A randomised controlled trial of two supervised exercise regimens and their impact on inflammatory burden in patients with intermittent claudication.

OBJECTIVE: This study assesses the impact of treadmill-based SET alone or in combination with resistance training on systemic inflammatory response, in patients with intermittent claudication (IC). METHODS: Thirty-five patients with IC were randomised to 12 weeks of treadmill-only SET (Group 1) or a combination of treadmill and lower-limb resistance SET (Group 2). A panel of pro- and anti-inflammatory markers were assessed before, during and after the SET. RESULTS: Over the duration of SET, homocysteine increased within Group 1 (12.0-15.5 µmol/L, p = 0.003) but not Group 2, (13.7-14.7 µmol/) while neutrophil elastase (NE) increased within Group 2 (174.5-238.2 ng/mL, p = 0.007) but not Group 1 (300.8-312.0 ng/mL). In both groups NE increased following acute exercise at the start of the SET. Differences in cytokine expression was evident between the two groups (in Group 1, pro-inflammatory cytokines interleukin-12 and interferon-gamma decreased following an acute bout of exercise at the end of SET, where as in Group 2 pro-inflammatory cytokines interleukin-6 and 8 were seen to increase after an acute bout of exercise at the end of SET). CONCLUSION: SET in patients with IC influences the complex immune-modulatory state of atherosclerosis through inflammatory pathways that induce both pro-inflammatory and immunosuppressive responses.

Estimating energy expenditure in vascular surgery patients: Are predictive equations accurate enough?

BACKGROUND & AIMS: Malnutrition is prevalent in vascular surgical patients who commonly seek tertiary care at advanced stages of disease. Adjunct nutrition support is therefore pertinent to optimise patient outcomes. To negate consequences related to excessive or suboptimal dietary energy intake, it is essential to accurately determine energy expenditure and subsequent requirements. This study aims to compare resting energy expenditure (REE) measured by indirect calorimetry, a commonly used comparator, to REE estimated by predictive equations (Schofield, Harris-Benedict equations and Miller equation) to determine the most suitable equation for vascular surgery patients. METHODS: Data were collected from four studies that measured REE in 77 vascular surgery patients. Bland-Altman analyses were conducted to explore agreement. Presence of fixed or proportional bias was assessed by linear regression analyses. RESULTS: In comparison to measured REE, on average REE was overestimated when Schofield (+857 kJ/day), Harris-Benedict (+801 kJ/day) and Miller (+71 kJ/day) equations were used. Wide limits of agreement led to an over or underestimation from 1552 to 1755 kJ. Proportional bias was absent in Schofield (R2 = 0.005, p = 0.54) and Harris-Benedict equations (R2 = 0.045, p = 0.06) but was present in the Miller equation (R2 = 0.210, p < 0.01) even after logarithmic transformation (R2 = 0.213, p < 0.01). CONCLUSIONS: Whilst the Miller equation tended to overestimate resting energy expenditure and was affected by proportional bias, the limits of agreement and mean bias were smaller compared to Schofield and Harris-Benedict equations. This suggested that it is the preferred predictive equation for vascular surgery patients. Future research to refine the Miller equation to improve its overall accuracy will better inform the provision of nutritional support for vascular surgery patients and subsequently improve outcomes. Alternatively, an equation might be developed specifically for use with vascular surgery patients.

The impact of abdominal aortic aneurysm on muscle mass and energy expenditure: A novel preliminary investigation.

