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Biomedical subjects

R M Cayton

Publications and source records attributed to R M Cayton.

At least 37 records · Page 2Linked to original sources
PubMed1991

The effect of sustained-release theophylline in nocturnal asthma.

Nocturnal symptoms are common and often disabling in asthmatic subjects. Furthermore, they often persist, in spite of appropriate dosages of inhaled beta 2-agonists and topical steroids. In such a clinical situation, theophylline preparations may have a therapeutic role. This double-blind, placebo-controlled, cross-over trial was designed to evaluate the effectiveness of a twice-daily Bioavail slow-release theophylline capsule in a group of out-patient asthmatics, with a history of nocturnal and/or early morning wheeze or chest tightness. Theophylline was initially prescribed and monitored in an 'open' phase to obtain the drug dosage required to achieve a serum level in the therapeutic range of 10-20 mg/l. In the ten patients who completed the study, serum theophylline levels were stable throughout. During active treatment there was an improvement in morning peak expiratory flow rate (PEFR), and a reduction in measurements of diurnal variation. In addition, the bronchodilator response to an inhaled beta 2-agonist was preserved. Bioavail theophylline has thus been shown to be an effective agent in the management of adults with nocturnal asthma.

Adult↗
PubMed1990

The twenty-metre shuttle-running test: a combined test for maximal oxygen uptake and exercise-induced asthma?

A maximal multistage 'twenty-metre shuttle-running test' has already been developed to estimate maximal oxygen uptake (VO2 max). This field test requires little equipment or expertise, can be performed simultaneously by several subjects, and is widely used in physical education lessons. The present study assessed the potential for this test to provoke exercise-induced asthma in 73 schoolboys, aged 15-16 years. Measurements of the forced expiratory volume in one second (FEV1) were made at rest and 10 min after the twenty-metre shuttle-running test; exercise-induced asthma was defined as greater than a 10% fall in FEV1 after exercise. The pupils achieved 73 +/- 19 shuttles (mean +/- SD) giving a VO2 max of 47.0 +/- 5.3 ml kg-1 min-1. Exercise-induced asthma was documented in eight pupils (11%); two were known asthmatics who, despite taking pre-exercise B2 agonist treatment, had sharp falls in FEV1 (-25.4 and -25.6%); two had previously experienced occasional chest tightness or wheeze with exercise (-16.5 and -13.2% fall FEV1); but four were asymptomatic, with no previous asthmatic symptoms (-20.0, -18.2, -15.3 and -11.4% fall FEV1). This study has demonstrated the potential of the twenty-metre shuttle-running test to provoke exercise induced-asthma, and may therefore be a useful clinical test to assess for exercise-induced asthma when an estimate of VO2 max would also be helpful. Furthermore, physical education teachers should take basic precautions when using this test.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Association between risk factors for coronary heart disease in schoolboys and adult mortality rates in the same localities.

Risk factors for coronary heart disease were compared in fifth year boys (15-16 years old) from two schools that were chosen from localities with a fourfold difference in adult mortality from coronary heart disease. One school was in an underprivileged urban locality in the area of increased incidence of heart disease ('high risk') and the other in a semi-rural affluent locality with an incidence of heart disease similar to the national average ('low risk'). Smoking, hypertension, hypercholesterolaemia, obesity, physical fitness, and inactivity were evaluated as risk factors for coronary heart disease. Smoking, increased body fat, poor diet, and physical inactivity were found increased among pupils from the school in the high risk area compared with those in the low risk area. Lipids, maximum oxygen uptake, and hypertension were similar in both schools. The risk of coronary heart disease seems to reflect the adult mortality rates in the area. To reduce the overall incidence of coronary heart disease, health education should be directed towards prevention of smoking, improving diets, and increasing amounts of activity among school children, with special attention directed toward children in regions where there is a high mortality from coronary heart disease among adults.

Adolescent↗
PubMed1990

Effects of exercise on gas exchange in patients recovering from acute severe asthma.

The effect of exercise on gas exchange was studied in 17 patients (seven male and 10 female) recovering in hospital from acute severe asthma. On admission the patients (mean age 26 (SD 8) years) had a mean peak expiratory flow (PEF) of 26.8% (5.7%) predicted, a mean arterial oxygen tension (PaO2) of 8.63 (1.26) kPa, and a mean alveolar-arterial oxygen difference (A-aDO2) of 5.98 (1.34) kPa. Once resting symptoms had resolved (after 3.7 (1.6) days) patients performed a constant load exercise test (100 watts for men, 75 watts for women) on a bicycle ergometer for five minutes. PEF was measured before exercise and at five minute intervals for 30 minutes after exercise. Blood gas tensions were measured on capillary blood before, during, and 10 minutes after exercise. Treatment was not interrupted for this study. Mean PEF at rest was 87.6% (21.1%) predicted and showed no significant change after exercise. Mean PaO2 was 13.13 (1.37) kPa before exercise; it showed no significant change during exercise (13.93 (1.34) kPa) or 10 minutes after exercise (13.50 (2.15) kPa). Mean A-aDO2 also showed no change, being 1.82 (1.31) kPa before exercise, 1.79 (1.27) kPa during exercise, and 2.53 (0.93) kPa after exercise. It is concluded that moderate exercise carried out shortly after treatment for acute severe asthma is unlikely to result in worsening gas exchange during or after exercise if resting PEF, PaO2 and A-aDO2 have attained normal or near normal values.

