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Biomedical subjects

L J Hands

Publications and source records attributed to L J Hands.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of mortality prediction models after open abdominal aortic aneurysm repair.

OBJECTIVES: Comparison of the accuracy of prediction of contemporary mortality prediction models after open Abdominal Aortic Aneurysm (AAA) surgery. METHODS: Post-operative data were collected from AAA patients from 2 UK Intensive Care Units (ICU). POSSUM and VBHOM based models were compared to the APACHE-AAA model which was able to adjust for the hospital-related effect on outcome. Model performance was assessed using measures of calibration, discrimination and subgroup analysis. RESULTS: 541 patients were studied. The in-hospital mortality rate for elective AAA repair (325 patients) was: 6.2% (95% confidence interval (c.i.) 3.5 to 8.8) and for emergency repair (216 patients) was: 28.7% (95% c.i. 22.5-34.9). The APACHE-based model had the best overall fit to the whole population of AAA patients, and also separately in elective and emergency patients. The V-POSSUM physiology-only (p<0.001) and VBHOM (p=0.011) models had a poor fit in elective patients. The RAAA-POSSUM physiology-only (p<0.001) and VBHOM models (p=0.010) had a poor fit in emergency patients. CONCLUSIONS: The APACHE-AAA model with its ability to adjust for both the hospital-related "effect" as well as the patient case-mix, was a more accurate risk stratification model than other contemporary models, in the post-operative AAA patient managed in ICU.

APACHE↗
PubMed2005

Quantification of mortality risk after abdominal aortic aneurysm repair.

BACKGROUND: The study was designed to evaluate the Acute Physiology And Chronic Health Evaluation (APACHE) II risk scoring system in abdominal aortic aneurysm (AAA) surgery. The aim was to create an APACHE-based risk stratification model for postoperative death. METHODS: Prospective postoperative APACHE II data were collected from patients undergoing AAA repair over a 9-year interval from 24 intensive care units (ICUs) in the Thames region. A multilevel logistic regression model (APACHE-AAA) for in-hospital mortality was developed to adjust for both case mix and the variation in outcome between ICUs. RESULTS: A total of 1896 patients were studied. The in-hospital mortality rate among the 1289 patients who had elective AAA repair was 9.6 (95 per cent confidence interval (c.i.) 8.0 to 11.2) per cent and that among the 605 patients who had an emergency repair was 46.9 (95 per cent c.i. 43.0 to 50.9) per cent. Four independent predictors of death were identified: age (odds ratio (OR) 1.05 (95 per cent c.i. 1.03 to 1.07) per year increase), Acute Physiology Score (OR 1.14 (95 per cent c.i. 1.12 to 1.17) per unit increase), emergency operation (OR 4.86 (95 per cent c.i. 3.64 to 6.52)) and chronic health dysfunction (OR 1.43 (95 per cent c.i. 1.04 to 1.97)). The APACHE-AAA model was internally valid, as shown by calibration (Hosmer-Lemeshow C statistic: chi(2) = 6.14, 8 d.f., P = 0.632), discrimination properties (area under receiver-operator characteristic curve 0.845) and subgroup analysis. There was no significant variation in outcome between hospitals. CONCLUSION: APACHE-AAA was shown to be an accurate risk-stratification model that could be used to quantify the risk of death after AAA surgery. It might also be used to determine the relative impact of ICU over high-dependency unit care.

APACHE↗
PubMed2004

Histological correlates of carotid plaque surface morphology on lumen contrast imaging.

