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Biomedical subjects

P A Grace

Publications and source records attributed to P A Grace.

At least 19 recordsLinked to original sources
PubMed2005

Haemodynamic study examining the response of venous blood flow to electrical stimulation of the gastrocnemius muscle in patients with chronic venous disease.

OBJECTIVES: The aim of this study was to explore the option of stimulating calf muscle contraction through externally applied neuromuscular electrical stimulation (NMES) and to measure venous blood flow response to this stimulation. METHODS: Ten patients with class 6 chronic venous disease (CEAP clinical classification) were recruited. Measurements of peak venous velocities in the popliteal vein were recorded by Duplex scanning in response to six test conditions; 1. Standing, 2. Voluntary calf muscle contraction, 3. Standing with NMES applied, 4. Standing with compression bandaging applied to the leg, 5. Voluntary calf muscle contraction with compression bandaging applied to the leg, 6. Stationary with compression bandaging applied to the leg and NMES applied. Comfort assessment was completed using visual analogue scales at each test stage and on study completion each patient completed a short structured interview to determine comfort and acceptability of NMES. Statistical analyses were carried out using SPSS, Version 9. Non-parametric testing was used in all analyses using the Wilcoxon Signed Ranks Test for paired samples. RESULTS: There was a significant increase in venous velocities on voluntary contraction of the calf muscle (median resting vel 7.3 cm/s; voluntary contraction median 70 cm/s) and with the introduction of NMES, both with compression (median velocity 15 cm/s, p = 0.005 Wilcoxon) and without compression (median velocity 13 cm/s, p = 0.005 Wilcoxon). The greatest increase with NMES was when combined with compression bandaging. All patients reported the stimulus as an acceptable treatment option with 90% reporting NMES as comfortable. CONCLUSIONS: Healing rates in venous ulceration with the application of compression bandaging remain between 50 and 70%. This study shows a positive haemodynamic response to NMES. Further research is needed to quantitatively measure the effect of NMES on ulcer healing.

Chronic Disease↗
PubMed2005

Local anaesthetic flush reduces postoperative pain and haematoma formation after great saphenous vein stripping--a randomised controlled trial.

OBJECTIVES: To observe the effect of local anaesthetic flush through the great saphenous vein (GSV) tunnel on postoperative pain and haematoma formation following saphenous vein stripping operations. DESIGN: Prospective, double-blind, randomised, control trial. METHODS: One hundred patients were randomized to receive 20 ml of local anaesthetic (bupivacaine 0.25% + adrenaline) or saline control flush through the GSV tunnel after stripping in a double-blind study. Visual analogue pain scores were used to measure postoperative pain daily for the 1st week, then at 3 weeks and 6 weeks. Patients were examined during the 1st, 3rd and 6th week for haematoma formation. RESULTS: In the control group the median postoperative pain score was 4 (range 0-7) in the immediate postoperative period compared to a median of 1 (range 0-4) in the LA group (p<0.001). The median pain score on day-4 was 4 (range 1-6) (control) vs. 1 (range 0-3) (LA group) (p<0.001, Mann-Whitney Utest) and on day-6 it was 1 (range 0-5) (control) vs. 0 (range 0-5) (LA group) (p<0.001, Mann-Whitney). Twelve patients (24%) developed a haematoma in the GSV tunnel in the control group compared to three patients (6%) in the LA group (p = 0.007). CONCLUSION: Flushing of the GSV tunnel with bupivacaine plus adrenaline significantly reduces postoperative pain and haematoma formation in patients undergoing GSV stripping for varicose veins.

Adult↗
PubMed2005

A description of an accelerometer-based mobility monitoring technique.

