Intercellular adhesion molecule-1 regulation in the canine lung after cardiopulmonary bypass

Elevated free fatty acid level is a risk factor for early postoperative hypoxemia after on-pump coronary artery bypass grafting: association with endothelial activation

BACKGROUND

We aimed to investigate the relationship between increased free fatty acid (FFA) level and early postoperative hypoxemia after coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB).

METHODS

Ninety-eight consecutive patients undergoing CABG were enrolled. Early postoperative hypoxemia was defined as the lowest of the ratio of arterial oxygen tension (PaO2) to inspired oxygen fraction (FiO2) ≤ 200 mm Hg within 24 h without pleural effusion and pneumothorax. The 26 perioperative factors, serum levels of FFA and inflammatory cytokines between the hypoxemia and non-hypoxemia groups were recorded or detected using autoanalyzer and enzyme-linked immunosorbent assay, respectively. Additionally, the risk factors for early postoperative hypoxemia were evaluated using multiple logistic regression analysis.

RESULTS

The incidence rate of early postoperative hypoxemia was 37.8 %. Serum FFA levels were significantly higher in the hypoxemia group than in the non-hypoxemia group (P<0.001). Further, postoperative serum FFA levels were inversely related to the lowest of the ratio of PaO2/FiO2 at 24 h after CABG (r= - 0.367, P<0.001). Multiple logistic regression analysis confirmed that age, body mass index and postoperative serum FFA concentrations were independently associated with early postoperative hypoxemia. Notably, patients with hypoxemia had markedly higher serum intercellular adhesion molecule-1 (ICAM-1) levels than those without (P<0.001). Moreover, serum FFA levels at 2 h after CABG correlated positively with ICAM-1 concentrations (r=0.492, P<0.001).

CONCLUSIONS

Elevated FFA concentration is a risk factor for early postoperative hypoxemia after on-pump CABG, which may be closely associated with endothelial activation.

Impact of off-pump coronary artery bypass surgery on systemic inflammation: current best available evidence

The systemic inflammatory response after coronary artery bypass grafting using cardiopulmonary bypass (CPB) contributes substantially to postoperative organ dysfunction and coagulation disorders. Important features of this inflammatory reaction include the activation of complement and leukocytes, the release of proinflammatory cytokines, alterations in the metabolism of nitric oxide, and an increase in the production of oxygen-free radicals, which in some cases may lead to oxidant stress injury. Several strategies including the use of steroids, use of aprotinin, heparin-coated CPB circuits, and hemofiltration have been reported to reduce the inflammatory reaction induced by CPB and its consequences. A more radical and effective way of counteracting the effects of the inflammatory reaction and oxidative stress may be the omission of CPB itself. The development and application of off-pump coronary artery bypass (OPCAB) technology has largely been driven by this theme of avoiding systemic inflammatory reaction to decrease the incidence and/or severity of adverse outcomes. This review article discusses the influence of cardiopulmonary bypass on systemic inflammation and attempts to evaluate the current best available evidence on the impact of OPCAB on systemic inflammation.

Evaluation of oxidative stress in the thrombolysis of pulmonary embolism

BACKGROUND

To analyse leukocyte function parameters and oxidative stress (OS) in patients with acute pulmonary embolism (PE) treated with thrombolytics.

METHODS

Fifteen patients undergoing thrombolysis (TL) with ultra-high dose streptokinase (n = 8), or alteplase (tPA) (n = 7) treatment were studied. Blood samples were collected prior to TL, and then 8 h, 1, 3, 5 and 30 days after treatment. Malondialdehyde (MDA), reduced glutathione (GSH), plasma protein sulfhydryl groups (PSH) levels, superoxide dismutase (SOD) and myeloperoxidase enzyme (MPO) activities were measured in plasma or whole blood for monitoring of the OS markers. Production of reactive oxygen species (ROS) in whole blood was measured by luminol dependent chemiluminescence. Flow cytometry was used to determine CD11a, CD18, and CD97 surface antigen expression on leukocytes.