OBJECTIVE: Vascular surgical patients, including those with abdominal aortic aneurysm (AAA), are nutritionally vulnerable. The aim of this study was to compare resting energy expenditure (REE) of patients with AAA relative to age- and gender-matched controls and explore relationships between aneurysm size and muscle mass. METHODS: Twenty patients with AAA underwent assessment of REE using indirect calorimetry. Mid-arm circumference and triceps skinfold thickness were measured and corrected arm muscle area calculated. Twenty gender- and age-matched controls were assessed using the same procedures. RESULTS: Mean (SD) age of participants with AAA was 74.7 (7.7) years, size of AAA ranged from 45 to 70 mm. Median (IQR) REE was significantly higher than controls [5990 (5469, 7017) kJ/day versus 5086 (4536, 5886) kJ/day, p = .011; or 69 (64, 80) kJ/kg/day versus 66 (61, 69) kJ/kg/day, p = .046]. While weight-adjusted REE was independent of aneurysm size (r = .200; p = .397), as aneurysm size increased, weight-adjusted corrected arm muscle area decreased (r = -.576; p = .008). CONCLUSION: The raised REE and decline in muscle mass associated with larger AAA suggest that early detection and attention to nutritional requirements of patients with AAA may be warranted.

Lower pain and faster treatment with mechanico-chemical endovenous ablation using ClariVein®.

OBJECTIVES: To assess the efficacy of the ClariVein(®) system of mechanico-chemical ablation of superficial vein incompetence. METHOD: ClariVein(®) treatment uses a micropuncture technique and a 4-Fr sheath to allow a catheter to be placed 1.5 cm from the saphenofemoral junction. Unlike laser (endovenous laser treatment (EVLT)) or radiofrequency ablation (RFA), no tumescence is required. The technique depends on a wire rotating at 3500 r/min causing endothelial damage whilst liquid sclerosant (1.5% sodium tetradecyl sulphate) is infused. The wire is pulled back whilst continuously infusing sclerosant along the target vessel's length. Initially, 8 mL of dilute sclerosant was used, but this was subsequently increased to 12 mL. No routine post-op analgesia was prescribed and specifically no non-steroidal anti-inflammatory drugs. Procedure times and pain scores (visual analogue scale) were recorded and compared to EVLT and RFA. All patients were invited for duplex post-procedure. RESULTS: Fifty-one great saphenous veins and six short saphenous veins were treated and followed up with duplex in the 10 months from July 2011. No major complications or deep vein thrombosis were reported. Duplex showed patency of three treated veins with two more veins having only a short length of occlusion, giving a technical success rate of 91%. Comparison with 50 RFA and 40 EVLT showed procedure times were significantly less for ClariVein(®) (23.0 ± 8.3 min) than for either RFA (37.9 ± 8.3 min) or EVLT (44.1 ± 11.4 min). Median pain scores were significantly lower for ClariVein(®) than RFA and EVLT (1 vs. 5 vs. 6, p < 0.01). CONCLUSION: Mechanochemical ablation with the ClariVein(®) system is safe and effective. After some initial failures, the use of 12 mL of dilute sclerosant results in a very high technical success rate >90% which accords with the limited published literature. Procedure times and pain scores are significantly better than for RFA and EVLT. We await the long-term clinical outcomes.

A randomised controlled trial of supervised exercise regimens and their impact on walking performance, skeletal muscle mass and calpain activity in patients with intermittent claudication.

OBJECTIVES: Supervised exercise training (SET) is recommended for patients with intermittent claudication (IC). The optimal exercise programme has not been identified, and the potential adverse effects of exercise on these patients warrant consideration. Calpain proteases have been linked with tissue atrophy following ischaemia-reperfusion injury. High calpain activity may therefore cause muscle wasting in claudicants undergoing SET, and skeletal muscle mass (SMM) is integral to healthy ageing. This study assesses the impact of (1) treadmill-based SET alone; and (2) treadmill-based SET combined with resistance training on pain-free walking distance (PFWD), SMM, and calpain activity. METHODS: Thirty-five patients with IC were randomised to 12 weeks of treadmill only SET (group A), or combined treadmill and lower-limb resistance SET (group B). PFWD via a 6-minute walking test, SMM via dual energy X-ray absorptiometry, and calpain activity via biopsies of gastrocnemius muscles were analysed. RESULTS: Intention-to-treat analyses revealed PFWD improved within group A (160 m to 204 m, p = .03), but not group B (181 m to 188 m, p = .82). There was no between group difference (p = .42). Calpain activity increased within group A (1.62 × 10(5) fluorescent units [FU] to 2.21 × 10(5) FU, p = .05), but not group B. There was no between group difference (p = .09). SMM decreased within group A (-250 g, p = .11) and increased in group B (210 g, p = .38) (p = .10 between groups). Similar trends were evident for per protocol analyses, but, additionally, change in SMM was significantly different between groups (p = .04). CONCLUSIONS: Neither exercise regimen was superior in terms of walking performance. Further work is required to investigate the impact of the calpain system on SMM in claudicants undertaking SET.

