a type B phenomenon as previously suggested.

Extracorporeal Carbon Dioxide Removal to De-escalate Venovenous Extracorporeal Membrane Oxygenation in Severe COVID-19 Acute Respiratory Distress Syndrome.

OBJECTIVES: In a subset of patients with COVID-19 acute respiratory distress syndrome (ARDS), there is a need for extracorporeal membrane oxygenation (ECMO) for pulmonary support. The primary extracorporeal support tool for severe COVID-19 ARDS is venovenous (VV) ECMO; however, after hypoxemic respiratory failure resolves, many patients experience refractory residual hypercarbic respiratory failure. Extracorporeal carbon dioxide removal (ECCO2R) for isolated hypercarbic type II respiratory failure can be used in select cases to deescalate patients from VV ECMO while the lung recovers the ability to exchange CO2. The objective of this study was to describe the authors' experience in using ECCO2R as a bridge from VV ECMO. DESIGN: Hemolung Respiratory Assist System (RAS) is a commercially available (ECCO2R) device, and the United States Food and Drug Administration accelerated its use under its Emergency Use Authorization for the treatment of refractory hypercarbic respiratory failure in COVID-19-induced ARDS. This created an environment in which selected and targeted mechanical circulatory support therapy for refractory hypercarbic respiratory failure could be addressed. This retrospective study describes the application of Hemolung RAS as a VV ECMO deescalation platform to treat refractory hypercarbic respiratory failure after the resolution of hypoxemic COVID-19 ARDS. SETTING: A quaternary-care academic medical center, single institution. PARTICIPANTS: Patients with refractory hypercarbic respiratory failure after COVID-19 ARDS who were previously supported with VV ECMO. MEASUREMENTS AND MAIN RESULTS: Twenty-one patients were placed on ECCO2R after VV ECMO for COVID-19 ARDS. Seventeen patients successfully were transitioned to ECCO2R and then decannulated; 3 patients required reescalation to VV ECMO secondary to hypercapnic respiratory failure, and 1 patient died while on ECCO2R. Five (23.8%) of the 21 patients were transitioned off of VV ECMO to ECCO2R, with a compliance of <20 (mL/cmH2O). Of these patients, 3 with low compliance were reescalated to VV ECMO. CONCLUSIONS: Extracorporeal carbon dioxide removal can be used to continue supportive methods for patients with refractory type 2 hypercarbic respiratory failure after COVID-19 ARDS for patients previously on VV ECMO. Patients with low compliance have a higher rate of reescalation to VV ECMO.

Cerebral Autoregulation: A Target for Improving Neurological Outcomes in Extracorporeal Life Support.

Despite improvements in survival after illnesses requiring extracorporeal life support, cerebral injury continues to hinder successful outcomes. Cerebral autoregulation (CA) is an innate protective mechanism that maintains constant cerebral blood flow in the face of varying systemic blood pressure. However, it is impaired in certain disease states and, potentially, following initiation of extracorporeal circulatory support. In this review, we first discuss patient-related factors pertaining to venovenous and venoarterial extracorporeal membrane oxygenation (ECMO) and their potential role in CA impairment. Next, we examine factors intrinsic to ECMO that may affect CA, such as cannulation, changes in pulsatility, the inflammatory and adaptive immune response, intracranial hemorrhage, and ischemic stroke, in addition to ECMO management factors, such as oxygenation, ventilation, flow rates, and blood pressure management. We highlight potential mechanisms that lead to disruption of CA in both pediatric and adult populations, the challenges of measuring CA in these patients, and potential associations with neurological outcome. Altogether, we discuss individualized CA monitoring as a potential target for improving neurological outcomes in extracorporeal life support.

Low postoperative perfused vessel density is associated with increased soluble endothelial cell adhesion molecules during circulatory shock after cardiac surgery.

