Leukocyte activation and phagocytotic activity in cardiac surgery and infection

Anti-inflammatory effect of colchicine on organ damage during the perioperative period of cardiac surgery: a study protocol for a multicentre, randomised, double-blind, placebo-controlled clinical trial

INTRODUCTION

The systemic inflammatory response syndrome during the perioperative period of cardiac surgery can lead to serious postoperative complications and significantly increase the hospital mortality rate. Colchicine, a widely used traditional anti-inflammatory drug, has good clinical value in cardiovascular anti-inflammatory therapy. Our preliminary single-centre study had confirmed the protective value of colchicine in patients undergoing cardiac surgery with cardiopulmonary bypass. For this multicentre investigation, we aim to further validate the anti-inflammatory and organ-protective effects of low-dose colchicine during the perioperative period in a low-risk population.

METHODS AND ANALYSIS

This study is a multicentre, randomised, double-blind, placebo-controlled clinical trial. A total of 768 patients undergoing elective cardiac surgery will be enrolled from eight heart centres in China. The participants will be randomly assigned to two groups: the colchicine group will receive low-dose colchicine (0.5 mg once-a-day dosing regimen (QD) orally for 3 days before the surgery and 0.5 mg dosing frequency of every other day (QOD) continuously for 10 days after the surgery), whereas the placebo group will be given starch tablets for the same time and dosage. Primary endpoints are the occurrence of postoperative inflammatory diseases, including postoperative atrial fibrillation, acute respiratory distress syndrome, preoperative myocardial injury and post-pericardiotomy syndrome. Secondary endpoints included laboratory tests on postoperative days 1, 3, 5, 7 and 10, intensive care unit data, APACHE II score, Murray lung injury score, medication-related gastrointestinal reactions, 30-day and 90-day all-cause mortality, surgical data, chest radiograph on postoperative days 1, 2 and 3, and chest CT within 14 days after surgery.

ETHICS AND DISSEMINATION

This research has received approval from the Medical Ethics Committee of Affiliated Nanjing Drum Tower Hospital, Nanjing University Medical College (approval number 2023-366-01). The study findings will be made available by publishing them in an open access journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (NCT06118034).

A human model of bilateral pulmonary vein sampling to assess the effects of one-lung ventilation on neutrophil function

BACKGROUND

Neutrophil activation drives lung complications after cardiopulmonary bypass (CPB). Evidence suggests the healthy, ventilated lung may beneficially re-condition pro-inflammatory neutrophils. However, evidence in humans is lacking, due to a paucity of good models. CPB with simultaneous central venous and bilateral pulmonary vein sampling provides an opportunity to model effects of one-lung ventilation. The study's primary objectives were to establish a model of intra-operative, bilateral pulmonary vein sampling and to determine whether neutrophil function differed after passing through inflated or deflated lungs.

METHODS

Seventeen patients having "on pump" coronary artery bypass grafting (CABG) with one-lung ventilation (in two cohorts with tidal volume 2ml kg-1 and FiO2 0.21, or tidal volume 4 ml kg-1 and FiO2 0.5 respectively) were recruited. Cohort 1 consisted of 9 patients (7 male, median age 62.0 years) and Cohort 2 consisted of 8 male patients (median age 65.5 years). Recruitment was via prospective screening of scheduled elective and non-elective CABG procedures with cardiopulmonary bypass. Each patient had five blood samples taken-central venous blood pre-operatively; central venous blood pre-CPB; central venous blood post-CPB; pulmonary venous blood draining the ventilated lung post-CPB; and pulmonary venous blood draining the deflated lung post-CPB. Neutrophil phagocytosis and priming status were quantified. Plasma cytokines were measured.

RESULTS

Phagocytosis and priming were not significantly different in neutrophils returning from the ventilated lung as compared to the non-ventilated lung. Plasma IL-6, IL-8 and IL-10 were significantly elevated by CPB.

CONCLUSIONS

The intra-operative, bilateral pulmonary vein sampling model provides unique opportunities to assess biological effects of interventions to one lung, with the other lung acting as an internal control. Single-lung ventilation during CPB had no significant effects on neutrophil function.