Accurate monitoring of the mobility status of older adults, over the long-term, is important in rehabilitation medicine, as regular physical activity is central to maintaining both physical and mental health, as well as evaluating quality of life. This technical note describes an accelerometer-based mobility monitoring technique, which can distinguish between static and dynamic activities and can detect the basic postures of sitting, standing and lying. The technique allows thresholds for these postures to be set and two different posture threshold methods are described: mid-point and "best estimate". Preliminary results from using these methods are presented. This preliminary evaluation of the technique was carried out over the long-term (>29 h) in an uncontrolled environment and the method used to carry out the evaluation is described in detail. The two different posture thresholding methods were tested on long-term mobility data from one older adult subject. The subject did not have to follow a specific activity protocol during the recording period (4 days) and was shadowed by an observer in order to evaluate the accuracy of this technique. The monitoring hardware consisted of two accelerometer devices, one on the trunk and the other on the thigh and a pocket-sized ambulatory data-logger. Applying 'best estimate' thresholding, as opposed to mid-point thresholding, improved sitting detection accuracy by 18%, to 93% and lying detection accuracy by 5%, to 84%. Thus, based on these preliminary data, an accurate mobility monitoring system for older adults is described and it was observed that the actual posture threshold limits applied have a high impact on the mobility monitoring system's accuracy and are particularly important for accurately detecting postures when used over the long-term, in an uncontrolled environment.

Acceleration↗
PubMed2005

Information leaflets for venous leg ulcer patients: are they effective?

OBJECTIVE: To validate the usefulness of written information for patients with venous leg ulcers and test the hypothesis that patients who receive written information retain more knowledge than those who receive verbal information alone. METHOD: Twenty patients newly diagnosed with venous leg ulcers were recruited into this prospective trial. Patients were randomised either to the control group (given verbal information on their condition) or the intervention group (same verbal information and an information leaflet). The verbal information was in the same format as in the leaflet. Patients' knowledge of the condition was ascertained at an initial interview and at follow-up four to six weeks later. RESULTS: At follow-up both groups showed an overall improvement in knowledge, with no statistical difference between them. CONCLUSION: The results indicate there is limited value in providing information leaflets to this patient group, who were predominantly older patients with low levels of education. The relatively small sample size may explain the disappointing results. Further research may reveal a benefit of providing these leaflets to carers.

Aged↗
PubMed2005

A review of technological approaches to venous ulceration.

Leg ulceration is a chronic condition affecting about 1-2% of the adult population. The main causes of leg ulceration are venous hypertension, arterial insufficiency, diabetes, or a combination of these aetiologies (causes) or malignancy. Venous ulcers account for approximately 80% of all leg ulcers and are a result of venous hypertension. The current mainstay of treatment of venous ulcers is the application of graduated compression bandaging to the limb. In spite of the application of the best evidence-based therapy, healing rates for venous leg ulcers remain disappointing, at 50-70% after 12 weeks of treatment, depending on initial size and chronicity of the ulcer. Thus, a large number of ulcers are unhealed by this time, and many patients suffer from long-term leg ulceration, some remaining for years, and those that heal often recur. There is an obvious need to develop new treatments that would improve healing rates. This review provides a complete overview of the anatomy of venous circulation and the physiology pertaining to it, the pathophysiology of venous disease, the pathogenesis of ulceration, and a review of treatments currently employed in healing venous leg ulcers and their supporting evidence. The aim of this article is to encourage a fresh look at this chronic problem and stimulate ideas on how healing rates can be improved.

Bandages↗
PubMed2004

An investigation of the effect of electrode size and electrode location on comfort during stimulation of the gastrocnemius muscle.