A comparison of flow-mediated dilatation and peripheral artery tonometry for measurement of endothelial function in healthy individuals and patients with peripheral arterial disease.

OBJECTIVE: Flow-mediated dilatation (FMD) and peripheral artery tonometry (PAT) are commonly used methods for assessing endothelial function in a research setting but it is unclear how well they correlate. This study aimed to compare and correlate these methods in patients with peripheral arterial disease (PAD) and in healthy individuals. MATERIALS AND METHODS: FMD and PAT measurements were obtained as samples of convenience from 26 patients with PAD and 25 healthy subjects. FMD was defined as the percentage increase in the brachial artery diameter after distal occlusion and PAT was measured using the reactive hyperaemia index (RHI). RESULTS: Patients with PAD had a significantly lower FMD than healthy subjects (2.43% vs. 5.80%, p < 0.001). No difference was found in RHI between the two groups. No correlation was found between the FMD and RHI in subjects with PAD (r = 0.284, p = 0.160), in healthy subjects (r = 0.153, p = 0.464) or when both groups were combined (r = 0.174, p = 0.22). CONCLUSION: The lack of change in RHI in PAD patients suggests that PAT is not a sensitive measure of endothelial function. The lack of correlation suggests that FMD and PAT are not interchangeable. PAT should not be used as a substitute for FMD as a measure of endothelial function.

Curative resection and reconstruction of the inferior vena cava after extensive infiltration with low-grade endometrial stromal sarcoma.

Endometrial stromal sarcoma (ESS) rarely infiltrates the great vessels. We report a successful surgical resection of the inferior vena cava (IVC) after extensive infiltration with metastatic low-grade ESS. A case of presumed recurrence of low-grade ESS demonstrated complete IVC occlusion from tumour thrombus with extensive local disease. Radical resection of the tumour and caval reconstruction was performed. The IVC graft was thrombosed at short-term follow-up. Curative resection of extensive caval infiltration with metastatic low-grade ESS can be achieved. Caval reconstructive procedures may be redundant in the presence of an adequate collateral circulation.

Is endovenous laser ablation possible while taking warfarin?

PURPOSE: The subgroup of patients with venous ulcers requiring anticoagulation for co-morbid conditions has traditionally created a therapeutic dilemma. Perioperative management of anticoagulation can be costly and increase the risk of surgical complications. This group of patients is often elderly and shows poor compliance with compression hosiery. The aim of this study was to investigate the outcome of endovenous laser ablation (EVLA) of the great saphenous vein (GSV) in patients remaining on therapeutic anticoagulation. MATERIALS AND METHODS: Fifteen consecutive patients (CEAP [clinical, aetiological, anatomical and pathological elements] classification 5 or 6) were treated with standard GSV EVLA using tumescent anaesthesia and a diode 1470-nm radial laser fibre while maintaining international normalized ratio at therapeutic levels. Clinical and duplex follow-up at six weeks and three, six and 12 months were performed. RESULTS: The GSV was successfully occluded in 14/15 (93%) of patients. The remaining patient had a second successful treatment three months later. No significant complications requiring intervention were encountered. CONCLUSION: EVLA using the diode 1470-nm radial fibre is efficacious with minimal complications in patients therapeutically anticoagulated. This treatment should be added to the armamentarium in this problematic patient group.

