Effects of cardiopulmonary bypass on lymphocytes and their subset counts with or without use of autotransfusion devices

Inflammation and Oxidative Stress in the Context of Extracorporeal Cardiac and Pulmonary Support

Extracorporeal circulation (ECC) systems, including cardiopulmonary bypass, and extracorporeal membrane oxygenation have been an irreplaceable part of the cardiothoracic surgeries, and treatment of critically ill patients with respiratory and/or cardiac failure for more than half a century. During the recent decades, the concept of extracorporeal circulation has been extended to isolated machine perfusion of the donor organ including thoracic organs (ex-situ organ perfusion, ESOP) as a method for dynamic, semi-physiologic preservation, and potential improvement of the donor organs. The extracorporeal life support systems (ECLS) have been lifesaving and facilitating complex cardiothoracic surgeries, and the ESOP technology has the potential to increase the number of the transplantable donor organs, and to improve the outcomes of transplantation. However, these artificial circulation systems in general have been associated with activation of the inflammatory and oxidative stress responses in patients and/or in the exposed tissues and organs. The activation of these responses can negatively affect patient outcomes in ECLS, and may as well jeopardize the reliability of the organ viability assessment, and the outcomes of thoracic organ preservation and transplantation in ESOP. Both ECLS and ESOP consist of artificial circuit materials and components, which play a key role in the induction of these responses. However, while ECLS can lead to systemic inflammatory and oxidative stress responses negatively affecting various organs/systems of the body, in ESOP, the absence of the organs that play an important role in oxidant scavenging/antioxidative replenishment of the body, such as liver, may make the perfused organ more susceptible to inflammation and oxidative stress during extracorporeal circulation. In the present manuscript, we will review the activation of the inflammatory and oxidative stress responses during ECLP and ESOP, mechanisms involved, clinical implications, and the interventions for attenuating these responses in ECC.

The effect of methylprednisolone on cytokine concentration and leukocyte adhesion molecule expression in an isolated cardiopulmonary bypass system

This study examines the effect of methylprednisolone on cytokine balance and adhesion molecule expression within an isolated cardiopulmonary bypass (CPB) system. This isolated CPB system is an in vitro model which simulates the pro-inflammatory immune response. Whole blood from 10 volunteers was obtained in two equal amounts. Heparin and saline were added to the control group while heparin and methylprednisolone were added to the methylprednisolone group. The blood was added to two identical CPB circuits and bypass commenced by a trained perfusionist. Samples were taken at blood donation (Sample 0), 10 min after the addition of drugs (Sample 1) and after 30, 60 and 90 min of CPB (Samples 2, 3 and 4, respectively). Cytokines interleukin-8 (IL-8), interleukin-10 (IL-10), interleukin-1 receptor antagonist (IL-1ra) and tumour necrosis factor soluble receptor 2 (TNFsr2) and the leucocyte adhesion molecules L-selectin, HLA DR, CD18 and CD11b were determined. IL-8 increased in both groups. This increase was significantly less in the methylprednisolone group. Increases in granulocyte CD11b and CD18 expression were less in the methylprednisolone group than in the control group but did not reach statistical significance. These results indicate that methylprednisolone significantly reduces the production of IL-8 in an isolated CPB system. This effect occurs in the absence of IL-10.

Are leukocytes in salvaged washed autologous blood harmful for the recipient? The results of a pilot study

To explore whether polymorphonuclear leukocytes (PMNL) are activated to the priming threshold through intraoperative blood salvage, and are thus able to induce endothelial damage, we investigated chemotactic response (n = 20) and respiratory burst (RB; n = 20) of PMNL without (basal respiratory burst, bPMNL-RB) and after in vitro stimulation with formyl-Met-Leu-Phe (fMLP-RB) and phorbol myristate acetate (PMA-RB). Blood was processed with a continuous autotransfusion device (CATS). Heparin (Heparin group) and sodium citrate (Citrate group) were used alternately as an anticoagulant for each half of the chemotaxis and RB studies. Comparison of measurements from the processed autologous erythrocyte concentrates (paEC) to pre- and intraoperative arterial blood samples showed no statistically significant difference for any test of PMNL functional responses in an orthopedic patient population. Analysis of intraindividual changes demonstrated a significantly increased bPMNL-RB (both groups, P = 0.0032; Heparin group, P = 0.0098), fMLP-RB (both groups, P = 0.0484; Citrate group, P = 0.0371), and PMA-RB (Citrate group, P = 0.002) in the paEC compared with intraoperative arterial samples, whereas the chemotactic response did not change. Nevertheless, median values of all RB measurements in the paEC were within the range of pre- and intraoperative values, indicating that PMNLs contained in the paEC are neither impaired nor activated to the priming threshold. The results confirm the clinical experience that intraoperative blood salvage is safe to use during major orthopedic surgery and questions the beneficial effect of special leukocyte-removing filters.

