Biomedical subjects

R C Kester

Publications and source records attributed to R C Kester.

At least 55 records · Page 3Linked to original sources

PubMed1994

Platelet activation during hand vibration.

The level of beta-thromboglobulin, the circulating platelet aggregate ratio and platelet sensitivity to aggregation with adenosine 5'-diphosphate (ADP) and collagen were assessed in 12 control subjects, 16 patients with vibration white finger (VWF) and 15 patients with primary Raynaud's disease; this was done before and after a 1-min exposure to hand vibration. The beta-thromboglobulin level increased significantly in controls, from a median (interquartile range) of 35.5 (22-47) to 47.5 (27-52) ng/ml, and in the VWF group from 44.0 (39-60) to 47.5 (42-109) ng/ml (P < 0.005). Vibration had no effect on circulating platelet aggregate ratio in any group. The platelets of normal subjects tended to be more sensitive to aggregation with low-dose ADP (1 mmol/l) than those of patients with VWF or primary Raynaud's disease. Significant change occurred in the lag phase of the aggregation response to vibration in the control group at an ADP concentration of 2 and 5 mmol/l. These results indicate that intravascular platelet aggregation occurs as a result of exposure to vibration. Platelet sensitivity to aggregation with ADP may be decreased in patients with VWF or established Raynaud's disease.

Adenosine Diphosphate↗

PubMed1994

Assessment of chemical lumbar sympathectomy in critical limb ischaemia using thermal imaging.

Objective assessment of chemical lumbar sympathectomy (CLS) is lacking. Its success is usually judged in terms of the patient's clinical improvement. We have thermographically measured the immediate temperature changes of the lower limb following CLS using a thermal imager (SAN-EI Thermotracer 6T61). Seven patients with critical limb ischaemia and one patient with Raynaud's phenomenon underwent unilateral ablation of the lumbar sympathetic chain using 5% phenol. Four patients were diabetic, two of whom had undergone previous sympathectomy on the same side. Within fifteen minutes of injection, all patients showed a rise in skin temperature in parts of the sock distribution of between 0.8 degrees C and 8.5 degrees C. We conclude that the haemodynamic effects of CLS are immediate and can be objectively measured with thermal imaging.

Aged↗

PubMed1994

Systemic heparinization during peripheral vascular surgery: thromboelastographic, activated coagulation time, and heparin titration monitoring.

Fifteen patients (9 male, 6 female) undergoing peripheral vascular surgery were monitored during surgery for evidence of subclinical anticoagulation using the activated coagulation time (ACT), thromboelastography (TEG), and heparin titration monitoring. Assessments were made at 30-minute intervals before and after the occlusion clamp. Mean (+/- SD) ACT values preoperatively were 111 (17) seconds, and 10 minutes after 5,000 IU of heparin, the ACT was 264 (57) seconds (P < 0.001). Intraoperatively, there was a significant decline in ACT values at 30 minutes (ACT 228 [50] sec, P < 0.005) and 60 minutes (200 [46] sec, P < 0.001) postheparin. No significant difference in ACT was observed between samples drawn distally and proximally to the clamp. TEG profiles were abolished in all patients immediately following heparinization. However, in 2 patients nearly complete return of the TEG coagulation profile was observed prior to the termination of the procedure and was associated with ACT values less than 160 seconds. The heparin device was unable to accurately monitor heparin elimination at these low doses. Variability of patient response to heparinization necessitates the use of intraoperative monitoring of anticoagulation during peripheral vascular surgery.

Aged↗

PubMed1994

Percutaneous laser recanalisation of femoropopliteal occlusions using continuous wave Nd-YAG laser and sapphire contact probe delivery system.

