Aortobifemoral surgery induces complement activation and release of interleukin-6 but not tumour necrosis factor-alpha

Grading Distress of Different Animal Models for Gastrointestinal Diseases Based on Plasma Corticosterone Kinetics

Simple Summary

Animal welfare is an important aspect of biomedical research. Many regulations have been implemented to combine high quality of research with minimal harm to laboratory animals. These guidelines also demand a prospective severity assessment of each animal model. A comparison of distress between animal models could allow realistic harm and benefit analysis and an appropriate use of refinement methods. However, studies comparing distress between different animal models are still rare. One good parameter for analyzing distress is the concentration of the stress hormone corticosterone in the blood. Therefore, we compared the corticosterone kinetics of distinct gastrointestinal animal models. The aim of this study was to evaluate which parameter the highest corticosterone concentration or the duration of increased stress hormone level could be used to quantify distress. We observed a significant increase of corticosterone 30 min after stress induction in all animal models. However, the corticosterone kinetics differed between the distinct interventions. Both the absolute value and the duration of increased corticosterone level correlated directly with an assessed distress score. We conclude that both variables of corticosterone kinetics are valid parameters to compare distress between animal models.

Abstract

Comparative studies for evaluating distress in established animal models are still rare. However, this issue is becoming more important as a consequence of worldwide appreciation of animal welfare. One good parameter for evaluating distress is the quantification of corticosterone. We hypothesized that not just the absolute value but also the duration of increased corticosterone concentration in the blood is an important aspect for evaluating animal distress. Therefore, we analyzed plasma corticosterone concentrations 30, 60, 120, and 240 min after induction of pancreatitis by cerulein, liver damage by carbon tetrachloride, liver damage by bile duct ligation, and after orthotopic injection of pancreatic cancer cells. We also evaluated corticosterone kinetics after injection of distinct carrier substances. Compared to phosphate buffered saline, dimethyl sulfoxide leads to dose-dependent higher and longer-lasting circulating corticosterone concentrations. In all disease models, we observed significantly increased corticosterone concentration 30 min after stress induction. However, the corticosterone kinetics differed among the animal models. Both the absolute value of corticosterone concentration and the duration correlated positively with the quantification of animal distress by a score sheet. This suggests that both variables of corticosterone kinetics might provide a solid basis for comparing and grading distress of different animal models.

Comparison of the acute-phase response after laparoscopic versus open aortobifemoral bypass surgery: a substudy of a randomized controlled trial

PURPOSE

Minimally invasive surgical techniques have been shown to reduce the inflammatory response related to a surgical procedure. The main objective of our study was to measure the inflammatory response in patients undergoing a totally laparoscopic versus open aortobifemoral bypass surgery. This is the first randomized trial on subjects in this population.

PATIENTS AND METHODS

This is a substudy of a larger randomized controlled multicenter trial (Norwegian Laparoscopic Aortic Surgery Trial). Thirty consecutive patients with severe aortoiliac occlusive disease eligible for aortobifemoral bypass surgery were randomized to either a totally laparoscopic (n=14) or an open surgical procedure (n=16). The inflammatory response was measured by perioperative monitoring of serum interleukin-6 (IL-6), IL-8, and C-reactive protein (CRP) at six different time points.

RESULTS

The inflammatory reaction caused by the laparoscopic procedure was reduced compared with open surgery. IL-6 was significantly lower after the laparoscopic procedure, measured by comparing area under the curve (AUC), and after adjusting for the confounding effect of coronary heart disease (P=0.010). The differences in serum levels of IL-8 and CRP did not reach statistical significance.

CONCLUSION

In this substudy of a randomized controlled trial comparing laparoscopic and open aortobifemoral bypass surgeries, we found a decreased perioperative inflammatory response after the laparoscopic procedure measured by comparing AUC for serum IL-6.

A Global Assessment of the Inflammatory Response Elicited Upon Open Abdominal Aortic Aneurysm Repair

The inflammatory response during elective open infrarenal abdominal aortic aneurysm repair and its impact on outcome is investigated. Twenty high-risk patients were enrolled, and blood samples were obtained at 8 perioperative time points. Endotoxin, cytokines (tumor necrosis factor-α and interleukin-1β, and interleukin-6), CD11b expression, and nitric oxide were measured. Peak endotoxin levels occurred within 30 minutes of reperfusion and were higher among patients developing complications. Interleukin-6 levels increased during reperfusion, reaching a peak on the first postoperative day. Interleukin-6 increase correlated with aortic clamp time and morbidity. CD11b expression increased 30 minutes after reperfusion, and this effect was greater among patients who developed complications. Endotoxin may be important in the pathogenesis of multiple organ dysfunction syndrome. Activated neutrophils may have a central role in tissue injury after reperfusion. Intraoperative CD11b upregulation may be an early marker for postoperative complications after infrarenal abdominal aortic aneurysm repair.

