Aprotinin and methylprednisolone equally blunt cardiopulmonary bypass-induced inflammation in humans

Can statins reduce the inflammatory response to cardiopulmonary bypass? A clinical study

OBJECTIVE

In addition to lowering lipid levels, statins might reduce leukocyte-endothelial cell interactions. Therefore, we assessed whether this effect could limit the inflammatory response to cardiopulmonary bypass (CPB) in cardiac surgical patients.

METHODS

Twenty patients undergoing valve or coronary operations with tepid (34 degrees C) CPB were randomized to receive an oral dose of atorvastatin (40 mg the evening before and 40 mg the morning of surgery) or to serve as controls. Pre- and post-CPB blood samples were assayed for neutrophil CD11b surface adhesion molecule and oxidative burst. Plasma levels of interleukins 6 and 8, P-selectin, soluble intercellular adhesion molecule-1, and lactoferrin were measured by enzyme-linked immunosorbent assay (ELISA). In addition, right atrial biopsies were taken before and at the end of CPB, and processed for the expression of the transcription nuclear factor-kappa B (NF-kappaB).

RESULTS

The two groups did not differ with regard to pre- and intraoperative data. Except for P-selectin, postbypass values of all markers significantly increased over baseline values, but atorvastatin therapy failed to attenuate the magnitude of this increase. In the two groups, the expression of NF-kappaB significantly (p = 0.004) increased over baseline without group effect. Postoperative clinical outcomes did not differ either between the two groups.

CONCLUSION

These data show that acute preoperative statin therapy fails to limit the inflammatory response to CPB; however, the data also document a major upregulation of NF-kappaB during cardiac operations, thereby providing a sound rationale for interventions targeted at inactivating this key component of the inflammatory cascade.

Cardiopulmonary Complications Following Cardiac Surgery

There are numerous cardiac and pulmonary complications that can occur after operations that involve the use of cardiopulmonary bypass (CPB). We have chosen to focus on perioperative myocardial ischemia, left ventricular (LV) dysfunction, ventricular arrhythmias, atrial arrhythmias, and inflammation and pulmonary dysfunction as the most important. If left untreated, these complications can be life-threatening. Moreover, their presence is associated with higher hospital expenses due to therapies and longer inpatient stays.

Sustained elevated plasma aprotinin concentration in mice following intraperitoneal injections of w/o emulsions incorporating aprotinin

This study was initiated to test the feasibility of w/o emulsions as a sustained release system for aprotinin following intraperitoneal injection in mice. The emulsion was well tolerated in mice and sustained release was observed over a period of 96 h. The time for maximum plasma concentration of aprotinin was 10 min and 12 h after injection of a control solution and the emulsion dosage form, respectively. Furthermore, the hemolytic activity of the emulsion constituents was low indicating a low acute toxicological potential of the emulsion. The present study also showed that the lipolytic activity in peritoneal exudate from mice is important for the clearance of oily vehicles from the peritoneal cavity with lipolytic rate constants ranging from 50 to 130 nmol free fatty acid released/min/mg exudate protein at 37 degrees C, pH 8.5. It was concluded that the w/o emulsion was well suited to provide sustained elevated plasma aprotinin concentrations in mice.

Treatment of sepsis in cardiac surgery: role of immunoglobulins

Cardiopulmonary bypass (CPB) is associated with an injury that may cause pathophysiological changes such as systemic inflammatory response syndrome, multiple organ dysfunction syndrome, and mediator-induced multiorgan failure. Systemic endotoxinaemia, release of proinflammatory cytokines, and interactions between neutrophils and endothelium have been reported to correlate with a high incidence of organ dysfunction, infection and sepsis following cardiac surgery. This review discusses the dysregulation of the immune response as a major reason for the higher susceptibility to infections following cardiac surgery, various treatment strategies to reduce CPB-induced inflammation, and especially the prophylactic use of immunoglobulins in cardiac surgery.

Leukodepletion and aprotinin improve clinical outcome after extracorporeal circulation

Most cardiac operations involve the use of extracorporeal circulation with its attendant systemic inflammatory response syndrome. Many anti-inflammatory strategies hold promise for reducing the associated morbidity of cardiopulmonary bypass. The application of pharmacological and mechanical strategies to control this inflammatory response now has demonstrable clinical benefit. The additional costs of these successful strategies are offset by the economic savings and improved quality of care.

Methylprednisolone does not benefit patients undergoing coronary artery bypass grafting and early tracheal extubation

OBJECTIVE

We sought to determine whether methylprednisolone, when administered to patients undergoing cardiac surgery, is able to ward off the detrimental hemodynamic and pulmonary alterations associated with cardiopulmonary bypass.

METHODS

After institutional review board approval and informed consent was obtained, 90 patients scheduled for elective cardiac surgery were randomized to 1 of 3 groups. Group 30MP patients received 30 mg/kg intravenous methylprednisolone during sternotomy and 30 mg/kg during initiation of cardiopulmonary bypass, group 15MP patients received 15 mg/kg methylprednisolone at the same 2 times, and group NS patients received similar volumes of isotonic sodium chloride solution at the same 2 times. Perioperative care was standardized, and all caregivers were blinded to treatment group. Various hemodynamic and pulmonary measurements were obtained perioperatively, as well as fluid balance, weight, peak postoperative blood glucose level, and tracheal extubation time.

RESULTS

Demographic and clinical characteristics of patients and intraoperative data were similar among the 3 groups. Patients receiving methylprednisolone (either dose) exhibited significantly increased cardiac index (P =.0006), significantly decreased systemic vascular resistance (P =.0005), and significantly increased shunt flow (P =.0020) during the immediate postoperative period. All 3 groups exhibited significant increases in alveolar-arterial oxygen gradient (P <.0001), significant decreases in dynamic lung compliance (P <.0001), and significant decreases in static lung compliance (P <.0001) during the immediate postoperative period, with no differences between groups. Perioperative fluid balance and weights were similar between groups. A statistically significant difference in peak postoperative blood glucose level existed (P =.016) among group NS (234 +/- 96 mg/dL), group 15MP (292 +/- 93 mg/dL), and group 30MP (311 +/- 90 mg/dL). In patients extubated within 12 hours of intensive care unit arrival, a statistically significant difference in extubation times existed (P =.025) between group NS (5.7 +/- 2.3 hours), group 15MP (5.9 +/- 2.2 hours), and group 30MP (7.5 +/- 2.7 hours).

CONCLUSIONS

Methylprednisolone, as used in this investigation, offers no clinical benefits to patients undergoing elective coronary artery bypass grafting with cardiopulmonary bypass and may in fact be detrimental by initiating postoperative hyperglycemia and possibly hindering early postoperative tracheal extubation for undetermined reasons.

Aprotinin and the systemic inflammatory response after cardiopulmonary bypass

Cardiopulmonary bypass is associated with a systemic inflammatory response, a spectrum of pathophysiologic changes ranging from mild organ dysfunction to multisystem organ failure. Complications include coagulation disorders (bleeding diathesis, hyperfibrinolysis) from platelet defects and plasmin activation, as well as pulmonary dysfunction from neutrophil sequestration and degranulation. Diverse injuries are a consequence of multiple inflammatory mediators (complement, kinins, kallikrein, cytokines). Both plasmin and kallikrein amplify the inflammatory response by activating components of the contact activation system. The full-Hammersmith (high dose) of aprotinin, a serine protease inhibitor approved for reducing blood loss and transfusion requirements in cardiopulmonary bypass, inhibits kallikrein and plasmin, resulting in suppression of multiple systems involved in the inflammatory response. Specifically, inhibition of factor XII, bradykinin, C5a, neutrophil integrin expression, elastase activity, and airway nitric oxide production are observed. Clinical correlates include reduced capillary leak, preserved systemic vascular resistance and blood pressure, and improved myocardial recovery following ischemia. Overall, evidence indicates that aprotinin attenuates the systemic inflammatory response associated with cardiopulmonary bypass.