A conventional continuous wave Nd-YAG medical laser system delivered by transparent sapphire tipped optical fibres was used for percutaneous recanalisation of 32 chronic femoropopliteal occlusions in 27 patients (19 men, eight women; median age 68 years, range 46-83 years). Twenty-four patients had severe intermittent claudication and three had critical ischaemia. The median occlusion length was 8 cm (range 3-35 cm) and lesions were not negotiable by guidewire. Laser energy was delivered at powers of 10-15 Watts using intermittent 1 second emissions (mean total energy 315 Joules, range 30-1015]). The sapphire tips used were 1.8 to 3.0 mm diameter. After laser recanalisation adjunctive balloon dilatation was necessary to widen the resulting lumen. All patients received anti-platelet therapy. Initial clinical success was achieved in 22 limbs (69%) with symptomatic relief and increase in mean (+/- S.D.) ankle-brachial pressure ratio from 0.52 (+/- 0.25) to 0.80 (+/- 0.21) [Mann-Whitney U, p < 0.001]. Recanalisation was unsuccessful in all calcified lesions (four cases). There was a high incidence of vessel perforation (28%) and wall dissection (25%). Emergency surgery was not required after failed procedures. The median follow-up was 12 months (range 6-20 months). By 6 months, 15 of 22 successfully recanalised lesions (68%) had reoccluded. The cumulative primary patency at 1 year was only 12%. These disappointing results do not support routine use of this system. Clearly, modifications of the laser/delivery system or the technique, or both, are required. The aim should be to achieve sole laser recanalisation without concomitant balloon dilatation.

Aged↗

PubMed1994

Radionuclide limb blood flow measurements to resolve diagnostic problems in vascular surgery.

This paper describes the application of radionuclide limb blood flow measurements in 60 patients presenting to the vascular surgeons with exercise-induced leg pain. All patients were considered to be diagnostic problems since either their symptoms were atypical for peripheral vascular disease, or they had normal peripheral pulses and/or a normal ankle/brachial pressure index. Thirty-one patients were ultimately shown to have peripheral vascular disease and underwent treatment. In all these cases the limb blood flow to one or both legs was below the normal range. Twenty-three patients were shown, by myelography, computed tomography or plain radiography, to have orthopaedic disease and in all cases their limb blood flow to both legs was within the normal range. In five patients, the limb blood flow was normal and the symptoms spontaneously resolved, no cause for the leg pain having been found (one patient refused angiography). Radionuclide limb blood flow is a simple and reliable diagnostic test which is superior to the assessment of peripheral pulses or their ankle to brachial pressure index in resolving diagnostic problems in vascular surgery.

Humans↗

PubMed1994

The cold hemiplegic arm.

BACKGROUND AND PURPOSE: Vasomotor changes occur in the arm after hemiplegic stroke. Previous studies have provided conflicting results, with most showing an increase in skin temperature of the hemiplegic arm. However, a number of patients complain of distressing coldness of the hemiplegic arm. METHODS: Eleven patients with symptomatic coldness and 10 patients with hemiplegia but no coldness were recruited. The severity of the symptom of coldness was compared by questionnaire with other common symptoms after stroke. A thermographic camera was used to record the finger skin temperature response to cold stress. Blood flow to both hands was also measured simultaneously by means of two plethysmographs. In all patients there were no symptoms in the unaffected arm, and this was used as a control. RESULTS: The symptom of coldness rated highly compared with other symptoms. In the symptomatic group the finger temperature on the hemiplegic side was lower at rest (median difference at rest, 0.65 degrees C; P < .0001) and at all times after cold stress. In the asymptomatic group the fingers on the hemiplegic side were colder at rest and after initial cooling (median temperature difference, 0.2 degrees C) but at no other time. Hand blood flow on the hemiplegic side was also decreased in the symptomatic group by 35%. This was not seen in the asymptomatic group. CONCLUSIONS: Coldness of the hand may be a severe and distressing symptom in some patients after hemiplegia. Symptomatic patients have lower finger skin temperatures at rest and after standard cold stress. These symptomatic patients also had reduced blood flow to the hemiplegic hand.

Aged↗

PubMed1994

Comparison of three methods for measuring cigarette smoking in patients with vascular disease.