RESULTS

The elevated MDA, ROS and MPO, decreased GSH and PSH levels indicated the presence of OS in patients with PE. MDA significantly (P < 0.05) increased, GSH significantly (P < 0.05) decreased following thrombolysis. ROS production peaked on the 3rd and 5th days. TL was accompanied by significant decrease in granulocyte and monocyte CD11a and CD18 as well as in granulocyte CD97 expression (P < 0.05).

CONCLUSION

PE led to OS that was augmented following TL. Decreased adhesion molecule expression of circulating leukocytes in the early phase of TL reflects the pathological leukocyte endothelial cell interactions.

Coagulation Activation and Organ Dysfunction Following Cardiac Surgery

STUDY OBJECTIVES

Cardiac surgery with cardiopulmonary bypass (CPB) is associated with major inflammatory triggers that cause marked activation of the microcirculation. This inflammatory response is associated with significant organ dysfunction. How this response causes organ dysfunction is not well understood; consequently, few interventions exist to prevent or treat it. In other acute inflammatory conditions, such as sepsis, increased coagulation activation in the microcirculation may be a cause of organ injury. We documented the association between coagulation activation and organ dysfunction to investigate whether coagulation activation also plays a role in organ injury following cardiac surgery with CPB.

DESIGN

Prospective study of 30 patients undergoing cardiac surgery with CPB. Prothrombin fragment (PTF) 1 + 2 and plasminogen activator inhibitor (PAI) activity were measured, and levels correlated with postoperative measures of organ function including the left-ventricular stroke work index, the Pao(2)/fraction of inspired oxygen (Fio(2)) ratio, and creatinine levels.

RESULTS

PTF levels increased eightfold (p < 0.05), and PAI activity increased threefold (p < 0.05) over the first 4 h after CPB. PTF levels were correlated with deteriorations in the left-ventricular stroke work index (p = 0.04), the Pao(2)/Fio(2) ratio (p = 0.02), and creatinine levels (p = 0.02).

CONCLUSIONS

Levels of coagulation activation are associated with markers of postoperative organ dysfunction. Additional studies are warranted to investigate whether strategies that limit coagulation activation are associated with reductions in postoperative organ dysfunction.

Lung perfusion with protective solution relieves lung injury in corrections of Tetralogy of Fallot

BACKGROUND

The aim of this study was to evaluate the protective effect of pulmonary perfusion with hypothermic protective solution on lung function after cardiopulmonary bypass in corrections of Tetralogy of Fallot.

METHODS

Sixty-four consecutive children with Tetralogy of Fallot were randomly divided into a control group (n = 30) and a protective group (n = 34). Hypothermic protective solution was infused to the main pulmonary artery in the protective group. Hemodynamics and lung functions were monitored. Concentrations of malondialdehyde, tumor necrosis factor-alpha, von Willebrand factor, and endothelin in plasma were measured. The interleukin-6 and interleukin-8 levels in bronchoalveolar lavage fluid were also determined. Lung biopsy specimens were obtained after weaning from cardiopulmonary bypass.

RESULTS

Oxygenation values (oxygen index and alveolar-arterial O(2) gradient) were better preserved in the protective group than in the control group. The time of mechanical ventilation and length of intensive care unit stay were shorter in the protective group compared with the control group. The tumor necrosis factor-alpha and malondialdehyde levels in plasma increased in both groups after operations, and the rising extents were lower in the protective group than in the control group. The von Willebrand factor and endothelin levels in plasma increased more significantly in the control group than in the protective group. The concentrations of interleukin-6 and interleukin-8 in bronchoalveolar lavage fluid were lower in the protective group than in the control group. The examination of histopathology demonstrated capillary hyperemia and hemorrhage, intra-alveolar edema, leukocytes accumulation, mitochondria swelling and vacuolation, and gas-blood barrier broadening in the control group, whereas there were no significant changes in the protective group. The intercellular adhesion molecule-1 expression on lung vascular endothelial cells was stronger in the control group.

CONCLUSIONS

Lung perfusion with hypothermic protective solution during cardiopulmonary bypass relieved lung injury in corrections of Tetralogy of Fallot. The inhibition of lung vascular endothelial cell injury may be the major mechanism of relieving cardiopulmonary bypass-induced lung injury.

