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Biomedical subjects

J G Bennett

Publications and source records attributed to J G Bennett.

32 records · Page 2Linked to original sources
PubMed1986

Evaluation and treatment of anterior knee pain using eccentric exercise.

Various authors have indicated that muscle imbalances might lead to knee pain and the potential for knee injury during sports. However, few reports have been published to substantiate such a hypothesis. But in all of the existing studies, only concentric torque measurements were evaluated. The purpose of the present study was to document any torque deficiencies which might be present during eccentric exercise in patients with knee pain. Of 130 patients with various knee disorders, 41 demonstrated a suppression in torque production during the eccentric exercise and generally in the portion of the range of movement between 30 degrees and 60 degrees of knee flexion (P less than 0.05). These individuals fit the criteria for anterior knee pain syndrome and demonstrated remarkable improvement after training 3 times/wk at concentric-eccentric exercises of the knee extensors at various speeds (30 degrees, 60 degrees, and 90 degrees . s-1) on a computer-controlled dynamometer (KIN/COM). In some cases, the pain as well as their torque deficiency was relieved after only 2 wk of training, most others were relieved after 2 to 4 wk of training.

Adolescent↗
PubMed1984

The role of echocardiography in suspected bacterial endocarditis.

We evaluated the clinical application of echocardiography (M and 2D modes) in the assessment of cardiac patients with fever and an underlying valvular abnormality in whom the diagnosis of infective endocarditis was suspected. One or more of the classic clinical features of the disease were present in 50 patients (group A). Vegetations were detected by echocardiography in 17 (47%) out of the 36 patients within this group A who had positive blood cultures. Four (28.5%) of the remaining 14 patients with unequivocal endocarditis clinically and negative blood cultures had demonstrable vegetations on ultrasound. Anatomical complications resulting from the septic process (valve destruction or detachment, aortic root abscess) were visualized in 18 (36%) of the 50 patients in group A. The clinical features of endocarditis were lacking in the other 53 patients with fever and murmur (group B). This group included 12 patients with other sources of bacteraemia besides endocarditis. Unsuspected vegetations were detected only in 2 (3.7%) out of the 53 cases. Thus echocardiography is useful in confirming the clinical diagnosis of infective endocarditis, but only rarely detects vegetations in patients who lack the characteristic clinical features of endocarditis, regardless of whether they have positive negative blood cultures.

Bioprosthesis↗
PubMed1984

Study of electrophysiological ischemic events during coronary angioplasty.

The electrophysiological and mechanical events that follow transient therapeutic coronary artery balloon occlusion were analyzed in five patients. A marked (mean, 60 msec) decrease in the repolarization time of the left ventricular ischemic zone (assessed indirectly from endocardial monophasic action potential [MAP] recordings) ensued within 6 to 10 beats of occlusion. Abnormalities in left ventricular relaxation occurred almost simultaneously and preceded contraction abnormalities. A shift in the ST segment in the electrocardiogram (ECG) usually followed within the next 5 to 10 beats. An increase in heart rate (approximately 10 beats per minute) appeared last in the sequence of events. Angina was a variable parameter, frequently absent. Thus, intracavitary recordings of the electrical and mechanical changes are sensitive indicators of the early ischemic changes that follow coronary occlusion, and may be used to assess the effects of therapeutic interventions on events resulting from a myocardial perfusion deficit.

Journal Article↗
PubMed1982

Autotransfusion of drained mediastinal blood.

The Sorenson equipment for transfusion of drained mediastinal blood has been widely used in the United States. We have tested its use postoperatively in 10 patients, assessing its ease of use from the medical and nursing views as well as analyzing the blood constituents which would be infused into the patients. The hemoglobin content of the infused drainage averaged 6 g/dl compared with 12 g/dl in the patients' blood. Platelet counts were very low, averaging 15 X 10(9)/l compared with levels of 110 X 10(9)/l for the patient. Platelet aggregation in response to ADP stimuli was assessed and was grossly deficient in the collected blood showing that the platelets that were present were not capable of aggregating. Protein and electrolyte levels were substantially the same in both series of specimens. Handling difficulties with the equipment together with these rather disappointing hematological results suggest that the equipment is only useful where excessive postoperative bleeding is encountered or where there is particular need to conserve red blood cells.

Blood Cell Count↗
PubMed1982

Irreversible morphological changes contributing to depressed cardiac function after surgery for chronic aortic regurgitation.

The timing of surgery in chronic aortic regurgitation remains a difficult problem. To identify variables predictive of postoperative haemodynamic improvement, changes in left ventricular mass, volume, morphology, and histochemistry were analysed in 67 patients undergoing surgery for chronic aortic regurgitation. Patients were divided into two groups: those in whom the left ventricular echo diameters returned to normal after operation (51 patients, group A), and those with postoperative dilatation (16 patients, group B). A preoperative biopsy was obtained in all patients; postoperative tissue samples were available in 13 patients (five from group A, eight from group B). Data were correlated with the postoperative clinical, haemodynamic state over a follow-up period of three years. Regression of hypertrophy was usually incomplete. Echocardiographic and angiographic data could not define the type and degree of dysfunction which was irreversible. Massive fibre hypertrophy (mean 34.1 micrometers), moderately or severely increased interstitial fibrous tissue, reduced levels of the myofibrillar and mitochondrial enzymes adenosine triphosphates and succinate dehydrogenase in pre- and post-operative tissue samples correlated with persistent dilation, cardiac failure, and early death (group B). Irreversible morphological and functional changes contributed to a depressed cardiac function after operation. Preoperative ventricular biopsies are thus of prognostic importance in volume overload.

