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Biomedical subjects

A Parkin

Publications and source records attributed to A Parkin.

At least 55 records · Page 3Linked to original sources
PubMed1990

The application of isotope limb blood flow measurement to diagnostic problems in vascular surgery.

A new method of limb blood flow measurement has been developed; normal flow is 10-22 ml/100 ml of tissue/min and flow to limbs with claudication is 1.8-2.3. Does this technique help to deal with diagnostic problems in vascular surgery? Twenty-five patients presented with exercise-induced leg pain. Twelve had a convincing history of claudication but seven of these had palpable pedal pulses, the other five had normal Doppler ratios. Of 13 with a poor history six had absent pulses; of the other seven with palpable pulses, two had abnormal and five had normal Doppler ratios. All 25 patients have had blood flow to both legs measured. For the five with a poor history, palpable pulses and normal Doppler ratios: (Table: see text). Twelve had reduced flows consistent with claudication (less than 8 ml/100 ml of tissue/min); 10 of these have undergone arteriography which demonstrated significant vascular disease, one had surgery to rheumatoid toes deferred and one refused further investigation. Of 13 with normal flows nine have been found to have significant orthopaedic problems affecting spine, hips or knees, the other four have all had normal arteriograms. In every case the history, signs or Doppler ratios were potentially misleading, but all cases of significant arterial disease were detected. It is cheap, readily available and effectively selected cases for referral or arteriography.

Gamma Cameras↗
PubMed1989

Limb volume measurements in peripheral arterial disease.

A simple method for measuring limb volumes of patients with peripheral arterial disease undergoing limb blood flow measurement is described. The device uses the change in surface level of water in a cylindrical reservoir to generate a voltage which is amplified and converted to a volume. The plethysmograph is stable and accurate over a wide range of limb volumes. For patients with leg ulcers or gangrene, where water immersion is not possible, a geometrical model has been developed which allows the volume to be calculated from a series of six external measurements. Comparison with measured volumes in 46 patients has shown this model to be accurate with a mean error of 3.3%. It provides a convenient alternative to direct measurement in these patients.

Blood Volume↗
PubMed1989

Working memory, comprehension ability and the resolution of text anomaly.

This article examines possible working memory deficits in 7-8-year-olds who are accurate readers but relatively poor comprehenders. In Expt 1, poor comprehenders scored below good comprehenders on a non-linguistic test of working memory (reading series of digits and recalling the last digit in each series) on the more taxing items. Experiment 2 examined the relationship between working memory and text comprehension using an anomaly resolution task. Good and poor comprehenders heard stories describing an adult's anomalous emotional response to a child's action, some of which contained information to resolve the anomaly. The load on working memory imposed by the need to integrate the resolution with the anomaly was varied in two ways: the resolution was presented immediately next to, or two sentences distant from, the anomaly, and appeared either before or after the anomaly. Poor comprehenders were worse than good ones at anomaly resolution only when the anomalous and resolving information were separated. The results support the hypothesis that text processing is influenced by working memory demands and suggest that children's comprehension is related to the efficiency of a general non-linguistic working memory system.

Attention↗
PubMed1989

Which routine test for kidney function?

Eighty measurements of plasma creatinine concentration, height:creatinine ratio, and plasma beta 2 microglobulin concentration were made on 72 children (age 4 months-18.5 years) with known renal disease. Results were compared with simultaneous measurements of glomerular filtration rate using plasma clearance of 51Cr edetic acid to assess the performance of each test as an initial screening procedure of renal insufficiency. Height:creatinine index less than 2.1 was found to have a higher sensitivity and predictive value of a normal result than the other tests and is therefore the preferred test for a screening procedure.

Adolescent↗
PubMed1989

Formality and the law in the administration of the Mental Health Act.

In March a conference of medical records officers, managers, nurses and others was held at Rampton Hospital on the theme "The Mental Health Act 1983; staying within the law". The purpose was to examine the way in which legal responsibilities under the Act are allocated. What the reasoning is behind the allocation and what the consequences are if for any reason the formalities are not correct. This article by Alan Parkin is a revised version of the talk he gave at the conference.

England↗
PubMed1989

Comparison of the effects of enteral feeding with continuous and intermittent parenteral nutrition on hepatic triglyceride secretion in human beings.