Anatomical suitability for endovascular AAA repair may affect outcomes following rupture.

OBJECTIVES: Single centre series have suggested that endovascular aneurysm repair (EVAR) for ruptured abdominal aortic aneurysms (rAAA) may reduce mortality versus open surgery. This has not been substantiated in the only randomized controlled trial, leading to suggestion that anatomical suitability for rEVAR may independently improve prognosis of rAAA. Our aim was to assess the outcome of open rAAA repair in patients dependant on their suitability for rEVAR on pre-operative computed tomography (CT) assessment. METHODS: A retrospective review of all ruptured aneurysms presenting to our unit since January 1998 was performed. Patients were grouped based on anatomical suitability for rEVAR by pre-operative CT. RESULTS: Of 118 patients presenting with rAAA, 48 underwent pre-operative CT. Of these 9 scans had been "culled" and were excluded. 16 patients were suitable for rEVAR and 23 unsuitable. The groups were well matched demographically with no difference in Glasgow Aneurysm Score between groups. There was a non-significant trend towards reduction in 30-day mortality for patients suitable for EVAR (suitable 6.9% versus unsuitable 30.4%; P = 0.066) with no difference in operative time, transfusion requirement, length of stay or in-hospital morbidity. CONCLUSIONS: Anatomical suitability for EVAR seems to beneficially affect outcome following open repair for ruptured AAA. Further study is required to confirm these findings.

The use of ultrasound to assist deployment of the StarClose vascular closure device in arterial access sites.

Access site complication rates remain relatively high following interventional procedures and have not been shown to be reduced by the use of vascular closure devices. This report describes an ultrasound-assisted technique of deploying one type of vascular closure device, the StarClose (Abbott Vascular, Illinois, USA). This technique has significantly reduced failure rates and complication rates since its introduction. The technique is relatively simple but requires familiarity with the use of ultrasound and the StarClose device.

Incomplete cellular depopulation may explain the high failure rate of bovine ureteric grafts.

BACKGROUND: The aim was to assess the results of a decellularized bovine ureter graft (SynerGraft) for complex venous access. METHODS: Bovine ureter conduits were implanted in patients with a failed fistula or access graft in whom native vessels were unsuitable as conduits. Graft histories were obtained from all patients who had undergone this procedure at one institution. Failed grafts were explanted and subjected to histological examination. A sample of fresh bovine ureter was immunostained for galactose (alpha1 --> 3) galactose (alpha-Gal). RESULTS: Nine patients with a median age of 46 (range 25-70) years underwent complex venous access surgery between August 2004 and November 2006 using a SynerGraft. Graft types included loop superficial femoral artery to stump of long saphenous vein (four patients), loop brachial artery to vein (two), brachial artery to axillary vein (two) and left axillary artery to innominate vein (one). Three grafts developed aneurysmal dilatation and two thrombosed. Histological assessment of the explanted bovine ureters revealed acute and chronic transmural inflammation. Immunostaining of fresh bovine ureter suggested residual cells and the xenoantigen alpha-Gal. CONCLUSION: Graft failure with aneurysmal dilatation and thrombosis in complex arteriovenous conduits using bovine ureter may be due to residual xenoantigens.

Should cardiac troponins be used as a risk stratification tool for patients with chronic critical limb ischaemia?