Evidence for inflammatory responses of the lungs during coronary artery bypass grafting with cardiopulmonary bypass

OBJECTIVE

The occurrence of a systemic inflammatory reaction during cardiac surgery with cardiopulmonary bypass (CPB) has been well established, and the heart itself has been shown to release inflammatory mediators after ischemia. The hypothesis of the present study was that the lungs are also a site of inflammatory responses during early reperfusion.

METHODS

In 20 consecutive patients undergoing coronary artery bypass grafting, blood was simultaneously drawn from the right atrium (RA) and the pulmonary vein (PV) before CPB and at 1 min, 10 min, and 20 min of reperfusion. The levels of interleukin (IL)-6, IL-8, IL-10, and tumor necrosis factor (TNF)-alpha were determined, as well as the adhesion molecules CD41 and CD62 on platelets and CD11b and CD41 on leukocytes. As a measure of the pulmonary release, ratios of PV and RA levels were calculated.

RESULTS

Before CPB, the concentrations of cytokines tended to be lower in the PV compared with the RA. At 1 min of reperfusion, no significant concentration increases were found in the PV. At 10 min of reperfusion, the PV/RA ratio (mean +/- SEM) for IL-6 was 2.06 +/- 0.37 and 1.24 +/- 0.15 for IL-8 (p = 0.02 and p = 0.04, respectively, compared with the pre-CPB ratios of 0.89 +/- 0.4 and 0.99 +/- 0.2). At 20 min of reperfusion, PV/RA ratios for IL-6 (1.95 +/- 0.37) and IL-10 (0.99 +/- 0.4) were higher than before CPB (0.89 +/- 0.04, p = 0.05 and 0.85 +/- 0.06, p = 0.03, respectively). Adhesion molecule counts on platelets and polymorphonuclear neutrophils (PMNs) tended to be higher in the PV than in the RA before CPB. At 1 min of reperfusion, the PV/RA ratio of CD41 on monocytes (0.89 +/- 0.04) and of CD41 on PMNs (1.05 +/- 0.05) was less than before CPB (1.24 +/- 0.08, p = 0.0002 and 1.55 +/- 0.14, p = 0.0002). At 10 min and 20 min of reperfusion, similar changes were found.

CONCLUSIONS

The observed changes indicate an inflammatory response of the lungs. Proinflammatory cytokines are increased in pulmonary venous blood. At the same time, activated blood cells are retained in the pulmonary circulation. This may contribute to pulmonary dysfunction almost routinely observed after CPB.

Leucodepletion during cardiopulmonary bypass reduces blood transfusion and crystalloid requirements

Cardiopulmonary bypass (CPB) is associated with the production of inflammatory responses, which can have significant influence on prognosis. We studied the effects of leucocyte-depletion filters on inflammatory parameters and early postoperative prognosis during coronary revascularization. Twenty patients undergoing elective coronary revascularization were randomly divided into two groups. Ten patients had leucocyte-depletion filters added to the CPB circuit (treatment group) and 10 were used as control cases (control group). Expression of CD11b on neutrophils, and production of myeloperoxidase and lactoferrin, were measured in arterial samples between induction and 3 h postbypass. In addition, clinical parameters were measured during inpatient recovery. CD11b neutrophil expression, and myeloperoxidase and lactoferrin production, were found to be upregulated during CPB and then to decline to preoperative levels by the third postoperative hour. Blood transfusion requirements were reduced in the treatment group, equalling 1.5 +/- 1.2 units, compared to 2.7 +/- 1.1 units for the control group (p value = 0.034) and so were the volumes of crystalloid infused during the first 24 h postoperatively, equalling 3.9 +/- 1.21 in the treatment group and 3.3 +/- 0.71 in the control group (p value = 0.021). Overall, the application of leucocyte depletion produced an early clinical advantage, underlining the need for an improved understanding and manipulation of the inflammatory response to CPB.

Role of aprotinin in the management of patients during and after cardiac surgery

Management of patients undergoing cardiac surgery has evolved in recent years as more is understood about the physiological changes and responses that occur during and after cardiopulmonary bypass (CPB). In particular, our understanding of the mechanisms involved in haemostasis and in the inflammatory response to bypass surgery, has allowed significant refinements in patient management. Improvements in the pharmacological conservation of blood loss have been striking, particularly with the development of the serine protease inhibitor, aprotinin (Trasylol, Bayer). Aprotinin represents a significant improvement, especially for patients at high risk, since it reduces the need for allogeneic and (sometimes scarce) blood products. However, in view of its cost, making an appropriate selection of patients most at risk of serious blood loss is a major consideration in the use of aprotinin. While its mechanisms of action are not well understood, the use of aprotinin also appears to reduce inflammatory response to CPB.

High-dose aprotinin modulates the balance between proinflammatory and anti-inflammatory responses during coronary artery bypass graft surgery

OBJECTIVE

To rule out the effect of high-dose aprotinin in respect to the balance of proinflammatory and anti-inflammatory mediators induced by cardiopulmonary bypass (CPB).

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

University-affiliated cardiac center.

PARTICIPANTS

Twenty patients scheduled for coronary artery bypass graft surgery.

INTERVENTIONS

In group A patients (n = 10), high-dose aprotinin was administered (2 x 106 KIU pre-CPB, 2 x 10(6) KIU in prime, 500,000 KIU/hr during CPB). In group C patients (n = 10), placebo was used instead. Proinflammatory interleukin (IL)-6, anti-inflammatory IL-1-receptor antagonist, and clinical parameters were measured 8 times perioperatively. The values are presented as mean +/- SEM.

MEASUREMENTS AND MAIN RESULTS

Four hours after CPB, IL-6 concentration reached the maximum value, being significantly lower in group A patients as compared with group C patients (615 +/- 62 pg/mL v 1,409 +/- 253 pg/mL; p = 0.019). On the first postoperative day, the concentration of IL-6 in group A patients remained lower (219 +/- 24 pg/mL v 526 +/- 123 pg/mL; p = 0.015). In contrast, IL-1-receptor antagonist concentration was higher in group A patients as compared with group C patients after CPB (13,857 +/- 4,264 pg/mL v 5,675 +/- 1,832 pg/mL; p = 0.03). Total postoperative blood loss was lower in group A patients as compared with group C patients (648 +/- 64 mL v 1,284 +/- 183 mL; p = 0.002).

CONCLUSIONS

High-dose aprotinin treatment reduced the inflammatory reaction and postoperative blood loss. The anti-inflammatory reaction was significantly enhanced in these patients, which suggests that the physiologic reaction of the organism to reduce the deleterious effects from CPB is more pronounced by using high-dose aprotinin.

Risks and benefits of preoperative high dose methylprednisolone in surgical patients: a systematic review

BACKGROUND

A single preoperative high dose of methylprednisolone (15 to 30 mg/kg) has been advocated in surgery, because it may inhibit the surgical stress response and thereby improve postoperative outcome and convalescence. However, these potential clinical benefits must be weighed against possible adverse effects.

OBJECTIVE

To conduct a risk-benefit analysis using a meta-analysis, to compare complication rates and clinical advantages associated with the use of high dose methylprednisolone in surgical patients.

METHODS

Randomised controlled trials of high dose methylprednisolone in elective and trauma surgery were systematically searched for in various literature databases. Outcome data on adverse effects, postoperative pain and hospital stay were extracted and statistically pooled in fixed-effects meta-analyses.

RESULTS

We located 51 studies in elective cardiac and noncardiac surgery, as well as traumatology. Pooled data failed to show any significant increase in complication rates. In patients treated with corticosteroids, nonsignificantly more gastrointestinal bleeding and wound complications were observed; the 95% confidence interval boundaries of the numbers-needed-to-harm were 59 and 38, respectively. The only significant finding was a reduction of pulmonary complications (risk difference -3.5%; 95% confidence interval -1.0 to -6.1), mainly in trauma patients.

CONCLUSION

For patients undergoing surgical procedures, a perioperative single-shot administration of high dose methylprednisolone is not associated with a significant increase in the incidence of adverse effects. In patients with multiple fractures, limited evidence suggests promising benefits of glucocorticoids on pulmonary complications.

