Neutrophil adhesion molecule expression during cardiopulmonary bypass: a comparative study of roller and centrifugal pumps

Neutrophil CD64 is an improved indicator of infection or sepsis in emergency department patients

CONTEXT

Sepsis, affecting millions of individuals annually with an associated high mortality rate, is among the top 10 causes of death. In addition, improvements in diagnostic tests for detecting and monitoring sepsis and infection have been limited in the last 25 years. Neutrophil CD64 expression has been proposed as an improved diagnostic test for the evaluation of infection and sepsis.

OBJECTIVE

To evaluate the diagnostic performance of a quantitative flow cytometric assay for leukocyte CD64 expression in comparison with the standard tests for infection/sepsis in an ambulatory care setting.

DESIGN

Prospective analysis of 100 blood samples from patients from an emergency department setting in a 965-bed tertiary care suburban community hospital was performed for neutrophil CD64 expression, C-reactive protein, erythrocyte sedimentation rate, and complete blood count. The laboratory findings were compared with a clinical score for the likelihood of infection/sepsis, which was obtained by a blinded retrospective chart review.

RESULTS

The diagnostic performance, as gauged by the clinical score, varied with neutrophil CD64 (sensitivity 87.9%, specificity 71.2%, efficiency 76.8%) and outperformed C-reactive protein (sensitivity 88.2%, specificity 59.4%, efficiency 69.4%), absolute neutrophil count (sensitivity 60.0%, specificity 50.8%, efficiency 53.8%), myeloid left shift (sensitivity 68.2%, specificity 76.3%, efficiency 73.3%), and sedimentation rate (sensitivity 50.0%, specificity 65.5%, efficiency 61.0%).

CONCLUSION

Neutrophil CD64 expression quantitation provides improved diagnostic detection of infection/sepsis compared with the standard diagnostic tests used in current medical practice.

Comparison of neutrophil CD64 expression, manual myeloid immaturity counts, and automated hematology analyzer flags as indicators of infection or sepsis

There is a clear need for improved indicators of infection or sepsis to increase the sensitivity and specificity of both diagnosis and therapeutic monitoring. One of the effects of inflammatory cytokines on the innate immune response is the rapid up-regulation of CD64 expression on the neutrophil membrane. We and others have hypothesized that the measurement of neutrophil CD64 expression might represent an improved diagnostic indicator of infection and sepsis. In this study we assessed the relative ability of flow cytometric neutrophil CD64 measurements, neutrophil counts, myeloid immaturity differential counts, and flagging on an automated hematology analyzer to correlate with the presence of infection, as determined by a retrospective clinical scoring system of infection or sepsis. A total of 160 blood samples were randomly selected to derive equal proportions of the 3 categories of flags on a Coulter STKS blood counter that indicate the presence of a myeloid left shift. The patients for these samples were scored by retrospective chart review and placed into 4 groups on the basis of likelihood of infection, sepsis, or severe tissue injury. Neutrophil CD64 expression demonstrated a superior sensitivity (94.1%), specificity (84.9%), and positive predictive likelihood ratio (6.24), compared with neutrophil counts (sensitivity, 79.4%; specificity, 46.8%; positive predictive likelihood ratio, 1.49), band counts (sensitivity, 87.5%; specificity, 43.5%; positive predictive likelihood ratio, 1.55), myeloid immaturity fraction (sensitivity, 94.6%; specificity, 84.5%; positive predictive likelihood ratio, 2.12), and flagging on an automated hematology analyzer (sensitivity, 94.1%; specificity, 40.5%; positive predictive likelihood ratio, 1.58). Relative to the other laboratory parameters, the neutrophil CD64 parameter also provided the best separation of the 4 clinical groups. The findings indicate that neutrophil CD64 expression as determined by quantitative flow cytometry is an improved diagnostic indicator of infection/sepsis relative to current laboratory indicators of relative or absolute myeloid cell counts or hematology analyzer flagging algorithms.

Blood Damage Related to Cardiopulmonary Bypass:In Vivo and In Vitro Comparison of Two Different Centrifugal Pumps

Cardiopulmonary bypass (CPB) induces hemolysis and the activation of the inflammatory and coagulation systems. Several components of the CPB equipment may contribute to such phenomenon. We tested the effects of two differently designed centrifugal pumps (Bio-Pump, Medtronic and Revolution, Cobe) on several markers of hemolysis, coagulation, and inflammation: plasma free hemoglobin,prothrombin fragment 1.2, platelet factor 4, and P-selectin. Twenty patients requiring coronary artery bypass grafting were randomized to undergo CPB with one of the study centrifugal pumps, and 10 experiments (5 for each pump) were performed with a closed loop circuit to assess pumps' performances over 6 circulation hours using human blood. CPB induced a significant elevation of all the tested markers. Neither in the in vivo nor in the in vitro study were significant differences observed between the groups. Because the Revolution centrifugal pump, which was recently designed and distributed, produced results comparable with those obtained with the BioPump, it should be considered as safe as the Bio-Pump to perform clinical CPB.