OBJECTIVES: Cardiovascular mortality in patients with chronic critical lower limb ischaemia (CCLI) is high and early risk stratification in these patients may aid clinical management improving outcomes. Cardiac troponin I (cTnI) has prognostic significance in patients with unstable angina. The aim of this study was to evaluate the prognostic significance of cardiac troponins in CCLI patients who had no clinical evidence of unstable coronary heart disease. METHODS: Patients (n=152) admitted with CCLI to a single vascular unit over a two-year period were included prospectively in this study. Patients with clinical evidence of unstable coronary disease were excluded from the study. Patient demographics, clinical history, co-morbidity and risk factors for peripheral vascular disease were documented. Admission cTnI levels were recorded using a threshold, 0.1 ng/ml. The primary endpoint was mortality. RESULTS: Fifty-two patients (34.2%) had an elevated cTnI, whilst 100 (65.8%) had cTnI <0.1 ng/ml. Sixty-two patients died during the follow-up period, 38 with an elevated admission cTnI. Death rate in patients with cTnI >0.1 ng/nl was 73% compared with 24% in those with levels below the threshold (p<0.0001). Patients with elevated cTnI were significantly older than those with normal level (median age 76 years vs 71 years, p<0.001). An elevated cTnI was found to independently predict disease-specific mortality on Cox regression analysis (Hazard Ratio 4.2; 95% Confidence Interval 1.3-12.7). CONCLUSION: In this series of patients with CCLI the measurement of cTnI on admission was a significant independent predictor of survival. cTnI has potential as a prognostic test to stratify patients with a high cardiovascular risk and may enable further optimisation of these high-risk patients.

Hyperhomocysteinaemia is associated with the rate of abdominal aortic aneurysm expansion.

OBJECTIVES: Previous literature has suggested an association between AAA and the presence of elevated plasma homocysteine levels (HCY). Homocysteine can stimulate elastolysis in the arterial media via activation of elastase and matrix metalloproteinases. No evidence in the literature exists correlating aneurysm expansion and HCY. The study objective is to identify whether the rate of AAA expansion is related to HCY. METHODS: 108 patients undergoing surveillance for AAA were identified at our vascular surgical unit. AAA size and growth rate were assessed by serial ultrasonographic measurements. Fasting total HCY levels were measured using fluorescence polarisation immunoassays. Demographic details and atherosclerotic risk factors were noted all AAA patients. A multivariate analysis was performed for growth rate vs. HCY, hypertension and hypercholesterolaemia. The correlation between AAA growth rate, AAA size and HCY levels were calculated. RESULTS: 60% of patients with AAA had some degree of hyperhomocysteinaemia (> 15 micromol/l). Multivariate analysis showed HCY to be the only significant factor affecting AAA growth rate. A positive correlation was demonstrated between HCY levels and AAA growth rate using a linear regression model (R=0.28, p=0.003). Median growth rate among patients with hyperHCY was double that of patients with normal HCY (0.5 mm/month vs. 0.25 mm/month, p=0.003). A growth rate of > 10 mm/year was seen in 25% of hyper HCY patients and in only 2% of patients with normal HCY. In addition patients with hyper HCY and larger AAAs (> 4 cm) had a growth rate twice as fast as patients with hyper HCY and AAAs < 4 cm. CONCLUSIONS: A correlation between HCY and growth rate exists, although this is weak due to the multifactorial aetiology of AAAs. HyperHCY patients have faster expansion rates than patients with normal HCY, with significant numbers demonstrating rapid expansion (> 10 mm/year) and therefore an increased risk of rupture.

Randomized clinical trial of intraoperative autotransfusion in surgery for abdominal aortic aneurysm.

BACKGROUND: Perioperative homologous blood transfusion (HBT) is associated with adverse reactions and risks transmission of infection. It has also been implicated as an immunosuppressive agent. Intraoperative autotransfusion (IAT) is a potential method of autologous transfusion. METHODS: This was a single-centre randomized clinical trial of IAT in surgery for abdominal aortic aneurysm. Forty patients were randomized to IAT and 41 underwent surgery with HBT only. Patients in both groups received HBT to maintain haemoglobin levels above 8 g/dl. Transfusion requirements, and incidence of systemic inflammatory response syndrome (SIRS) and infection, were compared. RESULTS: Significantly fewer patients in the IAT group required HBT (21 versus 31; P = 0.038) and the median blood requirement per patient was 2 units lower (P = 0.012). There was a higher incidence of chest infection (12 versus four patients; P = 0.049) and SIRS (20 versus nine patients; P = 0.020) in the HBT group. Risk of SIRS was related to aortic cross-clamp time in the IAT group only. CONCLUSION: Use of autotransfusion effectively reduced the need for HBT and was associated with a reduced incidence of postoperative SIRS and infective complications.