Does aprotinin reduce lung reperfusion damage after cardiopulmonary bypass?

OBJECTIVE

The role of aprotinin in the prevention of lung reperfusion injury was investigated in the patients undergoing cardio-pulmonary bypass (CPB) for coronary artery bypass grafting (CABG) operations.

METHODS

The study was planned randomly and prospectively. Two hundred milliliters of physiological saline solution was added to the prime solution of patients in group I (n=10) whereas, 200 ml aprotinin (Trasylol, Bayer AG) was given to patients in group II (n=10). In order to measure lung tissue malondialdehyde (MDA) levels, glutathion peroxidase (GSH-Px) activity levels and polymorphonuclear leukocytes (PMNs) numbers, lung tissue samples were taken before CPB and 5 min after removing the cross clamp. In addition, alveolo-arterial oxygen difference (AaDO(2)) for tissue oxygenation was calculated by obtaining arterial blood gas samples.

RESULTS

MDA levels before CPB increased from 41.72+/-21.00 nmol/g tissue to 66.71+/-13.44 nmol/g tissue in group I and from 43.44+/-5.16 nmol MDA/g tissue to 53.22+/-10.95 nmol MDA/g tissue in group II after cross clamp removal (P=0.001 and P=0.021, respectively). The increase in group II was found to be significantly lower than group I (P=0.048). With the initiation of reperfusion, GSH-Px activity decreased in group I from 3.05+/-0.97 to 2.31+/-0.46 U/mg protein (P=0.015) whereas GSH-Px activity in group II decreased from 3.18+/-1.01 to 2.74+/-0.81 U/mg protein (P=0. 055). This decrease in the group II was less than group I (P=0.049). AaDO(2) significantly increased in the group I and II (P=0.012 and P=0.020, respectively), but elevation in the group I was significant than in the Group II (P=0.049). In histopathological examination, it was observed that neutrophil counts in the lung parenchyma rose significantly following removal of cross clamp in both groups (P=0. 001). The increase in group I was significantly larger than in group II (P=0.050).

CONCLUSION

Results represented in our study indicate that addition of aprotinin (2 million units) into the prime solution during CPB can reduce lung reperfusion injury.

Bench to bedside: tumor necrosis factor-alpha: from inflammation to resuscitation

Proinflammatory mediators such as tumor necrosis factor-alpha (TNF) have been implicated in the pathophysiology in a number of acute disease states. Tumor necrosis factor-alpha can contribute to cell death, apoptosis, and organ dysfunction. Tumor necrosis factor-alpha can be generated with sepsis or ischemia-reperfusion by activation of cell mitogen-activated protein kinases and nuclear factor kappa B, leading to TNF production. A number of strategies to modulate TNF have been recently explored, including factors directed toward mitogen-activated protein kinases, TNF transcription, anti-inflammatory ligands, heat shock proteins, and TNF-binding proteins. However, TNF may also play an important role in the adaptive response to injury and inflammation. Control of the deleterious effects of TNF and other proinflammatory cytokines represents a realistic goal for clinical emergency medicine. The purpose of this article is to provide a background of relevance to emergency medicine academicians on the production and regulation of TNF, the acute effects of TNF on pathophysiology, and the rationale for therapeutic interventions directed toward TNF and the clinical experience with these strategies.

An anti-inflammatory property of aprotinin detected at the level of leukocyte extravasation

BACKGROUND

Aprotinin is a serine protease inhibitor used extensively in cardiac operations to reduce postoperative bleeding. It has also been used in trials aimed at reducing the systemic inflammatory response to cardiopulmonary bypass. It remains unclear whether the anti-inflammatory action of aprotinin is related to its general ability to suppress leukocyte activation or whether aprotinin can exercise effects during the leukocyte-endothelial cell adhesion cascade.

METHODS

We used intravital microscopy to study the 3 main stages of the adhesion cascade (leukocyte rolling, firm adhesion, and extravasation) within the mesenteric microcirculation of rats. This in vivo technique allows leukocyte recruitment to be viewed directly through the transparent mesentery of anesthetized animals.

RESULTS

Aprotinin, given by continuous infusion at a clinically relevant dose, exerted no effect on the rolling or firm adhesion responses toward local chemoattractant N -formyl-methyl-leucyl-phenylalanine but significantly inhibited extravasation of leukocytes (73% at 40 minutes, P =.04) into surrounding tissues. In parallel in vitro experiments, aprotinin (used at 200, 800, and 1600 kIU/mL) dose dependently inhibited neutrophil transmigration through cultured endothelial cells in response to 3 different chemoattractants: N -formyl-methyl-leucyl-phenylalanine (P <.001 at 800 and 1600 kIU/mL), interleukin 8 (P <.05 at 200 kIU/mL and P <.001 at 800 and 1600 kIU/mL), and platelet-activating factor (P <.05 at 1600 kIU/mL).

CONCLUSIONS

Our studies have therefore revealed a novel anti-inflammatory mechanism of aprotinin operating at the level of leukocyte extravasation. These findings may be relevant in the prevention of systemic inflammation after cardiopulmonary bypass through the use of protease inhibitors.

Effects of selectin-sialyl Lewis blockade on mesenteric microvascular permeability associated with cardiopulmonary bypass

OBJECTIVES

Cardiopulmonary bypass is associated with an inflammatory response that is associated with a neutrophil-mediated microvascular barrier injury. We studied the effects of blocking neutrophil-endothelial tethering on microvascular permeability and edema formation during cardiopulmonary bypass. Using a selectin antagonist that prevents interactions with their ligands, we hypothesized that there would be less neutrophil infiltration into the tissue and a reduction in microvascular permeability and edema formation.

METHODS

A canine mesenteric lymphatic fistula was created to measure Starling forces and to determine microvascular permeability. Normothermic, atrial-femoral cardiopulmonary bypass was initiated (70-90 mL. kg(-1). min(-1)). Intestinal tissue water was determined with microgravimetry. Ileal tissue myeloperoxidase was measured as an index of neutrophil tissue infiltration. One experimental group received the selectin antagonist TBC 1269 before the initiation of bypass, and the control group received saline solution.

RESULTS

There was a modest increase in microvascular permeability in both groups, as evidenced by significantly increased transvascular protein clearance and a trend toward a decrease in reflection coefficient. There were no differences in the experimental group compared with the control group. Ileal tissue myeloperoxidase levels were lower in the experimental group than in the control group.

CONCLUSIONS

The selectin antagonist TBC 1269 reduces neutrophil infiltration into the ileum without altering ileal microvascular permeability or edema associated with cardiopulmonary bypass.

Corticosteroids during operations using cardiopulmonary bypass

Although corticosteroids have been used for more than 30 years in the context of extracorporeal circulation, there is an ongoing debate about the benefits of their routine application. Methylprednisolone was given as early as 1966 to reduce vasoconstriction during cardiopulmonary bypass (CPB) and to prevent low output syndrome thereafter. An explanation for these findings was recently published. Lipid mediators lead to vasoconstriction and inflammatory cytokine production during CPB. There is no doubt about the potential of corticosteroids to reduce inflammatory and enhance anti-inflammatory mediators, while their possible influence on clinical parameters and their side effects are controversial, as discussed in the literature. There have been contradictory results with respect to pulmonary oxygenation, while an increase in the patient's blood glucose levels, however clinically unimportant, could be demonstrated. The influence of other drugs affecting the inflammatory response has to be taken into account, leading to a patient-specific recommendation for the use of corticosteroids during operations requiring CPB.

Pulmonary artery perfusion with protective solution reduces lung injury after cardiopulmonary bypass

BACKGROUND

The inflammatory response and higher temperature of lung tissue during cardiopulmonary bypass can result in lung injury. This study was to evaluate the protective effect of pulmonary perfusion with hypothermic antiinflammatory solution on lung function after cardiopulmonary bypass.