Time course of early induction of intracellular adhesion molecule-1 messenger RNA during reperfusion, following cardiopulmonary bypass with hypothermic circulatory arrest in lambs

OBJECTIVE

We investigated the time course of intracellular adhesion molecule-1 messenger RNA induction following cardiopulmonary bypass with hypothermic circulatory arrest.

DESIGN

Animal case study.

SETTING

An animal research laboratory and molecular biology laboratory at a university children's hospital.

SUBJECTS

Neonatal lambs.

INTERVENTIONS

Neonatal lambs were cooled on cardiopulmonary bypass for 30 mins, followed by hypothermic circulatory arrest at 15 degrees C for 120 mins and warming on cardiopulmonary bypass for 30 mins. Animals were killed after 0, 3, or 6 hrs of reperfusion. Control animals had sternotomy only. To generate a species-specific probe, ovine intracellular adhesion molecule-1 complementary DNA was cloned and sequenced. By using a ribonuclease protection assay, we measured intracellular adhesion molecule-1 messenger RNA in lung, cardiac ventricle, and brain, with nonmuscle actin as an internal control. Data were quantitated by Phosphorlmager.

MEASUREMENTS AND MAIN RESULTS

In lung, intracellular adhesion molecule-1 messenger RNA was induced immediately following cardiopulmonary bypass/hypothermic circulatory arrest with no reperfusion (mean increase of 1.7-fold vs. control). The highest intracellular adhesion molecule-1 messenger RNA levels were found at 3 hrs reperfusion (mean increase of 2.8-fold vs. control), but the levels remained significantly elevated at 6 hrs reperfusion (mean increase of two-fold vs. control). Although not statistically significant, cardiac ventricle showed the highest intracellular adhesion molecule-1 messenger RNA levels at 6 hrs reperfusion. The brain had lower levels of intracellular adhesion molecule-1 messenger RNA than lung or ventricle and did not demonstrate induction.

CONCLUSIONS

We found an earlier peak induction of intracellular adhesion molecule-1 messenger RNA in lung compared with ventricle. This may represent both local ischemic injury and filtering of bypass-related inflammatory mediators in the pulmonary capillary bed. Early intracellular adhesion molecule-1 messenger RNA induction may reflect its role in neutrophil-mediated, ischemia-reperfusion injury.

Pulmonary dysfunction after cardiac surgery

Postoperative lung injury is one of the most frequent complications of cardiac surgery that impacts significantly on health-care expenditures and largely has been believed to result from the use of cardiopulmonary bypass (CPB). However, recent comparative studies between conventional and off-pump coronary artery bypass grafting have indicated that CPB itself may not be the major contributor to the development of postoperative pulmonary dysfunction. In our study, we review the associated physiologic, biochemical, and histologic changes, with particular reference to the current understanding of underlying mechanisms. Intraoperative modifications aiming at limiting lung injury are discussed. The potential benefits of maintaining ventilation and pulmonary artery perfusion during CPB warrant further investigation.

Inflammation After Cardiopulmonary Bypass: Therapy for the Postpump Syndrome

Cardiopulmonary bypass (CPB) is used in most, but not all, complex heart operations. CPB is associated with a systemic inflammatory response in adults and children. Many materials-dependent (exposure of blood to non- physiologic surfaces and conditions) and materials-in dependent (surgical trauma, ischemia-perfusion to the organs, changes in body temperature, and release of endotoxin) factors during CPB have been implicated in the etiology of this complex response. The mechanisms involved may include complement activation, release of cytokines, leukocyte activation with expression of ad hesion molecules, and production of various vasoactive and immunoactive substances. Postpump inflamma tion may lead to postoperative complications and may result in respiratory failure, renal dysfunction, bleeding disorders, neurologic dysfunction, altered liver func tion, and ultimately multiple organ failure. Significant efforts are being made to decrease the generation and effects of postpump inflammation. Interventions to this end have included avoiding CPB when possible, im proving the biocompatibility of the involved mechani cal devices, and administering medications that main tain cellular integrity. This article provides an overview of the etiology, pathophysiology, and treatment of postpump inflammation. Perhaps with additional in sight into this syndrome, CPB can be made a safer and more efficacious modality of cardiorespiratory support. Copyright© 2001 by W.B. Saunders Company.