The use of surface neuromuscular electrical stimulation (SNMES) in medicine is well established. However, discomfort has been identified as limiting the use of SNMES in these applications. This pilot study investigated the influence of various electrode sizes and their positioning on perceived pain and discomfort during neuromuscular electrical stimulation (NMES) of the gastrocnemius muscle using surface electrodes. This study formed part of a research project to develop a therapeutic device for calf muscle blood flow assist applications. Twelve healthy subjects (n=12) participated in this pilot study. Each participant attended the trial centre for testing which consisted of SNMES to four different electrode stimulation sites using two electrode sizes (round with areas 19.63 and 38.48 cm2). Comfort was assessed by asking the subjects to indicate the stimulation amplitude corresponding to the onset of discomfort (pain threshold) and the amplitude at which the discomfort became unbearable (pain tolerance). Of the four stimulation sites tested, two were deemed unsuccessful as it was very difficult to obtain a muscle contraction using these sites, while the remaining two sites elicited good muscle contraction. The most comfortable stimulation was achieved by placing the cathode electrode high on the calf, below the proximal end of the muscle heads and the anode electrode towards the end of the muscle belly and when the 19.63 cm2 electrodes were used at these sites (p=<0.001).

Adult↗
PubMed2004

Long-term mobility monitoring of older adults using accelerometers in a clinical environment.

OBJECTIVE: To assess the accuracy of accelerometer-based mobility monitoring during extended measurements on older adults in a clinical setting and to evaluate two different approaches to thresholding. DESIGN: The monitoring device consisted of two Analog Devices ADXL202 accelerometers, an ambulatory data-logger and associated cabling. The monitoring system used custom-designed analysis software to detect activities of daily living, namely duration of sitting, standing, lying and moving during the period monitored. An investigator shadowed the subjects throughout the recording period. SUBJECTS AND SETTING: This study monitored five older adults, with varying degrees of mobility, resident in a rehabilitation clinic, over four days. INTERVENTIONS: The accelerometer data were analysed using a MATLAB program that allowed trunk and thigh threshold angles to be set to distinguish between sitting, standing, lying and moving. Two different approaches to setting these thresholds were investigated: (1) using a midpoint tolerance value of 45 degrees and (2) using a 'best estimate' tolerance value. The analysis program generates a summary of activities, which is then compared line-by-line with the manual summary created by the observer. The result was a hit/miss ratio representative of the system's accuracy. RESULTS: The detection accuracies for sitting and lying using a mid-point tolerance value were poor, with an average detection accuracy of 75% obtained. The 'best estimate' approach improved the detection accuracies for sitting and lying by approximately 18% to an average value of 93%. CONCLUSION: In a population of older adults, the static activities of sitting, standing and lying and dynamic activities can be distinguished using the technique and threshold values outlined here to a degree of accuracy of 92% and higher.

Activities of Daily Living↗
PubMed2003

Randomized clinical trial and economic analysis of four-layer compression bandaging for venous ulcers.

BACKGROUND: The aim of this study was to compare the cost-effectiveness of four-layer compression bandaging for venous leg ulcers with that of other available treatments. METHODS: In this pragmatic trial, 200 patients with a venous leg ulcer were randomized either to four-layer bandaging (intervention group; n = 100) or to continue their usual system of care (control group; n = 100). The follow-up for each patient was 12 weeks. Analysis was by intention to treat; the main outcome measures were time to healing and cost to the health board per leg healed. RESULTS: Baseline characteristics were well matched in the two groups. The Kaplan-Meier estimate of the healing rate at 3 months was 54 per cent with four-layer bandaging and 34 per cent in the control group. Throughout the 3 months, four-layer bandaging healed leg ulcers significantly earlier (P = 0.006). There was a significant reduction in the median cost per leg healed with four-layer bandaging (euro 210 versus euro 234; P = 0.040). CONCLUSION: Four-layer bandaging is currently the most effective method of treating venous leg ulcers in a community setting.

Aged↗
PubMed2003

On the existence of an optimum end-to-side junctional geometry in peripheral bypass surgery--a computer generated study.