Muscle glutathione metabolism during ischemia and reperfusion in patients undergoing aorto-bifemoral bypass surgery

BACKGROUND

After an ischemia time of 1 h during aortic aneurysm surgery, muscle glutathione redox-status is not altered, indicating that this ischemic insult is well within the scavenging capacity of muscle glutathione, the most important endogenous scavenger. In the present study, the impact of elective aorto-bifemoral bypass surgery, involving a longer ischemia time, on muscle glutathione and its redox-status was investigated.

METHODS

Leg muscle biopsies were obtained pre-operatively, at maximal ischemia, after 10 min and 24 h of reperfusion from 12 patients undergoing aorto-bifemoral bypass surgery. Muscle glutathione, free amino acids and energy-rich compounds were determined.

RESULTS

Clamping times were 113 (99-120 min); median (quartiles). At maximal ischemia, muscle lactate increased by 7.5 (4.0-10.7) mmol/kg dry weight (dw) (P < 0.001) and phosphocreatine (PCr) decreased by 14.6 (8.9-23.3) mmol/kg dw (P < 0.001). At maximal ischemia, reduced glutathione (GSH) was unaltered but muscle glutamate decreased by 0.51 (0.30-0.85) mmol/kg wet weight (ww) (P < 0.001). At 24 h post-operatively, the reduced glutathione decreased by 0.47 (0.34-0.65) mmol/kg (ww) (P < 0.001) without changes in oxidized glutathione (GSSG) or in glutathione redox-status. Cysteine and glycine, the two other constituent amino acids to glutathione, did not change during the study period.

CONCLUSION

Ischemia of 2 h during aorto-bifemoral bypass was associated with changes in muscle energy-rich compounds but without any changes in glutathione redox-status. A decreased antioxidative capacity, as reflected by a decrease in muscle glutathione concentrations, was seen 24 h post-operatively, still without changes in glutathione redox-status. This is not different from the changes seen after abdominal surgery not involving ischemia-reperfusion.

Effects on Skeletal Muscle Glutathione Status of Ischemia and Reperfusion Following Abdominal Aortic Aneurysm Surgery

Glutathione (GSH) is an important endogenous scavenger against reactive oxygen species. Elective abdominal surgery without ischemia and reperfusion leads to decreased muscle GSH concentrations 4-72 hr postoperatively without altering GSH redox status. In the present study, we investigated to what extent muscle GSH status was affected during and following elective abdominal aortic aneurysm repair. From patients (n = 10) undergoing abdominal aortic repair, thigh muscle specimens were taken preoperatively, at maximal ischemia, and at 10 min and 4, 24, and 48 hr of reperfusion. Specimens were analyzed for GSH, amino acids, and energy-rich compounds. At maximal ischemia, phosphocreatine decreased by 37% (p < 0.05) and lactate and creatine increased by 274% and 57% (p < 0.001 and 0.05), respectively, indicating ischemia during the clamping of aorta. Adenosine triphosphate, on the other hand, remained unaltered during the entire study period. Total GSH (tGSH) decreased by 46% at 24 hr and by 43% at 48 hr of reperfusion (p < 0.001), while reduced GSH decreased by 48% at 24 hr and by 44% at 48 hr (p < 0.001). The redox status (GSH/tGSH) of GSH and oxidized GSH remained unaltered. Among the constituent amino acids of GSH, glycine and cysteine remained unaltered while glutamine and glutamate decreased by 55% and 55%, respectively (p < 0.001). Abdominal aortic aneurysm repair induces metabolic alterations characteristic for ischemia. The antioxidative capacity in terms of muscle levels of GSH was decreased. However, the oxidative stress during reperfusion did not change GSH status more than what has been reported following abdominal surgery without ischemia and reperfusion. The results indicate that the oxidative stress elicited by elective abdominal aortic aneurysm repair is outbalanced by a compensated GSH metabolism not giving rise to an increased amount of oxidized GSH or an altered GSH redox status.

