Vasoplegic Syndrome after Cardiopulmonary Bypass in Cardiovascular Surgery: Pathophysiology and Management in Critical Care

The mystery of methylene blue and its role in managing post-cardiac surgery vasoplegic shock

BACKGROUND

Vasoplegic syndrome is associated with high mortality. Methylene blue (MB) is a guanylate cyclase inhibitor that ameliorates this re-distributive type of shock. This study aims to investigate the outcome in patients who received MB early postoperatively.

METHODS

2753 patients who underwent cardiac surgery utilizing cardiopulmonary bypass at our institution in a time interval of two years were identified. The incidence of vasoplegic syndrome was 7.2% (n = 200). Pharmacy records identified 84 patients (group 1, MB group) who received methylene blue and 116 patients (group 2, Control group) who didn't receive the drug. This single-center retrospective cohort study's primary outcome was in-hospital mortality. Secondary outcomes were postoperative hemodialysis, serum lactate levels at 24 h postoperatively, and intensive care unit stay length in days.

RESULTS

MB patients have a shorter ICU stay as compared to the control group (9 ± 8 days vs. 16 ± 6.9; p-value <.001). In the control group, postoperative hemodialysis was higher (20% in the MB group and 40% in the control group; p-value <.05). At 24 h post-op, the methylene blue group had reduced serum lactate levels (1.8 ± 1.2 vs. 4 ± 1.8 in the control group; p-value <.001). The methylene blue group had a decreased 24-hour norepinephrine dose (1.5 ± 1.2 vs. 2.8 ± 2 in the control group; p-value <.05). In-hospital mortality was not significantly different between the two groups (38% in the MB group vs. 43% in the control group).

CONCLUSION

Early postoperative administration of methylene blue in patients with vasoplegic syndrome shortens intensive care unit stay and contributes to less end-organ damage.

Intraoperative Hemoadsorption in Heart Transplant Surgery: A 5-Year Experience

BACKGROUND

Hyperimmune response and cytokine release post-reperfusion might occur after orthotopic heart transplantation (HTx). Intraoperative hemoadsorption (HA) has been introduced to remove such elevated cytokines. We aimed to analyze the effect of intraoperative HA in patients undergoing orthotopic HTx.

METHODS

Between 2018 and 2022, 40 consecutive orthotopic HTx patients who underwent intraoperative hemoadsorption HA integrated into the cardiopulmonary bypass were compared to 41 historical controls. Primary outcome measures included postoperative hemodynamic stability and blood product requirements, while secondary outcomes were the incidence of acute kidney injury requiring dialysis (AKI-d) and 30-day mortality.

RESULTS

Postoperatively, the vasoactive-inotropic score (VIS) did not significantly differ between the groups. However, the use duration for milrinone and dobutamine was shortened by one day compared to controls. The HA group had fewer red blood cell transfusions (765 vs. 1330 mL, p = 0.01) and lower fresh frozen plasma requirements (945 vs. 1200 mL, p = 0.04). Mechanical ventilation duration was reduced (22 vs. 28 h, p = 0.02). AKI-d rates were similar, and 30-day mortality favored non-significantly the HA group (5% vs. 14.6%, p = ns). No device-related adverse events were observed.

CONCLUSION

These findings suggest that intraoperative HA might improve immediate postoperative outcomes; however, further validation in larger randomized controlled trials is warranted.

Vasoplegic Syndrome in Cardiac Surgery: A Narrative Review of Etiologic Mechanisms and Therapeutic Options

Vasoplegic syndrome, a form of distributive shock that may manifest during or after cardiopulmonary bypass, is a serious complication that increases morbidity and mortality after cardiac surgery. No consensus definition exists, but vasoplegic syndrome is generally described as a state of pathologic vasodilation causing hypotension refractory to fluid resuscitation and vasopressor therapy, and resulting in organ malperfusion despite a normal or increased cardiac output. Diagnosis can be complex as there is a broad differential diagnosis for low systemic vascular resistance in the cardiac surgical patient. Interpretation of hemodynamic data can also be challenging in the setting of mixed shock states and mechanical support. This narrative review summarizes the pathophysiology of vasoplegic syndrome, the literature concerning its incidence and risk factors, the hemodynamic parameters important to the diagnosis of vasoplegic syndrome, a consensus definition of the syndrome, and a proposed goal-directed treatment framework.

