Search PubMed⌕ Search

Biomedical subjects

J E Clague

Publications and source records attributed to J E Clague.

At least 37 records · Page 2Linked to original sources
PubMed1994

Operations research survey and computer simulation of waiting times in two medical outpatient clinic structures.

Outpatient services are increasingly recognised as an important component of health care provision and may be improved through the application of modern management techniques. We have performed a time and role audit of consultation and waiting times in two medical clinics using different queuing systems: namely, a serial processing clinic where patients wait in a single queue and a quasi-parallel processing clinic where patients are directed to the shortest queue to maintain clinic flow. Data collected were used to construct a computer simulation of patient flows in clinic. Assessment of patient satisfaction in the clinic process was determined using a self-administered questionnaire. Mean waiting time was shorter in the quasi-parallel processing clinic: 26 (SD 17) minutes compared with 36(24) minutes in the serial processing clinic. In the serial processing clinic 61% of patients waited more than 30 minutes compared with 41% in the quasi-parallel processing clinic. In the serial processing clinic 8% of 142 patients surveyed complained of the time spent waiting. The computer simulation we produced was able to determine waiting times with different clinic structures. The simulation showed that reductions in waiting time up to 30% might be achieved by changing our serial processing clinic to a quasi-parallel processing one. Performance of medical outpatient clinics can be improved by examining and changing clinic management. Computer simulation of outpatient clinics offers a means of assessing the impact of such changes on waiting time in clinic and on waiting lists.

Algorithms↗
PubMed1994

Respiratory effort perception at rest and during carbon dioxide rebreathing in patients with dystrophia myotonica.

BACKGROUND: Breathlessness appears to be closely related to the perception of the outgoing motor command to breathe and should be increased in the presence of muscle weakness. However, breathlessness is not a common symptom in patients with chronic muscle disease who have weak respiratory muscles. The factors that determine the perception of respiratory effort in such patients have not been examined. METHODS: The inspiratory effort sensation during resting breathing and progressive hypercapnia was investigated in 12 patients with dystrophia myotonica with weak respiratory muscles (nine men and three women of mean (SD) age 41.1 (10.5) years; maximum inspiratory pressure 43.1 (17.2) cm H2O) and an age and sex matched control group of normal subjects of mean age 39.6 (10.6) years and a maximum inspiratory pressure of 123 (15.2) cm H2O. RESULTS: During resting breathing with a mouthpiece no differences were seen in inspiratory effort sensation, mouth occlusion pressure, or tidal volume, but inspiratory time and cycle duration were significantly shorter in the patients with dystrophia. Minute ventilation (VE) was significantly higher in the patients (15.8 (4.0) l/min v 12.5 (2.6) l/min), while resting breathing was no more variable in the patients than in controls. The ventilatory response to carbon dioxide (VE/PCO2) was not significantly lower in the patients (14.9 (6.9) l/min/kPa) than in the controls (17.4 (4.3) l/min/kPa). Effort sensation responses to carbon dioxide driven breathing were similar in the control subjects and the patients. With regression analysis of pooled data neither maximum inspiratory pressure nor disease state contributed to perceived inspiratory effort during hypercapnia. CONCLUSIONS: Moderately severe global respiratory muscle weakness does not appear to influence the ventilatory response to rising carbon dioxide tension or the perception of inspiratory effort in patients with dystrophia myotonica.

Adult↗
PubMed1993

Muscle histopathology and physiology in chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is characterized by fatigue at rest which is made worse by exercise. Previous biopsy studies on small numbers of CFS patients have shown a range of morphological changes to which have been attributed fatigue and myalgia. We have now studied 108 patients with CFS or muscle pain and 22 normal volunteers by light and electron microscopy. There was no consistent correlation between symptoms and changes in fibre type prevalence, fibre size, degenerative or regenerative features, glycogen depletion, or mitochondrial abnormalities. Physiological contractile properties of quadriceps (maximal isometric force generation, frequency: force characteristics and relaxation rate) were also examined before and for up to 48 hours after a symptom-limited incremental cycle ergometer exercise test in 12 CFS patients and 12 normal volunteers. Voluntary and stimulated force characteristics were normal at rest and during recovery. Exercise duration was similar in the two groups although CFS patients had higher perceived exertion scores in relation to heart rate during exercise, indicating a reduced effort sensation threshold. On physiological and pathological grounds it is clear that CFS is not a myopathy. Psychological/psychiatric factors appear to be of greater importance in this condition.

