A Specific Thromboxane Receptor Blocking Drug, AH23848, Reduces Platelet Deposition on Vascular Grafts in Man

The antithrombotic effect of a specific thromboxane A2 receptor blocking drug, AH23848, on radio-labelled platelet deposition in mature Dacron aorto-bifemoral grafts has been evaluated in patients. Thirty patients were randomly allocated to AH23848 70 mg, aspirin 300 mg plus dipyridamole 75 mg or placebo 8-hourly for 9 days. AH23848 inhibited platelet aggregarion induced by the thromboxane ,A2 mimetic U-46619; no such effect was observed with aspirin plus dipyridamole. 111In-platelet uptake was measured as the thrombogenicity index (TI) which is a measure of the daily rate of accumulation of platelets by the graft. The mean (s.e. mean) value of 0.193 (0.029) on placebo was significantly reduced to 0.115 (0.022) by AH23848 (p <0.05) but only to 0.175 (0.028) by aspirin plus dipyridamole. There was no difference in mean platelet life span between the three treatment groups. The pronounced antithrombotic effect of AH23848 implicates thromboxane ,A2 in the process of platelet deposition in arterial prostheses and demonstrates the considerable promise of thromboxane receptor blocking drugs as antithrombotic therapy.

The Effects of Thromboxane Antagonism on the Transit Time of Platelets Through the Spleen

The spleen is well-known as a site for platelet pooling, although the mechanisms controlling intrasplenic platelet transit are essentially unknown. We tested the possibility that thromboxane A2 might be involved in this control by measuring intrasplenic platelet transit time in 10 subjects receiving a specific thromboxane A2 receptor antagonist (AH23848B; 70 mg; Glaxo Group Research Ltd), in 10 receiving aspirin (300 mg) plus dipyridamole (75 mg), and in 9 receiving placebo. All doses were administered 3 times daily commencing 4 days prior to transit time measurement.

Mean intrasplenic platelet transit time was measured by monitoring the kinetics of equilibration of 111In radiolabelled platelets between blood and spleen following intravenous injection. There was no difference between the mean transit time in the 3 groups of subjects, lending no support to the hypothesis that thromboxane A2 is involved in the control of platelet traffic through the spleen.

Platelet Inhibitory Drugs: An In Vivo Method of Evaluation in Patients

The measurement of platelet deposition in human thrombi is essential for the evaluation of platelet-inhibitory drugs and prosthetic materials for use in patients. The rate of 111Indiumlabelled platelet accumulation on Dacron arterial grafts was measured in 27 patients randomised to take either aspirin and dipyridamole (ASA + DPM) or placebo. Autologous platelets were labelled and re-injected seven days following surgery and the graft thrombogenidty index calculated as the daily rise in the ratio of emissions from the graft over a reference site.

The mean (± SD) thrombogenidty index in 12 patients undergoing femoro-popliteal bypass was 0.25 ± 0.09 on placebo and 0.16 ± 0.07 on ASA + DPM started pre-operatively (p Ã0.05). Post-operative ASA + DPM therapy started two days following platelet labelling in 15 patients with aorto-femoral grafts also significantly reduce thrombogenidty to 0.12 ± 0.05 compared with 0.25 ± 0.08 on placebo (p Ã0.01). In the latter patients the ratio of emissions from the graft over reference fell significantly on starting ASA + DPM, suggesting a net loss of platelets from the graft. These results indicate that the rate of in vivo platelet accumulation on Dacron grafts can be quantitated and that ASA + DPM reduced this rate in man.

Repeated Exercise Induces Release of Soluble P-Selectin in Patients with Intermittent Claudication

Controversy exists as to whether exercise in patients with intermittent claudication causes a harmful biochemical effect associated with an ischaemia-reperfusion injury of skeletal muscle. We report on exercise-induced changes in neutrophil activation, soluble P-selectin and von Willebrand factor in 34 patients with intermittent claudication and 12 matched controls.

Von Willebrand factor (vWF) showed a cyclical pattern of response to exercise in control subjects (rising from 103 ± 8 to 119 ± 7 U/dl); claudicants did not show this pattern but had higher levels of vWF throughout (p <0.03). There was no consistent pattern of response in neutrophil hydrogen peroxide production to exercise in either claudicants or control subjects. Soluble P-selectin levels increased after exercise, but this only reached statistical significance after repeated exercise in claudicants (rising from 320 ± 28 to 357 ± 28 ng/ml). This rise in soluble P-selectin after exercise may indicate progressive platelet activation which may contribute to the excess cardiovascular mortality that claudicants are prone to.

von Willebrand Factor, Soluble P-Selectin, Tissue Plasminogen Activator and Plasminogen Activator Inhibitor in Atherosclerosis

Tissue plasminogen activator antigen (tPA), plasminogen activator inhibitor antigen (PAI-1), soluble P-selectin and von Willebrand factor antigen (vWf) were measured by ELISA in 41 patients with peripheral vascular disease (PVD), 41 with ischaemic heart disease (IHD) and in 46 age and sex matched asymptomatic controls. Increased vWf was found in patients with IHD (p = 0.0002) and in patients with PVD (p = 0.0011) relative to the controls but levels did not differ between the two patients groups. Raised tPA found in both PVD (p = 0.0006) and IHD (p = 0.0061) compared to the controls also failed to differentiate the two groups of patients. Soluble P-selectin was also raised in both groups (p = 0.003 in IHD and p = 0.0102 in PVD) with no difference between the groups. There were no differences in levels of PAI-1 between the groups. In the subjects taken as a whole, there were significant Spearman’s correlations between tPA and vWf (r = 0.37, p <0.001), tPA and triglycerides (r = 0.38, p <0.001), tPA and P-selectin (r = 0.19, p = 0.032), vWf and age (r = 0.25, p = 0.005) and inversely between vWf and HDL (r = -0.25, p = 0.006). These data support the concept that increased levels of tPA may be important in atherosclerosis, and indicate that soluble P-selectin may be useful in further analysis of the role of platelets and the endothelial cell in this disease.

Oxidised and native low-density lipoproteins induce the release of von Willebrand factor from human endothelial cells in vitro

Increased low-density lipoprotein (LDL)-cholesterol is a risk factor for atherosclerosis--a disease in which damage to the endothelium is believed to be an important early step. Increased levels of the endothelial marker von Willebrand factor (vWF) in the plasma of patients with hypercholesterolaemia and atherosclerosis probably reflect this process. In this study we seek to link the established observation that oxidised LDL-cholesterol is cytotoxic to human umbilical vein endothelial cells (HUVECs) in vitro with the common finding of raised plasma vWF in patients with atherosclerosis by incubating HUVECs with physiological/pathological levels of native and oxidised LDL-cholesterol for up to 48 h. Microphotography revealed morphological changes in the HUVECs within 24 h, becoming severe at 48 h, which was mirrored by increased levels of vWF (ELISA) and the release of preloaded radioactive (111)indium tracer into culture supernatants. Our data support and extend the hypothesis that oxidised LDL is directly cytotoxic to HUVECs, and, in addition, provide an important link between in vitro studies and clinical studies where endothelial cell markers such as vWF are increased in the plasma of patients with hypercholesterolaemia and atherosclerosis.