Plasma triglyceride turnover was measured during steady-state conditions in 22 postoperative patients. Nine had received nutritional support with an enteral regimen, seven had received an equivalent regimen as continuous parenteral nutrition, and six received the same parenteral regimen as a cyclical infusion. After 5 days of nutritional support, each patient received an intravenous bolus of tritiated glycerol. Plasma radiolabeled triglyceride content was measured during the subsequent 24 hours. The data were analyzed by means of a simple deterministic model of plasma triglyceride kinetics and compared with the results obtained by stochastic analysis. The rates of hepatic triglyceride secretion obtained by deterministic analysis were higher than those obtained by the stochastic approach. However, the mode of delivery of the nutritional regimen did not affect the rate of hepatic triglyceride secretion regardless of the method of analysis. The results suggest that neither complete nutritional bypass of the gastrointestinal tract nor interruption of parenteral nutrition in an attempt to mimic normal eating has any effect on hepatic triglyceride secretion. Any beneficial effect that enteral feeding or cyclical parenteral nutrition may have on liver dysfunction associated with standard parenteral nutrition appears to be unrelated to changes in hepatic triglyceride secretion.

Aged↗
PubMed1989

The clinical application of forearm and hand blood flow measurements using a gamma camera.

A new method of measuring blood flow to forearms and hands during reactive hyperemia is described. Subjects are positioned with forearms and hands over a gamma camera, and the circulation below the elbows is isolated for 4 minutes with pneumatic cuffs. The remaining blood pool is labeled with technetium-99m-labeled human serum albumin given via a vein in the dorsum of the foot. The rate of rise of activity in the arms after cuff release is measured from the gradient of time activity curves, and these are calibrated for flow by counting a sample of venous blood. Blood flow per unit volume is obtained from measurements of the limb volume, done by water displacement. Results for eight normal control subjects showed a mean flow per unit volume to forearm plus hand of 32.9 +/- 6.4 ml/100 ml/min and to hand alone 36.5 +/- 6.9 ml/100 ml/min. Case studies of patients with a variety of large- and small-vessel diseases are presented, illustrating the use of the technique to aid diagnosis and measure response to treatment.

Adult↗
PubMed1989

Forearm blood flow measurements using technetium-99m human serum albumin following brachial arteriotomy.

A simple, low cost method for measuring forearm blood flow during reactive hyperemia has been developed. Subjects are seated with hands and forearms over a large field-of-view gamma camera. Blood pressure cuffs inflated above the elbows isolate the blood in the forearms and hands and induce a hyperemic response. The remaining blood pool is labeled with technetium. The rate of increase of activity following release of the cuffs is measured from the gradient of time-activity curves and is calibrated for flow by counting a venous blood sample. The technique has been applied to a group of normal controls and to symptomatic and asymptomatic patients following right brachial arteriotomy. Forearm blood flow in normal subjects was 32.9 +/- 6.4 ml/100 ml/min and for subjects with occlusion of the brachial artery was 6.4 +/- 2.1 ml/100 ml/min. The method is simple, widely available, and reproducible. The good signal to noise ratio allows it to be used in cases of very low flow either as an aid to diagnosis or to measure treatment response.

Adult↗
PubMed1988

Dynamic liver scanning in cirrhosis.

Dynamic hepatic scintigraphy was performed in 49 patients with established cirrhosis, using intravenous 99Tcm-pertechnetate and 99Tcm-sulphur colloid in a prospective study of its predictive value. There was a close correlation between the hepatic perfusion index (reflecting the ratio of arterial to total hepatic blood flow) obtained with pertechnetate (HPI-P) and with sulphur colloid (HPI-C) (r = 0.775; p less than 0.0001), and both indices correlated with disease severity (HPI-P p less than 0.0001; HPI-C p less than 0.01). HPI-P was significantly increased in patients who died, in patients with varices and in those with hepatic encephalopathy. HPI-C was significantly increased in patients with varices, in patients with hepatic encephalopathy and in those who had bled from varices. Neither HPI-P nor HPI-C was able accurately to predict the development of complications during the follow-up period. The trapping index (TI), reflecting a combination of hepatic extraction efficiency, degree of intrahepatic shunting and extrahepatic extraction of colloid, was significantly impaired in patients who died and in those with ascites, varices and/or variceal bleeding, but not in patients with hepatic encephalopathy. The trapping index correlated with disease severity, as did the computer-derived spleen-liver ratio (S-L ratio). Neither TI nor S-L ratio was able to predict the development of complications. The clearance rate constant of colloid from peripheral blood, the uptake rate constants for liver and spleen, and splenic volume were all found to be unhelpful as indicators of disease severity or as predictors of complications. While perfusion indices derived by dynamic hepatic scintigraphy reflect the severity of the underlying liver disease, their determination on a single occasion appears to offer no benefit in predicting the likelihood of major complications.