Adolescent↗
PubMed1993

Physiological determinants of inspiratory effort sensation during CO2 rebreathing in normal subjects.

1. The physiological basis of inspiratory effort sensation remains uncertain. Previous studies have suggested that pleural pressure, rather than inspiratory muscle fatigue, is the principal determinant of inspiratory effort sensation. However, only a limited range of inspiratory flows and breathing patterns have been examined. We suspected that inspiratory effort sensation was related to the inspiratory muscle tension-time index developed whatever the breathing pattern or load, and that this might explain the additional rise in sensation seen with hypercapnia. 2. To investigate this we measured hypercapnic rebreathing responses in seven normal subjects (six males, age range 21-38 years) with and without an inspiratory resistive load of 10 cm H2O. Pleural and transdiaphragmatic pressures, mouth occlusion pressure and breathing pattern were measured. Diaphragmatic and ribcage tension-time indices were calculated from these data. Inspiratory effort sensation was recorded using a Borg scale at 30s intervals during each rebreathing run. 3. Breathing pattern and inspiratory pressure partitioning were unrelated to changes in inspiratory effort sensation during hypercapnia. Tension-time indices reached pre-fatiguing levels during both free breathing and inspiratory resistive loading. 4. Stepwise multiple regression analysis using pooled mechanical, chemical and breathing pattern variables showed that pleural pressure was more closely related to inspiratory effort sensation than was transdiaphragmatic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Exercise performance and fatiguability in patients with chronic fatigue syndrome.

To examine the role of delay in recovery of peripheral muscle function following exercise in the fatigue experienced by patients with the chronic fatigue syndrome (CFS) and to examine the influence of effort perception in limiting exercise performance in these patients, a study was carried out on a group of twelve patients with chronic fatigue syndrome and 12 sex and age-matched sedentary control subjects. Symptom limited incremental cycle exercise tests including measurements of perceived exertion were performed followed by examination of the contractile properties of the quadriceps muscle group for up to 48 hours. Muscle function was assessed by percutaneous electrical stimulation and maximum voluntary contractions. Muscle function at rest and during recovery was normal in CFS patients as assessed by maximum isometric voluntary contraction, 20:50 Hz tetanic force ratio and maximum relaxation rate. Exercise duration and the relationship between heart rate and work rate during exercise were similar in both groups. CFS patients had higher perceived exertion scores in relation to heart rate during exercise representing a reduced effort sensation threshold of 3.2 units on an unmodified Borg scale in CFS patients. Patients with chronic fatigue syndrome show normal muscle physiology before and after exercise. Raised perceived exertion scores during exercise suggest that central factors are limiting exercise capacity in these patients.

Adolescent↗
PubMed1992

Magnetic resonance spectroscopy and imaging of muscle--a physiological approach.

Magnetic resonance spectroscopy (MRS) and imaging (MRI) are now well established techniques for the study of cellular metabolism and gross structure of muscle. Using non-ferrous materials, we have constructed a system for the measurement of isometric force of quadriceps in response to percutaneous electrical stimulation and voluntary effort within the bore of a 48 cm diameter 1.5 T General Electric SIGNA whole body MR system. Using this system we have been able to study the relationship between electromechanical coupling and chemistry of muscle, with 31P MRS for the measurement of high-energy phosphates and pH, during electrically stimulated activity. Image analysis using the Context Vision system enables a distinction to be made, in 1H MRI by T1/T2 mapping, of muscle, fat and connective tissue to give force per unit cross sectional area of muscle. The combination of MR and functional measurements provide a valuable tool for further detailed analysis of human muscle weakness and fatigue.

Electric Stimulation↗
PubMed1992

Effort sensation, chemoresponsiveness, and breathing pattern during inspiratory resistive loading.