Role of ambulatory venous pressure measurement in the assessment of venous disease

Objectives: The gold standard assessment of venous hypertension is ambulatory venous pressure (AVP). Aims of this study were to determine the relationship of AVP with clinical severity of venous disease and whether AVP accurately identifies sites of incompetence.

Methods: 117 limbs (93 subjects) underwent classification of venous signs, duplex imaging and AVP measurement. Eleven limbs had no disease, 28 had varicose veins (VVs), 45 had chronic venous insufficiency, 15 had healed ulceration, and 18 had active ulceration.

Results: Mean (standard error of the mean) pressure relief index (PRI) showed a step-wise decrease from 1794 (±317) in controls to 167 (±46) in active ulcers ( P <0.001, ANOVA). PRI correlated with clinical severity of venous disease (r = -0.60, P <0.01, Pearson). Superficial reflux alone was most common in VVs (60%), deep reflux in active ulceration (11%) and combined reflux in healed ulceration (93%). Tourniquet tests showed an increase in PRI only in combined reflux ( P <0.028, ANOVA).

Conclusions: AVP correlates with skin condition but is inaccurate in identifying sites of incompetence.

Recurrence following Varicose Vein Surgery

Objective:

To determine the site-specific rates of recurrence following varicose vein surgery.

Design:

Postal questionnaire followed up by telephone enquiries. Full clinical review, including continuous wave and duplex Doppler investigations were carried out for all patients with responses suggesting recurrence.

Setting:

Surgicare Manchester, an independent provider of specialist varicose vein treatments. All procedures were guided by Doppler ultrasound and performed by surgeons working to the same protocol.

Subjects:

A consecutive series of 250 operations on 246 Patients. Of these, 208 (85%) could be contacted for follow-up. Mean time to re-examination was 27 months.

Results:

Twelve patients returned spontaneously and 51 were recalled for examination based on questionnaire responses. Recurrences were divided into ‘site’, ‘perforator’ or ‘new site’ recurrence. Primary surgery to the sapheno-femoral junction (SFJ) had the lowest ‘site’ recurrence rate of 2.3% compared with 9.5% for SFJ re-operation. Primary surgery and re-operation of the sapheno-popliteal junction (SPJ) had higher recurrence rates of 8.3% and 7.8% respectively. New incompetence was detected in 5% and 2% of previously competent SFJ and SPJ respectively. Minor perforator incompetence was found in a further 14%.

Conclusions:

Varicose veins were progressive in some individuals, with new sites of incompetence appearing over time. However, ‘cure’ remains possible for most Patients and major recurrence can be reduced by Doppler diagnosis and precise surgery.

Randomised Trial Comparing Two Four-Layer Bandage Systems in the Management of Chronic Leg Ulceration

Objective:

To compare a new four-layer bandage system (Profore) with the original 4LB in the closure of chronic leg ulceration.

Design:

Prospective randomised stratified parallel-groups open trial.

Methods:

Patients newly presenting to community leg ulcer services with chronic leg ulceration were screened for inclusion in this trial. Patients with arterial disease (ankle brachial pressure index <0.8) and causes of ulceration other than venous disease were excluded. In patients with bilateral ulceration, the limb with the larger area of ulceration was studied. The ulcer was dressed with a simple low-adherent dressing and all bandages were changed weekly unless required more frequently. Patients were randomised to receive either the original four-layer bandage or the newer system (Profore).

Results:

In all 233 patients were randomised, of whom 232 attended at least one follow-up visit (115 original, 117 Profore). At 12 weeks complete healing of the ulcerated limb, analysed by ‘intention-to-treat’ was 60% using the original 4LB compared with 72% using Profore. The difference of 11.8% (95% confidence interval (CI) −0.3% to 23.9%) had largely disappeared after 24 weeks, with 73% healed using the original 4LB and 76% using Profore, a difference of 3.0% (95% CI −8.2% to 14.2%). After 24 weeks of treatment the Kaplan-Meier estimate of complete healing was 82% using the original system and 84% using the Profore system. Overall, there was a higher healing rate for patients on Profore (hazard ratio = 1.18, 95% CI 0.87 to 1.59), but this did not achieve statistical significance ( p = 0.28).

Conclusion:

Ulcer healing using the newer Profore system is as good as with the original four-layer system.

Effect of leg elevation on healing, venous velocity and ambulatory venous pressure in venous ulceration

Objective: Current treatment of venous leg ulcers (VLU) includes four-layer bandaging, appropriate superficial venous surgery and leg elevation. The aims of this study were to: investigate a device designed to measure leg elevation; assess how long patients elevate; and to assess the effect of elevation on ulcer healing, femoral vein velocity (FVV) and popliteal vein cross-sectional area (PVCSA), and venous pressure.

Patients and methods: A datalogger and accelerometer were manufactured to measure leg elevation. The device was validated in eight control subjects; elevation was measured in 24 patients with VLU. Ulcers were traced over six weeks in 29 patients and elevation measured to correlate healing with elevation. Ten patients and 10 controls underwent duplex measurement of FVV and PVCSA to measure flow in relation to posture; nine patients underwent measurement of venous pressure with postural changes. Non-parametric statistical analysis was used.

Results: The datalogger accurately recorded all episodes of elevation. Median (range) elevation time was 53 (0–350) mins/24 h; correlation between ulcer healing and elevation was poor at 0.103 ( P=0.616, Spearman); change in posture from sitting to supine produced a significant increase in median (range) FVV from 11 (7–24) to 34 (22–66) in VLU ( P=0.005) and 15 (12–34) to 38 (16–69) in controls ( P=0.005, Wilcoxon). Change in posture from supine to 25 degrees elevation produced no change in FVV in either group ( P=0.173 in VLU, P=0.327 in controls, Wilcoxon). In VLU, sitting PVCSA was 1.07 (0.51–1.45) cm2. Supine position significantly reduced the area to 0.46 (0.27–1.01) cm2 ( P=0.005, Wilcoxon). On elevation to 25°, PVCSA was further reduced to 0.28 (0.07–0.63) cm2 ( P=0.058, Wilcoxon). In controls, sitting PVCSA was 0.79 (0.31–1.56) cm2, supine was reduced to 0.46 (0.27–1.09) cm2 ( P=0.047, Wilcoxon) and on elevation was reduced to 0.23 (0.10–0.44) cm2 ( P=0.005, Wilcoxon). Venous pressure standing was 99 (73–116) mmHg, reduced to 76 (53–113) mmHg on sitting ( P=0.084), and further reduced to 23 (7–36) mmHg supine ( P=0.008, Wilcoxon).

Conclusions: Leg elevation in patients with VLU is poor but can be accurately measured. Elevation in the presence of compression may not improve ulcer healing. Postural changes of the leg can produce an increase in deep venous flow and a reduction in venous pressure.