INTRODUCTION: Microcirculatory dysfunction after cardiovascular surgery is associated with significant morbidity and worse clinical outcomes. Abnormal capillary blood flow can occur from multiple causes, including cytokine-mediated vascular endothelial injury, microthrombosis, and an inadequate balance between vasoconstriction and vasodilation. In response to proinflammatory cytokines, endothelial cells produce cellular adhesion molecules (CAMs) which regulate leukocyte adhesion, vascular permeability, and thus can mediate tissue injury. The relationship between changes in microcirculatory flow during circulatory shock and circulating adhesion molecules is unclear. The objective of this study was to compare changes in plasma soluble endothelial cell adhesion molecules (VCAM-1, ICAM-1, and E-Selectin) in patients with functional derangements in microcirculatory blood flow after cardiovascular surgery. METHODS: Adult patients undergoing elective cardiac surgery requiring cardiopulmonary bypass who exhibited postoperative shock were enrolled in the study. Sublingual microcirculation imaging was performed prior to surgery and within 2 h of ICU admission. Blood samples were taken at the time of microcirculation imaging for biomarker analysis. Plasma soluble VCAM-1, ICAM-1, and E-selectin in addition to plasma cytokines (IL-6, IL-8, and IL-10) were measured by commercially available enzyme-linked immunoassay. RESULTS: Of 83 patients with postoperative shock who were evaluated, 40 patients with clinical shock had a postoperative perfused vessel density (PVD) >1 SD above (High PVD group = 28.5 ± 2.3 mm/mm2, n = 20) or below (Low PVD = 15.5 ± 2.0 mm/mm2, n = 20) the mean postoperative PVD and were included in the final analysis. Patient groups were well matched for comorbidities, surgical, and postoperative details. Overall, there was an increase in postoperative plasma VCAM-1 and E-Selectin compared to preoperative levels, but there was no difference between circulating ICAM-1. When grouped by postoperative microcirculation, patients with poor microcirculation were found to have increased circulating VCAM-1 (2413 ± 1144 vs. 844 ± 786 ng/mL; p < 0.0001) and E-Selectin (242 ± 119 vs. 87 ± 86 ng/mL; p < 0.0001) compared to patients with increased microcirculatory blood flow. Microcirculatory flow was not associated with a difference in plasma soluble ICAM-1 (394 ± 190 vs. 441 ± 256; p = 0.52). CONCLUSIONS: Poor postoperative microcirculatory blood flow in patients with circulatory shock after cardiac surgery is associated with increased plasma soluble VCAM-1 and E-Selectin, indicating increased endothelial injury and activation compared to patients with a high postoperative microcirculatory blood flow. Circulating endothelial cell adhesion molecules may be a useful plasma biomarker to identify abnormal microcirculatory blood flow in patients with shock.

A different approach to teaching pre-clerkship students physical diagnosis: standardized patient instructor-senior medical student teaching teams.

BACKGROUND: Faculty have traditionally taught the physical examination (PE) to novice medical students (pre-clerkship students.), despite recruiting and cost issues and problems standardizing their approach. ACTIVITY: We present a model using standardized patient instructor (SPI)-fourth year medical student (MS4) teams to teach PE to pre-clerkship students, leveraging the benefits of co-teaching and peer-assisted learning. RESULTS: Surveys of pre-clerkship students, MS4s and SPIs indicate positive perceptions of the program, including MS4s reporting significant growth in their professional identities as educators. Pre-clerkship students' performance on the spring clinical skills exams was equivalent to or better than their peer performance pre-program implementation. IMPLICATIONS: SPI-MS4 teams can effectively teach novice students the mechanics and clinical context of the beginners' physical exam.

First-in-man successful use of the SPECTRUM percutaneous dual-stage right ventricle and right atrium to pulmonary artery ventricular assist device.

BACKGROUND: Over the past decade, several minimally invasive mechanical support devices have been introduced into clinical practice to support the right ventricle (RV). Percutaneous cannulas are easy to insert, minimally invasive, and treat acute RV failure rapidly. In December 2021, the Food and Drug Administration approved a new 31 French dual lumen single cannula for use as a right ventricular assist device. AIMS: Descirbe the use of the new dual lumen percutaneous right ventricular assist device (RVAD) cannula. MATERIAL AND METHODS: Deployment of the RVAD can be done surgically or percutaneously. This cannula, manufactured by Spectrum, is dual staged. It has inflow ports positioned both in the right atrium (RA) as well as the RV for maximal drainage of the right heart. The distal end of the cannula which includes the outflow port is positioned in the pulmonary artery (PA). RESULTS: Deployment of the Spectrum RVAD can be done percutaneously with transesophageal and flouroscopy guidence. Cannulation requires requisite wire skills in order to navigate into the main pulmonary artery. Utilization of this cannula can be done in acute RV failure secondary to ischemia, post cardiotomy shock, acute respiratory failure or other causes of isolated RV failure. DISCUSSION: The dual stage drainage design optimizes venous drainage as well as limits suck-down events. Theoretically, direct RV decompression also decreases RV dilation and wall tension, and facilitates improved transmural pressure gradient to reduce RV strain. CONCLUSION: Here we describe the first-in-man successful use of the dual-stage RA and RV to PA Spectrum cannula in a patient with severe COVID acute respiratory distress syndrome and acute right ventricular failure, bridged to recovery.