Vasoplegia in Cardiac Surgery: A Systematic Review and Meta-analysis of Current Definitions and Their Influence on Clinical Outcomes

OBJECTIVES

To identify differences in the reported vasoplegia incidence, intensive care unit (ICU) length of stay (LOS), and 30-day mortality rates as influenced by different vasoplegia definitions used in cardiac surgery studies.

DESIGN

A systematic review was performed covering the period 1977 to 2023 using PubMed/MEDLINE, Embase, Web of Science, Cochrane Library, and Emcare and a meta-analysis (PROSPERO: CRD42021258328) was performed.

SETTING AND PARTICIPANTS

One hundred studies defining vasoplegia in cardiac surgery patients were systematically reviewed. Sixty studies with 20 or more patients, irrespective of design, reporting vasoplegia incidence, ICU LOS, or 30-day mortality were included for meta-analysis.

INTERVENTIONS

Cardiac surgery on cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Studies were categorized depending on the used mean arterial pressure (MAP) thresholds. Random intercept logistic regression models were used for meta-analysis of incidence and mortality. Random effect meta-analysis was used for ICU LOS. One hundred studies were reviewed systematically. MAP and cardiac index thresholds varied considerably (<50-80 mmHg and 2.0-3.5 L·min-1m-2, respectively). Vasopressor dosages also differed between definitions. The reported incidence (60 studies; mean incidence, 19.9%; 95% confidence interval [CI], 16.1-24.4) varied largely between studies (2.5%-66.3%; I2 = 97%; p < 0.0001). Meta-regression models, including the MAP-threshold, did not explain this heterogeneity. Similarly, the effect of vasoplegia on ICU LOS, and 30-day mortality was very heterogeneous among studies (I2 = 99% and I2 = 73%, respectively).

CONCLUSIONS

The large variability in vasoplegia definitions is associated with significant heterogeneity regarding incidence and clinical outcomes, which cannot be explained by factors included in our models. Such variations in definitions leads to inconsistent patient diagnosis and renders published vasoplegia research incomparable.

Hemodynamic Management with Vasopressin for Cardiovascular Surgery

Background and Objectives: Vasopressin increases blood pressure through aquaporin-2-mediated water retention and is useful for managing hemodynamics after surgery. However, even after decades of study, clear clinical guidelines on doses and ideal use cases after cardiovascular surgery remain unclear. Here, the existing literature is synthesized on vasopressin use for cardiac surgeries and coupled with real-world clinical experience to outline a clearer clinical path for vasopressin use. Materials and Methods: Literature from 1966 to the present was searched, and information on surgical outcomes for cardiovascular surgery was extracted. Clinicians from the University of Tsukuba with extensive vasopressin experience in pediatric cardiovascular patients were consulted for general use guidelines. Results: Vasopressin response after cardiovascular surgery is multifaceted, and low-power trials, plus conflicting study reports, generally render it as a secondary choice behind norepinephrine. Clinical experience indicates that low doses of 0.2-0.3 mU/kg/min with constant blood pressure and oxygen monitoring for response are required. Although sole use is not recommended, vasopressin may aid in controlling hemodynamics when given with other volemic or osmolal drugs. Conclusions: Vasopressin may work in a select population of first-line non-responders, but relevant response factors remain unanalyzed and clear guidelines for use remain unestablished. Future, large-scale studies are needed to delineate temporal and demographic characteristics that affect response to vasopressin for the purpose of managing post-surgical capillary leakage and hemodynamics.

Enhancing lung transplantation with ECMO: a comprehensive review of mechanisms, outcomes, and future considerations

BACKGROUND

Lung transplantation (LTx) is a critical intervention for patients with end-stage lung disease. However, challenges such as donor organ scarcity and post-transplant complications significantly affect its success. Recent advancements in Extracorporeal Membrane Oxygenation (ECMO) have shown promise in improving the outcomes and expanding eligibility for LTx.

METHODS

A comprehensive literature review was conducted, focusing on studies that explore the use of ECMO in lung transplantation. A thorough search of relevant studies on ECMO and LTx was conducted using multiple scholarly databases and relevant keywords, resulting in 73 studies that met the inclusion criteria. Sources included peer-reviewed journals and clinical trial results, with emphasis on articles captured recent advancements in ECMO technology and techniques.

RESULTS

ECMO has been crucial in supporting patients before, during, and after LTx. It serves as a bridge to transplantation by maintaining pulmonary and circulatory stability in critically ill patients awaiting donor organs. ECMO also aids in the evaluation of marginal donor lungs and supports patients through acute post-transplant complications. Recent technological advancements have improved the safety and efficacy of ECMO, further solidifying its role in LTx.