Community Leg Ulcer Clinics: Effect on Quality of Life

Objective:

To investigate changes in the quality of life of patients with leg ulcers being treated in community leg ulcer clinics.

Design:

Patients were interviewed using a standard questionnaire, and then reinterviewed after 12 weeks of compression bandaging to observe changes.

Setting:

Community ulcer clinics held in health centres within Riverside Health District.

Patients:

All new patients presenting to community leg ulcer clinics up to 6 months from the start of a clinic and treated with four-layer compression bandaging.

Main outcome measures:

Changes in quality of life, interference in daily activities caused by leg ulceration and general health after 12 weeks of treatment.

Results:

Treatment over 12 weeks resulted in a mean reduction in anxiety (2.79 v 1.73, p < 0.001), depression (2.61 v 1.89, p < 0.001), hostility (1.59 v 1.00, p < 0.001) and cognition (1.29 v 0.87, p = 0.015). Pain significantly improved following treatment (χ2 trend = 103.7, 1d.f., p < 0.001). Changes in depression and hostility were related to complete ulcer healing.

Conclusions:

There were clear changes in quality of life following 12 weeks in a community leg ulcer clinic, which were related to the healing of the ulcer. Systems of care that offer rapid healing and improve patients' well-being must be considered when planning an effective leg ulcer service.

Compression stockings in the management of fractures of the ankle: a randomised controlled trial

In this randomised controlled trial, we evaluated the role of elastic compression using ankle injury stockings (AIS) in the management of fractures of the ankle. A total of 90 patients with a mean age of 47 years (16 to 79) were treated within 72 hours of presentation with a fracture of the ankle, 31 of whom were treated operatively and 59 conservatively, were randomised to be treated either with compression by AIS plus an Aircast boot or Tubigrip plus an Aircast boot. Male to female ratio was 36:54. The primary outcome measure was the functional Olerud-Molander ankle score (OMAS). The secondary outcome measures were; the American Orthopaedic Foot and Ankle Society score (AOFAS); the Short Form (SF)-12v2 Quality of Life score; and the frequency of deep vein thrombosis (DVT). Compression using AIS reduced swelling of the ankle at all time points and improved the mean OMAS score at six months to 98 (95% confidence interval (CI) 96 to 99) compared with a mean of 67 (95% CI 62 to 73) for the Tubigrip group (p < 0.001). The mean AOFAS and SF-12v2 scores at six months were also significantly improved by compression. Of 86 patients with duplex imaging at four weeks, five (12%) of 43 in the AIS group and ten (23%) of 43 in the Tubigrip group developed a DVT (p = 0.26). Compression improved functional outcome and quality of life following fracture of the ankle. DVTs were frequent, but a larger study would be needed to confirm that compression with AISs reduces the incidence of DVT.

Comparison of three contemporary risk scores for mortality following elective abdominal aortic aneurysm repair

Objective/background

A number of contemporary risk prediction models for mortality following elective abdominal aortic aneurysm (AAA) repair have been developed. Before a model is used either in clinical practice or to risk-adjust surgical outcome data it is important that its performance is assessed in external validation studies.

Methods

The British Aneurysm Repair (BAR) score, Medicare, and Vascular Governance North West (VGNW) models were validated using an independent prospectively collected sample of multicentre clinical audit data. Consecutive, data on 1,124 patients undergoing elective AAA repair at 17 hospitals in the north-west of England and Wales between April 2011 and March 2013 were analysed. The outcome measure was in-hospital mortality. Model calibration (observed to expected ratio with chi-square test, calibration plots, calibration intercept and slope) and discrimination (area under receiver operating characteristic curve [AUC]) were assessed in the overall cohort and procedural subgroups.

Results

The mean age of the population was 74.4 years (SD 7.7); 193 (17.2%) patients were women and the majority of patients (759, 67.5%) underwent endovascular aneurysm repair. All three models demonstrated good calibration in the overall cohort and procedural subgroups. Overall discrimination was excellent for the BAR score (AUC 0.83, 95% confidence interval [CI] 0.76–0.89), and acceptable for the Medicare and VGNW models, with AUCs of 0.78 (95% CI 0.70–0.86) and 0.75 (95% CI 0.65–0.84) respectively. Only the BAR score demonstrated good discrimination in procedural subgroups.

Conclusion

All three models demonstrated good calibration and discrimination for the prediction of in-hospital mortality following elective AAA repair and are potentially useful. The BAR score has a number of advantages, which include being developed on the most contemporaneous data, excellent overall discrimination, and good performance in procedural subgroups. Regular model validations and recalibration will be essential.

National risk prediction model for elective abdominal aortic aneurysm repair

BACKGROUND

Mortality results for elective abdominal aortic aneurysm (AAA) repair are published by the Vascular Society of Great Britain and Ireland. These mortality results are not currently risk-adjusted. The objective of this study was to develop a national risk prediction model for elective AAA repair.

METHODS

Data for consecutive patients undergoing elective AAA repair from the National Vascular Database between April 2008 and March 2011 were analysed. Multiple logistic regression and backwards model selection were used for model development. The study outcome measure was in-hospital mortality. Model calibration and discrimination were assessed for all AAA repairs, and separately for open repair and endovascular aneurysm repair (EVAR) subgroups.

RESULTS

There were 312 in-hospital deaths among 11,423 AAA repairs (2.7 (95 per cent confidence interval (c.i.) 2.4 to 3.0) per cent): 230 after 4940 open AAA repairs (4.7 (4.1 to 5.3) per cent) and 82 after 6483 EVARs (1.3 (1.0 to 1.6) per cent). Variables associated with in-hospital death included in the final model were: open repair, increasing age, female sex, serum creatinine level over 120 µmol/l, cardiac disease, abnormal electrocardiogram, previous aortic surgery or stent, abnormal white cell count, abnormal serum sodium level, AAA diameter and American Society of Anesthesiologists fitness grade. The area under the receiver operating characteristic (ROC) curve was 0.781 (95 per cent c.i. 0.756 to 0.806) with a bias-corrected value of 0.774. Model calibration was good (P = 0.963) based on the Hosmer-Lemeshow goodness-of-fit test, (bias-corrected) calibration curves, risk group assessment and recalibration regression.

CONCLUSION

This multivariable model for elective AAA repair can be used to risk-adjust outcome analyses and provide patient-specific estimates of in-hospital mortality risk for open AAA repair or EVAR.

Preoperative cardiopulmonary exercise testing and risk of early mortality following abdominal aortic aneurysm repair

BACKGROUND

Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity. The aim of this study was to assess whether preoperative CPET identifies patients at risk of early death following elective open and endovascular abdominal aortic aneurysm (AAA) repair.

METHODS

Prospective data were collected from a pilot study between September 2005 and February 2007, and from all patients who underwent CPET before elective AAA repair at two vascular centres between February 2007 and November 2011. Symptom-limited, maximal CPET was performed on each patient. Univariable and multivariable analyses were used to identify risk factors for 30- and 90-day mortality.