Coronary Artery Bypass Grafting in Cardiogenic Shock: Decision-Making, Management Options, and Outcomes.

Coronary artery bypass grafting is a highly efficacious mode of myocardial revascularization that reduces mortality from ischemic heart disease. The patient presenting after acute myocardial infarction in cardiogenic shock presents a unique challenge. Early revascularization is proven to reduce mortality, but many questions remain, including the optimal mode and extent of revascularization, the role of mechanical circulatory support, and which patients are candidates for surgical intervention. Unprecedented attention to the outcomes of cardiac surgery means decisions about the management of the acute myocardial infarction in cardiogenic shock patients are influenced by risk aversion. The authors here review this topic to arm the reader with a comprehensive understanding of the literature to better guide surgical decision-making and perioperative management.

Pilot Study Suggests Smartphone Application Knowledge Improves Resident Transesophageal Echocardiography Knowledge: A Randomized Controlled Trial.

OBJECTIVE: The objective of this study was to determine whether an asynchronous smartphone-based application with image-based questions would improve anesthesiology resident transesophageal echocardiography (TEE) knowledge compared with standard intraoperative teaching alone. DESIGN: Prospective, single-blinded, pilot, randomized controlled trial. SETTING: Large university teaching hospital. PARTICIPANTS: Participants were anesthesiology residents on their cardiac anesthesiology rotation. INTERVENTIONS: EchoEducator, a TEE image-based smartphone application of learning content through questions, was developed. Content was derived from the Examination of Special Competence in Basic Perioperative Transesophageal Echocardiography and the Objective Structured Clinical Examination portion of the APPLIED Examination and focused on identification of basic TEE views, cardiac structures, and pathology. Residents were randomly assigned to receive access to either the application or to standard intraoperative teaching. Thirty residents met inclusion criteria, and 18 residents completed the study. A pre-intervention assessment was given at the beginning of the rotation, and a post-intervention assessment was given after 2 weeks. MEASUREMENTS: The primary outcome was the difference between the post-test score and the pre-test score. Standard bivariate statistics and the chi-square test were used for categorical variables, and the Student t test was used for continuous variables. Tests were 2-sided, and statistical significance was set at p < 0.05. The intervention group demonstrated a greater increase in score; (+19.19% [95% confidence interval 4.14%-34.24%]; p = 0.02) compared with the control group. CONCLUSIONS: This study supports the hypothesis that use of a smartphone-based asynchronous educational application improves TEE knowledge compared with traditional modalities alone. This supports an opportunity to improve medical education by expanding the role of web-based asynchronous learning.

The Ross Operation in the Adult: What, Why, and When?

The normal aortic valve is a sophisticated and dynamic structure whose equal replacement has not yet been actualized by modern technology. The use of the pulmonary autograft as a substitute for a diseased aortic valve (the Ross procedure) has been in practice for several decades in many types of patient. In the adult, it has not been adopted widely due to concerns about its technical challenge, complex perioperative care, the development of pulmonic valve disease, and concerns about long-term dilatation of the neo-aortic root, among others. There has been a substantial body of data showing excellent long-term survival, freedom from reoperation, and quality of life, in contradistinction to these preconceptions. The authors review the available data pertinent to these questions to further define the role of the Ross procedure in the adult cardiac surgery patient.

Transaortic TAVR and Mitral Repair Under Deep Hypothermic Circulatory Arrest in a Porcelain Aorta Patient.

Vascular and valvular calcifications, commonly seen in renal patients, increase operative mortality and can preclude conventional valvular management. We show a novel approach to treat aortic stenosis and degenerative mitral regurgitation under hypothermic circulatory arrest in a hemodialysis patient with aortic, mitral disease and porcelain aorta with surgical and transcatheter contraindications.

Lung transplant outcomes after acute respiratory distress syndrome requiring extracorporeal life support: Lessons from the COVID-19 pandemic.