METHODS

Twelve adult mongrel dogs were randomly divided into two groups. The procedure was carried out through a midline sternotomy, cardiopulmonary bypass was established using cannulas placed in the ascending aorta, superior vena cava, and right atrium near the entrance of the inferior vena cava. After the ascending aorta was clamped and cardioplegic solution infused, the right lung was perfused through a cannula placed in the right pulmonary artery with 4 degrees C lactated Ringer's solution in the control group (n = 6) and with 4 degrees C protective solution in the antiinflammation group (n = 6). Antiinflammatory solution consisted of anisodamine, L-arginine, aprotinin, glucose-insulin-potassium, and phosphate buffer. Plasma malondialdehyde, white blood cell counts, and lung function were measured at different time point before and after cardiopulmonary bypass; lung biopsies were also taken.

RESULTS

Peak airway pressure increased dramatically in the control group after cardiopulmonary bypass when compared with the antiinflammation group at four different time points (24 +/- 1, 25 +/- 2, 26 +/- 2, 27 +/- 2 cm H2O versus 17 +/- 2, 18 +/- 1, 17 +/- 1, 18 +/- 1 cm H2O; all p < 0.01). Pulmonary vascular resistance increased significantly in the control group than in the antiinflammation group at 5 and 60 minutes after cardiopulmonary bypass (1,282 +/- 62 dynes x s x cm(-5) versus 845 +/- 86 dynes x s x cm(-5) and 1,269 +/- 124 dynes x s x cm(-5) versus 852 +/- 149 dynes x s x cm(-5), p < 0.05). Right pulmonary venous oxygen tension (PvO2) in the antiinflammation group was higher than in the control group at 60 minutes after cardiopulmonary bypass (628 +/- 33.3 mm Hg versus 393 +/- 85.9 mm Hg, p < 0.05). The ratio of white blood cells in the right atrial and the right pulmonary venous blood was lower in the antiinflammation group than in the control group at 5 minutes after the clamp was removed (p < 0.05). Malondialdehyde were lower in the antiinflammation group at 5 and 90 minutes after the clamp was removed (p < 0.01 and p < 0.05, respectively). Histologic examination revealed that the left lung from both groups had marked intraalveolar edema and abundant intraalveolar neutrophils, whereas the right lung in the control group showed moderate injury and the antiinflammation group had normal pulmonary parenchyma.

CONCLUSIONS

Pulmonary artery perfusion using hypothermic protective solution can reduce lung injury after cardiopulmonary bypass.

Dexamethasone reduces the inflammatory response to cardiopulmonary bypass in children

BACKGROUND

A randomized, prospective, double-blind study of 29 children was performed to evaluate the hypothesis that dexamethasone administration prior to cardiopulmonary bypass would decrease the inflammatory mediator release and improve the postoperative clinical course.

METHODS

Fifteen children received dexamethasone (1 mg/kg intravenously) and 14 (controls) received saline solution 1 hour prior to CPB. Serial blood analyses for interleukin-6, tumor necrosis factor-alpha, complement component C3a, and absolute neutrophil count were performed. Postoperative variables evaluated included temperature, supplemental fluids, alveolar-arterial oxygen gradient, and days of mechanical ventilation.

RESULTS

Dexamethasone caused an eightfold decrease in interleukin-6 levels and a greater than threefold decrease in tumor necrosis factor-alpha levels after CPB (p < 0.05). Complement component C3a and absolute neutrophil count were not affected by dexamethasone. The mean rectal temperature for the first 24 hours postoperatively was significantly lower in the group given dexamethasone than in the controls (37.2 degrees +/- 0.4 degrees C versus 37.7 degrees +/- 4 degrees C; p = 0.007). Dexamethasone-treated patients required less supplemental fluid during the first 48 hours (22 +/- 28 mL/kg versus 47 +/- 34 mL/kg; p = 0.04). Compared with controls, dexamethasone-treated children had significantly lower alveolar-arterial oxygen gradients during the first 24 hours (144 +/- 108 mm Hg versus 214 +/- 118 mm Hg; p = 0.02) and required less mechanical ventilation (median duration, 3 days versus 5 days; p = 0.02).

CONCLUSIONS

Dexamethasone administration prior to CPB in children leads to a reduction in the postbypass inflammatory response as assessed by cytokine levels and clinical course.

Leukocyte integrin expression in patients undergoing cardiopulmonary bypass

BACKGROUND

The recruitment of leukocytes to vascular endothelium is controlled by adhesion events mediated through the beta2 integrins, whereas the response of extravasated leukocytes within the tissues is controlled through the beta1 integrins. Although cardiopulmonary bypass (CPB) has been shown to be associated with a systemic inflammatory response and elevated levels of beta2 integrins on leukocytes, its effect on the beta1 integrins is not known. This study investigated the effect of the protease inhibitor aprotinin on the expression of the beta1 and beta2 integrins on circulating leukocytes in patients undergoing CPB.

METHODS

Patients undergoing primary elective coronary artery bypass grafting were randomized into full-dose aprotinin or placebo groups. Blood samples were obtained at nine time points preoperatively, intraoperatively, and up to 6 days postoperatively. The surface expression of the beta1 integrins VLA-1, -3, -4, -5, and -6 and of the beta2 integrins CD11a/CD18, CD11b/CD18, and CD11c/CD18 was measured by flow cytometry on gated neutrophil and monocyte subpopulations in whole blood.

RESULTS

Expression of the beta1 integrins was not significantly altered during the study period and, therefore, aprotinin had no effect on the expression of these molecules. Of the beta2 integrins, CD11b/CD18 expression was significantly increased on neutrophils at 15 minutes after onset of CPB in the placebo group (p < 0.01) but not in the aprotinin group.

CONCLUSIONS

This study showed that expression of the beta1 integrins on neutrophils and monocytes did not alter during the first 6 days after CPB. Expression of the beta2 integrin CD11b/CD18 increased significantly on neutrophils during CPB in control patients but not in patients treated with full-dose aprotinin.

Cytokine release and neutrophil activation are not prevented by heparin-coated circuits and aprotinin administration

BACKGROUND

Cardiopulmonary bypass (CPB) initiates a whole-body inflammatory response where complement and neutrophil activation and cytokine release play an important role. This prospective trial examined the effects of both heparin-coated circuits and aprotinin on the inflammatory processes during CPB, with respect to cytokine release and neutrophil activation.

METHODS

Two hundred patients undergoing cardiac surgery were randomized in four groups of 50 patients each: heparin-coated circuit with aprotinin (HCO-A) or without aprotinin (HCO) administration, and uncoated circuit with aprotinin (C-A) or without aprotinin administration (C). In groups receiving aprotinin, a high-dose regimen was given. In all groups, high initial doses of heparin were used (3 mg/kg intravenously). Tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and IL-8, and myeloperoxidase and elastase levels were measured in plasma samples taken before, during, and after CPB.

RESULTS

In all groups, the TNF-alpha, IL-6, and IL-8 levels reached a maximum after protamine administration. After 24 hours, they remained significantly elevated (IL-6 and IL-8) or returned to baseline values (TNF-alpha). A similar pattern was observed with myeloperoxidase and elastase levels. No significant intergroup differences were observed.

CONCLUSIONS

CPB is associated with cytokine release and neutrophil activation, which are not attenuated by the use of heparin-coated circuits or by the administration of aprotinin. Aprotinin and heparin-coated circuits do not show additive effects.

Sodium nitroprusside in patients with compromised left ventricular function undergoing coronary bypass: reduction of cardiac proinflammatory substances

OBJECTIVE

The aim of the present study was to investigate whether the nitric oxide donor sodium nitroprusside can reduce the cardiac inflammatory response during coronary artery bypass grafting in patients with severely compromised left ventricular function.

METHODS

Patients (n = 30) were assigned to receive placebo or sodium nitroprusside (0.5 microg. kg(-1). min(-1)) for the first 60 minutes of reperfusion. Interleukin 6, interleukin 8, and tumor necrosis factor alpha levels; platelet adhesion molecule CD41 and CD62 levels; and CD11b on leukocytes were determined in the radial artery and coronary sinus before cardiopulmonary bypass and during reperfusion (1, 5, 10, 35, and 75 minutes).