The diagnostic accuracy of procalcitonin in infectious patients after cardiac surgery: a systematic review and meta-analysis

Cardiac surgery with cardiopulmonary bypass (CPB) induces an acute inflammatory response that may lead to a systemic inflammatory response syndrome. The interest in procalcitonin (PCT) in the diagnosis of bacterial infection in patients after cardiac surgery remains less defined. The aim of this meta-analysis is to prospectively examine the discriminatory power of PCT as markers of infection in hospitalized patients with after cardiac surgery. The bivariate generalized nonlinear mixed-effect model and the hierarchical summary receiver operating characteristic model were used to estimate the pooled sensitivity, specificity and summary receiver operating characteristic curve. The pooled sensitivity and specificity were 0.81 (95% CI 0.75-0.87) and 0.78 (95% CI 0.73-0.83), respectively. The pooled positive likelihood ratio, and negative likelihood ratio of PCT were 3.74 (95% CI 2.98-4.69) and 0.24 (95% CI 0.17-0.32), respectively. The pooled area under the summary receiver operating characteristic curve of PCT using the HSROC method was 0.87 (95% CI 0.84- 0.90). This study indicated that PCT is a promising marker for the diagnosis of sepsis for those patients who undergo cardiac surgery.

Normal Reference Interval of WBC Count After On - Pump Coronary Artery Bypass Graft; When Values Could Be Misleading

Background

Applying the cardiopulmonary pump produces inflammatory responses and induces leukocytosis. White Blood Cell (WBC) count has a diagnostic value for detecting different infections. In this study, we want to redefine the normal value reference intervals of WBC count in Coronary Artery Bypass Graft (CABG) patients, to prevent misdiagnose leukocytosis as a sign of infection.

Methods

In an observational study, 140 patients who underwent on - pump CABG were enrolled to find out normal values of the reference interval. WBC counts were evaluated for all of them one day before the operation, first 30 minutes of ICU entrance, after 24 hours, and 48 hours after operation. Normal values of reference intervals were calculated for each measurement by two different statistical methods.

Results

There were 102 men and 38 women with age average of 61 years. There was no significant difference between genders’ WBC counts before operation (P = 0.151), ICU entrance (P = 0.391), 24 hours after surgery (P = 0.698), and 48 hours after surgery (P = 0.523). The mean values of WBC after surgery were higher than the normal range of reference interval and had an increasing trend in the first 48 hours after surgery. The WBC values were significantly different between pre and post operation (before operation and ICU admission (P = 0.001), ICU admission and 24 hours later (P = 0.001), 24 hours after surgery, and 48 hours after surgery (P = 0.001)). All post - operative reference values were significantly higher than the range for the general population.

Conclusions

There is a significant increase in WBC count after on - pump CABG. The normal range of WBC should be revised and adjusted to prevent misinterpretation as a sign of infection.

Procalcitonin and white blood cells, combined predictors of infection in cardiac surgery patients

BACKGROUND

Sepsis is strongly associated with an increased risk of postoperative mortality, longer length of hospital stay, and elevated health care costs. Early clinical symptoms overlap with those of systemic inflammatory response syndrome, a response that commonly occurs after cardiac surgery with cardiopulmonary bypass. Since a combination of biomarkers has been demonstrated to improve the prediction of postoperative infection, the objective of the present study was to test whether the combination of C-reactive protein (CRP), white blood cells (WBC), and procalcitonin (PCT) is able to predict postoperative infection in a large cohort of cardiac surgery patients.

MATERIAL AND METHODS

Case-control study involving 423 patients who underwent cardiac surgery with cardiopulmonary bypass. Patients were retrospectively classified into two groups based on whether they developed severe sepsis or septic shock during the postoperative period. Blood samples for biological measurements (PCT, CRP, and WBC) were drawn on the first day in the intensive care unit, then once daily in the morning until the 10th postoperative day.

RESULTS

CRP median values were similar in both groups. WBC and PCT median values were significantly higher in patients with infection than without during the first 10 postoperative days. With elevation cutoffs ≤3 times (OR: 4.058; 95% CI: 2.206-7.463; P = 0.001) and ≥4 times (OR: 10.274, 95% CI: 3.690-28.604; P < 0.001), the median value for PCT (1.7 ng/mL) and/or WBC (13,000 cells/mm³) on the second postoperative day was significantly associated with the development of infection.

CONCLUSIONS

The goal of this study was to use a large cohort of cardiac surgery patients to ensure that the results were representative of this population. The combination of PCT and WBC levels over the first three postoperative days was able to predict postoperative infection within the 30 d following cardiac surgery.