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

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

Liquid lung ventilation reduces neutrophil sequestration in a neonatal swine model of cardiopulmonary bypass

OBJECTIVE

Liquid lung ventilation has been demonstrated to improve cardiorespiratory function after cardiopulmonary bypass. We hypothesized that liquid lung ventilation (LLV) would decrease the pulmonary inflammatory response after cardiopulmonary bypass (CPB).

DESIGN

Prospective, randomized, experimental, controlled, nonblinded study.

SETTING

Animal research laboratory at a university setting.

SUBJECTS

A total of 24 neonatal piglets.

INTERVENTIONS

After intubation with a cuffed endotracheal tube, swine were conventionally ventilated. After surgical cannulation, each piglet was placed on conventional nonpulsatile CPB and cooled to 18 degrees C (64.4 degrees F). Subsequently, the animals were exposed to 90 mins of low-flow CPB (35 mL/kg/min). Animals were rewarmed to 37 degrees C (98.6 degrees F), removed from CPB, and ventilated for 90 min. Ten animals received conventional gas ventilation only (control), seven received initiation of LLV before CPB (prevention), and seven received initiation of LLV during the rewarming phase of CPB (treatment). After the animals were killed, the lungs were removed en bloc. The left lobe was dissected and formalin-fixed at 20 cm H2O overnight, followed by paraffin embedding. Sections were taken from the paraffin-embedded lungs. Neutrophil accumulation and lung injury were assessed by histochemical staining with leukocyte esterase and morphometrics, respectively. One hundred microscopic images were digitized from each tissue sample for lung morphometrics, and neutrophil counts were obtained from every fifth image.

MEASUREMENTS AND MAIN RESULTS

Lung tissue sections showed a significantly lower number of neutrophils per alveolar area in the prevention and treatment groups than in the control group (control 681 +/- 65, prevention 380 +/- 49, treatment 412 +/- 101 neutrophils per alveolar area [cells/mm2]; p <.05 for both prevention and treatment compared with control). There were no differences in lung injury as assessed with morphometrics or hemodynamic measurements between any of the three groups.

CONCLUSIONS

The data suggest that LLV reduces the CPB-induced neutrophil sequestration in the pulmonary parenchyma independent of its effects on the circulatory physiology or evidence of early lung injury.

Low degree of activation of circulating neutrophils determined by flow cytometry during cardiac surgery with cardiopulmonary bypass

BACKGROUND

Enhanced expression of adhesion molecules LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18) following cardiac surgery with cardiopulmonary bypass (CPB) is held responsible for postoperative complications. Surface expression of these molecules, intracellular pH (pH(i)), and oxidative burst capacity was analyzed to test for neutrophil activation during pediatric cardiac surgery.

METHODS

Blood samples were drawn from 36 patients (age: 3--16 years) 24 h preoperatively, after onset of anesthesia, after connection to CPB (CPB1, before and after passing CPB, n = 15), at reperfusion (CPB2), and up to 7 days postoperatively. Cells adhering to CPB filters were isolated (n = 11). Antigen expression, pH(i), and oxidative burst capacity on neutrophils was analyzed by flow cytometry.

RESULTS

During surgery, oxidative burst capacity was at low level with a mild increase only 1 day after surgery. pH(i) was decreased throughout the surgery. Surgery induced more than 36% decrease of LFA-1 and Mac-1 expression (P < 0.03). Up to postoperative day 7, no increase of antigen expression above baseline was found. Neutrophils isolated from filters of the CPB had increased LFA-1 and Mac-1 expression (all P < 0.05). Integrin expression on neutrophils passing the CPB at CPB1 was decreased (P < 0.05).

CONCLUSION

Reduced adhesion molecule expression on neutrophils may be due to selective filtration of highly adhesive cells. This, in combination with low-level oxidative burst capacity, induced by immunosuppressive cytokines (e.g., interleukin-10), reduced the neutrophil activity. Our data indicate that increased activity of circulating neutrophils cannot exclusively be held responsible for postoperative complications after surgery with CPB.

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.