CONCLUSION

In conclusion, this review underscores ECMO's critical role in enhancing outcomes across all stages of lung transplantation. Its various configurations and strategies have shown promise in stabilizing critically ill patients and improving transplant success rates. Looking ahead, it's important to gather more information about the long-term outcomes and potential complications associated with ECMO use. More research and data collection will help us understand the benefits and risks better, leading to improved decision-making and patient care in this field.

Systemic Mastocytosis Successfully Managed using Cytosorb ® During Cardiopulmonary Bypass for Aortic Valve Replacement

ABSTRACT

We describe the case of a 72-year-old male with a history of systemic mastocytosis scheduled for on-pump aortic valve replacement for severe aortic insufficiency. Anesthesia and peri-operative management included avoidance of histamine-releasing drugs, methylprednisolone and clemastin prophylaxis. Furthermore, a CytoSorb ® cartridge has been added to the bypass circuit and hemoadsorption was performed throughout the entire cardiopulmonary bypass (CPB) duration. CytoSorb ® is a hemoadsorption device designed to remove various cytokines and drugs from the blood. The use of CytoSorb ® during CPB in our case was not associated with adverse events, and the patient did not present any allergic or anaphylactic reaction.

Relationship between Preoperative Red Cell Distribution Width and Prolonged Postoperative Use of Catecholamines in Minimally Invasive Mitral Valve Surgery Patients: A Retrospective Cohort Study

Background/Objectives: Elevated RDW has emerged in cardiac surgery as a potential means of preoperative risk stratification with the capacity to predict short- and long-term postoperative mortality, acute kidney injury, and postoperative atrial fibrillation. The question as to whether perioperative hemodynamic instability may be predicted by such a marker remains a topic of ongoing debate. The aim of this study was to explore the relationship between preoperative RDW and prolonged postoperative catecholamine use in minimally invasive mitral valve surgery. Methods: We performed a retrospective monocentric cohort study in an academic hospital; we enrolled patients who had undergone minimally invasive mitral valve surgery (including both robot-assisted and non-robot-assisted procedures) between January 2019 and December 2022. We considered the use of inotropes and/or vasopressors for at least twelve hours after post-surgery ICU admission to qualify as the prolonged postoperative use of catecholamines (PPUC). The RDW was obtained from the routine full blood count analysis performed upon admission or a maximum of 72 h before surgery. We also performed a multivariable logistic regression analysis with PPUC as the dependent variable. Results: We finally enrolled 343 patients. Upon multivariate analysis, RDW >14.4% was independently associated with prolonged postoperative catecholamine use when compared to the reference group (OR 2.62 [1.06-4.84]; p = 0.03). Moreover, the EuroSCORE II score (OR 1.38 [1.03-1.85]; p = 0.03), the cross-clamp time (OR 1.01 [1.01-1.02]; p < 0.01), and robot-assisted mitral valve surgery (OR 0.53 [0.30-0.93]; p < 0.03) were independently associated with the prolonged postoperative use of catecholamines. Conclusions: This study identified that an elevated preoperative RDW (>14.4%), the EuroSCORE II score, and the cross-clamp time independently predict prolonged postoperative catecholamine use in minimally invasive mitral valve surgery patients. Conversely, the robot-assisted approach was associated with a smaller hemodynamic impairment.

Ion Channels Remodeling in the Regulation of Vascular Hyporesponsiveness During Shock

Shock is characterized with vascular hyporesponsiveness to vasoconstrictors, thereby to cause refractory hypotension, insufficient tissue perfusion, and multiple organ dysfunction. The vascular hyporeactivity persisted even though norepinephrine and fluid resuscitation were administrated, it is of critical importance to find new potential target. Ion channels are crucial in the regulation of cell membrane potential and affect vasoconstriction and vasodilation. It has been demonstrated that many types of ion channels including K+ channels, Ca2+ permeable channels, and Na+ channels exist in vascular smooth muscle cells and endothelial cells, contributing to the regulation of vascular homeostasis and vasomotor function. An increasing number of studies suggested that the structural and functional alterations of ion channels located in arteries contribute to vascular hyporesponsiveness during shock, but the underlying mechanisms remained to be fully clarified. Therefore, the expression and functional changes in ion channels in arteries associated with shock are reviewed, to pave the way for further exploring the potential of ion channel-targeted compounds in treating refractory hypotension in shock.