Although smoking has been identified as an independent risk factor in peripheral vascular disease, smokers do not accurately report their habit. Therefore, a cheap, non-invasive, objective method of measuring smoking behaviour in vascular surgical units is desirable. The value of end-expiratory carbon monoxide monitoring, which is both simple and inexpensive, was compared with two well-established, validated techniques (serum thiocyanate and blood carboxyhaemoglobin levels). Some 33 surgical patients with peripheral vascular disease provided samples of expired air for measurement of carbon monoxide and blood for carboxyhaemoglobin and thiocyanate levels. Carboxyhaemoglobin was the most sensitive test (90%) and had a high specificity (100%). Expired carbon monoxide was the least sensitive (60%) but had a high specificity (100%). The carbon monoxide and carboxyhaemoglobin levels correlated significantly (r = 0.829; P = 0.0001). Serum thiocyanate was relatively sensitive (80%) but had a lower specificity (70%). Conventional methods for assessing smoking behaviour have not gained widespread use because they are time-consuming, relatively invasive and require technical support. Non-invasive measurement of carbon monoxide gives immediate accurate results and is a useful inexpensive method for measuring cigarette smoking in patients attending a follow-up vascular unit.

Aged↗

PubMed1994

Perfusion defects in vibration white finger: a clinical assessment using isotope limb blood flow.

Vibration white finger is a vasospastic disorder caused by long-term exposure to vibration tools. In an attempt to assess the extent of obliterative vessel disease in this disorder, hyperaemic hand blood flow was measured using technetium-labelled human albumin and a gamma camera. This method quantitates blood flow in ml/100 ml of tissue per min in addition to providing a perfusion image used to assess vessel disease. A perfusion score is then given to this image to reflect the extent of disease. The results of this study demonstrate that 78% of patients with vibration white finger had evidence of organic vessel disease. Moreover, patients with advanced disease tend to be bilaterally affected. The use of this simple method is advocated to aid in the diagnosis of vibration white finger; this may be particularly important for medicolegal purposes.

Adult↗

PubMed1993

Laser angioplasty.

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Angioplasty, Balloon↗

PubMed1993

Iatrogenic vascular injury following arterial cannulation: the importance of early surgery.

Prospective data were collected over a 7-year period on patients undergoing repair of iatrogenic vascular injury following arterial cannulation. From 9375 procedures (7790 coronary angiograms, 835 coronary angioplasties, 445 other cardiac catheterizations, 155 femoral angiograms, 150 peripheral angioplasties) surgical repair was required in 26 patients. The overall incidence of significant injury was 0.28% and higher in therapeutic than diagnostic procedures. The mode of presentation included: critical limb ischaemia in 18 cases, false aneurysm in three, haematoma in three and claudication in two. The common femoral artery was the most common site of injury. No patient presenting with false aneurysm or haematoma suffered any deleterious sequelae. However, 50% of those presenting with critical ischaemia suffered permanent disability after operation. The median delay to surgery was significantly longer in this group (24 versus 4 h; P < 0.001) but there was no difference in age or incidence of underlying peripheral vascular disease. The physical, psychological and litigious sequelae of the complications of iatrogenic vascular injury cannot be overstated. It is strongly advocated that immediate surgical consultation be applied when limb ischaemia is suspected.

Adolescent↗

PubMed1993

Double-blind, controlled, multicenter study of indobufen versus placebo in patients with intermittent claudication.