BACKGROUND: Carotid angiographic plaque surface morphology is a powerful risk factor for stroke and systemic vascular risk. However, the underlying pathology is unclear, and a better understanding is required both to evaluate other forms of carotid imaging and to develop new treatments. Previous studies comparing angiographic plaque surface morphology with pathology have been small and unblinded, and the vast majority assessed only the crude macroscopic appearance of the plaque. We performed the first large study comparing angiographic surface morphology with detailed histology. METHODS AND RESULTS: Carotid plaque surface morphology was classified as ulcerated, irregular, or smooth on 128 conventional selective carotid artery angiograms from consecutive patients undergoing endarterectomy for severe symptomatic stenosis. Blinded angiographic assessments were compared with 10 histological features recorded on detailed microscopy of the plaque using reproducible semiquantitative scales. Angiographic ulceration was associated with plaque rupture (P=0.001), intraplaque hemorrhage (P=0.001), large lipid core (P=0.005), less fibrous tissue (P=0.003), and increased instability overall (P=0.001). For example, angiographically ulcerated plaques were much more likely than smooth plaques to be ruptured (OR=15.4, 95% CI=2.7 to 87.3, P<0.001), show a large lipid core (OR=26.7, 95% CI=2.6 to 270, P<0.001) or a large hemorrhage (OR=17.0, 95% CI=2.0 to 147, P=0.02). The equivalent odds ratios for angiographically irregular versus smooth plaque were 6.3 (1.3 to 31, P=0.02), 6.7 (1.5 to 30, P=0.008), and 9.2 (1.1 to 77, P=0.02), respectively. CONCLUSIONS: In contrast to previous studies based on macroscopic assessment, we found very strong associations between detailed histology and carotid angiographic plaque surface morphology. Plaque surface morphology on carotid angiography is a highly sensitive marker of plaque instability. Studies of the predictive value of MR- and CT-based lumen contrast plaque surface imaging are required.

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PubMed2004

Changes in blood coagulability as it traverses the ischemic limb.

OBJECTIVE: We undertook this study to determine whether changes in blood coagulability associated with peripheral arterial occlusive disease are due to contact with the atherosclerotic arterial wall or passage through distal ischemic tissue. METHODS: Thirty patients with peripheral arterial occlusive disease undergoing angiography participated in the study. Ankle-brachial pressure index was recorded before intervention. Blood samples taken from the aorta, common femoral artery, and common femoral vein were analyzed at thromboelastography. Angiograms were scored for stenotic disease by a radiologist blinded to the other results. RESULTS: When femoral artery samples were compared with aortic samples there was a decrease in reaction time (R; P <.05), an increase in maximum amplitude (MA; P <.05), and an increase in coagulation index (CI; P <.002), indicating an increase in coagulability as blood flowed down the iliac segment. These changes also correlated (DeltaR, r = 0.442, P <.05; DeltaMA, r = 0.379, P <.05; DeltaCI, r = 0.429, P <.05) with the severity of disease in the ipsilateral iliac segment. Significant differences in R (P <.05), angle (P <.05), MA (P <.005), and CI (P <.001) between common femoral arterial and venous samples confirmed that venous samples were more coagulable in this group of patients. This difference in Thromboelastography parameters across the arteriovenous segment correlated inversely with the degree of ischemia (represented by ankle-brachial pressure index; DeltaCI, r = -0.427, P <.05; DeltaMA, r = -0.370, P <.05) in the puncture side limb. CONCLUSION: Passage of blood down an atherosclerotic artery leads to an increase in coagulability proportional to the degree of stenosis in that vessel. Passage of blood through ischemic tissue may also contribute to increased coagulability in peripheral arterial occlusive disease.

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PubMed2004

The use of telemedicine in the management of vascular surgical referrals.

We have performed a feasibility study of telemedicine as an alternative to conventional outpatient appointments for the making of diagnostic and management decisions for patients referred for vascular surgery. Twenty-two sequential patients referred by a single general practice to a vascular centre were offered a telemedicine clinic appointment as an alternative to a conventional hospital outpatient appointment. A referral pro forma and digital photograph (where appropriate) were transmitted in advance of the videoconference. The videoconference involved patient, practice nurse and vascular consultant. All patients opted for the teleconsultation. The majority had leg ulceration or leg pain. Six patients required only the initial teleconsultation and were managed thereafter in the community. Thirteen were referred to the vascular laboratory for investigation. Three proceeded to angioplasty and four to surgery. Two patients had a conventional outpatient appointment for follow-up but all others were followed up via telemedicine. Overall 27 conventional outpatient appointments were replaced by a teleconsultation.

Adult↗
PubMed2001

Improved quality of life among patients with symptomatic carotid artery disease undergoing carotid endarterectomy.