Adolescent↗
PubMed1982

Emission tomography in embolic lung disease.

Ventilation-perfusion lung scans and emission tomography studies were performed in 84 patients with suspected embolic lung disease. Concordant data were obtained in 72 patients (57 positive, 15 negative); results were discordant in ten patients and indeterminate in two. Although the diagnosis of pulmonary embolism with the conventional two-dimensional planar projections of standard ventilation-perfusion lung scans is still the mainstay, a greater sensitivity in lesion detection can be expected with multiplane detection imaging.

Journal Article↗
PubMed1981

Prostacyclin administration during cardiopulmonary bypass in man.

In a double-blind trial prostacyclin was given to 12 of 23 patients undergoing coronary vein grafting. The treatment group showed a preservation of platelet number and function, with a halving of blood loss in the first 18 h postoperatively. The heparin sparing effect of prostacyclin was confirmed, as were the vasodilator effects which were not troublesome.

Adult↗
PubMed1981

Clinical experience with the Carpentier-Edwards porcine xenograft.

The first 101 patients to undergo aortic, mitral or double valve replacement with a Carpentier-Edwards bioprosthesis at the National Heart Hospital are reviewed. A total of 112 valves were replaced (69 aortic, 43 mitral), with an operative mortality of 12.9%. The 88 operative survivors were followed for up to 52 months. There were 9 thromboembolic episodes (3.9% per patient year), most of which were not confined to the early postoperative months. They were most common after mitral valve replacement (6.3% per patient year), particularly in the presence of atrial fibrillation. A low incidence of prosthetic endocarditis was noted, principally involving the valve in the aortic position. Three valves were removed for calcific degeneration and small structural defects were noted incidentally in 3 valves removed for other reasons. The possible etiology and significance of these is discussed. Seven of the 10 reoperations and 5 of the 9 late deaths were considered to be xenograft-related. Over a 4-year follow-up period there was a 9% incidence of valve-related deaths, an overall survival of 87% and a complication-free survival of 73%.

Adolescent↗
PubMed1981

Factors predisposing to the development of progressive massive fibrosis in coal miners.

Altogether 238 759 miners employed by the National Coal Board were examined in the third of the Board's radiological surveys from 1969 to 1973 inclusive. Excluding those diagnosed as having progressive massive fibrosis (PMF) on that occasion, 210 847 were in collieries still operating at the time of the fourth survey four to five years later 132 728 attended for radiography at the same colliery on the second occasion, and were used to study the attack rate of PMF. In all groups in the age range 35-54 and having category 2 simple pneumoconiosis (SPN) or less, 80% or more had a second radiograph. It was found that the probability of developing PMF increased sharply with rising category of SPN; however, half the cases occurred in men having SPN categories 0 or 1, who were in the majority. Current coalface work had no significant effect on the attack rate. Age increased the attack rate of PMF within each major SPN category (0, 1, 2, and 3), especially the higher categories. All or part of this effect may have been due to the fact that SPN in younger men with categories 1 and 2 tends to lie in the lower range within these categories. Similarly, a lower distribution of SPN within each category associated with a low overall local prevalence may account wholly or in part for the great difference between the attack rates of PMF supervening on each category of SPN in Scotland and South Wales. The rank (quality) of coal mined had no effect on the attack rate.

Adult↗
PubMed1979

The relationship between coal rank and the prevalence of pneumoconiosis.

As part of the Periodic X-ray Scheme of the National Coal Board (NCB), a comparison is made between the previous and new films of all miners who were face-workers on the former occasion, five years earlier. This assessment is made by distributing the films randomly to all the NCB readers. This paper compares the rank of coal mined in each colliery with each colliery's percentage prevalence of pneumoconiosis of at least ILO category 1 in the films of previous face-workers obtained during the third survey round (1969-73). Of the NCB's 291 collieries in Britain, information enabling a rank classification to be made was available for 250, employing 62 362 face-workers. In these 250 mines a progressive and five-fold increase in prevalence was observed from collieries mining low-rank (bituminous) coal to those mining coal of high ranks (anthracite and high-grade steam and coking coal). A possible reason for this is that, in the past, high-rank collieries may have had the highest mass-concentrations of respirable dust.

Carbon↗
PubMed1977

Prognostic indices for survival during postcardiotomy intra-aortic balloon pumping. Methods of scoring and classification, with implications for left ventricular assist device utilization.

To define more clearly a salvageable patient for possible utilization of a left ventricular assist device prior to multiple organ failure and irretrievability during postcardiotomy intra-aortic balloon pumping (IABP), we made prospective and retrospective analyses to determine prognostic indices for survival. Serial left ventricular function curves (IABP on-off), scoring methods, hemodynamic and renal function tracking trajectories, survival versus nonsurvival data envelopes, and classification methods were developed and used. All patients requiring postcardiotomy IABP support who were in Class A survived; 80 percent of the patients in Class B survived. All patients who remained in Class C for 12 hours or more following operation with IABP support died. These preliminary analyses suggest that the postcardiotomy IABP-supported patient with a score of less than 6 who remains in Class C for 12 hours or more is at the highest possible risk and is a probably candidate for more effective support with a left ventricular assist device.

Assisted Circulation↗