The role of statins in vascular disease.

BACKGROUND: Recent publications have highlighted the benefits of statins in non-cardiac occlusive disease but also the failure of vascular surgeons to recognise and treat the risk factors for atherosclerosis, in particular hypercholesterolaemia. The aim of this review is to clarify the current experimental and clinical evidence for the use of statins in vascular disease. METHODS: Literature compiled from an extensive search of Medline and the Cochrane database has been used for the basis of this review. RESULTS: Experimental and clinical evidence consistently reports that statins improve endothelial dysfunction, are anti-inflammatory, anti-proliferative, anti-thrombogenic and anti-proteolytic. These effects are known to inhibit atherogenesis and improve plaque stability. Independent groups support the use of statins in the prevention of both primary and secondary cardiac events. The National Stroke association recommends their use to reduce strokes following myocardial infarction and the Heart Protection Study reports benefits in patients with non-cardiac occlusive disease. CONCLUSIONS: There is substantial evidence advocating the use of statins in patients with clinically significant vascular disease. In the future this may evolve to include those patients at risk from neointimal hyperplasia, aneurysmal disease and ischaemia reperfusion injury.

The incidence of hyperhomocysteinaemia in vascular patients.

INTRODUCTION: Hyperhomocysteinaemia has recently been identified as an important risk factor for atherosclerotic vascular disease. Screening for hyperhomocysteinaemia has been recommended, however, the incidence of hyperhomocysteinaemia in vascular patients is not known. AIMS: To determine the incidence of hyperhomocysteinaemia in vascular patients, to determine the relation of hyperhomocysteinaemia with folate, vitamin B12 levels and lipid profiles in vascular patients. To examine if there is a relationship between the degree of vascular injury and homocysteine concentration. METHODS: New vascular patients at The Queen Elizabeth Hospital were recruited and divided into peripheral, and aneurysmal presentations. Patients demographics were recorded, blood samples were taken for fasting lipid profile, and homocysteine concentration. Samples were also taken for vitamin B12, plasma and red cell folate levels. Sixty age and sex matched controls were included for comparison. RESULTS: One hundred and twenty-six patients have been recruited, (95 men and 31 women) with a median age of 68 years (61-74 years). The incidence of elevated homocysteine, and cholesterol levels was 33, 47 and 24%. The levels of vitamin B12 and folate were normal in all patients. Homocysteine was elevated in 27% of claudicants, 50% of patients with rest pain and 53% of patients with an aortic aneurysm. CONCLUSION: There is a high rate of hyperhomocysteinaemia in vascular patients with a higher incidence in patients with rest pain. There was also a high incidence of elevated homocysteine levels in patients with an abdominal aortic aneurysm. The rate of growth of these aneurysms is currently under review. Low folate or B12 concentrations is not the cause of raised homocysteine levels.

Patients with chronic critical limb ischaemia have reduced total antioxidant capacity and impaired nutritional status.