BACKGROUND: To investigate hemodynamic flow changes associated with vein cuffs and patches that may be responsible for improved patency of prosthetic infrainguinal grafts. METHODS: The role of the graft-artery junction angle was examined by computational fluid dynamics to assess the influence of anastomotic geometry on wall shear stress (WSS) distributions. Three geometrically different junction configurations were studied and the WSS and WSS gradient (WSSG) values were compared. RESULTS: The inclusion of a patch or a cuff moves the bed stagnation point (BSP) distally, increasing the area on the bed of the junction which experiences a BSP and reducing the strength of the recirculation region opposite the heel of the junction by 54.8 and 50.8%, respectively. The patched geometry promotes earlier recovery of the flow in the distal outflow segment (DOS) than for the unpatched model. Also, the helical flow patterns in the DOS associated with the cuffed geometry are stronger. The net effect of these changes are that peak WSSG values for the patched and cuffed geometries are three times lower than those for the uncuffed geometry. CONCLUSION: This study provides some additional insights into the hemodynamics of graft-artery junction geometry which may influence future clinical practice.

Anastomosis, Surgical↗
PubMed2003

Endovascular exclusion of iliac artery to iliac vein fistula after lumbar disk surgery.

Iliac arteriovenous (AV) fistula is rare after lumbar disk surgery. Traditionally, open repair through the arterial lumen was performed. We report endovascular exclusion of an iliac AV fistula in a 41-year-old woman 8 years after lumbar diskectomy. An angiogram showed an AV fistula connecting the right common iliac artery and vein. This was repaired with placement of two covered wall stents in the right common artery and external iliac artery, and embolization of the right internal iliac artery. Contrast medium-enhanced computed tomography scan at 5 months confirmed elimination of the AV fistula and right iliac artery patency. This technique should be considered in management of iliac AV fistulas.

Adult↗
PubMed2000

Attenuation of reperfusion injury by renal ischaemic preconditioning: the role of nitric oxide.

OBJECTIVE: To determine the effect on nitric oxide (NO) release and renal NO synthase (endothelial, eNOS and inducible, iNOS) activity of renal ischaemia-reperfusion (I/R) in vivo in an animal model, and to examine the possible involvement of NO in ischaemic preconditioning (IP) of the kidney. MATERIALS AND METHODS: In a right-nephrectomized rat model, 42 animals were randomized in four groups: controls; IP-only (4 min of ischaemia followed by 11 min of reperfusion, total of four cycles); renal warm ischaemia (45 min) and 6 h reperfusion; ischaemia (45 min) preceded by IP pretreatment. Serum NO metabolites were assayed 2 and 6 h after ischaemia or the control equivalent. NOS expression in the kidney was detected immuno-histochemically, and damage assessed morphologically in sections stained with haematoxylin and eosin. Kidney function was assessed by the levels of serum creatinine, urea and electrolytes. RESULTS: Compared with before ischaemia, the concentration of serum NO metabolites at 6 h was increased in the IP-only animals (P = 0. 016) and in the IP + I/R group (P = 0.002). There was greater eNOS expression in the IP-only group (P = 0.009) and in the IP + I/R group than in controls (P = 0.050). iNOS expression was greater in the IP-only animals than in the control group (P = 0.050). Histological assessment showed less evidence of cellular damage in IP + I/R animals than in the I/R-alone group (P = 0.020). Serum creatinine level was not significantly different between the IP-only group and the control. There were no differences after 2 h of reperfusion. CONCLUSION: Ischaemic preconditioning has a protective effect on renal structure and function, which may be produced by increased NO release arising from increased NOS expression by 6 h after reperfusion.

Animals↗
PubMed1999

Ischaemic preconditioning protects the rat kidney from reperfusion injury.