Perioperative myocardial infarction in non-cardiac surgery. Pathophysiology and clinical implications

Advances in surgical and anaesthetic techniques and an aging patient population have resulted in more complex procedures being performed in greater numbers of aged subjects and in patients with a high likelihood of significant cardiovascular disease. Nearly one fourth of non-cardiac surgical procedures (major intra-abdominal, thoracic, vascular, and orthopaedic procedures) performed in persons older than 65 years have been found to be associated with significant perioperative cardiovascular morbidity and mortality. During previous years the main attempt was to define strategies to accurately estimate perioperative cardiovascular risk based either on the characteristics of surgery and on patient characteristics. More recently preventive medical strategies have been proposed. Therefore, the physician has to be aware of the key elements useful to calculate the perioperative cardiovascular risk, and of the medical preventive treatment or further interventions to adopt in patients candidate to surgery.

The Inflammatory Response and its Consequence for the Clinical Outcome Following Aortic Aneurysm Repair

OBJECTIVE

to review published studies on the outcome of the inflammatory response after abdominal aortic aneurysm (AAA) repair.

METHODS

a literature search on PubMed was performed. All studies that determined the inflammatory response (cytokine release) after AAA repair were included. The results of the studies and differences between open and endoluminal repair were compared and evaluated.

RESULTS

seventeen studies were identified. In most studies the investigated cytokines were TNF-alpha and IL-6. Determination of IL-1 beta, IL-8, TNFsr1 and TNFsr2 were less often performed. TNF-alpha may reflect, but not strictly predict, the clinical outcome in patients with ruptured AAA. IL-6 levels correlate well with the surgical trauma per se. Variations in recorded cytokine release during endovascular AAA repair may depend on the times of blood sampling.

CONCLUSION

both open and endovascular AAA repair provoke a cytokine response. This response is greater during open repair than during endovascular aortic aneurysm exclusion.

Recombinant bactericidal/permeability-increasing protein attenuates the systemic inflammatory response syndrome in lower limb ischemia-reperfusion injury

OBJECTIVES

Hind limb ischemia-reperfusion (I/R) injury increases gut permeability, and resultant endotoxemia is associated with an amplified systemic inflammatory response syndrome leading to multiple organ dysfunction syndrome. We studied the potential role of recombinant bactericidal/permeability-increasing protein (rBPI(21) ), a novel antiendotoxin therapy, in modulating endotoxin-enhanced systemic inflammatory response syndrome in hind limb I/R injury.

METHODS

In this prospective, randomized, controlled, experimental animal study, 48 male Wistar rats, weighing 300 to 350 g, were randomized to a control group (sham) and five groups undergoing 3 hours bilateral hind limb ischemia with 2 hours reperfusion (I/R) (n = 8 per group). The control and untreated I/R groups received thaumatin, a control-protein preparation, at 2 mg/kg. Treatment groups were administered rBPI(21) intravenously at 1, 2, or 4 mg/kg body weight at the beginning of reperfusion; an additional group was administered rBPI(21) intravenously at 2 mg/kg after 1 hour of reperfusion. Plasma interleukin-6 concentration was estimated by bioassay as a measure of systemic inflammation. Plasma endotoxin concentration was determined by use of an amebocyte lysate chromogenic assay. Crossreactive immunoglobulin G and M antibodies to the highly conserved inner core region of endotoxin were measured by use of an enzyme-linked immunosorbent assay. The lung tissue wet-to-dry weight ratio and myeloperoxidase concentration were used as markers of edema and neutrophil sequestration, respectively.

RESULTS

I/R provoked highly significant elevation in plasma interleukin-6 concentrations (1351.20 pg/mL [860.16 - 1886.40 pg/mL]) compared with controls (125.32 pg/mL [87.76-157.52 pg/mL; P <.0001]), but treatment with rBPI(21) 2 mg/kg at onset of reperfusion (715.89 pg/mL [573.36-847.76 pg/mL]) significantly decreased interleukin-6 response compared with the nontreatment group ( P <.016). I/R increased plasma endotoxin concentrations significantly (21.52 pg/mL [6.20-48.23 pg/mL]), compared with control animals (0.90 pg/mL [0.00-2.30 pg/mL; P <.0001]), and treatment with rBPI(21) 4 mg/kg at reperfusion significantly decreased endotoxemia (1.30 pg/mL [1.20-2.20 pg/mL]), compared with the untreated group ( P <.001). The lung tissue myeloperoxidase level was significantly increased in the untreated I/R group (208.18% [128.79%-221.81%]), compared with in controls (62.00% [40.45%-80.92%; P <.0001]), and attenuated in those treated with rBPI(21) 2 mg/kg (129.54% [90.49%-145.78%; P <.05]). Data represent median and interquartile range, comparisons made with the nonparametric Mann-Whitney U test.