RESULTS

Some 415 patients underwent CPET before elective AAA repair. Anaerobic threshold (AT), peak oxygen consumption (peak V.O(2) ) and ventilatory equivalents for carbon dioxide were associated with 30- and 90-day mortality on univariable analysis. On multivariable analysis, open repair (odds ratio (OR) 4·92, 95 per cent confidence interval 1·55 to 17·00; P = 0·008), AT below 10·2 ml per kg per min (OR 6·35, 1·84 to 29·80; P = 0·007), anaemia (OR 3·27, 1·04 to 10·50; P = 0·041) and inducible cardiac ischaemia (OR 6·16, 1·48 to 23·07; P = 0·008) were associated with 30-day mortality. Anaemia, inducible cardiac ischaemia and peak V.O(2) less than 15 ml per kg per min (OR 8·59, 2·33 to 55·75; P = 0·005) were associated with 90-day mortality on multivariable analysis. Patients with two or more subthreshold CPET values were at increased risk of both 30- and 90-day mortality.

CONCLUSION

An AT below 10·2 ml per kg per min, peak V.O(2) less than 15 ml per kg per min and at least two subthreshold CPET values identify patients at increased risk of early death following AAA repair.

Evaluation of five risk prediction models for elective abdominal aortic aneurysm repair using the UK National Vascular Database

Background

There is no consensus on the best risk prediction model for mortality following elective abdominal aortic aneurysm (AAA) repair. The objective was to evaluate the performance of five risk prediction models using the UK National Vascular Database (NVD).

Methods

Data on elective AAA repairs from the NVD between January 2008 and December 2010 were analysed. The models assessed were: Glasgow Aneurysm Score (GAS), Vascular Biochemical and Haematological Outcome Model (VBHOM), physiological component of the Vascular Physiological and Operative Severity Score for enUmeration of Mortality (V-POSSUM), Medicare and Vascular Governance North West (VGNW). Overall model discrimination and calibration in equally sized risk-group quintiles were assessed.

Results

The study cohort included 10 891 patients undergoing elective AAA repair (median age 74 years, 87·3 per cent men). The in-hospital mortality rates following endovascular and open repair were 1·3 and 4·7 per cent respectively (2·9 per cent overall). The Medicare and VGNW models both showed good discrimination (area under receiver operating characteristic (ROC) curve 0·71), whereas the GAS, VBHOM and V-POSSUM models showed poor discrimination (area under ROC curve 0·60, 0·61 and 0·62 respectively). The VGNW model was the only one to predict the overall mortality rate in the cohort (3·3 per cent predicted versus 2·9 per cent observed; P = 0·066). The VGNW model demonstrated good calibration, predicting risk accurately in four risk-group quintiles. The Medicare, V-POSSUM and VBHOM models accurately predicted risk in three, two and no risk-group quintiles respectively.

Conclusion

The Medicare and VGNW models contain similar risk factors and showed good discrimination when applied to the NVD. Both models would be suitable for risk prediction after elective AAA repair in the UK.

Ultrasound measurement of aortic diameter in a national screening programme

OBJECTIVE

Currently there is no universally accepted standard for ultrasound measurement of abdominal aortic aneurysm (AAA). The aim was to investigate the reliability and reproducibility of inner to inner (ITI) versus outer to outer (OTO) ultrasound measurement of AAA diameter.

METHODS

A prospective study design was used to collect 60 random images of aorta (1.4-7.1 cm). Inner and outer wall diameter measurements were then performed by 13 qualified AAA screening technicians and 11 vascular sonographers.

RESULTS

The mean (range) diameter for all 60 aortas by ITI was 3.91 cm (1.39-6.80) and by OTO was 4.18 cm (1.63-7.09), a significant mean difference of 0.27 cm (95% CI: 0.23-0.32 cm). The reproducibility coefficients for differences between technicians were 0.30 cm (95% CI: 0.24-0.36) for ITI and 0.42 cm (95% CI: 0.35-0.49) for OTO indicating significantly better repeatability using ITI. Finally, 15 images were measured twice in random order by all screeners and sonographers. For AAAs > 5 cm, repeatability was significantly better with ITI than OTO (0.14 vs. 0.21; p = 0.016).

CONCLUSION

There was the expected difference in AAA diameter between the two methods (0.27 cm). However, ITI wall method was measurably more reproducible.

Early changes in the haemostatic and procoagulant systems after chemotherapy for breast cancer

Venous thromboembolism (VTE) following breast cancer chemotherapy is common. Chemotherapy-induced alterations in markers of haemostasis occur during chemotherapy. It is unclear how rapidly this occurs, whether this is upregulated in patients developing VTE and whether changes predict for VTE. Markers of haemostasis, functional clotting assays and vascular endothelial growth factor were measured before chemotherapy and at 24 h, 4 days, 8 days and 3 months following commencement of chemotherapy in early and advanced breast cancer patients and in age- and sex-matched controls. Duplex ultrasound imaging was performed after 1 month or if symptomatic. Of 123 patients, 9.8% developed VTE within 3 months. Activated partial thromboplastin time (APTT), prothrombin time (PT), D-dimer, fibrinogen, platelet count, VEGF and fibrinogen were increased in cancer. Fibrinogen, D-dimer, VEGF and tissue factor were increased, at baseline, in patients subsequently developing VTE. D-dimer of less than 500 ng ml⁻¹ has a negative predictive value of 97%. Activated partial thromboplastin time, PT and thrombin–antithrombin showed significantly different trends, as early as within 24 h, in response to chemotherapy in patients subsequently developing VTE. Markers of coagulation and procoagulants are increased, before chemotherapy, in patients who subsequently develop VTE. A group of patients at minimal risk of VTE can be identified, allowing targeted thrombopropylaxis to the higher risk group.

Prevention of venous thromboembolism in surgical patients with breast cancer

Background

No randomized trial has yet studied venous thromboembolism (VTE) prophylaxis in patients undergoing surgery for breast cancer.

Methods

Relevant articles were identified using Medline searches. Secondary articles were identified from the reference lists of key papers.

Results and conclusion

The absence of randomized trials comparing different methods of VTE prophylaxis with controls makes an evidence-based consensus among breast cancer surgeons difficult. Intermittent pneumatic compression (IPC) and graduated compression (GC) are effective in reducing VTE without the haemorrhagic complications associated with heparin; their effects are additive. The authors suggest the following strategy. All patients undergoing surgery for breast cancer should receive both IPC and GC, with heparin reserved for those at very high risk. A controlled trial should randomize women to receive heparin or not, and all women should have both IPC and GC. The primary endpoints should be the development of VTE and/or haemorrhagic complications.

Current UK practice of thromboprophylaxis for breast surgery

A plea for evidence

Arterial graft maturation: The duration of thrombotic activity in Dacron aortobifemoral grafts measured by platelet and fibrinogen kinetics

Dacron is thrombogenic, hence small arterial grafts of this material frequently thrombose in the period prior to graft maturation. Anti-thrombotic therapy may therefore be indicated to preserve patency during this risk period. To evaluate the thrombogenicity of immature Dacron grafts, platelet and fibrinogen kinetics using 51Cr and 125I respectively were measured before operation and at 3, 6 and 9 months in 10 patients following aortobifemoral bypass and in 6 age-matched volunteers.