The objective of the study was to evaluate the efficacy and safety of indobufen compared with placebo in the treatment of moderately severe intermittent claudication. The study consisted of a four-week single-blind, placebo-controlled run-in phase, followed by a six-month double-blind randomized treatment period. A total of 302 patients were allocated to treatment with either placebo (154 patients) or indobufen (148) 200 mg twice daily. The results of the overall intention-to-treat analysis of the study population showed statistically significant superiority of indobufen over placebo after six months for both the initial (ICD) and absolute claudication distances (ACD). The ICD before treatment with indobufen or placebo averaged 137.9 +/- 68.2 and 136.6 +/- 63.2 m (mean +/- SD), respectively. After six months' treatment with active drug or placebo, this parameter reached 227.9 +/- 174.4 and 153.1 +/- 86.8 m (mean +/- SD), respectively (p < 0.01). Similar results were obtained on ACD. The reduction of lower limb symptoms also suggested a greater clinical benefit in the indobufen-treated patients. There was no significant change in either group in the ankle/arm pressure ratio at the end of treatment. Adverse events of any type were reported by 18 patients (12.2%) in the indobufen group and by 11 patients (7.2%) in the placebo group. The mechanism whereby the drug is effective in this clinical condition could be related to both its antiplatelet and hemorheologic effects.

Double-Blind Method↗

PubMed1992

Exogenous chromophores for the argon and Nd:YAG lasers: a potential application to laser-tissue interactions.

Chromophore dyes can be employed to modify laser-tissue interaction. A number of dyes have been investigated for their effect on the absorption and transmission of argon and Nd:YAG laser energy by vascular tissue in vitro. Three histological dyes have been assessed as potential chromophores for the argon laser and four infrared dyes for the Nd:YAG. Segments of porcine coronary artery to which dye had been applied were lased (1,064 nm, 2.5 W, 83 W/cm2, 60 s and 488/514 nm, 400 mW, 10.5 W/cm2, 60s) and the tissue temperature measured remotely using an infrared thermometer. In addition, energy transmission was measured with a photodiode and tissue morphological changes assessed histologically. All three argon dyes significantly increased energy absorption (typically 60 degrees C v. 20 degrees C at 60 s, P less than 0.001, 2-way ANOVA). Three of the four infrared dyes behaved similarly (40-70 degrees C v. 20 degrees C, P less than 0.001). All dyes significantly increased the initial rate of rise in tissue temperature during lasing. A reduction in energy transmission was observed for each of the Argon dyes but not for the Nd:YAG dyes. Histological evidence of thermal damage in control tissue first occurred for the argon and Nd:YAG lasers at 800 mW and 7.5 W without chromophore and at 400 mW and 2.5 W with the chromophore, respectively. A number of effective chromophores have therefore been identified at each wavelength.

Absorption↗

PubMed1992

Acute vibration--its effect on digital blood flow by central and local mechanisms.

In order to establish underlying mechanisms responsible for the vasospastic disorder vibration white finger (VWF), the acute effect of vibration on digital blood flow was assessed. Thirteen patients with primary Raynaud's phenomenon (RP), 15 patients with WVF and 13 controls were exposed to acute vibration in the middle digit of one hand for 1 and 3 minutes. Blood flow was measured in that digit and in the middle finger of the contralateral hand using strain gauge plethysmography before and after vibration. The measurements were then repeated following digital nerve blockade using 2% Lignocaine in the vibrated digit. The results demonstrate that vibration affects digital blood flow through two independent mechanisms. Vibration appears to cause both an axonal vasoconstrictor reflex and an active local vasodilation phenomenon. In patients with established vasospastic disorders this vasoconstrictor reflex is exaggerated.

Adult↗

PubMed1992

Teicoplanin vs cephradine and metronidazole in the prophylaxis of sepsis following vascular surgery: an interim analysis of an ongoing trial.

This paper presents further preliminary results of a trial of the prophylaxis of sepsis in 165 patients undergoing vascular surgery. The efficacy and safety of a single dose of teicoplanin was examined and compared with three doses of cephradine plus metronidazole. No significant differences were detected in the prophylactic efficacy in either group. The first interim report indicated abnormalities in liver function, maximum at 7 days, in both groups. These findings are confirmed in this second interim report. Raised levels of GGT and alkaline phosphatase are more prominent in patients receiving teicoplanin. Liver function improved by 28 days, however, suggesting that any abnormality is transient.

Alkaline Phosphatase↗

PubMed1992

Is antibiotic penetration compromised in the ischaemic tissues of patients undergoing amputation?