CONCLUSIONS

These findings show that hind limb ischemia-reperfusion injury is associated with endotoxemia, elevations in plasma interleukin-6, and pulmonary leukosequestration. Treatment with rBPI(21) after ischemia reduces endotoxemia, the interleukin-6 response, and attenuates pulmonary leukosequestration in response to hind limb reperfusion injury.

Response of inflammatory markers to balloon angioplasty in peripheral arterial occlusive disease

OBJECTIVES

To study the inflammatory response to balloon angioplasty (PTA).

DESIGN

Prospective study.

MATERIALS

Blood samples were drawn for cytokine analysis from 10 patients undergoing PTA before, after 60 min and 6 h after the balloon inflation. Adhesion molecules were analysed in 14 patients undergoing PTA and in seven patients undergoing angiography only. Arterial samples were taken in eight patients, before PTA, immediately after and 15 min later. Venous samples were taken in six patients and in the group undergoing angiography only. The sampling was before, 60, 90 and 120 min after the procedure. As controls served 15 patients with no signs of peripheral arterial disease.

METHODS

Cytokines (IL-6, TNF-alpha) were analysed using ELISA. Adhesion molecule expression on WBC was measured by flow cytometry.

RESULTS

A significant increase of IL-6 in the sample taken 6 h after the last balloon inflation was seen in five patients. TNF-alpha was raised only in one patient. The group of patients with peripheral arterial occlusive disease (PAOD) expressed pre-interventionally a higher level of adhesion molecules on WBC compared to the controls. The expression of adhesion molecules (CD11b/CD18) was significantly decreased after PTA.

CONCLUSION

Only a very limited cytokine response is caused by PTA reflecting the small surgical trauma. PTA results in a downregulation of detectable CD11b/CD18 expression on WBC in the circulation, which may reflect removal of activated cells through adhesion and extravasation.

Early inflammatory response after elective abdominal aortic aneurysm repair: a comparison between endovascular procedure and conventional surgery

OBJECTIVE

To determine the nature of and to compare the inflammatory responses induced by (1) endovascular and (2) conventional abdominal aortic aneurysm (AAA) repair.

MATERIAL AND METHODS

Twelve consecutive patients undergoing elective infrarenal AAA repair were prospectively studied. Seven patients were selected for endovascular procedures (the EAAA group); five patients underwent open surgery (the OAAA group). Three control patients undergoing carotid thromboendarterectomy were also included. Serial peripheral venous blood samples were collected preoperatively, immediately after declamping or placement of the endograft, and at hours 1, 3, 6, 12, 24, 48, and 72. Acute phase response expression of peripheral T lymphocyte and monocyte activation markers and adhesion molecules (flow cytometry), soluble levels of cell adhesion molecules (enzyme-linked immunosorbent assay), cytokine (tumor necrosis factor alpha, interleukin-6, and interleukin-8) release (enzyme-linked immunosorbent assay), and liberation of complement products (nephelometry) were measured.

RESULTS

Regarding acute phase response, the EAAA and OAAA groups showed significant increases in C-reactive protein (P <.001 and P =.001), body temperature (P =.035 and P =.048), and leukocyte count (P <.001 and P <.001). Similar time course patterns were observed with respect to body temperature (P =.372). Statistically significant different patterns were demonstrated for C-reactive protein (P =.032) and leukocyte count (P =.002). Regarding leukocyte activation, a significant upregulation of peripheral T lymphocyte CD38 expression was observed in the OAAA group only (P =.001). Analysis of markers such as CD69, CD40L, CD25, and CD54 revealed no perioperative fluctuations in any group. Regarding circulating cell adhesion molecules, the EAAA and OAAA groups displayed significant increases in soluble intercellular adhesion molecule-1 (P =.003 and P =.001); there was no intergroup difference (P =.193). All groups demonstrated high soluble von Willebrand factor levels (P =.018, P =. 007, and P =.027), there being no differences in the patterns (P =. 772). Otherwise, soluble vascular cell adhesion molecule-1, soluble E-selectin, and soluble P-selectin did not appear to vary in any group. Regarding cytokine release, although a tendency toward high tumor necrosis factor alpha and interleukin-8 levels was noticed in the EAAA group, global time course effects failed to reach statistical significance (P =.543 and P =.080). In contrast, interleukin-6 showed elevations in all groups (P =.058, P <.001, and P =.004). Time course patterns did not differ between the EAAA and OAAA groups (P =.840). Regarding complement activation, the C3d/C3 ratio disclosed significant postoperative elevations in the EAAA and OAAA groups (P =.013 and P =.009). This complement product release was reduced in the EAAA group (P <.001).