BACKGROUND: Few studies have examined how carotid endarterectomy affects patients' view of their quality of life. METHODS: Patients undergoing carotid endarterectomy from January 1996 to March 1997 at the John Radcliffe Hospital completed the United Kingdom Short Form 36 (SF-36) Health Survey Questionnaire before undergoing the procedure and again at 3 months afterward. Scores were compared with population normal values. RESULTS: In 50 patients with symptomatic carotid artery disease, there was significant improvement in the SF-36 overall "change in health" score after the procedure compared with beforehand (61.0 +/- 3.7 vs 44.5 +/- 3.4, P =.003, Wilcoxon signed rank test). There were, however, no statistically significant differences in the group's mean SF-36 subscores after operation compared with before the procedure. The physical subscores were below age-adjusted healthy population means but similar to those for chronically ill patients (physical function subscore P =.015 vs normal, P =.89 vs ill; role limitation-physical subscore P =.007 vs normal, P =.89 vs ill). Patients with postoperative complications did not have an improved change in health score (-12.5 vs 22.0, P =.03, Mann-Whitney U test). There was no effect on change in health score because of other risk factors or in patients with contralateral carotid artery occlusion or a history of preoperative stroke. CONCLUSIONS: Patients with symptomatic carotid artery disease undergoing an uncomplicated carotid endarterectomy perceive improved quality of life and overall health. There is no perception of worsened pain, energy, or physical or mental function after the procedure. These results confirm that patients believe that performance of carotid endarterectomy improves their overall health, supporting the surgical approach to carotid artery disease.

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PubMed2000

The long-term outcome after axillo-axillary bypass grafting for proximal subclavian artery disease.

OBJECTIVES: to investigate the outcome of patients undergoing axillo-axillary bypass grafting for symptomatic subclavian artery stenoses or occlusions. DESIGN: retrospective case-note review and prospective review of patients available for follow-up. PATIENTS AND METHODS: sixteen patients had axillo-axillary grafts in a 17-year period. Ten patients were available for review and assessed clinically, by measurement of arm blood pressures, and by duplex scanning of their grafts. RESULTS: one patient died and three grafts occluded within 30 days of operation. Nine out of 10 grafts scanned were patent, with three further grafts clinically patent at death. Overall secondary patency was 75% at a combined median follow-up of 56 months (range 12-204 months). Recurrent symptoms occurred in two patients, one with an occluded graft and one with a patent graft. CONCLUSION: axillo-axillary bypass grafts give good long-term symptom-free results.

Axillary Artery↗
PubMed1999

Preoperative prediction of graft patency for infrapopliteal arterial bypass using pulse-generated runoff.

OBJECTIVE: to assess: (i) pulse-generated runoff (PGR) as a tool for preoperative prediction of graft patency; (ii) the effect of PGR use on graft patency. DESIGN: retrospective analysis of continuous patient data. MATERIALS: all patients undergoing bypass to the infrapopliteal vessels in the Oxford Regional Vascular Unit between 1989 and 1993. METHODS: preoperative assessment using ankle-brachial indices, intra-arterial digital subtraction angiography and PGR. Six-monthly and then yearly clinical and duplex sonography follow-up to assess graft patency. Univariate analysis of graft patency to assess discriminatory ability of PGR for graft patency. RESULTS: a biphasic signal in the artery of insertion was associated with significantly better graft patency rate at 1 month and at maximum follow-up than was a monophasic signal. A monophasic signal was associated with a 12-month patency of 25% and a mortality of 37.7%. Use of PGR did not affect graft patency significantly. CONCLUSION: PGR is a useful, non-invasive, means of preoperative patient assessment to determine the potential for maintained graft patency.

Adult↗
PubMed1998

Prospective evaluation of quality of life after conventional abdominal aortic aneurysm surgery.