Platelet survival was reduced from 8.8±0.2 d before surgery to 7.4±0.24 d at 3 months. This was accompanied by an increase in platelet turnover from 39±2.4 × 109 l−1 d−1 to 46.9±2.9 × 109 l−1 d−1. Fibrinogen t1/2 fell from 3.72±0.13 d preoperatively to 3.36±0.11 d at 3 months, while fibrinogen fractional catabolic rate rose from 0.27±0.014 to 0.34±0.014. These changes were all significant (P &lt; 0.01). Fibrinogen consumption had returned to normal by 6 months following surgery but platelet kinetics only equated to pre-operative levels at 9 months. We suggest that Dacron grafts are thrombogenically active for about 9 months. When anti-thrombotic therapy is indicated it should be continued throughout this period.

Alteration in platelet function in patients with early breast cancer

The aim of this study was to examine our hypothesis that platelets of patients with breast cancer were functionally altered compared to healthy controls. The results have shown that the platelets from women with early breast cancer released significantly more vascular endothelial growth factor (VEGF) when stimulated with thrombin, tissue factor, clotting, or over a period of time. Similarly, release of thrombospondin (TSP) with thrombin and tissue factor was higher, but failed to reach a significant level. Thus, the observed differences in platelet response support our hypothesis, but warrant further work to determine the reason underlying the observed difference and potential clinical relevance of our findings.

Effect of Superficial Venous Surgery on Venous Function in Chronic Venous Insufficiency

Patients with chronic venous insufficiency often have combined superficial and deep venous incompetence. The aims of this study were to determine the effects of superficial venous surgery (SVS) on deep venous haemodynamics and on ambulatory venous pressure (AVP) and to determine if the AVP tourniquet test can predict the effect of SVS. Of 119 legs, 42 legs (32 subjects) with chronic venous insufficiency, healed ulceration, or active ulceration and with combined superficial and deep incompetence underwent preoperative duplex imaging and AVP measurement followed by appropriate SVS. Four months later, all underwent postoperative duplex imaging and AVP measurement. The pressure relief index (PRI) was calculated from the AVP measurement as an overall assessment of venous function. Seventeen of 119 (14%) showed no tourniquet improvement in PRI and were therefore excluded from SVS. Of those suitable for SVS, median (range) age was 56 (32-78) years. Twenty-two limbs underwent long saphenous surgery, four limbs short saphenous surgery, and 16 limbs both, based on duplex findings. Segmental deep incompetence resolved in 11/21 (52%) limbs after surgery compared to 6/21 (29%) with multisegment incompetence. Median (range) PRI improved from 319 (4-1,600) preoperatively to 1,300 (360-2,670) postoperatively (p < 0.001, Wilcoxon). PRI with thigh tourniquet correlated with postoperative PRI (r = +0.828, p = 0.01, Spearman), as did calf tourniquet (r = +0.996, p = 0.004) and both tourniquets (r = 0.535, p = 0.046). The majority of patients with combined superficial and deep incompetence can be selected for SVS on the basis of AVP measurement with tourniquets. SVS can improve segmental deep incompetence and PRI in those properly selected.

Spatial distribution of mast cells in chronic venous leg ulcers

Chronic venous leg ulcers (CVUs) show chronic inflammation but different pathological changes occur in different parts of the ulcer. There is a lack of re-epithelialisation and defective matrix deposition in the ulcer base but epidermal hyperproliferation and increased matrix deposition in the surrounding skin. The role of mast cells in wound healing, inflammation, fibrosis and epidermal hyperproliferation has been extensively studied but less is known about their role in CVUs. In the present study, we investigated the distribution of mast cells in CVUs with specific consideration of the differences between the ulcer base and the skin surrounding the ulcer. Both histochemical and immunohistological methods were used to detect the mast cell marker tryptase in frozen sections of CVU biopsies. Mast cells were counted in the dermis of normal skin, in the ulcer base and in the skin surrounding the ulcer. Double immunofluorescence staining was used to study the location of mast cells in relation to blood vessels. In normal skin few mast cells were seen in the dermis but none in the epidermis. However in CVUs there was a significant increase in intact and degranulated mast cells in the surrounding skin and ulcer edge (184 per field, p<0.003) of CVUs and a significant reduction in the ulcer base (20.5 per field p<0.05) in comparison to normal skin (61 per field). In CVUs mast cells showed a characteristic location near the epithelial basement membrane whilst mast cell granules and phantom cells (mast cells devoid of granules) were predominantly seen in the epidermis. In the dermis, mast cells were seen associated with blood vessels. The marked increase in mast cells in the surrounding skin of CVUs and depletion of mast cells in the ulcer base could implicate mast cell mediators in the pathological changes in CVUs particularly in the epidermal and vascular changes occurring in the surrounding skin.

Does washing swabs increase the efficiency of red cell recovery by cell salvage in aortic surgery?

BACKGROUND AND OBJECTIVES

We investigated the contribution of swab washing to the efficiency of red cell recovery by intraoperative cell salvage (ICS) in 10 patients undergoing elective aortic aneurysm repair.

MATERIALS AND METHODS

Volumes and haemoglobin (Hb) concentrations were recorded in the blood recovered by direct suction and from washed swabs, both before and after processing with a Haemonetics Cell Saver 5.

RESULTS

The mean +/- standard deviation (SD) estimated blood loss was 991 +/- 403 ml, resulting in a mean +/- SD salvaged RBC volume of 380 +/- 124 ml. The median [interquartile (IQR) range] Hb collected from suction was 84.9 (61.8-131.4) g, of which 50.1 (45-71.5) g was returned to the patient after processing, a median yield of 68 (49-77)%. The swab wash produced a median (IQR) Hb of 39.4 (28.4-64.9) g, of which 26.2 (16.8-31) g was reinfused, a 67 (33-98)% yield. Swab wash thus contributed with a median (IQR) of 31 (24-39)% of the total RBC recovery.

CONCLUSIONS

Washing swabs improves the efficiency of red cell recovery by ICS.

Mild and moderate varicose vein reflux does not deteriorate over time

Objective: To prioritize varicose vein (VV) waiting lists, superficial venous reflux was timed in patients with primary VVs using hand-held Doppler (HHD) and classified as 'severe' (≤4s), 'moderate' (>4; ≤6s) or 'mild' (>6s). Only patients with severe reflux were offered surgery. The progression of reflux in those not offered surgery was investigated over two years.

Methods: Patients seen in the VV clinic between November 1999 and October 2000 with reflux ≥4s were re-assessed two years later. Reflux was timed at the saphenofemoral (SFJ) and saphenopopliteal (SPJ) junctions using HHD. Patients completed a basic symptom questionnaire. The severity of VVs and skin changes of venous insufficiency were graded.