CONCLUSIONS

The current study indicated that both endovascular and coventional AAA repair induced significant inflammatory responses. Our findings showed that there were no large differences between the procedures with respect to circulating cell adhesion molecule and cytokine release. Moreover, the endoluminal approach produced a limited response in terms of acute phase reaction, T lymphocyte activation, and complement product liberation. This might support the concept that endovascular AAA repair represents an attractive alternative to open surgery. Given the relatively small sample size, further larger studies are required for confirmation of our observations.

The inflammatory response following treatment of abdominal aortic aneurysms: a comparison between open surgery and endovascular repair

OBJECTIVES

to compare the inflammatory response following endovascular and conventional AAA repair.

DESIGN

prospective study.

PATIENTS AND METHODS

ten patients were selected for open surgery (OPEN) and ten for endovascular (ENDO) AAA repair. Leukocytes, platelets, myeloperoxidase, lactoferrin, beta-thromboglobulin, C-reactive protein (CRP), interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-alpha) and complement activation products were measured before, during and after surgery.

RESULTS

in the OPEN group the median hospital stay was longer (6 vs. 12 days, p=0.001) and more patients required transfusion (p=0.02). IL-6 and CRP increased postoperatively, most in OPEN (p<0.01). Platelet counts decreased after the first angiography in ENDO (p<0.01) and before aortic cross-clamping in OPEN (p<0.05). The decrease was larger in OPEN (p=0.02). Leukocyte counts decreased after the first angiography in ENDO, and thereafter increased (p=0.001). An equivalent increase was observed in OPEN after declamping (p=0.001). Leukocyte and platelet degranulation products increased after the first angiography in ENDO and after declamping in OPEN. Changes in complement activation products were small. TNF-alpha did not change significantly.

CONCLUSION

endovascular AAA repair caused significant leukocyte and platelet activation. Based on the timing of activation this could be caused by radiographic contrast media.

Systemic consequences of oxidative stress following aortic surgery correlate with the degree of antioxidant defenses

The purpose of this study was to correlate the preoperative level of antioxidant defenses, measured by the plasma total antioxidant capacity (TAC), to the degree of postoperative systemic inflammatory response, measured by the severity of pulmonary injury following elective aortic surgery. Twenty-four patients had TAC measured preoperatively and 24 hr postoperatively. Chest radiography and arterial blood gases were obtained preoperatively and serially during the first 24 hr after surgery. Using objective radiologic criteria and blood gas analysis, the degree of pulmonary edema and pulmonary dysfunction were quantified. All patients showed evidence of pulmonary dysfunction in the first 24 hr following surgery. Fifteen of the 24 patients showed radiographic evidence of noncardiogenic pulmonary edema in the immediate postoperative period. In this group, the TAC was lower than in those without pulmonary edema immediately following surgery (p = 0.03). Preoperative TAC was associated with the degree of pulmonary edema in the postoperative period (r = -0.372, p = 0.067). These results suggest that preoperative antioxidant supplementation may favorably impact the severity of systemic inflammatory response following ischemia and reperfusion injury.

Impregnated polyester arterial prostheses: performance and prospects

Impregnated polyester arterial prostheses have gained wide acceptance by most vascular surgery teams, probably because these prostheses are easy to use, without any preclotting. We offer here a synthesis of the main studies that have appraised the experimental and clinical performance of these prostheses, and we delineate their major prospects.

Cytokine and fibrinogen response in patients undergoing open abdominal aortic aneurysm surgery

OBJECTIVES

To assess whether open abdominal aortic aneurysm (AAA) surgery influences cytokines and fibrinogen.

METHODS

Twenty-three consecutive patients operated on for AAA were compared to 11 operated controls and 20 age-matched controls. Cubital blood was sampled pre-, intra- and postoperatively and femoral blood also sampled intraoperatively.