Factors associated with vasoplegic shock in the postoperative period of cardiac surgery and influence on morbidity and mortality of the use of arginine vasopressin as rescue therapy

OBJECTIVES

Analyzing associated factors with vasoplegic shock in the postoperative period of Cardiac Surgery. Analyzing the influence of vasopressin as rescue therapy to first-line treatment with norepinephrine.

DESIGN

Cohort, prospective and observational study.

SETTING

Main hospital Postoperative Cardiac ICU.

PATIENTS

Patients undergoing cardiac surgery with subsequent ICU admission from January 2021 to December 2022.

INTERVENTIONS

Record of presurgical, perioperative and ICU discharge clinical variables.

MAIN VARIABLES OF INTEREST

chronic treatment, presence of vasoplegic shock, need for vasopressin, cardiopulmonary bypass time, mortality.

RESULTS

773 patients met the inclusion criteria. The average age was 67.3, with predominance of males (65.7%). Post-CPB vasoplegia was documented in 94 patients (12.2%). In multivariate analysis, vasoplegia was associated with age, female sex, presurgical creatinine levels, cardiopulmonary bypass time, lactate level upon admission to the ICU, and need for prothrombin complex transfusion. Of the patients who developed vasoplegia, 18 (19%) required rescue vasopressin, associated with pre-surgical intake of ACEIs/ARBs, worse Euroscore score and longer cardiopulmonary bypass time. Refractory vasoplegia with vasopressin requirement was associated with increased morbidity and mortality.

CONCLUSIONS

Postcardiopulmonary bypass vasoplegia is associated with increased mortality and morbidity. Shortening cardiopulmonary bypass times and minimizing products blood transfusion could reduce its development. Removing ACEIs and ARBs prior to surgery could reduce the incidence of refractory vasoplegia requiring rescue with vasopressin. The first-line treatment is norepinephrine and rescue treatment with VSP is a good choice in refractory situations. The first-line treatment of this syndrome is norepinephrine, although rescue with vasopressin is a good complement in refractory situations.

Severe Vasoplegic Shock After Heart Transplant Successfully Treated With Multimodal Therapeutic Approach

Vasoplegia describes a constellation of low vascular resistance and normal cardiac output. Vasoplegia is common after cardiac surgery in general and in heart transplant recipients more specifically and occurs in over one-half of all heart transplant recipients with a varying degree of severity. The pathophysiology of vasoplegia is multifactorial and associated with a cascade of inflammatory mediators. Routine treatment of vasoplegia is based on medical vasopressor therapy, but in severe cases this may be insufficient to maintain adequate blood pressure and does not address the underlying pathophysiology. We report a case of severe vasoplegic shock in a heart transplant recipient who was successfully managed with a multimodal therapy combination of methylene blue, immunoglobulins enriched with immunoglobulin M, cytokine adsorption, and broad-spectrum antibiotics. This represents a promising therapeutic approach for heart transplant patients with vasoplegia.

Adverse Clinical Effects Associated With Non-catecholamine Pharmacologic Agents for Treatment of Vasoplegic Syndrome in Adult Cardiac Surgery

Vasoplegic syndrome is a relatively common complication that can happen during and after major adult cardiac surgery. It is associated with a higher rate of complications, including postoperative renal failure, longer duration of mechanical ventilation, and intensive care unit stay, as well as increased mortality. The underlying pathophysiology of vasoplegic syndrome is that of profound vascular hyporesponsiveness, and involves a complex interplay among inflammatory cytokines, cellular surface receptors, and nitric oxide (NO) production. The pharmacotherapy approaches for the treatment of vasoplegia include medications that increase vascular smooth muscle contraction via increasing cytosolic calcium in myocytes, reduce the vascular effects of NO and inflammation, and increase the biosynthesis of and vascular response to norepinephrine. Clinical trials have demonstrated the clinical efficacy of non-catecholamine pharmacologic agents in the treatment of vasoplegic syndrome. With an increase in their use today, it is important for clinicians to understand the adverse clinical outcomes and patient risk profiles associated with these agents, which will allow better-tailored medical therapy.

Severe Refractory Vasoplegic Shock Syndrome after OPCABG Successfully Treated with Hydroxycobalamin: A Case Report and Review of the Literature

BACKGROUND

Vasoplegic shock syndrome (VSS) after an off-pump coronary artery bypass graft (OPCABG) is an extremely rare condition. Inotropic support is usually the first-line therapy, though it can precipitate several complications or be ineffective. We report the first case of severe refractory VSS after OPCABG successfully treated with hydroxycobalamin.