Results: In all, 38/54 patients attended for review at two years. There were 44 limbs with 48 sites of reflux, 38 at the SFJ and 10 at the SPJ. Reflux improved at 27 sites, remained the same at five and deteriorated at 16. Reflux became 'severe' in eight limbs, but only four patients requested surgery. Median (interquartile range) reflux time was 6.0 (5–6)s in 1999–2000 and 7.0 (4–10)s in 2002 ( P = 0.13). Median symptom scores for aching and the severity of VV remained unchanged. The cosmetic appearance of VV and skin signs of venous insufficiency significantly improved ( P < 0.01).

Conclusions: Mild and moderate reflux did not deteriorate in most VV patients. HHD may be a useful adjunct to grade venous reflux and prioritize patients for VV surgery.

Regional haemoglobin oxygen saturation during surgical haemorrhage

AIM

Experimental research and early clinical studies have shown that regional haemoglobin desaturation, measured by near infrared spectroscopy (NIRS), follows blood loss. To further assess NIRS as a blood loss monitor, we evaluated it on patients undergoing major surgery.

METHODS

Regional haemoglobin oxygen saturation from the cerebral cortex (CsO(2)) and the left gastrocnemius muscle (PsO(2)) was continuously monitored with an INVOS 4100 NIRS oximeter in 10 patients during surgery. Haemoglobin, mean arterial pressure, arterial and central venous oxygen saturation and tension, temperature, pH and lactate concentration were also measured.

RESULTS

The median (IQR) blood loss was 650 (400-1 800) ml, equivalent to 16% (11-35) of the patients' blood volume. During surgery, CsO(2) fell by a mean (95% CI) of 8.4% (2-14.8) (p=0.016) and PsO(2) fell by a mean (95% CI) of 3.3% (-1.5-8.1) (p=0.16). CsO(2), but not PsO(2), correlated with the volume of blood lost (R=0.44; p=0.004), central venous oxygen saturation (R=0.52; p=0.001), and venous oxygen tension (R=0.58; p<0.001). These correlations remained significant after calculations were adjusted for changes in arterial pressure, temperature and pH.

CONCLUSION

Cerebral, but not peripheral, haemoglobin oxygen saturation decreases proportionally to blood loss and correlates with measurements of systemic oxygen extraction. With further research, NIRS measurements of CsO(2) may be developed into a useful tool to monitor blood loss.

Early Carotid Surgery in Acute Stroke: A Multicentre Randomised Pilot Study

BACKGROUND

Standard practice has been to delay carotid endarterectomy (CEA) for 2 months following acute stroke to avoid a perceived risk of cerebral haemorrhage. We investigated whether early CEA reduces early recurrent stroke and improves outcome in partial anterior circulation infarction (PACI).

METHODS

Patients with PACI and a Barthel score of >18 before stroke underwent carotid duplex and CT imaging within 7 days of stroke. Forty consenting patients fit for surgery with greater than 70% ipsilateral carotid stenosis were randomised, 19 to 'early' (within 24 h) and 21 to 'delayed' surgery (at 8 weeks). Modified Rankin and Barthel scores were recorded at 1 week, 2 months, 6 and 12 months.

RESULTS

Rankin scores improved more rapidly following 'early' surgery to a score of 1 (0-4) at 2 and 6 months compared with 2.5 and 2 (1-4), respectively, for delayed surgery (p < 0.05). Barthel scores were also significantly improved following 'early' CEA at 7 days but both groups reached a median score of 20 by 2 months. Four 'delayed' and 3 'early' patients suffered extension or recurrence of neurological deficits with 1 death in each group.

CONCLUSIONS

Early CEA within 7 days of ischaemic stroke improved functional outcome with earlier hospital discharge. A large multicentre study is needed to exclude the possibility that 'early' CEA increases the risk of cerebral haemorrhage or death.

Carotid endarterectomy improves cognitive function in patients with exhausted cerebrovascular reserve

OBJECTIVE

To investigate changes in cognitive function following carotid endarterectomy (CEA).

DESIGN

Prospective study with controls.

METHODS

CEA patients (n=159) were compared to a urology surgery control group (n=20). In CEA patients cerebrovascular reserve (CVR) was measured preoperatively. During surgery emboli and blood flow velocity in the middle cerebral artery were measured by transcranial Doppler (TCD) and cerebral oxygen saturation (CsO2) by near infrared spectroscopy. Cognitive function was measured preoperatively and at 5 days and 8 weeks postoperatively using a standardised computer battery of tests.

RESULTS

Only 8% of patients had normal CVR bilaterally. The median number of emboli during CEA was 12 (range 0-181). On carotid clamping, TCD velocity fell a median of 41% and cerebral oxygen saturation by 5%. Attention deteriorated compared to controls 5 days following CEA (p=0.003) and this deterioration was related to the rise in TCD velocity on declamping (r=-0.3, p=0.002). Median attention reaction times improved significantly by 8 weeks (p=0.001) especially in patients' with severely impaired CVR before surgery (p=0.02).

CONCLUSIONS

Attention improved at 2 months following CEA in patients with impaired CVR. CEA may offer more than reduced stroke risk to patients with impaired CVR.

Pharmacological prevention of cardiac risk in claudicants with ischaemic heart disease

BACKGROUND

Claudicants rarely progress to critical limb ischaemia but have a threefold increase in mortality, mainly due to cardiac disease. Antithrombotic therapy, beta blockers, ACE inhibitors and statins have been shown to reduce mortality and cardiovascular morbidity in patients with ischaemic heart disease.

AIM

To investigate secondary pharmacological prevention of ischaemic heart disease in claudicants.

MATERIALS AND METHODS

We prospectively recorded comorbidity and drug treatment in 89 patients (67 men and 22 women) with a history of ischaemic heart disease recruited in a supervised exercise and lifestyle modification programme to improve claudication distance and prognosis.

RESULTS

Of the 89 cases, 40 had a history of angina only and 49 of myocardial infarction. Sixteen (18%) had diabetes, 47 (53%) had hypercholesterolaemia and 52 (58%) were hypertensive. Antithrombotic therapy was prescribed to 61 patients (68.5%), 64 (72%) with a history of myocardial infarction and 27 (67.5%) with angina only (p = 1). Beta-blockers were prescribed to 12 (13.5%) patients only, seven (15%) with a history of myocardial infarction and five (12.5%) with angina only (p = 1). Of the 47 patients with hypercholesterolaemia, 29 (62%) were on a statin.

CONCLUSION

Secondary pharmacological prevention of ischaemic heart disease in claudicants remains suboptimal, with only two thirds of patients receiving antithrombotic therapy and a small minority receiving beta blockers. Pharmacological prevention in claudicants should improve to reduce cardiac morbidity and mortality.

Soluble adhesion molecules in clinical ischaemic injury

BACKGROUND

Neutrophil adhesion is a prerequisite for ischaemic injury. In vitro research has shown that soluble adhesion molecules have an inhibitory effect on neutrophil binding

AIMS

To determine whether the circulating forms of adhesion molecules are consumed during skeletal muscle ischaemic injury in man.

METHODS

The response of the circulating forms of adhesion molecules ICAM-1 (intercellular adhesion molecule-1) and L-selectin to ischaemia and reperfusion was investigated in 23 patients during surgery involving aortic cross-clamping and in 20 volunteers with tourniquet-induced forearm ischaemia.