RESULTS

At 1 minute of reperfusion, coronary venous levels of CD41-positive polymorphonuclear leukocytes were 8% lower than arterial levels in the placebo group and 18% higher in the sodium nitroprusside group (P =.021). At 5 minutes of reperfusion, the respective levels were 29% and 1% for interleukin 6 (P =.015), -5% and 20% for CD41-positive monocytes (P =.032), and -2% and 16% for CD11b-positive monocytes (P =.038). At 10 minutes of reperfusion, these levels were -14% and 21% for CD41-positive monocytes (P =.006). At 35 minutes of reperfusion, these levels were -13% and 7% for CD41-positive monocytes (P =.017), -41% and 23% for CD11b-positive monocytes (P =.001), and 7% and 25% for CD62-positive platelets (P =. 041). At 75 minutes of reperfusion, the levels were 15% and -7% for tumor necrosis factor alpha (P =.025) and -10% and 10% for CD62-positive platelets (P =.041).

CONCLUSIONS

Transcardiac production of proinflammatory cytokines is reduced in patients undergoing coronary artery bypass grafting treated with the nitric oxide donor sodium nitroprusside. At the same time, less activated leukocytes and platelets are retained in the coronary circulation.

No benefit of reduced heparinization in thoracic aortic operation with heparin-coated bypass circuits

BACKGROUND

Heparin coating of the cardiopulmonary bypass circuit attenuates inflammatory response and confer clinical benefits in cardiac operations. The positive effects may be amplified with reduced systemic heparin dosage. We studied markers of inflammation and coagulation in thoracic aortic operations with heparin-coated circuits and standard vs reduced systemic heparinization.

METHODS

Thirty patients were randomized to standard (group S; 300 IU/kg initially; activated clotting times [ACT] > 480 seconds; 5,000 IU in prime; n = 16) or reduced (group R; 100 IU/kg initially; ACT > 250 seconds; 2,500 IU in prime; n = 14) dose systemic heparin. The following markers were analyzed perioperatively: (a) inflammatory response; acute phase cytokine interleukin-6, and granulocytic proteins myeloperoxidase and lactoferrin; (b) complement activation; factor C3a and the C5a-9 terminal complement complex [TCC]; and (c) coagulation; thrombin-antithrombin III complex.

RESULTS

The clinical outcome did not differ between groups. Four (29%) patients in group R had a perioperative thromboembolic event. All studied markers were significantly elevated during and throughout cardiopulmonary bypass in both groups. Maximal values were higher in group R for all variables except for TCC. There were no statistically significant intergroup differences regarding markers of inflammation, complement activation, or coagulation activation.

CONCLUSIONS

The blood trauma in thoracic aortic operation is extensive, as reflected by the elevation of the studied biochemical markers, even when heparin-coated cardiopulmonary bypass circuits are used. In this study, we did not detect any benefits, either biochemical or clinical, of reducing the dose of systemic heparin.

Off-pump bypass graft operation significantly reduces oxidative stress and inflammation

BACKGROUND

This study investigated whether off-pump coronary bypass graft operations on the beating heart under normothermic conditions reduces the systemic oxidative stress and inflammatory reaction seen in patients operated under cardiopulmonary bypass (CPB).

METHODS

A cardiac stabilizer (Octopus Tissue Stabilizer; Medtronic Inc, Minneapolis, MN) was used to perform the coronary anastomoses on the normothermic beating heart with or without CPB. Serial blood samples were taken at various intervals. Plasma was analyzed for several oxidative stress and inflammatory markers.

RESULTS

Significant increases from prior anesthesia values of lipid hydroperoxides (190% at 4 hours), protein carbonyls (250% at 0.5 hours) and nitrotyrosine (510% at 0.5 hours) were seen in the CPB group, but they were abolished or significantly reduced in the off-pump group. Complement C3a and elastase levels were rapidly increased upon the institution of CPB, and this was followed by increases in IL-8, TNF-alpha, and sE-selectin. In contrast, the rise of these factors was blunted in patients operated without CPB.

CONCLUSIONS

Off-pump coronary bypass graft operation on a beating heart significantly reduces oxidative stress and suppresses the inflammatory reaction associated with the use of CPB.

Aprotinin preserves myocardial biochemical function during cold storage through suppression of tumor necrosis factor

OBJECTIVE

Inflammatory cytokines, particularly tumor necrosis factor, contribute to myocardial dysfunction after ischemia-reperfusion injury. Aprotinin may improve outcomes in cardiac surgery through suppression of inflammatory mediators. We hypothesized that aprotinin may exert its beneficial effects through suppression of tumor necrosis factor alpha.

METHODS

Adult rat hearts were precision cut into slices with a thickness of 200 microm and stored in crystalloid cardioplegic solution alone or with one of the following additions: aprotinin or tumor necrosis factor alpha, aprotinin plus tumor necrosis factor alpha, a monoclonal antibody to tumor necrosis factor alpha, or a polyclonal antibody to the tumor necrosis factor alpha receptor. Myocardial biochemical function was assessed by adenosine triphosphate content and capacity for protein synthesis immediately after slicing (0 hours) and after 2, 4, and 6 hours of storage at 4 degrees C. The content of tumor necrosis factor alpha was measured by an enzyme-linked immunosorbent assay. Six slices were assayed at each time point for each solution. The data were analyzed by analysis of variance and are expressed as the mean +/- standard deviation.

RESULTS

When stored in cardioplegic solution containing aprotinin, the heart slices demonstrated (1) an increase in adenosine triphosphate content and protein synthesis (P <.0001), (2) a decrease in intramyocardial generation of tumor necrosis factor alpha (P </=.0311), and (3) a decrease in uptake of tumor necrosis factor alpha into the myocardium (P </=.002) compared with storage in cardioplegic solution alone. The presence of an antibody to tumor necrosis factor alpha or an antibody to the tumor necrosis factor alpha receptor in cardioplegic solution increased intramyocardial adenosine triphosphate content and protein synthesis (P <.0001).

CONCLUSIONS

Aprotinin preserves myocardial biochemical function during cold storage. This preservation of biochemical function is mediated through suppression of the release, uptake, and activity of tumor necrosis factor alpha.

Vascular changes after cardiopulmonary bypass and ischemic cardiac arrest: roles of nitric oxide synthase and cyclooxygenase

Cardiac surgery involving ischemic arrest and extracorporeal circulation is often associated with alterations in vascular reactivity and permeability due to changes in the expression and activity of isoforms of nitric oxide synthase and cyclooxygenase. These inflammatory changes may manifest as systemic hypotension, coronary spasm or contraction, myocardial failure, and dysfunction of the lungs, gut, brain and other organs. In addition, endothelial dysfunction may increase the occurrence of late cardiac events such as graft thrombosis and myocardial infarction. These vascular changes may lead to increased mortality and morbidity and markedly lengthen the time of hospitalization and cost of cardiac surgery. Developing a better understanding of the vascular changes operating through nitric oxide synthase and cyclooxygenase may improve the care and help decrease the cost of cardiovascular operations.

Inhibitory effect of milrinone on cytokine production after cardiopulmonary bypass

BACKGROUND

It has been suggested that cyclic adenosine monophosphate-elevating agents suppress cytokine production. To evaluate the effects of milrinone, a phosphodiesterase III inhibitor, on cytokine production after cardiopulmonary bypass, we conducted a prospective randomized study.

METHODS

Twenty-four patients undergoing coronary artery bypass grafting were randomized to receive either milrinone treatment (milrinone, n = 12) or no milrinone treatment (control, n = 12). Administration of milrinone (0.5 microg x kg(-1) x min(-1)) was started after induction of anesthesia and was continued for 24 hours. Blood samples for determination of plasma cyclic adenosine monophosphate, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and interleukin-8 levels were collected perioperatively.