Preoperative prediction of postoperative edema and effusion in pediatric cardiac surgery by altered antigen expression patterns on granulocytes and monocytes

Postoperative edema and effusion (POEE) following cardiopulmonary bypass (CPB) surgery in children retards recovery and may aggravate postpericardiotomy (PPS), capillary leak syndrome (CLS), or multiorgan failure (MOF). Compared with complication-free children, POEE affected children have different preoperative serum levels of circulating cytokines and adhesion molecules. These levels may be used preoperatively to assess POEE, but their determination is time consuming, costly, and a substantial blood volume is required. Altered serum levels of cytokines and adhesion molecules also may be reflected in altered antigen expression on circulating blood leukocytes. The predictive potential of flow cytometric (FCM) leukocyte immunophenotyping was explored as a sensitive and fast method that required small blood samples. Blood samples taken 24 h preoperatively from 49 patients (3-18 years old) were stained with monoclonal antibodies for adhesion molecules (ICAM-1, LFA-1, Mac-1) or constitutive/activation markers (CD4, CD14, CD16, CD25, CD54, CD69, HLA-DR) and measured on a microbead calibrated FCM. Neutrophils, monocytes, and eosinophils from POEE patients express higher preoperative levels of LFA-1, monocytes, HLA-DR, and other activation markers (all P < 0.03). Over 89% of the patients were classified correctly by using two discriminant analysis methods (sensitivity, >76%; specificity, >86%; positive prediction, >80%; negative prediction, >83%). Granulocytes and monocytes of postoperative POEE patients exhibit significant preoperative immune activation, suggesting an increased risk for patients with atopic/allergic predisposition. Surgical trauma and CPB cause additional immune activation, leading to POEE by a summative response. Most patients at risk for POEE can be identified preoperatively by using data pattern analysis on FCM-derived parameters.

Changes in T-cell receptor subsets after cardiac surgery in children

T cells are divided into two subsets, alphabeta and gammadelta, according to the T-cell receptor (TCR) expressed. Recent findings indicate that gammadelta T cells serve as the first defense against microbial pathogens, and represent a link between innate and acquired immunity. We conducted a study to investigate the changes in circulating TCR subsets after cardiac surgery in children. Blood samples from 24 children who underwent cardiac surgery with cardiopulmonary bypass (CPB) were collected serially to analyze TCR subsets by flow cytometry. The alphabeta T cells reached a nadir on postoperative day (POD) 1, but recovered to pre-CPB levels on POD 3. On the other hand, the gammadelta T cells decreased after CPB and did not recover to pre-CPB levels even after POD 7. The alphabeta/gammadelta T-cell ratio was increased after POD 3. In children, gammadelta T cells recover more slowly than alphabeta T cells after cardiac surgery. These changes in TCR subsets may contribute to postoperative immunosuppression.

Lymphocyte and monocyte subset changes during cardiopulmonary bypass: effects of aging and gender

Complications of cardiopulmonary bypass (CPB) may be associated with either immune suppression or immune activation, but the specific effects of CPB on many lymphocyte and monocyte subsets are unclear. In addition, the increasing age of patients undergoing cardiac surgery raises the possibility of even greater effects on the immune system in elderly patients. We measured immunophenotypic alterations of circulating lymphocytes and monocytes after CPB in male and female cardiac surgery patients who were either younger than 60 or older than 75 years of age. The total lymphocyte counts in all patients decreased postoperatively; older patients had significantly lower counts at all time points. The absolute decline was greatest among T cells and particularly CD4+ T cells, which reached an average nadir of 251 cells/microl on postoperative day 1 in the older patients. The percentages of CD8+, CD4+CD45RA+, and CD4+CD45RO+ T cells did not change significantly, whereas the percentages of B cells and natural killer cells increased. Both T and B lymphocytes and monocytes showed evidence of activation, with increased percentages of CD3+HLADr+, CD3+IL2R+, and CD19+CD23+ lymphocytes and increased expression of CD11b on monocytes. By contrast, expression of class II major histocompatibility antigen (HLADr) monocytes decreased significantly. We conclude that CPB produces a profound alteration in the pool of circulating lymphocytes and monocytes, evidenced by decreased numbers of lymphocyte subsets including CD4+ cells and decreased expression of monocyte surface membrane proteins important for antigen presentation; CPB also activates a variety of specific circulating mononuclear cell subsets. Older patients showed patterns of lymphocyte and monocyte activation comparable to those of younger patients; however, they had consistently lower lymphocyte numbers and a trend toward decreased monocyte HLADr expression, potentially placing them at greater risk for infectious complications. Gender had no effect.