OBJECTIVES: To evaluate the changes in quality of life following conventional abdominal aortic aneurysm repair. DESIGN: Prospective study. MATERIALS AND METHODS: Fifty-nine consecutive patients (50 men; nine women) in two surgical centres were investigated preoperatively, and at 6 weeks, 3 months and 6 months postoperatively. Quality of life was measured using the Short Form 36 (SF 36) questionnaire and the York Quality of Life questionnaire, from which the Rosser index was calculated. RESULTS: Rosser index assessment showed restoration of quality of life to preoperative levels by 3 months, and significant improvement at 6 months. Changes in the SF 36 revealed significant improvement in mental health, and physical role limitation at all times postoperatively. Social function worsened at 6 weeks but improved to preoperative levels by 3 and 6 months after surgery. CONCLUSIONS: Quality of life was improved after open aortic aneurysm repair. The time course of recovery shows a predominant improvement between 6 weeks and 3 months postoperatively.

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PubMed1997

A comparative study of treadmill tests and heel raising exercise for peripheral arterial disease.

OBJECTIVES: This two part study validated a 1 min treadmill exercise test and compared this with simple heel raising exercise. METHODS: In an initial study of 24 claudicants (aged 43-79, median 63 years), ankle pressures were measured immediately after repeated treadmill exercises: for 1 min, until onset of claudication, and until maximum tolerated walking distance. Absolute value, fall and percent change in pressures were calculated. The results of this part of the study were then used as a "gold standard" for comparison with 30 s of heel raising and treadmill exercise. This second stage was performed on 21 symptomatic limbs (14 claudicants aged 42-73, median 69 years). RESULTS: Variability was least for pressures expressed as percent change after 1 min of exercise. The paired t-test revealed a significant correlation between the two methods of exercise (p < 0.05). CONCLUSION: Heel raising produced changes in ankle pressure which correlated well with those induced by treadmill exercise. We recommend the use of simple heel raising when a stress test is required to diagnose lower limb arterial insufficiency in the outpatient clinic.

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PubMed1996

31P NMR studies of human skin using a modified zig-zag surface coil.

Results are presented from an in vivo study of human skin in which a zig-zag surface coil together with a three-pulse Fourier Series Window (FSW) protocol have been used to obtain minimally contaminated 31P skin spectra of the posterior calf. Phantom experiments indicate that while the fall-off in the B1 field profile of the zig-zag surface coil is superior to conventional surface coil designs, it is still not sufficient on its own to reduce muscle signal contamination to acceptable levels in human studies. The additional spatial localization required is provided by the FSW, which reduces signal contamination to less than 30% of the total signal collected. In a study of 18 normal controls the measured pH was found to be relatively high (7.39 +/- 0.08), while the ratios of skin PCr/ beta-ATP (1.04 +/- 0.35) and PCr/Pi (1.67 +/- 0.4) were found to be low compared with that of skeletal muscle. In addition, substantial signal from phosphomonoesters and phosphodiesters were also observed.

Adenosine Triphosphate↗
PubMed1996

Use of the Fourier series window protocol with a zig-zag surface coil in 31P NMR human skin spectroscopy. A theoretical study.

The use of a zig-zag surface coil with a three-pulse Fourier Series Window (FSW) has been suggested as a means by which in vivo NMR spectroscopic studies of human skin can be performed. Using direct numerical simulations of the magnetic field profile of a 10 limb zig-zag surface coil, the role of the FSW in reducing NMR signals originating from the deeper skeletal muscle layers is examined theoretically. The extent of muscle signal contamination is determined for different coil inter-limb spacings and pulse width settings. The optimum inter-limb spacing for studying living human skin, that which minimizes signal contamination and maximizes skin signal collected, is shown to be between 4 and 6 mm. These calculations demonstrate that the FSW and zig-zag surface coil offer a protocol for investigating the metabolism of large areas of surface tissue while keeping signal contamination from the deeper skeletal muscle layers down to an acceptable level.

Fourier Analysis↗
PubMed1996

A ten year audit of surgery for vascular trauma in a British teaching hospital.