RESULTS

No significant differences were observed in tumor necrosis factor-alpha and interleukin-8 levels between the groups. Interleukin-1beta and interleukin-6 levels after cardiopulmonary bypass were significantly (p < 0.05) lower in the milrinone group than in the control group. Plasma levels of cyclic adenosine monophosphate increased significantly (p < 0.05) after the administration of milrinone and the levels correlated inversely (r = -0.55, p < 0.01) with interleukin-6 levels.

CONCLUSIONS

The results indicate that milrinone suppresses cytokine production by elevating cyclic adenosine monophosphate levels in patients undergoing cardiopulmonary bypass. With its positive inotropic and vasodilator activities, milrinone may have antiinflammatory effects.

Release of cardiac troponin I in antegrade crystalloid versus cold blood cardioplegia

OBJECTIVE

The purpose of this study was to assess the efficacy of myocardial protection, comparing antegrade crystalloid cardioplegia with cold blood cardioplegia, in patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting. Release of cardiac troponin I was used as a marker for the effectiveness of myocardial protection.

METHODS

A consecutive series of 62 patients were randomly assigned to receive crystalloid or blood cardioplegia. Cardiac troponin I concentrations were determined in venous blood samples before the operation, immediately after unclamping, at 6, 9, 12, and 24 hours, and daily thereafter for 5 days.

RESULTS

Rising levels of troponin I were found in all patients. The time course and peak release were similar in the crystalloid cardioplegia and the blood cardioplegia groups. No patients in either group had electrocardiographic evidence of perioperative myocardial infarction. Cardiac troponin I was able to detect small areas of myocardial damage, not revealed by electrocardiography or creatine kinase MB release. Aprotinin administration was associated with lower cardiac troponin I release in both groups. Cardiac troponin I was lower in patients whose conditions did not require electrical defibrillation after aortic unclamping, irrespective of cardioplegia type. The presence of a main stem lesion was associated with higher cardiac troponin I release only in the crystalloid cardioplegia group.

CONCLUSIONS

Antegrade cold blood cardioplegia is equally effective as antegrade crystalloid cardioplegia in a randomized group of patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting. Aprotinin administration resulted in lower cardiac troponin I release, whereas electrical defibrillation was related to a higher release irrespective of cardioplegia type. The presence of a main stem lesion resulted in higher cardiac troponin I release in the crystalloid cardioplegia group.

Mechanisms of the systemic inflammatory response

The purpose of inflammation is to combat various agents that may injure the tissues. Conditions such as CPB can often cause systemic inflammation and dysfunction of major organs. Pulmonary, renal, myocardial and intestinal function may suffer various degrees of impairment during and after cardiac surgery. Although changes in major organs usually remain clinically insignificant, severe organ failure is not uncommon. The process of systemic inflammation proceeds through activation of serum proteins, activation of leucocytes and endothelial cells, secretion of cytokines, leucocyte-endothelial cell interaction, leucocyte extravasation and tissue damage. Several anti-inflammatory strategies have already been used, some of which have given promising results pertaining to further reduction in the rate of the inflammation-related complications in cardiac surgical patients.

Influence of combined zero-balanced and modified ultrafiltration on the systemic inflammatory response during coronary artery bypass grafting

OBJECTIVE

To evaluate whether combined zero-balanced and modified ultrafiltration affects the systemic inflammatory response in coronary artery bypass graft (CABG) patients.

DESIGN

Randomized and controlled.

SETTING

University-affiliated heart center.

PARTICIPANTS

Forty-three patients scheduled for elective CABG.

INTERVENTIONS

In the ultrafiltration group (UF group; n = 21), zero-balanced ultrafiltration was performed during rewarming and modified ultrafiltration immediately after the end of cardiopulmonary bypass (CPB). A control group of patients (n = 22) was treated identically to the treatment group except no ultrafiltration process was performed.

MEASUREMENTS AND MAIN RESULTS

Immediately after CPB (ie, after zero-balanced ultrafiltration), and again after the modified ultrafiltration, the concentrations of interleukin-6 and interleukin-8 were significantly less (p < 0.05) in the UF group compared with the control group. Both proinflammatory cytokine levels peaked at 2 and 4 hours after CPB, at which time no difference between the two groups could be observed. The levels of measured anti-inflammatory mediators (interleukin-10 and interleukin-1 receptor antagonist) did not show any difference between the two groups. Intrapulmonary shunt fraction decreased in the course of the modified ultrafiltration from 31% +/- 1.2% to 25% +/- 1.3% (p < 0.01), whereas mean arterial pressure increased (69 +/- 1.8 to 80 +/- 2.8 mmHg; p < 0.01); neither parameter changed in the control group. Time to extubation was shorter in the UF group (6.1 +/- 0.5 v 8.6 +/- 0.7 hours; p < 0.05).

CONCLUSION

It was concluded that the use of ultrafiltration diminished inflammatory response in a very limited time period immediately after CPB and, probably as a consequence, slightly improved clinical parameters.

Does high-dose methylprednisolone in aprotinin-treated patients attenuate the systemic inflammatory response during coronary artery bypass grafting procedures?

OBJECTIVE

To discover the possible effects of methylprednisolone on the systemic inflammatory response during aprotinin treatment.

DESIGN

Randomized, double-blinded study.

SETTING

University-affiliated heart center.

PARTICIPANTS

Fifty-two patients scheduled for elective coronary artery bypass grafting.

INTERVENTIONS

In the methylprednisolone group (n = 26), 1 g of methylprednisolone was administered 30 minutes before cardiopulmonary bypass (CPB). The 26 control patients received a placebo instead. High-dose aprotinin was administered to all participants.

MEASUREMENTS AND MAIN RESULTS

After CPB, the concentration of the proinflammatory cytokines, interleukin-6 and interleukin-8, was significantly less in the methylprednisolone group. The anti-inflammatory interleukin-10 concentration was, in contrast, greater. After CPB, PaO2 was greater in the methylprednisolone group (245+/-17 v 195+/-16 mmHg). Dynamic pulmonary compliance was also greater, whereas the alveolar-arterial oxygen difference was less (376+/-17 v 428+/-16 mmHg). On arrival in the intensive care unit, the oxygen delivery index was greater in the methylprednisolone group (62+/-2.7 v 54+/-2.3 mL/min/m2) and the oxygen extraction rate was less (25%+/-0.02% v 30%+/-0.02%). After CPB, the cardiac index was significantly greater in the methylprednisolone group (4.1+/-0.2 v 3.6+/-0.2 L/min/m2). These patients had less blood loss postoperatively (616+/-52 v 833+/-71 mL; p = 0.017) and a greater urine output (8,015+/-542 v 6,417+/-423 mL/24 h; p = 0.024).

CONCLUSION

The use of methylprednisolone attenuates the systemic inflammatory response during aprotinin treatment and improves clinical outcome parameters.

Methylprednisolone reduces the inflammatory response to cardiopulmonary bypass in neonatal piglets: timing of dose is important

INTRODUCTION

Cardiopulmonary bypass produces an inflammatory response that can cause significant postoperative pulmonary dysfunction and total body edema. This study evaluates the efficacy of preoperative methylprednisolone administration in limiting this injury in neonates and compares the effect of giving methylprednisolone 8 hours before an operation to the common practice of adding methylprednisolone to the cardiopulmonary bypass circuit prime.

METHODS

A control group of neonatal pigs (control; n = 6) received no preoperative medication. One experimental group (n = 6) received methylprednisolone sodium succinate (30 mg/kg) both 8 and 1.5 hours before the operation. A second experimental group received no preoperative treatment, but methylprednisolone (30 mg/kg) was added to the cardiopulmonary bypass circuit prime. All animals underwent cardiopulmonary bypass and 45 minutes of deep hypothermic circulatory arrest. Hemodynamic and pulmonary function data were acquired before cardiopulmonary bypass and at 30 and 60 minutes after bypass.

RESULTS

In the control group, pulmonary compliance, alveolar-arterial gradient, and pulmonary vascular resistance were significantly impaired after bypass (P <.01 for each by analysis of variance). In the group that received methylprednisolone, compliance (P =.02), alveolar-arterial gradient (P =.0003), pulmonary vascular resistance (P =.007), and extracellular fluid accumulation (P =.003) were significantly better after bypass when compared with the control group. Results for the group that received no preoperative treatment fell between the control group and the group that received methylprednisolone.