Procalcitonin cannot be used as a biomarker of infection in heart surgery patients with acute kidney injury

PURPOSE

We intended to assess how acute kidney injuy impacts on procalcitonin levels in cardiac surgery patients, with or without infection, and whether procalcitonin might be used as a biomarker of infection in acute kidney injuy.

MATERIAL AND METHODS

A case-control study was designed which included patients that had had cardiac surgery between January 2011 and January 2015. Every patient developing severe sepsis or septic shock (n = 122; 5.5%) was enrolled. In addition, consecutive cardiac surgery patients during 2013 developing systemic inflammatory response syndrome (n = 318) were enrolled. Those recruited 440 patients were divided into 2 groups, according to renal function.

RESULTS

Median procalcitonin levels were significantly higher during the 10 postoperative days in the acute kidney injury patients. Regression analysis showed that postoperatory day, creatinine, white blood cells and infection were significantly (P < .0001) associated to serum procalcitonin level. In patients with creatinine ≥2, median procalcitonin levels were similar in infected and non-infected patients. Only when creatinine was less than 2 mg/L, the median procalcitonin levels were significantly higher in patients with infection, as compared to those with no infection.

CONCLUSIONS

In acute kidney injuy patients, high procalcitonin levels are a marker of acute kidney injuy but will not be able to differentiate infected from non-infected patients.

Comparison of new technology integrated and nonintegrated arterial filters used in cardiopulmonary bypass surgery: a randomized, prospective, and single blind study

Background. Innovative cardiopulmonary bypass (CPB) settings have been developed in order to integrate the concepts of “surface-coating,” “blood-filtration,” and “miniaturization.” Objectives. To compare integrated and nonintegrated arterial line filters in terms of peri- and postoperative clinical variables, inflammatory response, and transfusion needs. Material and Methods. Thirty-six patients who underwent coronary bypass surgery were randomized into integrated (Group In) and nonintegrated arterial line filter (Group NIn) groups. Arterial blood samples for the assessments of complete hemogram, biochemical screening, interleukin-6, interleukin-2R, and C-reactive protein were analyzed before and after surgery. Need for postoperative dialysis, inotropic therapy and transfusion, in addition to extubation time, total amount of drainage (mL), length of intensive care unit, and hospital stay, and mortality rates was also recorded for each patient. Results. Prime volume was significantly higher and mean intraoperative hematocrit value was lower in Group NIn, but need for erythrocyte transfusion was significantly higher in Group NIn. C-reactive protein values did not differ significantly except for postoperative second day's results, which were found significantly lower in Group In than in Group NIn. Conclusion. Intraoperative hematocrit levels were higher and need for postoperative erythrocyte transfusion was decreased in Group In.

Syndecan-1 plasma levels during coronary artery bypass surgery with and without cardiopulmonary bypass

The glycocalyx covering the endothelium is shed during ischemia and reperfusion. The shedding is accompanied by increased levels of the glycocalyx component syndecan-1 in the circulation. Our aim was to compare plasma levels of syndecan-1 in patients undergoing coronary artery bypass grafting (CABG), with or without the use of cardiopulmonary bypass (CPB). Syndecan-1 plasma concentrations were measured in patients undergoing CABG on-pump (n = 22) or off-pump (n = 22). The syndecan-1 concentration increased significantly from 29.5 ± 4.6 ng/mL at baseline to 98.7 ± 9.8 ng/mL (p < 0.01) after the start of CPB or 30 minutes after the induction of anesthesia in the off-pump group. There were no significant differences in peak syndecan-1 plasma concentrations between on-pump and off-pump patients. Plasma levels of syndecan-1 increased significantly during CABG, with or without the use of CPB. There were no significant differences in syndecan-1 concentrations in the two groups.

Coronary Artery Bypass Grafting Ameliorates the Decreased Plasma Adiponectin Level in Atherosclerotic Patients