Vascular trauma is uncommon in the U.K. with the exception of Northern Ireland. In marked contrast to North America, gunshot wounds are rare and stabbings are infrequent. A 10 year audit was carried out in a regional vascular referral unit to determine the mechanisms, treatment and outcome of vascular injuries. Forty-seven patients were operated on during the period. The median age was 26 years (range 7-85 years); two-thirds were men. Road traffic accidents accounted for 21 (45%) of injuries, other accidents 15 (32%) and stabbings 11 (23%). There were no gunshot wounds. Most injuries were penetrating with no associated fracture. Commonly injured vessels were the brachial (30%) and superficial femoral (15%) arteries. Fifty-three primary operations were performed, 10 were vein interpositions and 21 were bypass grafts. There were three primary amputations (6%). Eleven patients suffered a complication including one death. One graft occluded requiring a further bypass. Two patients required fasciotomy as a secondary procedure. Median follow-up was 6 months. Eighty-one percent of patients were symptom free at last follow-up. There were no late vascular complications. Our experience is likely to represent that of other vascular units in countries with strict gun control legislation, little civil violence and modest levels of road traffic accidents.

Accidents, Traffic↗
PubMed1996

Changes in energy metabolism of calf muscle in patients with intermittent claudication assessed by 31P magnetic resonance spectroscopy: a phase II open study.

Energy status and metabolism in skeletal muscle of nine patients with peripheral arterial disease and suffering from intermittent claudication were evaluated using 31phosphorus magnetic resonance spectroscopy (MRS) before and after treatment for 3 months with propionyl-L-carnitine (PLC; 2 g/day p.o.). Maximum walking distance (MWD) was assessed on a standard treadmill (4 km/h, zero incline). For the group as a whole 31P MRS results did not change significantly with PLC. Although MWD increased by a mean of 36%, this change did not reach significance. However, when these variables were assessed with respect to the change in MWD, there were significant differences between those who increased MWD by > 30% (responders, R; n = 5) and those who did not (nonresponders, NR; n = 4). Compared with pretreatment values, during exercise the decrease in muscle pH in R relative to the decrease in phosphocreatine was less after PLC (p = 0.04). After exercise there was a significant inverse correlation between the changes in recovery half-time (t1/2) for phosphocreatine and in MWD (r = -0.91, p = 0.01). With PLC, Vmax increased in R (p = 0.04), but not in NR. For the patient group as a whole, the changes in Vmax and MWD correlated positively (r = 0.90, p = 0.01). This study helps to identify the changes in muscle metabolism that correlate with changes in exercise performance, and may accompany treatment with PLC.

Adenosine Diphosphate↗
PubMed1996

Carotid artery bifurcation advancement: an alternative to patching.

Carotid bifurcation advancement uses the in situ external carotid artery to patch the internal carotid after carotid endarterectomy. This avoids the potential complications of patch rupture and pseudo-aneurysm formation seen with vein and synthetic patches. In 25 cases a Dacron patch was used to close and nine bifurcation advancement closures were compared retrospectively with 30 cases using simple primary closure and 13 using a saphenous vein patch. Follow-up with carotid duplex scanning revealed six restenoses > 50% in the primary closure group, whereas the patch angioplasty and bifurcation advancement groups had no restenoses (P = 0.002). No significant difference in post-endarterectomy flow increase was shown between the patch angioplasty groups and the bifurcation advancement group. Operation times did not differ significantly between the patch closure and the bifurcation advancement groups. Carotid bifurcation advancement is an alternative method of vessel closure with comparable rates of restenosis, post-endarterectomy flow increase, and operation time as compared with conventional patch angioplasty closure techniques.

Blood Flow Velocity↗
PubMed1996

Duplex-guided compression of femoral artery false aneurysms reduces the need for surgery.

In a 1-year period, 13 patients underwent duplex-guided compression (DGC) of femoral artery false aneurysms. Of the 13 false aneurysms, 11 arose after cardiac catheterisation, and DGC was successful in 10 (77%) cases. The number of percutaneous cardiological procedures has risen over the past 5 years, and with time a greater proportion of these procedures have become more complex, involving coronary angioplasty or coronary stenting. The rate of vascular complications has risen from 0.2% in 1991-1992 to 0.61% in 1994-1995. Duplex-guided compression has reduced the number of operations performed for the vascular complications of percutaneous cardiological procedures by 50%. No complications have arisen from DGC, and it is recommended as the first line of management for femoral artery false aneurysms after percutaneous cardiological procedures.

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