Management of immune dysfunction after adult cardiac surgery

Preoperative prognostic nutritional index is an independent indicator for perioperative prognosis in coronary artery bypass grafting patients

OBJECTIVES

The prognostic nutritional index is widely used for surgery prognosis, but the association between preoperative prognostic nutritional index and short-term prognosis for coronary artery bypass grafting surgery and the profiles of perioperative prognostic nutritional index remain unclear.

METHODS

This study retrospectively enrolled a total of 879 adult patients undergoing coronary artery bypass grafting surgery in the Shanghai Chest Hospital from 2006 to 2022. The prognostic nutritional index was calculated based on serum albumin and peripheral lymphocyte count. In-hospital mortality, demographic characteristics, blood biochemistry parameters, cardiovascular medical history, and physical examination results were collected from the hospital information system. The propensity score matching method and multivariate logistic regression were used to detect the association between preoperative prognostic nutritional index and in-hospital mortality.

RESULTS

Patients were divided into a high-prognostic nutritional index group (n = 500) and a low-prognostic nutritional index group (n = 379), using a cutoff value of 48.1 according to receiver operating characteristic curve analysis. The propensity score matching-adjusted mean prognostic nutritional index levels decreased from 48.35 before the operation to 34.04 an in ≤24 h after the operation and rebounded to 43.36 before discharge. High preoperative prognostic nutritional index was inversely associated with in-hospital mortality for coronary artery bypass grafting surgery (odds ratio = 0.86; 95% CI, 0.77-0.97) in propensity score matching-adjusted multivariate logistic regression.

CONCLUSIONS

Preoperative prognostic nutritional index is an independent indicator for in-hospital mortality of for coronary artery bypass grafting surgery, and the variation trend of prognostic nutritional index during perioperation tends to be U-shaped.

MONOCYTIC MYELOID-DERIVED SUPPRESSOR CELL EXPANSION AFTER CARDIAC SURGERY WITH CARDIOPULMONARY BYPASS INDUCES LYMPHOCYTE DYSFUNCTION

ABSTRACT

Cardiac surgery with cardiopulmonary bypass (CPB) is associated with an immune paresis that predisposes to the development of postoperative infections and sepsis. Among factors responsible for CPB-induced immunosuppression, circulating myeloid-derived suppressor cells (MDSCs) have been found to induce early lymphocyte apoptosis and lymphocyte proliferation inhibition. However, the mechanisms involved are not fully understood. In this study, we found that the main lymphocyte subsets decreased significantly 24 h after cardiac surgery with CBP. As expected, cardiac surgery with CPB induced a monocytic MDSC expansion associated with an increased T-cell apoptosis and decreased proliferation capacity. Noteworthy, granulocytic MDSCs remain stable. Myeloid-derived suppressor cell depletion restored the ability of T-cell to proliferate ex vivo . After CPB, indoleamine 2,3-dioxygenase activity and IL-10 plasma level were increased such as programmed death-ligand 1 monocytic expression, whereas plasma level of arginine significantly decreased. Neither the inhibition of indoleamine 2,3-dioxygenase activity nor the use of anti-programmed death-ligand 1 or anti-IL-10 blocking antibody restored the ability of T-cell to proliferate ex vivo . Only arginine supplementation restored partially the ability of T-cell to proliferate.

Neutrophil function and bactericidal activity against Staphylococcus aureus after cardiac surgery with cardiopulmonary bypass

Staphylococcus aureus is the main bacterial pathogen encountered in mediastinitis after cardiac surgical procedures; it remains a devastating complication with a high mortality rate. As neutrophils have a primordial role in the defense against staphylococcus infection and cardiopulmonary bypass (CPB) is known to induce immunosuppression, the aim of this study was to investigate CPB impact on neutrophil functions. Patients without known immunosuppression scheduled for cardiac surgery with CPB were included. Bone marrow and blood samples were harvested before, during, and after surgery. Neutrophil phenotypic maturation and functions (migration, adhesion, neutrophil extracellular trap [NET] release, reactive oxygen species (ROS) production, phagocytosis, and bacteria killing) were investigated. Two types of Staphylococcus aureus strains (one from asymptomatic nasal carriage and another from mediastinitis infected tissues) were used to assess in vitro bacterial direct impact on neutrophils. We found that CPB induced a systemic inflammation with an increase in circulating mature neutrophils after surgery. Bone marrow sample analysis did not reveal any modification of neutrophil maturation during CPB. Neutrophil lifespan was significantly increased and functions such as NET release and ROS production were enhanced after CPB whereas bacteria killing and phagocytosis were not impacted. Results were similar with the two different isolates of Staphylococcus aureus. These data suggest that CPB induces a recruitment of mature neutrophils via a demargination process rather than impacting their maturation in the bone marrow. In addition, neutrophils are fully efficient after CPB and do not contribute to postoperative immunosuppression.