RESULTS

Preoperatively, interleukin (Il)-6 was elevated in AAA patients. During aortic clamping, Il-6, Il-10 and monocyte chemoattractant protein-1 (MCP-1) increased significantly (p < 0.001, p < 0.01 and p < 0.05 respectively) while soluble interleukin-2 receptor (sIl-2R) and fibrinogen decreased significantly (p < 0.001 for both). After aortic declamping, Il-6, Il-10 and MCP-1 had further significant increases compared with levels during aortic clamping while sIl-2R had a further non-significant and fibrinogen a significant decrease (p < 0.05 in cubital and p < 0.001 in femoral blood). One week postoperatively Il-6, Il-10 and MCP-1 had all decreased but were still significantly elevated compared with baseline values while sIl-2R and fibrinogen showed an increase in comparison with baseline (p < 0.001 for both). Intraoperative levels of Il-6 and Il-10 showed a significant co-variation with the magnitude of operative trauma.

CONCLUSIONS

These data indicate that open AAA surgery induces a profound inflammatory and coagulative response which persists at one week postoperatively.

Postoperative fever, bowel ischaemia and cytokine response to abdominal aortic aneurysm repair--a comparison between endovascular and open surgery

OBJECTIVES

To study bowel ischaemia in transfemorally placed endoluminal grafting (TPEG) for abdominal aortic aneurysms, and any relation to cytokine response or postoperative fever.

DESIGN

Prospective not randomised. University hospital setting.

MATERIAL

Fourteen cases of conventional surgery and 23 cases of endovascular technique for infrarenal abdominal aortic aneurysm repair.

METHODS

Tonometry was used for sigmoid colon pH, and ELISAs for serum IL-6.

RESULTS

Mucosal pH in the sigmoid colon fell significantly during clamping and reperfusion in both groups. Lowest measured sigmoid colon pH was 7.10 in the open group, compared to 7.22 in the TPEG group (p < 0.05). The IL-6 levels in serum peaked after 4 h of reperfusion; 249 pg/ml in the open group, compared to 89 pg/ml in the TPEG group (p < 0.05). High levels of IL-6 in the postoperative period and persisting low sigmoidal pH were associated with serious complications. Postoperative temperature did not differ significantly between the groups, and no significant correlation could be found with sigmoid colon pH or IL-6 levels.

CONCLUSIONS

The less pronounced perioperative bowel ischaemia in TPEG patients indicates an advantage of the TPEG technique. Splanchnic ischaemia was not related to postoperative fever, nor the IL-6 or TNF response.

The inflammatory response to vascular surgery-associated ischaemia and reperfusion in man: effect on postoperative pulmonary function

OBJECTIVES

To characterise the inflammatory response to vascular surgery and ischaemia/reperfusion (I/R) in man, regarding release of inflammatory mediators, recruitment and activation of neutrophils, and their relation to postoperative pulmonary function.

DESIGN

Prospective cohort study.

MATERIALS AND METHODS

Circulating neutrophil counts and plasma levels of elastase-alpha 1-antitrypsin (AT), a neutrophil degranulation product, were measured before and approx. 2.5 h (group 1, n = 19) after elective abdominal aortic surgery, and approx. 2.9 h after elective peripheral vascular surgery (group 2, n = 6), together with concentrations of neutrophil agonists, including activated complement (C3a), secretory phospholipase A2 (sPLA2), tumor necrosis factor (TNF-alpha), interleukin (IL)-6, IL-8 and granulocyte colony-stimulating factor (G-CSF). At the time of blood sampling, respiratory variables allowing computation of the lung injury score (LIS) were obtained in patients admitted after surgery in the intensive care unit (ICU), i.e. all group 1 patients and one group 2 patient.

RESULTS

Median (range) neutrophil counts rose by 80% (-28-208) and 90% (10-147) in groups 1 and 2, respectively (n.s. between groups). The increase (p < 0.05) in elastase-alpha 1-AT level was 121% (-5-439) in group 1 and 82% (18-792) in group 2 (n.s. between groups). There was a rise (p < 0.05) in C3a level by 93% (-42-751) and of sPLA2 level by 68% (-40-1400) after surgery for the groups together (n.s. between groups), and the rise of the elastase-alpha 1-AT related to that of the C3a levels. IL-6 and G-CSF concentrations increased more in group 1 than 2. The IL-8 concentration increased in group 1 only, and TNF-alpha was unchanged in all groups. In ICU patients, the LIS related to the postoperative rise in IL-6 level only, even though the rise in plasma concentrations of cytokines interrelated. No patient developed ARDS and all survived.

CONCLUSIONS

Vascular surgery and I/R in man activates complement, releases cytokines (except for TNF-alpha), and induces neutrophil recruitment and degranulation, which may primarily depend on complement activation. In contrast to the latter, the release of cytokines may depend on the extent of I/R and may contribute to transient pulmonary dysfunction after extensive I/R.