INTRODUCTION: it has previously been demonstrated that total antioxidant capacity (TAC) can help predict which patients undergoing femoro-distal reconstruction are susceptible to postoperative infections. AIMS: the aims of this study were to examine if TAC is influenced by the nutritional state of the patient and the degree of ischaemia. PATIENTS AND METHODS: thirty patients with rest pain (21 men and 9 women), with a median age of 69 years and fifteen controls (9 men and 6 women), median age of 66 years, were studied. Nutritional status was assessed using serum albumin, body mass index (BMI), maximum voluntary contraction using a hand grip dynamometer and bioelectrical impedance to determine lean body mass. Blood was also taken for total antioxidant capacity (TAC). RESULTS: patients with chronic critical limb ischaemia (CCLI) had a lower TAC than controls (752 vs 1,130 micromol/l, p<0.05 Mann-Whitney U -test). There was no difference in serum albumin concentration between the CCLI group compared with controls (31 mmol/L vs 35 mmol/L, p>0.05 Mann-Whitney U-test). There was also no difference in BMI (23 vs 27, p>0.05 U-test) between the two groups. The other markers of nutrition including, maximum voluntary contractions (28.6 kg/m(2)vs 37.4 kg/m(2), p<0.05 M-W U-test), and lean body mass (3.0 vs 3.8 M-W U-test), showed a significant reduction in the vascular patients. CONCLUSION: TAC is significantly reduced in patients with CCLI and this may, in part, be explained by their impaired nutritional status.

How effective is acute normovolaemic haemodilution in femoro-distal bypass surgery?

BACKGROUND: Recent guidelines have emphasised the use of autologous blood in the surgical setting. The aim of this study was to analyse the efficacy and efficiency of acute normovolaemic haemodilution (ANH) as a blood conservation intervention in patients undergoing elective femoro-distal surgery for critical limb ischaemia. METHODS: Forty patients were studied prospectively. The volume of the blood collected was derived as follows: Blood volume removed = patient's blood volume (initial haematocrit - final haematocrit/average haematocrit) where final haematocrit is 30% and patient's blood volume is 70 and 65 ml/kg for a man and a woman, respectively. RESULTS: Twenty-five patients were suitable for ANH and 15 patients were excluded because of poor ventricular function, anaemia or renal disease. Nine of the 25 patients (44%) had <500ml of surgical blood loss and would have avoided homologous blood transfusion (HBT). Four of the patients lost >2000ml of blood and could not avoid HBT through ANH. Twelve patients had moderate blood loss (950-1400 ml), with eight of these patients requiring transfusion. Four patients avoided exposure to homologous blood. CONCLUSION: ANH is in evolution and as a single blood conservation intervention, contributes only modestly to blood conservation.

Role of the neutrophil in the development of systemic inflammatory response syndrome and sepsis following abdominal aortic surgery.

INTRODUCTION: There is evidence to suggest that the polymorphonuclear neutrophil (PMN) plays a critical early step in the development of the ischaemia-reperfusion syndrome, the systemic inflammatory response syndrome (SIRS) and sepsis. The PMN receptor CD16 plays an important role in phagocytosis, cell-mediated cytotoxicity and the release of free radicals and proteolytic enzymes. The aim of this study was to determine whether there is any relationship between PMN CD16 expression, phagocytosis and the development of sepsis. METHODS: Fifty patients who underwent elective infrarenal abdominal aortic aneurysm repair were studied. Venous blood was taken before operation, throughout surgery and for 7 days after operation. CD16 expression was measured, unstimulated and following further stimulation, by means of flow cytometry. Phagocytosis was determined using flow cytometry. RESULTS: Some 36 patients had an uncomplicated recovery; 14 developed SIRS or sepsis. There was no difference between the two groups with respect to nutritional, co-morbid or technical factors. In the group that developed septic complications after operation, the level of PMN CD16 expression was significantly higher before surgery (mean channel fluorescence (MCF) 30.2 versus 10.4; P < 0.05, Mann-Whitney U test) and throughout the postoperative period. Surgery produced no change in CD16 expression. After operation, stimulation of PMNs in the septic group resulted in a fall in CD16 expression (40.8 versus 20.4 MCF; P < 0.05, Mann-Whitney U test); surgery produced no change in the level of expression in the uncomplicated group. CONCLUSION: This study provides evidence of phenotypic and functional differences in neutrophil behaviour in patients who develop sepsis following aneurysm surgery.