RESULTS

In the aortic model the levels of circulating ICAM-1 fell from an initial value of 250 +/- 20 to 210 +/- 13 ng/ml (p < 0.05) and soluble L-selectin fell from 642 +/- 62 to 487 +/- 49 ng/ml during ischaemia (p < 0.05). There was a similar pattern of reduced levels of circulating adhesion molecules in the model of forearm ischaemia. However the recovery of these molecules during the reperfusion period differed between the two models.

CONCLUSIONS

Soluble L-selectin and soluble ICAM-1 appear to be utilised during clinical models of ischaemia. This supports previous in vitro studies suggesting a role in competitive inhibition and these circulating molecules may be clinically important inhibitors of leukocyte adhesion.

Venous disease is associated with an impaired range of ankle movement

OBJECTIVES

to investigate the relationship between clinical severity of venous disease, calf muscle pump dysfunction and range of ankle movement (ROAM).

MATERIALS AND METHODS

ROAM was assessed by goniometry in the supine, nonweightbearing position. Calf muscle pump function was assessed by ambulatory venous pressure (AVP), calculating the pressure relief index (PRI). Venous disease was classified according to the CEAP classification (International Consensus Committee reporting standards on venous disease). Forty seven limbs in 38 adults were recruited and matched for age: 11 normal controls CEAP(0), 12 varicose veins CEAP(2), 12 chronic venous insufficiency CEAP(4,5) and 12 active ulceration CEAP(6).

RESULTS

mean (S.E.M.) age was 60.7 (1.3) years. Mean (S.E.M.) PRI was 1959.6 (313.7) in CEAP(0), 905.3 (139.3) in CEAP(2), 596.5 (148.5) in CEAP(4,5) and 170.6 (69.0) in CEAP(6) (p < 0.001, ANOVA). Mean (S.E.M.) ROAM was 61.3 (2.0) degrees in CEAP(0), but significantly reduced to 49.7 (2.0) in CEAP(2), 42.1 (2.6) in CEAP(4,5) and 40.9 (2.7) in CEAP(6) (p < 0.004, ANOVA post hoc Tukey). PRI correlated with ROAM (p < 0.001, Pearson correlation coefficientr = 0.52).

CONCLUSIONS

limbs with venous hypertension have a reduced range of ankle movement related to the clinical severity of venous disease.

Surgery for venous insufficiency: are venous function tests necessary?

Background

The role of duplex imaging and measurement of ambulatory venous pressure (AVP) in the preoperative assessment of patients with venous insufficiency (VI) and primary varicose veins (VV) was investigated.

Methods

Venous incompetence was confirmed by duplex imaging in 58 legs: 38 had VI, demonstrated by eczema, oedema or pigmentation, and 20 had VV and normal skin. AVP was measured from a cannulated dorsal foot vein before and after ten tip-toe exercises. This was repeated following occlusion of the superficial veins by narrow tourniquets. Pressure relief index (PRI) was calculated as the fall in AVP in calf exercise × 90 per cent refilling time in seconds. The criterion for superficial vein surgery was doubling of PRI on superficial vein occlusion.

Results

Superficial venous incompetence (SVI) was confirmed in all legs with duplex imaging. Deep vein incompetence (DVI) was found in 17 legs (45 per cent) with VI and in two (10 per cent) of the VV legs (P = 0·012, χ2 test). Venous function was normal (PRI greater than 1000) in six. Median PRI in patients with VI and VV was 177 and 289, rising to 717 and 1026 respectively after superficial vein occlusion. Initial PRI was significantly lower in patients with DVI (P &lt; 0·001). PRI improved by 135 per cent in SVI and by 318 per cent in legs with DVI (P = 0·01). PRI did not double following superficial venous occlusion in 20 legs (35 per cent) with SVI and in three (16 per cent) with deep incompetence (P = 0·01).

Conclusion

Clinical examination and duplex imaging alone cannot predict who will benefit most from superficial venous surgery. AVP measurement rationalizes decision-making and may avoid unnecessary operations.

Autologous or homologous transfusion in aortic surgery: randomized trial

Background

Aortic surgery often requires blood transfusion, which may cause complications and postoperative infection. Autologous transfusion was evaluated in a multicentre clinical trial.

Methods

Some 145 patients undergoing elective aortic surgery in eight hospitals were randomized to either ‘homologous’ or ‘autologous’ transfusion, a combination of acute normovolaemic haemodilution (ANH) and intraoperative cell salvage. Homologous blood was administered when the haemoglobin concentration fell below 8 g dl−1.

Results

Median (interquartile range (i.q.r.)) blood loss was 668 (400–862) ml or 17 (10–24) per cent of blood volume in aortobifemoral bypass, and 1120 (765–1700) ml or 24 (17–36) per cent in aneurysm repair (P &lt; 0·001). Autologous transfusion reduced homologous blood requirements from a median (i.q.r.) of 2 (0–4) units to 0 (0–2) units (P = 0·008). Independent predictors of blood transfusion were homologous transfusion strategy (odds ratio (OR) 2·3 (95 per cent confidence interval 1·1–5·0); P = 0·03), low preoperative haemoglobin concentration (OR 3·7 (1·7–8·2); P &lt; 0·001), prolonged surgery (OR 2·1 (1·0–4·8); P = 0·05) and blood loss (OR 3·0 (1·4–6·5); P = 0·007). Patients with a preoperative haemoglobin concentration greater than 13·5 g dl−1 and who lost less than 20 per cent of their blood volume rarely required transfusion. There was no significant difference between the groups in terms of morbidity, mortality and postoperative hospital stay.

Conclusion

Autologous transfusion reduced the need for homologous blood in aortic surgery, but was useful only in patients with low haemoglobin levels or when blood loss exceeded 20 per cent of the blood volume. ANH alone is indicated for patients undergoing aortobifemoral bypass and in those with a higher haemoglobin level and blood volume.

Prognosis following venous thromboembolism in women taking combined oral contraceptives

Background

It is widely believed that ‘post-thrombotic limb’ always follows deep vein thrombosis (DVT). Prognosis following both DVT and pulmonary embolism (PE) was investigated.

Methods

Some 155 women (mean age 25·5 (range 16–49) years) who developed venous thromboembolism while taking third-generation oral contraceptives were studied. The venous system was assessed by duplex imaging a mean of 4·8 years after DVT.

Results

Fourteen (15 per cent) of 96 women suffering PE died. Of the 82 surviving patients, 12 (15 per cent) had chest pain and/or dyspnoea at rest or on exertion. Of the 103 women with confirmed DVT, 59 (57 per cent) had had only calf thrombosis and 44 (43 per cent) had had iliofemoral vein thrombosis. At follow-up, 13 (22 per cent) and 21 (48 per cent) women with calf and iliofemoral thrombosis respectively had leg symptoms, including swelling, pain and lipodermatosclerosis (P = 0·011). Duplex imaging was normal in 60 patients (58 per cent). There was no significant difference in leg symptoms (31 versus 34 per cent) or incompetence on duplex imaging (41 versus 42 per cent) between those who were anticoagulated for 3 months (n = 39) or 6 months (n = 64) respectively. Leg symptoms were more frequent in the 41 women with DVT discharged without elastic stockings, affecting 19 (46 per cent) compared with only 15 (24 per cent) of 62 discharged with stockings (P = 0·034).