Antibiotic prophylaxis is indicated for patients undergoing amputation for severe ischaemia or gangrene. However, the adequacy of tissue levels of antibiotics in ischaemic tissue is not known. In this study the serum and tissue antibiotic levels were measured after intravenous administration of metronidazole (15 mg/kg body weight) and cephradine (20 mg/kg body weight). In 11 patients, venous samples were taken at time 0 (induction of anaesthesia) 10, 30 and 60 min. Samples of 2 g each of fat and muscle were collected from the amputation site and three distal sites. Metronidazole and cephradine levels were measured and the degree of limb ischaemia estimated preoperatively by an isotope limb blood flow method. Our results indicate that both metronidazole and cephradine penetrate ischaemic tissues to levels equivalent of a Mean Inhibitory Concentration (MIC) 50 for most organisms encountered in vascular surgery, and that the degree of ischaemia does not alter this.

Aged↗

PubMed1991

24-hour survival of autotransfused red cells in elective aortic surgery: a comparison of two intraoperative autotransfusion systems.

Twelve patients undergoing elective aortic surgery had intraoperative autotransfusion using either the Haemonetics Cell Saver or the Solcotrans device. The 24-h post-transfusion survival of the patients' preoperative red cells, labelled with indium-111, was compared with the survival of salvaged red cells labelled with chromium-51. A correction coefficient for the instability of the indium-111 label was calculated from the study of red cell survival in six healthy volunteers. There was no significant difference in the volume of circulating red cells measured using each isotope, indicating that extensive early destruction of the autotransfused red cells does not occur. The percentage survival of autotransfused red cells at 24 h was similar to that of the red cells that had not undergone salvage. Both devices were comparable with respect to the effects of cell salvage on the 24-h survival rate of autotransfused red cells.

Aortic Diseases↗

PubMed1991

Isotope limb blood flow measurement in patients undergoing peripheral laser angioplasty.

A technique of isotope limb blood flow (ILBF) measurement employing Technetium-labelled human albumin and a gamma camera, was used to assess limb perfusion in 19 patients undergoing percutaneous laser angioplasty, both before and one month after treatment. Twenty-three limbs with femoro-popliteal occlusions ranging in length from 3-35 cm (median 8 cm) were recanalized using an Nd-YAG laser and sapphire tipped optical fibre. Primary angiographic success was achieved in 19 lesions of which 6 re-occluded within the first month, and 13 remained patent with relief of symptoms. Clinically successful procedures were associated with a large increase in ILBF. However, normal blood flow was restored in only 54% of limbs. There was a slight decrease in limb perfusion after failed laser angioplasty but this was not statistically significant in this small series. Furthermore, there was no clinically apparent circulatory compromise, or need for urgent surgical bypass in failed cases. We conclude that ILBF is a useful means of assessing patients undergoing laser angioplasty, particularly for detecting small flow changes in patients who are unable to complete a standard exercise test. Its use can be recommended for assessing blood flow changes following other forms of limb revascularization.

Aged↗

PubMed1991

Comparing subjective and objective assessments of the severity of vibration induced white finger.

The present staging of the disease severity of vibration induced white finger (VWF) is based on the patients' symptoms. Forty patients, with a history of VWF, with disease severity stage III or stage IV, on the Taylor-Pelmear scale, were investigated. Total, reactive hyperaemic blood flow to the hands was measured using an isotope limb blood flow (ILBF) technique. Skin blood flow patterns were assessed using a cold provocation test, followed by thermographic assessment of hand rewarming. Thermographic abnormalities were detected in 39 patients (97%). Decreased post-occlusive, reactive hyperaemic blood flow occurred in 29 patients (73%). There was no difference in skin blood flow patterns or in total hand blood flow between the stage III and stage IV groups. Reduction of postocclusive reactive hyperaemic blood flow may be indicative of occlusive lesions of the digital vessels. We conclude that the classification of the severity of VWF using subjective assessment, needs to be augmented by objective evidence of altered blood flow.

Adult↗