OBJECTIVE: To examine the possible role of ischaemic preconditioning (IPC), an adaptive pathophysiological phenomenon that increases tolerance to ischaemia-reperfusion (I-R) injury, in renal protection when rats are presented with an I-R challenge. MATERIALS AND METHODS: Female Wistar rats (n=36) were divided randomly into four groups: (A) sham-operated controls; (B) IPC only; (C) renal ischaemia (RI) only; and (D) IPC+RI. The left kidney in groups B and D was preconditioned with four cycles of renal artery occlusion lasting 4 min, each occlusion separated by 11 min of reperfusion. The ischaemic insult, applied in groups C and D, comprised 40 min of sustained left renal artery occlusion. In Group D, the IPC cycle was completed 5 min before the start of the ischaemic insult. Differential left renal function was calculated by 99mTc-labelled dimercaptosuccinic acid scintigraphy at 0, 2 and 9 days after treatment, and expressed as a percentage of the total renal uptake. RESULTS: The mean (sem) maximum decrease in left renal function, to 14.5 (4.3)% of the total, occurred on day 2 in Group C. The equivalent value in Group D showed relative preservation of function, at 36.0 (3.5)% (P=0.001 compared with Group C). The mean left renal function improved by day 9, to 39.6 (6.7)% (Group C) and 48.6 (1.5)% (Group D). The mean left renal function in Group B (50.5-53.9%) did not differ from that in controls (49.4-51.4%). CONCLUSION: An IPC regimen applied 5 min before RI in the rat significantly protects it from the functional impairment associated with ischaemia and reperfusion.

Animals↗
PubMed1998

Quality of life following repair of ruptured and elective abdominal aortic aneurysms.

OBJECTIVE: To find out whether patients undergoing repair of ruptured abdominal aortic aneurysms (AAA) had more emotional problems and limitations of lifestyle than those listed for elective resection. DESIGN: Retrospective study SETTING: Teaching hospital, Eire. SUBJETS: 28 patients, 14 in each group, matched for age, sex, duration of stay in the intensive care unit (ICU), hospital stay postoperatively, and length of time since operation. INTERVENTIONS: Application of structured questionnaire. MAIN OUTCOME MEASURES: Emotional problems, mobility, activities of daily living, ability to sleep, degree of psychological stress, presence of symptoms, and Rosser index to measure quality of life (QoL). RESULTS: There were no significant differences between the groups in any measure. CONCLUSIONS: Patients have few emotional difficulties or disturbances of QoL after emergency or elective repair of AAA. Survivors after repair of ruptured AAA can expect as good a quality of life as those operated on electively. These results support an aggressive approach to the treatment of ruptured AAA.

Aged↗
PubMed1997

Ischaemia-reperfusion injury in the rat kidney: the effect of preconditioning.

OBJECTIVES: To design and establish a model to examine whether brief periods of renal artery occlusion (ischaemic preconditioning, IP) confers protection from the effects of a subsequent period of ischaemia and reperfusion of the rat kidney. MATERIALS AND METHODS: Ninety rats were randomized into six groups, i.e. sham-operated controls; IP alone; a 20 or 40 min period of left renal ischaemia (RI) alone; and IP followed by a 20 or 40 min period of RI. Preconditioning involved the sequential clamping of the left renal artery for 4 min and its release for 11 min, a total of four times, a 'critical interval' of 30 min before the ischaemic insult. Left renal tissue integrity was determined by dimercapto-succinic acid (DMSA) radionuclide imaging on a gamma-camera both immediately (day 0) and 2 and 9 days later. Acute tubular necrosis was also assessed histologically. RESULTS: RI for 20 min resulted in a significant decrease in left renal tissue integrity on day 2 only (P < 0.001), whereas RI for 40 min caused significant left renal dysfunction on day 0, day 2 and day 9 (P < or = 0.01). For a given duration of ischaemia, there was no significant difference between results from (IP + RI) rats compared with RI-only rats at any of the three times. There was no significant alteration in renal tissue integrity in the IP-only rats compared with sham-operated controls. Histological findings paralleled the data obtained from DMSA uptake. CONCLUSIONS: The IP regimen and 30 min 'critical interval' confers no protection to the kidney from a 20 or 40 min ischaemic episode. The IP regimen itself appears to have no effect, confirming the validity of our experimental model.

Animals↗