Adult↗
PubMed1987

Use of a gamma camera for measuring limb blood flow in peripheral vascular disease.

A method for measuring limb blood flow during reactive hyperaemia is described. Pneumatic cuffs inflated to 300 mmHg are used to isolate the blood in the limbs from the rest of the circulation. The remaining blood is labelled with technetium. The increase in radioactivity in the limb following release of the cuffs is measured using a gamma camera. The mean rate of flow of blood to the limb (in ml (100 ml)-1 tissue min-1) is derived from the graph of radioactivity versus time and from the radioactivity in a sample of venous blood. The results of measurements carried out in patients with peripheral vascular disease (30 limbs) and normal controls (24 limbs) are presented. Repeated studies in 10 subjects (20 limbs) showed the method to be highly reproducible at high and low flow rates (r = 0.99). Case studies illustrating the use of the method as a screening test for peripheral vascular disease and to monitor the effects of treatment are presented.

Aged↗
PubMed1987

A reliable and readily available method of measuring limb blood flow in intermittent claudication.

To evaluate isotope limb blood flow measurement in intermittent claudication we have assessed 58 non-diabetic patients comparing our new method with treadmill testing and Doppler assessment. Limb blood flow was applicable to all 58 patients; 25 patients were unable to walk on a treadmill and of the 33 who could 12 failed to walk for one minute, making a standard one minute exercise test inappropriate. In those patients who could perform exercise tests there was a significant correlation between maximum walking distance and limb blood flow (r = 0.35, P = 0.02). Resting, post-exercise and post-hyperaemic ankle-brachial systolic pressure indices bore no relationship to the maximum walking distance. Isotope limb blood flow measurement is reproducible (r = 0.97), can be applied to those patients who cannot walk on a treadmill and provides information about both legs. It correlated significantly with all the other tests and can be recommended for the minimally invasive assessment of intermittent claudication.

Adult↗
PubMed1987

Reproducibility of oesophageal transit studies: several 'single swallows' must be performed.

The 'single swallow' technique for the isotopic investigation of oesophageal function has been widely accepted. In our experience the results obtained when several consecutive 'single swallow' tests are performed show considerable variation. Although one or two swallows may be enough to diagnose abnormality, the exclusion of a motility disorder requires more, preferably six consecutive swallows.

Adult↗
PubMed1987

Hepatic perfusion index and the evolution of liver metastases.

A total of 150 patients with primary carcinoma of the gastrointestinal tract had first-pass technetium colloid scintigraphy to estimate the hepatic perfusion index (HPI). Postoperative follow-up over 2-4 years shows that the HPI remains a sensitive method of detecting hepatic metastases, even in patients whose liver appeared normal at laparotomy. HPI was elevated in 94% of patients with liver metastases found at laparotomy; 87% of patients with occult metastases which became overt within 3 years of surgery had elevated HPI; and 91% of all patients who have to date developed hepatic metastases had elevated HPI at presentation. Of all patients with elevated HPI, 82% had metastases which were either apparent at surgery or became detectable by other means within 3 years.

Gastrointestinal Neoplasms↗
PubMed1987

Initial clinical experience with degradable starch microspheres.

Four patients with advanced hepatic malignancy have been investigated with a view to intra-arterial treatment with degradable starch microspheres (DSM) and mitomycin-C (MMC). Computer-assisted interpretation of data gathered during the administration of technetium-labelled albumin allows the degree of arteriovenous shunting within the liver to be measured. In a similar way, the effectiveness of DSM in blocking hepatic arterial flow is determined. Two patients showed unacceptably high levels of shunting (75% and 100%) and were excluded from further study. One patient with hepatocellular carcinoma shunted only 24% of the macroaggregated albumin, and flow through the liver was reduced to 48% by DSM therapy. This patient has undergone four courses of MMC without significant toxic complications. The last patient had 25% shunting. The DSM titration and the first MMC administration had to be abandoned because of severe abdominal pain and nausea related to a fracture of the intra-arterial catheter. Complications directly associated with the procedures have been acceptable. The relationship between flow reduction and the amount of DSM administered is non-linear, and the appropriate dose of DSM for each treatment must be titrated against both the patient's symptoms and the computer-generated flow indices.

Adult↗