OBJECTIVE: Lung transplant for acute respiratory distress syndrome in patients supported with extracorporeal membrane oxygenation was rare before 2020, but was rapidly adopted to rescue patients with COVID-19 with lung failure. This study aims to compare the outcomes of patients who underwent lung transplant for COVID-associated acute respiratory distress syndrome and non-COVID acute respiratory distress syndrome, and to assess the impact of type and duration of extracorporeal membrane oxygenation support on survival. METHODS: Using the United Network for Organ Sharing database, we identified 311 patients with acute respiratory distress syndrome who underwent lung transplant from 2007 to 2022 and performed a retrospective analysis of the patients who required extracorporeal membrane oxygenation preoperatively, stratified by COVID-associated acute respiratory distress syndrome and non-COVID acute respiratory distress syndrome listing diagnoses. The primary outcome was 1-year survival. Secondary outcomes included the effect of type and duration of extracorporeal membrane oxygenation on survival. RESULTS: During the study period, 236 patients with acute respiratory distress syndrome and preoperative extracorporeal membrane oxygenation underwent lung transplant; 181 patients had a listing diagnosis of COVID-associated acute respiratory distress syndrome (77%), and 55 patients had a listing diagnosis of non-COVID acute respiratory distress syndrome (23%). Patients with COVID-associated acute respiratory distress syndrome were older, were more likely to be female, had higher body mass index, and spent longer on the waitlist (all P < .02) than patients with non-COVID acute respiratory distress syndrome. The 2 groups had similar 1-year survival (85.8% vs 81.1%, P = .2) with no differences in postoperative complications. Patients with COVID-associated acute respiratory distress syndrome required longer times on extracorporeal membrane oxygenation pretransplant (P = .02), but duration of extracorporeal membrane oxygenation support was not a predictor of 1-year survival (P = .2). CONCLUSIONS: Despite prolonged periods of pretransplant extracorporeal membrane oxygenation support, selected patients with acute respiratory distress syndrome can undergo lung transplant safely with acceptable short-term outcomes. Appropriate selection criteria and long-term implications require further analysis.

Percutaneous Venopulmonary Extracorporeal Membrane Oxygenation as Bridge to Lung Transplantation.

Mechanical circulatory support (MCS) as a bridge to lung transplant is an infrequent but accepted pathway in patients who have refractory end-stage pulmonary failure. The American Association of Thoracic Surgeons Expert Consensus Guidelines, published in 2023, recommends venovenous (VV) extracorporeal membrane oxygenation (ECMO) as the initial configuration for those patients who have failed conventional medical therapy, including mechanical ventilation, while waiting for lung transplantation and needing MCS. Alternatively, venoarterial (VA) ECMO can be used in patients with acute right ventricular failure, hemodynamic instability, or refractory respiratory failure. With the advancement in percutaneous venopulmonary (VP) ECMO cannulation techniques, this option is becoming an attractive configuration as bridge to lung transplantation. This configuration enhances stability of the right ventricle, prevents recirculation with direct introduction of pulmonary artery oxygenation, and promotes hemodynamic stability during mobility, rehabilitation, and sedation-weaning trials before lung transplantation. Here, we present a case series of eight percutaneous VP ECMO as bridge to lung transplant with all patients mobilized, awake, and successfully transplanted with survival to hospital discharge.

Placement of Temporary Left Ventricular Assist Device Using Monitored Anesthesia Care and Regional Anesthesia.

Patients with advanced cardiogenic shock requiring mechanical circulatory support are uniquely susceptible to clinical deterioration. Limiting physiologic perturbations via avoidance of general anesthesia and endotracheal intubation by awake Impella 5.5 placement is safe and may represent a novel strategy in mechanical circulatory support initiation among patients in cardiogenic shock. (Level of Difficulty: Intermediate.).

Technical considerations for percutaneous pulmonary artery cannulation for mechanical circulatory support.

Objectives: Percutaneous pulmonary artery cannulas, used as inflow for left ventricular venting or as outflow for right ventricular mechanical circulatory support, are easily and rapidly deployable with transesophageal and fluoroscopic guidance. Methods: We chose to review our institutional and technical experience with all right atrium to pulmonary artery cannulations. Results: Based on the review, we describe 6 right atrium to pulmonary artery cannulation strategies. They are divided into total right ventricular assist support, partial right ventricular assist support, and left ventricular venting. A single limb cannula or a dual lumen cannula can be used for right ventricular support. Conclusions: In the right ventricular assist device configuration, percutaneous cannulation may prove beneficial in cases of isolated right ventricular failure. Conversely, pulmonary artery cannulation can be used for left ventricular venting as drainage to a cardiopulmonary bypass or extracorporeal membrane oxygenation circuit. This article can be used as a reference for the technical aspects of cannulation, decision-making in patient selection, and management of patients in these clinical scenarios.