Although inspiratory resistive loading (IRL) reduces the ventilatory response to CO2 (VE/PCO2) and increases the sensation of inspiratory effort (IES), there are few data about the converse situation: whether CO2 responsiveness influences sustained load compensation and whether awareness of respiratory effort modifies this behavior. We studied 12 normal men during CO2 rebreathing while free breathing and with a 10-cmH2O.l-1.s IRL and compared these data with 5 min of resting breathing with and without the IRL. Breathing pattern, end-tidal PCO2, IES, and mouth occlusion pressure (P0.1) were recorded. Free-breathing VE/PCO2 was inversely related to an index of effort perception (IES/VE; r = -0.63, P less than 0.05), and the reduction in VE/PCO2 produced by IRL was related to the initial free-breathing VE/PCO2 (r = 0.87, P less than 0.01). IRL produced variable increases in inspiratory duration (TI), IES, and P0.1 at rest, and the change in tidal volume correlated with both VE/PCO2 (r = 0.63, P less than 0.05) and IES/VE (r = -0.69, P less than 0.05), this latter index also predicting the changes in TI with loading (r = -0.83, P less than 0.01). These data suggest that in normal subjects perception of inspiratory effort can modify free-breathing CO2 responsiveness and is as important as CO2 sensitivity in determining the response to short-term resistive loading. Individuals with good perception choose a small-tidal volume and short-TI breathing pattern during loading, possibly to minimize the discomfort of breathing.

Adult↗
PubMed1991

Screening for tuberculosis: current practices and attitudes of hospital workers.

To examine the current practices and attitudes of health workers to the prevention of tuberculosis in our 55-bed chest unit, we investigated the tuberculin reactor status, reviewed pre-employment screening and reviewed the action taken after contact with tuberculosis by staff members. We assessed all 61 staff members, including 44 nurses, 1 physiotherapist, 11 doctors and 5 domestic workers. 47/61 staff members had had BCG vaccination. Heaf testing revealed 3 Heaf-negative subjects and, of the remainder, 52 had grade 3 or stronger reactions. Only 3/11 doctors, 36/44 nurses and 4/5 domestic workers had had any pre-employment screening. No action was taken by any doctor after their last contact with tuberculosis, whereas 10/44 nurses and 3/5 domestic workers had had chest X-rays. This study shows the low importance with which the risk of tuberculosis is perceived, particularly by doctors and demonstrates the need for stricter supervision and improved quality of pre-employment screening.

Adult↗
PubMed1991

A double-blind comparison of the effects of cefaclor and amoxycillin on respiratory tract and oropharyngeal flora and clinical response in acute exacerbations of bronchitis.

Fifty-one patients admitted to hospital with severe exacerbations of chronic bronchitis entered a double-blind trial of treatment with cefaclor (500 mg tds) compared with amoxycillin (500 mg tds) for 7 days. Twenty-six patients received cefaclor and 25 amoxycillin. Sputum and throat swabs were collected on admission, after 7 days of therapy and at outpatient follow-up, 3 weeks after treatment had finished. Clinical status and spirometry were assessed on admission and at the third, seventh and 28th day. There was no significant difference between the two regimes for clinical outcome, spirometry or numbers of infecting pathogens. Opportunistic colonization with resistant Gram-negative organisms and Candida species was highly prevalent on admission (56%) in both groups, perhaps because of previous antibiotic administration and general debility of the majority of patients. The high prevalence of opportunistic colonizing organisms persisted at follow-up (48%) with a significant excess of new organisms (Enterobacter cloacae, Klebsiella species and Candida species) present in sputum in the amoxycillin-treated patients. Cefaclor may be less damaging to normal flora than amoxycillin with a consequently reduced risk of colonization and superinfection of the respiratory tract with resistant Gram-negative organisms and yeasts.

Acute Disease↗
PubMed1991

Medullary carcinoma of the thyroid presenting as multifocal bronchial carcinoid tumour.

A 21 year old man presented with diarrhoea and flushing after meals and later developed miliary shadowing on his chest radiograph. Multifocal bronchial carcinoid tumour was diagnosed initially, but at necropsy metastatic medullary carcinoma of the thyroid was found. Multifocal bronchial carcinoid tumour should not be accepted as a primary diagnosis without first excluding medullary carcinoma of the thyroid because of the need to screen relatives of affected patients.

Adult↗
PubMed1990

Relationship between inspiratory drive and perceived inspiratory effort in normal man.