Myeloid-Derived Suppressor Cells Mediate Immunosuppression After Cardiopulmonary Bypass

OBJECTIVES

Cardiopulmonary bypass is associated with severe immune dysfunctions. Particularly, a cardiopulmonary bypass-related long-lasting immunosuppressive state predisposes patients to a higher risk of postoperative complications, such as persistent bacterial infections. This study was conducted to elucidate mechanisms of post-cardiopulmonary bypass immunosuppression.

DESIGN

In vitro studies with human peripheral blood mononuclear cells.

SETTING

Cardiosurgical ICU, University Research Laboratory.

PATIENTS

Seventy-one patients undergoing cardiac surgery with cardiopulmonary bypass (enrolled May 2017 to August 2018).

INTERVENTIONS

Peripheral blood mononuclear cells before and after cardiopulmonary bypass were analyzed for the expression of immunomodulatory cell markers by real-time quantitative reverse transcription polymerase chain reaction. T cell effector functions were determined by enzyme-linked immunosorbent assay, carboxyfluorescein succinimidyl ester staining, and cytotoxicity assays. Expression of cell surface markers was assessed by flow cytometry. CD15 cells were depleted by microbead separation. Serum arginine was measured by mass spectrometry. Patient peripheral blood mononuclear cells were incubated in different arginine concentrations, and T cell functions were tested.

MEASUREMENTS AND MAIN RESULTS

After cardiopulmonary bypass, peripheral blood mononuclear cells exhibited significantly reduced levels of costimulatory receptors (inducible T-cell costimulator, interleukin 7 receptor), whereas inhibitory receptors (programmed cell death protein 1 and programmed cell death 1 ligand 1) were induced. T cell effector functions (interferon γ secretion, proliferation, and CD8-specific cell lysis) were markedly repressed. In 66 of 71 patients, a not yet described cell population was found, which could be characterized as myeloid-derived suppressor cells. Myeloid-derived suppressor cells are known to impair immune cell functions by expression of the arginine-degrading enzyme arginase-1. Accordingly, we found dramatically increased arginase-1 levels in post-cardiopulmonary bypass peripheral blood mononuclear cells, whereas serum arginine levels were significantly reduced. Depletion of myeloid-derived suppressor cells from post-cardiopulmonary bypass peripheral blood mononuclear cells remarkably improved T cell effector function in vitro. Additionally, in vitro supplementation of arginine enhanced T cell immunocompetence.

CONCLUSIONS

Cardiopulmonary bypass strongly impairs the adaptive immune system by triggering the accumulation of myeloid-derived suppressor cells. These myeloid-derived suppressor cells induce an immunosuppressive T cell phenotype by increasing serum arginine breakdown. Supplementation with L-arginine may be an effective measure to counteract the onset of immunoparalysis in the setting of cardiopulmonary bypass.

Risk factors of nosocomial infection after cardiac surgery in children with congenital heart disease

Background

The aim of our study was to analyze the risk factors of nosocomial infection after cardiac surgery in children with congenital heart disease (CHD).

Methods

We performed a retrospective cohort study, and children with CHD who underwent open-heart surgeries at Shanghai Children’s Medical Center from January 1, 2012 to December 31, 2018 were included. The baseline characteristics of these patients of different ages, including neonates (0–1 months old), infants (1–12 months old) and children (1–10 years old), were analyzed, and the association of risk factors with postoperative nosocomial infection were assessed.

Results

A total of 11,651 subjects were included in the study. The overall nosocomial infection rate was 10.8%. Nosocomial infection rates in neonates, infants, and children with congenital heart disease were 32.9, 15.4, and 5.2%, respectively. Multivariate logistic regression analysis found age (OR 0798, 95%CI: 0.769–0.829; P < 0.001), STS risk grade (OR 1.267, 95%CI: 1.159–1.385; P < 0.001), body mass index (BMI) <5th percentile (OR 1.295, 95%CI: 1.023–1.639; P = 0.032), BMI >95th percentile (OR 0.792, 95%CI: 0.647–0.969; P = 0.023), cardiopulmonary bypass (CPB) time (OR 1.008, 95%CI: 1.003–1.012; P < 0.001) and aortic clamping time (OR 1.009, 1.002–1.015; P = 0.008) were significantly associated with nosocomial infection in CHD infants. After adjusted for confounding factors, we found STS risk grade (OR 1.38, 95%CI: 1.167–1.633; P < 0.001), BMI < 5th percentile (OR 1.934, 95%CI: 1.377–2.715; P < 0.001), CPB time (OR 1.018, 95%CI: 1.015–1.022; P < 0.001), lymphocyte/WBC ratio<cut off value (OR 3.818, 95%CI: 1.529–9.533; P = 0.004) and AST>cut off value (OR 1.546, 95%CI: 1.119–2.136; P = 0.008) were significantly associated with nosocomial infection in CHD children.