Transcardiac release of soluble adhesion molecules during coronary artery bypass grafting: effects of crystalloid and blood cardioplegia

BACKGROUND

Dysfunction of myocardium as a result of ischemia/reperfusion during coronary artery bypass grafting (CABG) is currently one of the biggest problems in cardiovascular surgery. In previous studies, it has been well established that activated leukocytes and coronary vascular endothelial cells play an important role in the development of cardiac tissue damage during ischemia followed by reperfusion. Interactions between both of these cell types require the expression of adhesion molecules on their surface. In certain conditions, on cell activation, the adhesion proteins may be released from activated cells in soluble form into circulation. The purpose of our study was to establish whether the use of blood cardioplegia modifies plasma levels of soluble intracellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble E-selectin (sE-selectin), and soluble L-selectin (sL-selectin) in comparison with crystalloid cardioplegia in patients undergoing CABG.

METHODS

Patients undergoing CABG were classified into two groups to receive cold crystalloid cardioplegia (St. Thomas' Hospital) or cold blood cardioplegia (method of Buckberg), followed by a "warm-shot" of the solution. Coronary sinus and arterial blood samples were obtained from 50 patients (42 men and 8 women; age range, 34 to 73 years) before aortic cross-clamping, at the beginning of reperfusion, and after 30 min of reperfusion. Plasma levels of soluble adhesion molecules were measured using sensitive enzyme-linked immunosorbent assays.

RESULTS

The transcardiac release of sICAM-1 and sVCAM-1 following myocardial ischemia/reperfusion during CABG was evident in both groups of patients. However, the increase of soluble forms of both of these adhesion proteins was more significant in the group of patients receiving crystalloid cardioplegia. Crystalloid cardioplegia resulted in decreased plasma level of sE-selectin in the coronary sinus blood sample after 30 min of reperfusion. No significant changes in plasma levels of sL-selectin in either group were observed.

CONCLUSION

Cardioplegia may affect the release of soluble forms of adhesion molecules from ischemic myocardium and modify endothelium activation in patients undergoing CABG.

Mechanical Support After Cardiac Surgery

Mechanical circulatory support for low cardiac output after cariac surgery was first attempted in 1962. Since then, many ventricular assist devices have been developed and employed. The following is a discussion of the history, demographics, inications, and devices used for mechanical circulatory suport in this setting. lntra-aortic balloon pulsation, pulsatile verus non-pulsatile flow, volume bypass, roller and centrifugal pumps, extracorporeal membrane oxygenation, and imlantable devices are reviewed. Early postoperative care, reovery and weaning from mechanical circulatory support, and the special issues that relate to biventricular failure and control of right-sided ventricular function, as well as anticoagulation, and sepsis are addressed.

Soluble P-selectin and the postoperative course following cardiopulmonary bypass in children

BACKGROUND

Cytokine-inducible leucocyte-endothelial adhesion molecules were shown to affect the postoperative inflammatory response following cardiopulmonary bypass (CPB). Soluble P-selectin (sP-selectin) is one of these molecules. We investigated the correlation between plasma sP-selectin levels and the intra- and postoperative course in children undergoing CPB.

METHODS

Serial blood samples of 13 patients were collected preoperatively upon initiation of CPB and seven times postoperatively. Plasma was recovered immediately and frozen at - 70 degrees C until use. Circulating soluble selectin molecules were measured with a sandwich enzyme-linked immunoabsorbent assay technique.

RESULTS

The significant post-CPB changes in sP-selectins plasma levels were associated with patient characteristics, operative variables and postoperative course. sP-selectin levels correlated significantly with surgery time, aortic cross-clamping time and inotropic support, as well as with the postoperative Pediatric Risk of Mortality score, hypotension and tachycardia.

CONCLUSIONS

A relation between CPB-induced mediators and both early and late clinical effects is suggested. The up-regulation and expression of sP-selectin indicate neutrophil activation as a possible mechanism for the increase, and inhibiting it may reduce the inflammatory response associated with CPB.

Plasma-soluble E-selectin after cardiopulmonary bypass in children: is it a marker of the postoperative course?

OBJECTIVE

To investigate the relationship and possible role of soluble adhesion molecule E-selectin in the postoperative course in children undergoing cardiopulmonary bypass (CPB).

DESIGN

Prospective cohort study.

SETTING

Pediatric intensive care unit of a university hospital.

PARTICIPANTS

Thirteen children who were candidates for cardiac surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serial blood samples of 13 CPB patients were collected from the arterial catheter or from the bypass circuits preoperatively; on initiation of CPB; on termination of CPB; and 1, 2, 4, 8, 12, 18, 24, and 48 hours postoperatively. Plasma was recovered immediately, aliquoted, and frozen at -70 degrees C until use. Circulating soluble selectin molecules were measured with a sandwich enzyme-linked immunosorbent assay technique. There were significant changes in plasma levels of soluble E-selectins in patients after CPB, and these levels were associated with patient characteristics, operative variables, and postoperative course. Soluble E-selectin correlated significantly with inotropic support and the use of anti-inflammatory drugs. There was a significant association between the development of postoperative sepsis and soluble E-selectin levels. No correlation was found between soluble E-selectins and duration of CPB, aortic cross-clamping, or hemodynamic variables, including heart rate and mean systemic arterial pressure.

CONCLUSION

These results suggest a relationship between CPB-induced mediators and early and late clinical effects. Although the mechanism for the increase of soluble E-selectin remains to be elucidated, the upregulation of soluble E-selectin indicates neutrophil activation, and its inhibition may represent a target for reducing the inflammatory response associated with CPB.