Conclusion

The majority of women regained venous patency and became asymptomatic, despite extensive DVT. Elastic stockings were often omitted despite the evidence of long-term benefit.

Prosthetic femoropopliteal bypass: randomized comparison of polytetrafluoroethylene and heparin-bonded Dacron

Background

Dacron was largely abandoned for femoropopliteal bypass 30 years ago as saphenous vein achieved better patencies. As patency in prosthetic above-knee (AK) femoropopliteal bypass in patients on aspirin is equivalent to that with saphenous vein, heparin-bonded Dacron (HBD) and polytetrafluoroethylene (PTFE) have been compared in a randomized trial involving ten hospitals which also included below-knee (BK) popliteal or tibioperoneal trunk bypass where the long saphenous vein was absent or inadequate.

Methods

Over a 28-month recruitment period, 209 patients undergoing femoropopliteal bypass (180 AK, 29 BK) were randomized by the method of minimization to HBD (n = 106) or PTFE (n = 103). Aspirin 300 mg day−1 was started before surgery and continued unless the patient was intolerant.

Results

Mean follow-up was 34 (range 19–48) months. Fifteen patients (7 per cent) died with patent grafts and three (1 per cent) infected grafts were removed. Patency (measured by Kaplan–Meier survival analysis) was 70, 63 and 55 per cent at 1, 2 and 3 years for HBD, compared with 56, 46 and 42 per cent respectively for PTFE (P = 0·0444). Patency at 3 years for AK bypass was significantly better than that for BK bypass. A total of 70 interventions were performed on 47 patients, achieving long-term patency in only three. Amputations were performed in 23 patients, six with HBD and 17 with PTFE grafts (P = 0·015, Fisher's exact test).

Conclusion

In femoropopliteal bypass, primary patency was better with HBD than PTFE, and HBD was associated with a lower amputation rate.

Carotid sinus nerve blockade during carotid surgery: a randomised controlled trial

OBJECTIVES

we investigated whether carotid sinus nerve infiltration with lignocaine reduced blood pressure lability during the first 24h following carotid endarterectomy (CEA).

DESIGN

prospective randomised double-blind controlled trial.

MATERIALS

eighty patients undergoing CEA for significant symptomatic stenosis of the internal carotid artery.

METHODS

after initial dissection, 5 ml of 1% lignocaine or normal saline placebo according to randomisation was infiltrated around the carotid sinus nerve. Blood pressure was measured by intra-arterial cannula during surgery and for four hours afterwards every 15 min, then manually, hourly for 18 h.

RESULTS

patients having excision of the carotid sinus nerve were grouped separately for analysis: 29 patients had lignocaine, 33 placebo and 17 excision (one early death with incomplete data was excluded). Mean systolic, diastolic and pulse pressures did not differ significantly between the three groups before carotid sinus nerve infiltration. After infiltration, those patients who had carotid sinus nerve excision, had significantly higher systolic [mean (SD)=155 (16)mmHg] and diastolic [75 (9)mmHg] pressures than those receiving LA [systolic=136 (15)mmHg, diastolic=65 (10)mmHg] or placebo [systolic=136 (19)mmHg, diastolic=65 (9)mmHg], (p<0.005 ANOVA). Nerve excision also resulted in wider variability of blood pressure as defined by the mean of individual standard deviations (systolic=25 mmHg, diastolic=13 mmHg) compared to LA (systolic=19 mmHg, diastolic=12 mmHg) or placebo (systolic=18 mmHg, diastolic=10 mmHg) (p<0.05 ANOVA). Normotensive patients had significantly lower mean diastolic pressures (p<0.001 ANOVA) and variability (p<0.05) if they received lignocaine although this did not influence pulse pressure.

CONCLUSIONS

lignocaine injection of the carotid sinus nerve has no benefit in those patients with existing treated hypertension and only marginal effects in normotensives. It is more important to preserve the carotid sinus nerve if possible.

Cerebral and peripheral near-infrared spectroscopy: an alternative transfusion trigger?

BACKGROUND AND OBJECTIVES

To develop a transfusion trigger based on tissue oxygenation, near-infrared spectroscopy (NIRS) was evaluated in a model of compensated haemorrhage.

PATIENTS AND METHODS

Regional haemoglobin oxygen saturation from the cerebral cortex (CsO2) and the gastrocnemius muscle (PsO2) was monitored (using an INVOS 4100 near-infrared oximeter) in 30 patients during acute normovolaemic haemodilution to a target haemoglobin of 11 g/dl. Arterial oxygen saturation, end-tidal carbon dioxide tension, mean arterial pressure and haemoglobin concentration were also measured.

RESULTS

During blood collection, CsO2 and PsO2 fell by a mean (95% CI) of 8 (5.3-10.7)% (P < 0.001) and 5.5 (3.2-7.8)% (P < 0.001), respectively. Arterial pressure and oxygen saturation did not change, whilst the end-tidal carbon dioxide tension fell by 2.3 (0.8-3.8) mmHg (P = 0.004). Haemoglobin concentration correlated with CsO2 (R = 0.76, P < 0.001) and PsO2 (R = 0.63, P < 0.001), as did the volume of blood removed.

CONCLUSIONS

CsO2 and PsO2 fell predictably during compensated blood loss. With further research, NIRS may be developed into a transfusion trigger.

Relationship between plasma markers of endothelial cell integrity and the Framingham cardiovascular disease risk-factor scores in apparently healthy individuals

Separate reports have identified differences in plasma levels of the endothelial markers soluble E-selectin, von Willebrand factor (vWf) and soluble thrombomodulin in each of the major modifiable risk factors for atherosclerosis (smoking, hypertension and hypercholesterolaemia), and abnormal levels of some plasma markers predict various adverse cardiovascular events. However, it is unclear whether there is an increasing effect on the endothelium with a worsening risk-factor profile. We measured the three endothelial cell markers by enzyme-linked immunosorbent assay in the plasma of 200 subjects (mean age, 54 years; 58% men) free of the symptoms and clinical signs of atherosclerosis. Levels of the markers were then correlated with the Framingham coronary heart disease (CHD) and cerebrovascular disease (CVD) scores to help determine which (if any) may be useful as good laboratory predictors of future cardiovascular events in prospective epidemiological studies. vWf correlated with CHD (r(s) = 0.269, < 0.001) and CVD risk (r(s) = 0.331, P < 0.001), but soluble E-selectin correlated only with CHD risk (r(s) = 0.163, P = 0.021). We conclude that, of the three specific endothelial markers, vWf correlates most closely with the Framingham risk-factor prediction scores and therefore may be the better plasma endothelial marker of the future development of an atherothrombotic event.