METHODS

A 77-year-old gentleman underwent OPCABG for three vessels coronary artery disease. Preoperative LV ejection fraction was 28%, and the patient before surgery started sacubitril/valsartan titrated, then, at the highest dose. Surgery was uneventful and, by the end of the procedure, TEE showed improved biventricular contractility.

RESULTS

The patient was transferred to the ICU without inotropic support, but soon developed hypotension. TEE ruled out pericardial tamponade and confirmed fair contractility. Norepinephrine was titrated to a medium-high dose, vasopressin was started and a Swan-Ganz catheter was placed. SVR was 480 dyn·s·cm-5. Despite aggressive pharmacologic treatment (including methylprednisolone and methylene blue), no improvements were noticed. Ten grams of hydroxycobalamin were administered. One hour later, hemodynamic status re-assessment showed SVR > 800 dyn·s·cm-5. Afterward, vasopressors were gradually reduced.

CONCLUSIONS

Our case demonstrated the importance of adequate early treatment in VSS after OPCABG. This case report shows, for the first time, that hydroxycobalamin was effectively used to restore homeostasis.

Preoperative Sildenafil in Pediatric Patients Undergoing Congenital Heart Surgeries: A Systematic Review and Meta-Analysis

Background. Pulmonary hypertension (PH) is a common complication of congenital heart disease (CHD). With early surgical intervention, outcomes have improved over the last two decades. Persistent PH, however, may still occur following surgery. Sildenafil has been shown to be beneficial for postoperative pulmonary hypertensive crises. The role of preoperative sildenafil in controlling postoperative PH is poorly elucidated. This study aimed to evaluate the effect of preoperative sildenafil on pediatric patients undergoing congenital heart surgeries. Methods. A comprehensive literature search was conducted in scientific databases. We included randomized controlled trials which assessed the effect of preoperative sildenafil in pediatric patients with CHD undergoing repair surgeries. Primary outcomes were pre- and postoperative differences in mean pulmonary arterial pressure (mPAP) and mean pulmonary artery/aortic pressure ratio (PA/Ao ratio). Results. Four studies (n = 233) were retained for the final analysis. Dose of sildenafil ranged from .3 to .5 mg/kg every 4-6 hours via oral/nasogastric route, with timing of administration varied from 1 to 2 weeks before surgery. Compared to controls, preoperative sildenafil was associated with greater reduction in postoperative mPAP (MD -5.02; 95% CI [-8.91, -1.13]) and mean PA/Ao ratio (MD -.11; 95% CI [-.17, -.06]). Shorter CPB time, ICU length of stay, and duration of mechanical ventilation were also observed in the sildenafil group. Conclusion. Preoperative sildenafil is beneficial in reducing PAP, thereby reducing the risk of postoperative PH crisis. Further studies are warranted to identify the optimal dosage and timing of administration of sildenafil in CHD patients prior to surgery.

Alterations to Kidney Physiology during Cardiopulmonary Bypass-A Narrative Review of the Literature and Practical Remarks

INTRODUCTION

According to different authors, cardiac surgery-associated acute kidney injury (CSA-AKI) incidence can be as high as 20-50%. This complication increases postoperative morbidity and mortality and impairs long-term kidney function in some patients. This review aims to summarize current knowledge regarding alterations to renal physiology during cardiopulmonary bypass (CPB) and to discuss possible nephroprotective strategies for cardiac surgeries. Relevant sections: Systemic and renal circulation, Vasoactive drugs, Fluid balance and Osmotic regulation and Inflammatory response.

CONCLUSIONS

Considering the available scientific evidence, it is concluded that adequate kidney perfusion and fluid balance are the most critical factors determining postoperative kidney function. By adequate perfusion, one should understand perfusion with proper oxygen delivery and sufficient perfusion pressure. Maintaining the fluid balance is imperative for a normal kidney filtration process, which is essential for preserving the intra- and postoperative kidney function.

FUTURE DIRECTIONS

The review of the available literature regarding kidney function during cardiac surgery revealed a need for a more holistic approach to this subject.

Perioperative Management of Heart Transplantation: A Clinical Review

In this clinical review, the authors summarize the perioperative management of heart transplant patients with a focus on hemodynamics, immunosuppressive strategies, hemostasis and hemorrage, and the prevention and treatment of infectious complications.