1. To examine the relationship between the inspiratory effort sensation (IES) and respiratory drive as reflected by mouth occlusion pressure (P0.1) we have studied loaded and unloaded ventilatory responses to CO2 in 12 normal subjects. 2. The individual coefficient of variation of the effort sensation response to CO2 (IES/PCO2) between replicate studies was 21% and was similar to the variability of the ventilatory response (VE/PCO2) (18%) and the occlusion pressure response (P0.1/PCO2) (22%). 3. IES was well correlated with P0.1 (r greater than 0.9) for both free-breathing and loaded runs. 4. Resistive loading reduced the ventilatory response to hypercapnia from 19.3 l min-1 kPa-1 (SD 7.5) to 12.6 l min-1 kPa-1 (SD 3.9) (P less than 0.01). IES and P0.1 responses increased with resistive loading from 2.28 (SD 0.9) to 3.15 (SD 1.1) units/kPa and 2.8 (SD 1.2) to 3.73 (SD 1.5) cmH2O/kPa, respectively (P less than 0.01). 5. Experimentally induced changes in PCO2 and respiratory impedance were accompanied by increases in IES and P0.1. We found no evidence that CO2 increased IES independently of its effect on respiratory drive.

Adult↗
PubMed1987

The effect of nedocromil sodium on nasal provocation with allergen.

We have investigated the effect of nedocromil sodium in preventing the symptoms of rhinitis occurring immediately after allergen provocation in 10 patients with allergic rhinitis. The study had a double-blind, placebo-controlled, crossover design. Nedocromil sodium (1% w/v) and placebo were administered intranasally from identical metered-dose inhalers 20 minutes before allergen provocation. Three variables were measured: nasal airway resistance, the production of secretion, and the number of sneezes. Nedocromil sodium was significantly more effective than placebo in preventing nasal obstruction (p less than 0.01), rhinorrhea (p less than 0.01), and sneezing (p less than 0.05), suggesting that this drug may be useful in the treatment of allergic rhinitis.

Adult↗
PubMedDate not supplied

The effect of aging on the metabolic clearance rate and distribution of cortisol in man.

Previous studies of cortisol kinetics in old people have been flawed. All but one used a large dose of unlabelled cortisol, which will itself alter the kinetic parameters, and in none was metabolic clearance rate (MCR) calculated. We have, therefore, injected [(3)H]cortisol into men aged 20-38 and healthy (screened) men and women aged 63-83 years and followed its disappearance from the circulation for 3 h. In all three groups the disappearance curves corresponded closely to a double exponential, with half-lives of around 5 and 65 min. A two-pool model was assumed, one being purely a side-pool. The initial and total volumes of distribution and the MCR, but not the clearance rate for exchange between the two pools, tended to be lower in the elderly men than in the young; only the difference in total volume was significant. All these parameters were lower in the elderly women than in the elderly men. We conclude that any decline in cortisol MCR and related kinetic parameters with aging in men is small compared with variation from other sources. These parameters are lower in elderly women than men, in line with a reported sex difference in MCR in young subjects.

Journal Article↗
PubMedDate not supplied

Cortisol kinetics in elderly women with persistently high cortisol concentrations after proximal femur fracture.

OBJECTIVES: Elderly women with proximal femur fracture show abnormal persistence of increased cortisol concentrations, which could contribute to the high morbidity associated with this injury. Two weeks after injury, the authors found substantially increased urinary free cortisol excretion, which usually reflects the integrated concentration of free (bioactive) cortisol in plasma. However, there was a proportionally smaller increase in cortisol production rate. The authors have now tested the hypothesis that this was caused by a decreased metabolic clearance rate (MCR) rather than increased renal clearance, because the latter but not the former would invalidate free cortisol excretion as an index. SETTING: Orthopaedic wards in a teaching hospital. PATIENTS: Thirteen women aged seventy-one to ninety-two years who had sustained a proximal femur fracture approximately two weeks earlier were compared with ten healthy women aged sixty-seven to eighty-three years. These subjects are similar to those in the authors' previous study. MAIN OUTCOME MEASUREMENTS: The authors used single injections of [3H] cortisol to measure its MCR and estimated hepatic blood flow with indocyanine green. RESULTS: The patients with hip fractures had higher plasma cortisol concentrations than did the healthy subjects, as expected. Cortisol MCR was approximately 20 percent lower in the patients, and estimated hepatic blood flow was approximately 35 percent lower in the patients. Analysis of covariance showed that the difference in MCR was the result of the small difference in age between the groups rather than to injury per se. CONCLUSIONS: A lower cortisol MCR in the patients with hip fractures explains the authors' previous results and validates urinary free cortisol excretion as an index. The data suggest a roughly threefold mean increase in plasma cortisol bioactivity two weeks after hip fracture.

Aged↗