Conclusion

Our study suggested STS risk grade, BMI, CPB duration, low lymphocyte/WBC or high neutrophil/WBC ratio were independently associated with nosocomial infection in CHD infant and children after cardiac surgery.

Immunotherapy of Sepsis: Blind Alley or Call for Personalized Assessment?

Sepsis is the most frequent cause of death in noncoronary intensive care units. In the past 10 years, progress has been made in the early identification of septic patients and their treatment. These improvements in support and therapy mean that mortality is gradually decreasing, however, the rate of death from sepsis remains unacceptably high. Immunotherapy is not currently part of the routine treatment of sepsis. Despite experimental successes, the administration of agents to block the effect of sepsis mediators failed to show evidence for improved outcome in a multitude of clinical trials. The following survey summarizes the current knowledge and results of clinical trials on the immunotherapy of sepsis and describes the limitations of our knowledge of the pathogenesis of sepsis. Administration of immunomodulatory drugs should be linked to the current immune status assessed by both clinical and molecular patterns. Thus, a careful daily review of the patient's immune status needs to be introduced into routine clinical practice giving the opportunity for effective and tailored use of immunomodulatory therapy.

Presence of Hypogammaglobulinemia – A Risk Factor of Mortality in Patients with Severe Sepsis, Septic Shock, and SIRS

In this retrospective study we assessed the frequency of hypogammaglobulinemia in 708 patients with SIRS, severe sepsis and septic shock. We evaluated the relationship between hypogammaglobulinemia IgG, IgM and 28 day mortality. Total of 708 patients and 1,513 samples were analyzed. In the three subgroups we investigated, patients met the criteria of SIRS, severe sepsis and septic shock. IgG hypogammaglobulinemia was demonstrated in 114 patients with severe sepsis (25.2%), 11 septic shock patients (24.4%), and in 29 SIRS patients (13.9%). IgM hypogammaglobulinemia was documented in 55 patients with severe sepsis (12.2%), 6 septic shock patients (13.3%), and in 17 SIRS patients (8.1%). Mortality of patients with severe sepsis and normal IgG levels was significantly lower (111 patients; 32.8%) compared with those with IgG hypogammaglobulinemia (49 patients; 43.0%; p=0.001). Mortality of patients with septic shock and IgG hypogammaglobulinemia (n=5) was significantly higher compared with those with normal IgG levels (45.5% vs. 38.2%; p=0.001). Mortality of patients with severe sepsis and IgM hypogammaglobulinemia did not differ from that of patients with normal IgM levels (37.0 vs. 41.8%). Mortality of patients with septic shock and IgM hypogammaglobulinemia was significantly higher compared with those with normal IgM levels (50% vs. 38.5%; p=0.0001). This study documented relatively high incidence of hypogammaglobulinemia IgG and IgM in patients with severe sepsis, septic shock and SIRS respectively. The presence of IgG hypogammaglobulinemia in patients with severe sepsis is independent factor of mortality.

Outcome characteristics of multiple-valve surgery: comparison with single-valve procedures

OBJECTIVE

Multiple-valve (MUV) procedures currently exhibit higher operative mortality than do single-valve procedures, but a paucity of scientific information exists to explain the observation. This topic was examined using The Society of Thoracic Surgeons Database.

METHODS

All patients in the The Society of Thoracic Surgeons data set undergoing valve surgery (except pulmonary valve and aortic root operations) from 1993 through 2007 were identified (N = 623,039). Baseline characteristics and postoperative outcomes were contrasted between all seven combinations of single-valve and MUV procedures involving aortic, mitral, and tricuspid valves. Seven independent logistic regression analyses were performed, based on the seven procedures, and multivariable risk factors for mortality were compared, with emphasis on single-valve versus MUV procedures.

RESULTS

Baseline characteristics for MUV procedures (n = 67,926) shared many similarities to those for single-valve procedures (n = 555,113), including age, ejection fraction, and comorbidities. Preoperative renal failure, New York Heart Association class III to IV, nonelective presentation, and reoperation were slightly more common in MUV subsets, and coronary bypass was less frequent. Operative mortality was almost double for MUV as compared with single-valve procedures (10.7% vs 5.7%, P = 0.0001). Categorical predictors with the largest odds ratios for mortality were emergency status, renal failure, and second reoperation. However, predictors for mortality were generally consistent in order and magnitude between the single-valve and MUV subgroups.

CONCLUSIONS

Despite similarities in preoperative profiles of the patients undergoing single-valve and MUV procedures, mortality for MUV surgery remains considerably higher. Determinants of operative mortality and morbidity differ little across the procedural groups, and these findings serve as a benchmark for future studies, as well as suggest a continued search for explanations of poorer MUV outcomes.