CONCLUSIONS

When given 8 hours and immediately before the operation, methylprednisolone improves pulmonary compliance after bypass, alveolar-arterial gradient, and pulmonary vascular resistance compared with no treatment. The addition of methylprednisolone to the cardiopulmonary bypass circuit prime is beneficial but inferior to preoperative administration.

Pump prime only aprotinin inhibits cardiopulmonary bypass-induced neutrophil CD11b up-regulation

BACKGROUND

The expression of neutrophil integrin CD11b is up-regulated after cardiopulmonary bypass (CPB) and is the neutrophil adhesive molecule of most importance in neutrophil- endothelial adherence. This neutrophil-endothelial adherence is responsible for post-CPB neutrophil-induced reperfusion injury. Low-dose aprotinin protocols inhibit the CPB-induced neutrophil CD11b up-regulation. This investigation was undertaken to evaluate the effects of pump prime only aprotinin (280 mg) on the CPB-induced up-regulation of this neutrophil integrin.

METHODS

Twenty-two patients scheduled for elective myocardial revascularization were randomized into two groups: (1) control (n = 12), or (2) pump prime only aprotinin (280 mg) (n = 10). Neutrophils were isolated at baseline, 50 minutes of CPB, and 30 minutes after CPB and neutrophil CD11b expression was measured.

RESULTS

The control group demonstrated a significant (p < 0.05) increase in neutrophil CD11b immunofluorescent staining at 50 minutes of CPB and at 30 minutes after CPB when compared to same group baseline and to the pump prime only aprotinin group at similar time intervals.

CONCLUSIONS

These results indicate that pump prime only aprotinin modulates the CPB-induced up-regulation of neutrophil CD11b integrin, an important indicator of the systemic inflammatory response to CPB. In addition to blunting of the CPB-induced up-regulation of this neutrophil integrin expression, this pump prime only dose of aprotinin is also reported to be effective at reducing post-CPB bleeding and transfusion requirements. This salutary effect of pump prime only aprotinin suggests that such low-dose regimens can be both therapeutically effective and cost effective.

Reduced inotropic support after aprotinin therapy during pediatric cardiac operations

BACKGROUND

Several reports indicate that aprotinin treatment before and during cardiopulmonary bypass (CPB) might have a protective effect on the myocardium. We evaluated the hemodynamic effects of perioperative aprotinin treatment.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial in 34 infants (mean age, 2.5 years) who had cardiac operations. Half of the patients received high-dose aprotinin therapy. There were no significant differences between the aprotinin and placebo groups with respect to age, weight, sex, aortic cross-clamp time, and CPB time. The following data were recorded at arrival in the intensive care unit 6, 12, 24, and 48 hours after termination of CPB: heart rate, blood pressure, left atrial pressure, central-peripheral temperature difference, arterial-central venous oxygen saturation difference, urine output, serum creatinine, lactate and neutrophil elastase levels, the Doppler echocardiographic factors shortening fraction and preejection period/left-ventricular ejection time, and cumulative doses of catecholamines (epinephrine), enoximone, and furosemide.

RESULTS

No hemodynamic variable showed any significant difference between aprotinin and placebo groups. Urine output, creatinine, lactate, and elastase levels, as well as the cumulative doses of furosemide and epinephrine were not significantly different. Twelve hours after CPB 10 patients in the placebo group and 4 in the aprotinin group had received enoximone (p<0.05). The placebo group had received significantly larger doses of enoximone than the aprotinin group at arrival in the intensive care unit (0.13+/-0.05 versus 0 mg/kg), 12 hours after CPB (0.58+/-0.14 versus 0.18+/-0.09 mg/kg), 24 hours after CPB (1.11+/-0.24 versus 0.42+/-0.16 mg/kg), and 48 hours after CPB (1.61+/-0.40 versus 0.86+/-0.28). At 6 hours the difference did not reach statistical significance.

CONCLUSIONS

Clinical and hemodynamic status of the aprotinin-treated patients was similar to that of the placebo-treated patients in the first 48 hours after CPB. The placebo group, however, required significantly more inotropic support by enoximone than the aprotinin group to achieve this goal.

The effects of aprotinin on outcome from cerebral ischemia in the rat

The administration of aprotinin has been associated with a reduction in cardiac surgery-related stroke. Intrinsic neuroprotective properties of this drug have not been evaluated in laboratory outcome models of cerebral ischemia. The purpose of this study was to determine whether aprotinin exhibits neuroprotective effects against either global or focal cerebral ischemia in the rat. Fasted rats were administered aprotinin (30,000 or 60,000 KIU/kg) or vehicle (0.9% NaCl) IV before global ischemia (10 min bilateral carotid occlusion with mean arterial pressure 30 mm Hg) or focal ischemia (75 min of transient middle cerebral artery occlusion [MCAO]). Five days after global ischemia, the percentage of dead hippocampal CA1 neurons (mean +/- SD) was similar among the groups (small-dose aprotinin: 49+/-31, n = 15; large-dose aprotinin: 55+/-31, n = 13; vehicle: 47+/-31, n = 16; P = 0.74). After 7 days' recovery from MCAO, no difference among the groups was observed for either neurologic score (P = 0.99) or cerebral infarct volume (small-dose aprotinin: 136+/-80 mm3, n = 23; large-dose aprotinin: 132+/-101 mm3, n = 11; vehicle: 121+/-81 mm3, n = 21; P = 0.87).

IMPLICATIONS

Aprotinin offers no neuroprotection against either global or focal cerebral ischemia in the rat when administered as a single preischemic bolus.

'High dose' aprotinin and heparin-coated circuits: clinical efficacy and inflammatory response

Heparin-coated cardiopulmonary bypass circuits reduce the inflammatory response to cardiopulmonary bypass circuit, improve biocompatibility and may protect the postoperative hemostasic mechanisms in routine coronary bypass operations. 'High-dose' aprotinin reduces bloodloss, transfusion needs, and re-explorations as a result of bleeding, and may have an additional role in reducing the inflammatory response of the body to cardiopulmonary bypass circuit. It has not been established, however, if the addition of a heparin-coated circuit to the intraoperative administration of 'high dose' aprotinin further reduces the whole-body inflammatory response to cardiopulmonary bypass circuit and improves the postoperative clinical course of the patients who are undergoing coronary surgery. Thirty patients undergoing primary elective coronary artery bypass grafting were studied. All the patients received, intraoperatively, the serine-protease inhibitor aprotinin according to the 'Hammersmith' protocol and full heparin dose. Patients were randomly allocated to be treated either with a circuit completely coated with surface-bound heparin (n = 15) or with an uncoated, but otherwise identical, circuit (n = 15). Differences in the clinical course of the two groups of patients, as well as differences in the behavior of hematological and inflammatory (interleukin-6 (IL-6) and C-reactive protein) factors before, during and after bypass, were analyzed. There were no significant differences between the two groups in terms of bleeding and transfusional requirements, the time spent on a ventilator, or in duration of stay in the intensive care unit (ICU). In all patients, a significant increase in the total white blood cell count, neutrophils, serum IL-6 and C-reactive protein occurred in relation to cardiopulmonary bypass. This was not influenced by heparin precoating of the circuit. In addition, there was an increase in the monocyte count during follow-up, and there was a trend towards higher monocyte counts in the patients who were treated with heparin-coated circuits. These results suggest that the addition of a heparin-coated circuit to the intraoperative 'high-dose' aprotinin therapy probably had little influence on the clinical course and on the time-course of the inflammatory parameters of the adult patients undergoing primary coronary surgery with a full heparinization protocol.

