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 O 2 /s/10 6 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.

2023 Update on Vascular Anesthesia.

The authors thank the editors for this opportunity to review the recent literature on vascular surgery and anesthesia and provide this clinical update. The last in a series of updates on this topic was published in 2019.1 This review explores evolving discussions and current trends related to vascular surgery and anesthesia that have been published since then. The focus is on the major points discussed in the recent literature in the following areas: carotid artery surgery, infrarenal aortic surgery, peripheral vascular surgery, and the preoperative evaluation of vascular surgical patients.

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.

Severe Impairment of Microcirculatory Perfused Vessel Density Is Associated With Postoperative Lactate and Acute Organ Injury After Cardiac Surgery.

OBJECTIVE: Resuscitation after cardiac surgery needs to address multiple pathophysiological processes that are associated with significant morbidity and mortality. Functional microcirculatory derangements despite normal systemic hemodynamics have been previously described but must be tied to clinical outcomes. The authors hypothesized that microcirculatory dysfunction after cardiac surgery would include impaired capillary blood flow and impaired diffusive capacity and that subjects with the lowest quartile of perfused vessel density would have an increased postoperative lactate level and acute organ injury scores. DESIGN: Prospective, observational study. SETTING: A single, tertiary university cardiovascular surgical intensive care unit. PARTICIPANTS: 25 adults undergoing elective cardiac surgery requiring cardiopulmonary bypass. INTERVENTION: Sublingual microcirculation was imaged using incident dark field microscopy before and 2 to 4 hours after surgery in the intensive care unit. MEASUREMENTS AND MAIN RESULTS: Compared with baseline measurements, postoperative vessel-by-vessel microvascular flow index (2.9 [2.8-2.9] v 2.5 [2.4-2.7], p < 0.0001) and perfused vessel density were significantly impaired (20.7 [19.3-22.9] v 16.3 [12.8-17.9], p < 0.0001). The lowest quartile of perfused vessel density (<12.8 mm/mm2) was associated with a significantly increased postoperative lactate level (6.0 ± 2.9 v 1.8 ± 1.2, p < 0.05), peak lactate level (7.6 ± 2.8 v 2.8 ± 1.5, p = 0.03), and sequential organ failure assessment (SOFA) score at 24 and 48 hours. CONCLUSION: In patients undergoing cardiac surgery, there was a significant decrease in postoperative microcirculatory convective blood flow and diffusive capacity during early postoperative resuscitation. Severely impaired perfused vessel density, represented by the lowest quartile of distribution, is significantly related to hyperlactatemia and early organ injury.

The Program Evaluation Committee in the Adult Cardiothoracic Anesthesiology Fellowship - Harnessing Opportunities for Program Improvement.

The Program Evaluation Committee has an essential role in the quality improvement process of the adult cardiothoracic anesthesiology fellowship. The annual program evaluation presents all stakeholders with an opportunity to evolve with the changing needs and opportunities of the fellowship milieu. The active engagement of the program in this process is a high-quality approach to successful planning, preparation and conduct of the self-study and site visit that are important extensions of the annual program evaluation and the program evaluation committee.

Contemporary Challenges for Fellowship Training in Adult Cardiothoracic Anesthesiology: Perspectives From Program Directors Around the United States.

The fellowship in adult cardiothoracic anesthesiology has matured as an accredited program. This special article addresses current challenges in this educational milieu. The first challenge relates to serving as a program director in the contemporary era. The second challenge deals with the accreditation process, including the site visit. The third challenge discusses the integration of structural heart disease and interventional echocardiography into daily practice. The fourth challenge deals with the issues that face fellowship education in the near future. Taken together, these perspectives provide a review of the contemporary challenges facing fellowship education in adult cardiothoracic anesthesiology.

The Clinical Competency Committee in Adult Cardiothoracic Anesthesiology-Perspectives From Program Directors Around the United States.

The clinical competency committee offers a fellowship program a structured approach to assess the clinical performance of each trainee in a comprehensive fashion This special article examines the structure and function of this important committee in detail. Furthermore, the strategies for the optimal functioning of this committee are also discussed as a way to enhance the overall quality of the fellowship program.

Vasoplegia After Cardiovascular Procedures-Pathophysiology and Targeted Therapy.