In situ expression of intercellular adhesion molecule-1 (ICAM-1) mRNA in calves with acute Pasteurella haemolytica pneumonia

The in situ expression of intercellular adhesion molecule-1 (ICAM-1) mRNA in normal and pneumonic lung tissues of Holstein calves with bovine leukocyte adhesion deficiency (BLAD) was compared with that of age-matched non-BLAD Holstein calves by in situ hybridization. Twenty-four Holstein calves (both BLAD and non-BLAD) were randomly assigned to one of two experimental groups and inoculated intrabronchially with Pasteurella haemolytica or pyrogen-free saline. Lung tissues were collected and fixed in 10% neutral formalin at 2 or 4 hours postinoculation (PI). The expression and distribution of ICAM-1 mRNA in the different cell types of the lung tissue was detected by in situ hybridization with a 307-base-pair bovine ICAM-1 riboprobe. In lungs of both non-BLAD and BLAD saline-inoculated calves, ICAM-1 expression was present in epithelial cells but occurred in <30% of cells in bronchi, bronchioles, and alveoli. ICAM-1 expression in vascular endothelial cells was present in <30% of cells in pulmonary arteries and veins. The expression of ICAM-1 was significantly greater (>60% of cells) in bronchiolar and alveolar epithelial cells and pulmonary endothelial cells of arteries and veins in both BLAD and non-BLAD calves inoculated with P. haemolytica. Bronchiolar epithelium had the highest intensity of mRNA expression and highest percentage of cells that were stained, whereas bronchial epithelium had the lowest intensity and percentage of cells stained. Most alveolar macrophages and neutrophils in infected lungs also expressed ICAM-1. ICAM-1 expression was generally increased in infected BLAD calves at 2 hours PI as compared with non-BLAD calves but not at 4 hours PI. The increased expression of ICAM-1 during acute P. haemolytica pneumonia in calves suggests that ICAM-1 is upregulated and may play a role in leukocyte infiltration. The extent of ICAM-1 expression in P. haemolytica-inoculated calves with BLAD was initially enhanced but otherwise similar to that in non-BLAD calves.

Analysis of intestinal microvascular permeability associated with cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass (CPB) is associated with a generalized inflammatory response and splanchnic edema formation that are thought to be related to microvascular barrier injury. In particular, intestinal edema and dysfunction have been associated with sepsis and post-CPB complications. The purpose of this study was to measure the forces determining fluid flux induced by CPB across the intestinal microvascular barrier.

MATERIALS AND METHODS

An anesthetized canine model was used for this study (n = 12). To determine mesenteric microvascular permeability, a mesenteric lymphatic was cannulated and mesenteric venous pressure was elevated to 33 +/- 1 mm Hg to reach a minimal lymph protein concentration (CL). With simultaneous measurement of plasma protein concentrations (CP), the reflection coefficient, sigma, was calculated using the formula: sigma = 1 - CL/CP. Capillary pressures (PC), lymph flow (QL), lymph protein flux, transvascular protein flux, and intestinal tissue water were all measured using standard techniques. Normothermic cardiopulmonary bypass with flows of 75-80 ml/kg/min was initiated after a steady state was achieved, and CPB was continued for 2 h and then discontinued. Measurements were repeated 30 min after CPB was discontinued. A second group (n = 5) was studied without mesenteric venous pressure elevation to evaluate the role of capillary pressure on the increased fluid flux seen with the initiation of CPB.

RESULTS

Initiation of CPB was associated with an increase in intestinal microvascular permeability. Sigma decreased from 0.77 +/- 0.01 to 0.68 +/- 0.01 (P < 0.05) with the initiation of CPB. This corresponded with statistically significant increases in both transvascular protein flux from 310 +/- 22 to 465 +/- 39 ml/min at 30 min and intestinal tissue water from 82.8 +/- 0.7 to 84.3 +/- 0.5% after weaning from CPB. Capillary pressure did not significantly increase with the initiation of CPB.

CONCLUSIONS

Initiation of CPB results in a moderate increase in intestinal microvascular permeability to protein and an increase in intestinal tissue water. The increases in tissue water are not due to increased capillary pressure. A better understanding of the microvascular changes associated with extracorporeal circulation will facilitate the search for clinical interventions to minimize the impact of CPB.