Effects of cardiopulmonary bypass on leukocyte and endothelial adhesion molecules

During the inflammatory response, triggered by cardiopulmonary bypass, interaction between activated leukocytes, platelets, and endothelial cells is mediated through the expression of three main groups of adhesion molecules: the selectins, the integrins, and the immunoglobulin superfamily. The selectins, which mediate the initial rolling of the leukocyte on the endothelium, are divided in three subgroups: L-selectin is expressed on all three leukocyte types, P-selectin is expressed on platelets and endothelial cells, and E-selectin is only expressed on endothelial cells. Integrins can be found on most cell types, consist of an alpha and a beta subunit and mediate firm adhesion of the leukocyte and migration into the tissues. They are classified into subgroups according to the type of their beta subunit. Immunoglobulins such as ICAM-1 and VCAM-1 are expressed mainly on endothelium and act as ligands for certain integrins. This review article summarizes the existing, and rapidly expanding, literature concerning the effects of cardiopulmonary bypass on the expression of leukocyte and endothelial adhesion molecules. Deeper understanding of the, behavior and the role of adhesion molecules during cardiopulmonary bypass may facilitate effective intervention in the inflammatory response process and suppression of its adverse effects.

The efficacy and safety of aprotinin use in cardiac surgery

BACKGROUND

The serine protease inhibitor aprotinin has received much attention in cardiac surgical practice as a pharmacologic intervention to improve the hemostatic derangement associated with cardiopulmonary bypass. This review highlights the major studies undertaken to investigate the efficacy and safety of aprotinin use in both primary and repeat coronary artery bypass graft surgical procedures.

METHODS

There have been at least 45 controlled studies in more than 7,000 patients in a variety of patient populations. These have ranged from primary coronary artery bypass graft and valve operations to complex reoperation procedures, including aortic arch reconstructions and thoracic organ transplantation. The recently completed International Multicenter Graft Patency Experience trial, the largest study to date, involved 870 patients at 13 international sites. The study examined the effects of aprotinin on graft patency, incidence of myocardial infarction, and blood loss in patients undergoing primary coronary artery bypass graft operations with cardiopulmonary bypass.

RESULTS

Twenty-one studies in approximately 5,000 patients undergoing primary coronary artery bypass graft or valve operations reported 33% to 66% reduction in blood loss with full-dose aprotinin therapy; 15 of the same studies reported significant reductions in transfusion requirements, ranging from 31% to 85%. The recently completed International Multicenter Graft Patency Experience study observed a significant reduction in thoracic-drainage volume of 43% (p < 0.0001) and a 49% (p < 0.001) reduction in the requirement for allogeneic blood transfusions. Aprotinin did not affect the occurrence of definite myocardial infarction (aprotinin, 2.9% versus placebo, 3.8%) or mortality (aprotinin, 1.4% versus placebo, 1.6%). There was no observed difference in the patency of internal mammary artery bypass grafts from all study sites in aprotinin- versus placebo-treated patients (aprotinin, 98.2% versus placebo, 98.0%).

CONCLUSIONS

Given the risks and costs associated with excessive bleeding and transfusions and the limited supply of banked blood, aprotinin represents an important and safe approach to blood conservation.

Dexamethasone decreases the incidence of shivering after cardiac surgery: a randomized, double-blind, placebo-controlled study

Shivering after cardiac surgery is common, and may be a result of intraoperative hypothermia. Another possible etiology is fever and chills secondary to activation of the inflammatory response and release of cytokines by cardiopulmonary bypass. Dexamethasone decreases the gradient between core and skin temperature and modifies the inflammatory response. The goal of this study was to determine whether dexamethasone can reduce the incidence of shivering. Two hundred thirty-six patients scheduled for elective coronary and/or valvular surgery were randomly assigned to receive either dexamethasone 0.6 mg/kg or placebo after the induction of anesthesia. All patients received standard monitoring and anesthetic management. After arrival in the intensive care unit (ICU), nurses unaware of the treatment groups recorded visible shivering, as well as skin and pulmonary artery temperatures. Analysis of shivering rates was performed by using chi2 tests and logistic regression analysis. Compared with placebo, dexamethasone decreased the incidence of shivering (33.0% vs 13.1%; P = 0.001). It was an independent predictor of reduced incidence of shivering and was also associated with a higher skin temperature on ICU admission and a lower central temperature in the early postoperative period.

IMPLICATIONS

Dexamethasone is effective in decreasing the incidence of shivering. The effectiveness of dexamethasone is independent of temperature and duration of cardiopulmonary bypass. Shivering after cardiac surgery may be part of the febrile response that occurs after release of cytokines during cardiopulmonary bypass.

Modifying risk for extracorporeal circulation: trial of four antiinflammatory strategies

BACKGROUND

Despite recent rediscovery of beating heart cardiac surgical techniques, extracorporeal circulation remains appropriate for most heart operations. To minimize deleterious effects of cardiopulmonary bypass, antiinflammatory strategies have evolved.

METHODS

Four state-of-the-art strategies were studied in a prospective, randomized, preoperatively risk stratified, 400-patient study comprising primary (n = 358), reoperative (n = 42), coronary (n = 307), valve (n = 27), ascending aortic (n = 9), and combined operations (n = 23). Groups were as follows: standard, roller pump, membrane oxygenator, methylprednisolone (n = 112); aprotinin, standard plus aprotinin (n = 109); leukocyte depletion, standard plus a leukocyte filtration strategy (n = 112); and heparin-bonded circuitry, centrifugal pumping with surface modification (n = 67).

RESULTS

Analysis of variance, linear and logistic regression, and Pearson correlation were applied. Actual mortality (2.3%) was less than half the risk stratification predicted mortality (5.7%). The treatment strategies effectively attenuated markers of the inflammatory response to extracorporeal circulation. Compared with the other groups the heparin-bonded circuit had highly significantly decreased complement activation (p = 0.00001), leukocyte filtration blunted postpump leukocytosis (p = 0.043), and the aprotinin group had less fibrinolysis (p = 0.011). Primary end points, length of stay, and hospital charges, were positively correlated with operation type, age, pump time, body surface area, stroke, pulmonary sequelae, predicted risk for stroke, predicted risk for mortality, and risk strata/treatment group interaction (p = 0.0001). In low-risk patients, leukocyte filtration reduced length of stay by 1 day (p = 0.02) and mean charges by $2,000 to $6,000 (p = 0.05). For high-risk patients, aprotinin reduced mean length of stay up to 10 fewer days (p = 0.02) and mean charges by $6,000 to $48,000 (p = 0.0007).

CONCLUSIONS

These pharmacologic and mechanical strategies significantly attenuated the inflammatory response to extracorporeal circulation. This translated variably into improved patient outcomes. The increased cost of treatment was offset for selected strategies through the added value of significantly reduced risk.

Methylprednisolone inhibition of TNF-alpha expression and NF-kB activation after spinal cord injury in rats

Post-traumatic inflammatory reaction has been implicated in the secondary injury after SCI. TNF-alpha is a key inflammatory mediator, which plays a pathogenetic role in cell death in inflammatory disorders and traumatic brain injury. TNF-alpha exerts its effector actions, at least partially, through the activation of a pro-inflammatory transcription factor, NF-kB, which in turn upregulates such genes as iNOS, cytokines, adhesive molecules, and others. Consistent with a post-traumatic inflammatory reaction after SCI, we noted an increase in TNF-alpha expression by Western blotting (4.5-fold increase at 1 day after SCI, P<0.01) and immunohistochemistry in a rat SCI model. Post-traumatic TNF-alpha expression was accompanied by an increase in NF-kB binding activity in nuclear proteins isolated from the injured cord (3.9-fold increase, P<0.01). MP is the only drug proven effective in improving neurological function in patients with acute SCI. The mechanism of action of MP is not fully understood, but is thought to be related to its antioxidant effects. MP is also a potent anti-inflammatory agent, which has been recently shown to inhibit NF-kB binding activity. MP (30 mg/kg, i.v.) given immediately after SCI reduced TNF-alpha expression by 55% (P<0.01) and NF-kB binding activity. These findings suggest that post-traumatic inflammatory activity that is mediated by the TNF-alpha-NF-kB cascade can be suppressed by MP.