Vasoplegic syndrome, characterized by low systemic vascular resistance and hypotension in the presence of normal or supranormal cardiac function, is a frequent complication of cardiovascular surgery. It is associated with a diffuse systemic inflammatory response and is mediated largely through cellular hyperpolarization, high levels of inducible nitric oxide, and a relative vasopressin deficiency. Cardiopulmonary bypass is a particularly strong precipitant of the vasoplegic syndrome, largely due to its association with nitric oxide production and severe vasopressin deficiency. Postoperative vasoplegic shock generally is managed with vasopressors, of which catecholamines are the traditional agents of choice. Norepinephrine is considered to be the first-line agent and may have a mortality benefit over other drugs. Recent investigations support the use of noncatecholamine vasopressors, vasopressin in particular, to restore vascular tone. Alternative agents, including methylene blue, hydroxocobalamin, corticosteroids, and angiotensin II, also are capable of restoring vascular tone and improving vasoplegia, but their effect on patient outcomes is unclear.

Aortic Regurgitation in Acute Type-A Aortic Dissection: A Clinical Classification for the Perioperative Echocardiographer in the Era of the Functional Aortic Annulus.

The functional aortic annulus offers a clinical approach for the perioperative echocardiographer to classify the mechanisms of aortic regurgitation in acute type-A dissection. Comprehensive examination of the functional aortic annulus in this setting using transesophageal echocardiography can guide surgical therapy for the aortic root by considering the following important aspects: severity and mechanism of aortic regurgitation, extent of root dissection, and the pattern of coronary artery involvement. The final choice of surgical therapy also should take into account factors, such as patient presentation and surgical experience, to limit mortality and morbidity from this challenging acute aortic syndrome. This review explores these concepts in detail within the framework of the functional aortic annulus, detailed anatomic considerations, and the latest literature.

Diversity in the Emerging Critical Care Workforce: Analysis of Demographic Trends in Critical Care Fellows From 2004 to 2014.

OBJECTIVES: Diversity in the physician workforce is essential to providing culturally effective care. In critical care, despite the high stakes and frequency with which cultural concerns arise, it is unknown whether physician diversity reflects that of critically ill patients. We sought to characterize demographic trends in critical care fellows, who represent the emerging intensivist workforce. DESIGN: We used published data to create logistic regression models comparing annual trends in the representation of women and racial/ethnic groups across critical care fellowship types. SETTING: United States Accreditation Council on Graduate Medical Education-approved residency and fellowship training programs. SUBJECTS: Residents and fellows employed by Accreditation Council on Graduate Medical Education-accredited training programs from 2004 to 2014. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: From 2004 to 2014, the number of critical care fellows increased annually, up 54.1% from 1,606 in 2004-2005 to 2,475 in 2013-2014. The proportion of female critical care fellows increased from 29.5% (2004-2005) to 38.3% (2013-2014) (p < 0.001). The absolute number of black fellows increased each year but the percentage change was not statistically significantly different (5.1% in 2004-2005 vs 3.9% in 2013-2014; p = 0.92). Hispanic fellows increased in number from 124 (7.7%) in 2004-2005 to 216 (8.4%) in 2013-2014 (p = 0.015). The number of American Indian/Alaskan Native/Native Hawaiian/Pacific Islander fellows decreased from 15 (1.0%) to seven (0.3%) (p < 0.001). When compared with population estimates, female critical care fellows and those from racial/ethnic minorities were underrepresented in all years. CONCLUSIONS: The demographics of the emerging critical care physician workforce reflect underrepresentation of women and racial/ethnic minorities. Trends highlight increases in women and Hispanics and stable or decreasing representation of non-Hispanic underrepresented minority critical care fellows. Further research is needed to elucidate the reasons underlying persistent underrepresentation of racial and ethnic minorities in critical care fellowship programs.

Severity and Duration of Metabolic Acidosis After Deep Hypothermic Circulatory Arrest for Thoracic Aortic Surgery.