Adiponectin functions as an anti-inflammatory and anti-atherogenic factor, and the decreased plasma adiponectin is a risk factor for coronary disease. The aim of this study was to determine the changes in plasma levels of adiponectin, a potential parameter for atherosclerosis, in patients underwent surgical revascularization. We included forty patients with atherosclerosis (age, 58 +/- 9 years; body mass index [BMI] 26.93 +/- 2.3 kg/m(2)) undergoing coronary artery bypass grafting (CABG). Control group consisted of 40 healthy volunteers, matched for age, gender and BMI (age, 56 +/- 6 years; BMI, 26.78 +/- 2.3 kg/m(2)). We measured various parameters, including high sensitive C-reactive protein (hsCRP), homeostasis model assessment-insulin resistance (HOMA-IR) indexes, and adiponectin. The baseline profile of the patients before CABG showed higher levels of serum hsCRP (13.15 +/- 2.40 mg/l vs 3.97 +/- 1.07 mg/l) and HOMA-IR (1.86 +/- 0.30 vs 1.26 +/- 0.33) and lower plasma adiponectin levels (7.02 +/- 2.01 microg/ml vs 25.46 +/- 3.9 microg/ml), compared to controls (p < 0.001 for each parameter). Plasma adiponectin level was increased one month after CABG from the baseline level to 8.67 +/- 2.05 microg/ml(p < 0.001), although the level was still lower than the control value. Thus, postoperative adiponectin level might be helpful for evaluating the progression of atherosclerosis. Moreover, CABG significantly decreased hsCRP to 7.25 +/- 1.89 mg/l and HOMA-IR to 1.59 +/- 0.33, although these levels were higher than the controls. These results suggest that CABG decreases the cardiac risk factors in atherosclerotic patients.

Intraoperative Management of Hyperglycemia in the Cardiac Surgical Patient

The stress response of cardiac surgery leads to hyperglycemia, and undergoing cardiopulmonary bypass magnifies this response greatly. Counter-regulatory hormones, the cytokine response, and the automatic nervous system are all part of the coordinated host response that can lead to hyperglycemia. Postoperative hyperglycemia is associated with worsened perioperative outcomes, and there are data demonstrating this to also be true for the intraoperative period. Many factors affect intraoperative glucose control, including cardiopulmonary pump (CPB) prime fluid composition, temperature while on CPB, and medications such as catecholamines and glucocorticoids. Intraoperative glucose control has a significant impact on postoperative outcomes. No optimal intraoperative insulin regimen has been identified, but continuous intravenous infusions appear to be superior to intermittent sliding scale dosing. In addition, the technique of hyperinsulinemic glucose clamp shows the greatest promise of achieving normoglycemia while on CPB.

Leukocyte mitochondrial alterations after cardiac surgery involving cardiopulmonary bypass: clinical correlations

Cardiac surgery with the use of cardiopulmonary bypass (CPB) is known to initiate systemic inflammatory responses that are associated with immune dysregulations, but the pathomechanisms underlying these changes remain elusive. Mitochondrial transmembrane potential (MTP) is an important determinant of leukocytic functions and viability, and may be altered as a part of the cellular responses to systemic inflammatory insults. Therefore, we examined MTP in three subsets of peripheral leukocytes in 18 patients receiving uncomplicated cardiac surgery involving CPB. The MTP of neutrophils and lymphocytes significantly increased, whereas that of monocytes significantly declined, after the surgery. The alterations in leukocytic MTP were transient, normalizing 3 days to 1 week after the surgery, and were accompanied by transient overproduction of intracellular oxidants, including nitric oxide and superoxide. Despite these perturbations, the viability status of leukocytes remained unaltered. Positive correlations were found between the changes of leukocyte MTP and various clinical parameters, implying that leukocyte mitochondrial alterations are parts of the systemic immune perturbations induced by the bypass surgery.

Inflammatory response to cardiac surgery: cardiopulmonary bypass versus non-cardiopulmonary bypass surgery

Cardiac surgery has been routinely performed using cardiopulmonary bypass (CPB) ever since its clinical introduction during the 1950s. CPB is, however, associated with an intense inflammatory response because of conversion to laminar flow, blood contact with the artificial bypass surface, cold cardiac ischaemia and hypothermia. The inflammatory reaction can intensify to a systemic inflammatory response syndrome (SIRS) associated with serious morbidity and mortality. Strategies to suppress inflammation had some success but fell short of controlling SIRS. The development of cardiac immobilization techniques allowing complete revascularization has caused a renaissance of coronary artery bypass grafting surgery on the beating heart (OPCAB). This strategy avoids all inflammation caused by CPB and reduces the pro-inflammatory stimulus to sternotomy and the revascularization procedure itself. This review summarises the pathophysiological features of the inflammatory response to CPB, revisits therapeutic anti-inflammatory strategies designed to suppress CPB-induced inflammation and balances the clinical evidence available comparing off-pump and on-pump revascularization.