OBJECTIVE: To determine the severity, duration, and contributing factors for metabolic acidosis after deep hypothermic circulatory arrest (DHCA). DESIGN: Retrospective observational study. SETTING: University hospital. PATIENTS: Eighty-seven consecutive patients undergoing elective thoracic aortic surgery with DHCA. INTERVENTIONS: Regression analysis was used to test for relationships between the severity of metabolic acidosis and clinical and laboratory variables. MEASUREMENTS AND MAIN RESULTS: Minimum pH averaged 7.27±0.06, with 76 (87%) having a pH<7.35; 55 (63%), a pH<7.30; and 7 (8%), a pH<7.20. The mean duration of metabolic acidosis was 7.9±5.0 hours (range: 0.0 - 26.8), and time to minimum pH after DHCA was 4.3±2.0 hours (1.0 - 10.0 hours). Hyperchloremia contributed to metabolic acidosis in 89% of patients. The severity of metabolic acidosis correlated with maximum lactate (p<0.0001) and hospital length of stay (LOS) (r = 0.22, p<0.05), but not with DHCA time, DHCA temperature, duration of vasoactive infusions, or ICU LOS. Patient BMI was the sole preoperative predictor of the severity of postoperative metabolic acidosis. LIMITATIONS: This retrospective analysis involved short-term clinical outcomes related to pH severity and duration, which indirectly may have included the impact of sodium bicarbonate administration. CONCLUSIONS: Metabolic acidosis was common and severe after DHCA and was attributed to both lactic and hyperchloremic acidosis. DHCA duration and temperature had little impact on the severity of metabolic acidosis. The severity of metabolic acidosis was best predicted by the BMI and had minimal effects on short-term outcomes. Preventing hyperchloremic acidosis has the potential to decrease the severity of metabolic acidosis after DHCA.

The functional aortic annulus in the 3D era: focus on transcatheter aortic valve replacement for the perioperative echocardiographer.

The functional aortic annulus represents a sound clinical framework for understanding the components of the aortic root complex. Recent three-dimensional imaging analysis has demonstrated that the aortic annulus frequently is elliptical rather than circular. Comprehensive three-dimensional quantification of this aortic annular geometry by transesophageal echocardiography and/or multidetector computed tomography is essential to guide precise prosthesis sizing in transcatheter aortic valve replacement to minimize paravalvular leak for optimal clinical outcome. Furthermore, three-dimensional transesophageal echocardiography accurately can quantify additional parameters of the functional aortic annulus such as coronary height for complete sizing profiles for all valve types in transcatheter aortic valve replacement. Although it is maturing rapidly as a clinical imaging modality, its role in transcatheter aortic valve replacement is seen best as complementary to multidetector computed tomography in a multidisciplinary heart team model.

New frontiers in aortic therapy: focus on current trials and devices in transcatheter aortic valve replacement.

The first decade of clinical experience with transcatheter aortic valve replacement since 2002 saw the development of 2 main valve systems, namely the Edwards Sapien balloon-expandable valve series and the Medtronic self-expanding CoreValve. These 2 valve platforms now have achieved commercial approval and application worldwide in patients with severe aortic stenosis whose perioperative risk for surgical intervention is high or extreme. In the second decade of transcatheter aortic valve replacement, clinical experience and refinements in valve design have resulted in clinical drift towards lower patient risk cohorts. There are currently 2 major trials, PARTNER II and SURTAVI, that are both evaluating the role of transcatheter aortic valve replacement in intermediate-risk patient cohorts. The results from these landmark trials may usher in a new clinical paradigm for transcatheter aortic valve replacement in its second decade.

Incidental moderate mitral regurgitation in patients undergoing coronary artery bypass grafting: update on guidelines and key randomized trials.

Incidental moderate mitral regurgitation (MR) in patients presenting for coronary artery bypass grafting (CABG) is not only common but also probably adversely affects clinical outcome. The echocardiographic evaluation of incidental MR must be comprehensive and integrated, as it remains a cornerstone in management decisions. Current guidelines support surgical mitral intervention in this setting as a reasonable option, reflecting clinical equipoise towards moderate MR in the setting of planned CABG. There are currently 2 major randomized trials in progress that will test whether surgical correction of moderate MR combined with CABG improves major clinical outcomes as compared to CABG alone. These landmark trials will be completed in the near future. In the interim, significant progress in the fields of cardiac resynchronization therapy, transcatheter mitral valve intervention, and minimally invasive mitral valve surgery promise to affect the management alternatives for moderate MR in patients undergoing CABG regardless of operative risk. It is likely that in the coming decade there will be less tolerance for incidental moderate MR given its already known outcome effects and the multimodal interventions that continue to mature with better safety profiles.