Acute Disease↗
PubMed1989

Effect of nebulised salbutamol on maximal exercise performance in men with mild asthma.

The effect of 5 mg nebulised salbutamol on the cardiorespiratory responses to a progressive maximal exercise test was investigated in eight asthmatic (mean forced expiratory volume in one second (FEV1) 3.48 (1.0) litres) and eight non-asthmatic men. Exercise tests were performed on a bicycle ergometer after administration of nebulised salbutamol or matched saline placebo. In the asthmatic subjects salbutamol increased the resting FEV1 by 11%. The mean (SD) percentage fall in FEV1 after exercise did not change significantly (salbutamol 9.4 (12.8); placebo 15.0 (8.0], but because the FEV1 before exercise was increased the lowest FEV1 after exercise was also significantly higher after salbutamol than placebo (3.60 (1.13) v 2.85 (0.80) litres). Despite the improvement in FEV1 before exercise there was no significant difference in maximal workload, oxygen uptake, heart rate, or ventilation during exercise after salbutamol compared with placebo in the asthmatic patients. Tidal volume was higher at maximal exercise after salbutamol but there was no change in perception of breathlessness or exertion in the asthmatic subjects. During submaximal progressive exercise the perceived rate of exertion was reduced in the asthmatic patients and oxygen pulse was reduced in both groups owing to a small and non-significant increase in heart rate. The FEV1 and cardiorespiratory response to the progressive maximal exercise test in the non-asthmatic subjects were otherwise unchanged after salbutamol. The results suggest that 5 mg nebulised salbutamol has little effect on the cardiorespiratory responses to progressive maximal exercise in patients with mild asthma and in non-asthmatic subjects. Salbutamol in this dose may reduce the severity of exercise induced asthma, but no ergogenic effect on maximal exercise performance was shown.

Adult↗
PubMed1987

Blood fuel metabolites in asthma during and after progressive submaximal exercise.

Ten male stable asthmatic subjects and 10 matched control subjects performed a progressive exercise test on a treadmill to 85% of their predicted maximum heart rate. Blood lactate, pyruvate, hydrogen ion, glucose, alanine, glycerol and total ketone body concentrations were measured at frequent intervals during and up to 60 min after exercise. Carbon dioxide production, oxygen consumption, ventilation, respiratory exchange ratio and oxygen saturation were also measured during and up to 10 min after exercise. There were no significant differences between the asthmatic and control subjects in levels of carbon dioxide production, oxygen consumption and ventilation. The respiratory exchange ratio was greater in the asthmatic subjects during recovery from exercise (P less than 0.05). No changes in oxygen saturation were observed during exercise in either group. In both asthmatic and control subjects, lactate, pyruvate, hydrogen ion, alanine and glycerol concentrations showed an increase from baseline levels, reaching maximum levels up to 10 min after exercise and returning to baseline within 1 h after exercise. Total ketone body concentrations decreased during exercise. There were no significant differences between the asthmatic and control subjects in the concentration of any metabolite over the study period. These data indicate that fuel metabolism during and after short-term progressive exercise is similar in stable asthmatic and normal subjects.

Adult↗
PubMed1986

Comparison of right ventricular weight at necropsy in interstitial pulmonary fibrosis and in chronic bronchitis and emphysema.

The ventricular weights in 43 patients with interstitial pulmonary fibrosis were retrospectively compared with those in 172 patients with emphysema and chronic bronchitis. The mean right ventricular weight of patients with interstitial pulmonary fibrosis and those with emphysema and chronic bronchitis was 85.5 g (SD 23.2) and 88.8 g (34.3), respectively. Thirty five patients (81%) with interstitial pulmonary fibrosis had a right ventricular weight over 65 g compared with 124 (72%) of those with emphysema. Fifty three per cent of both those with interstitial pulmonary fibrosis and those with chronic bronchitis and emphysema had a right ventricular weight greater than 80 g. Differences between the two groups were not significant. These results suggest that the prevalence of right ventricular hypertrophy and pulmonary hypertension in interstitial pulmonary fibrosis is similar to that found in chronic bronchitis and emphysema.

Aged↗
PubMed1985

A double-blind comparison of amoxycillin with trimethoprim in acute exacerbations of chronic bronchitis.

Thirty-seven patients with untreated acute exacerbations of severe chronic bronchitis (mean FEV1 0.81), were entered into a double-blind randomized trial comparing amoxycillin 250 mg three times a day with trimethoprim 200 mg twice a day, each given for seven days. Seventeen patients received amoxycillin, from which there was one treatment failure, and 18 patients received trimethoprim, amongst which there were six treatment failures. There were no major differences between the treatments, in this small group of patients, although a significant difference (in favour of amoxycillin) was demonstrated in the patients' subjective dyspnoea score. Because of the difficulties in collecting sufficient patients from a single centre, the definition of the possible role of trimethoprim alone in the treatment of acute axacerbations of chronic bronchitis may have to await multicentre trials.

Aged↗
PubMed1984

A dose-response and duration of action assessment of a combined preparation of fenoterol and ipratropium bromide (Duovent).

The dose-response relationships of a combination of the selective beta adrenergic agonist, fenoterol, and the synthetic anticholinergic drug, ipratropium bromide, were studied. In an open cross-over assessment, 20 patients with evidence of reversible airways obstruction inhaled 2, 4, 6 or 8 puffs from a metered dose inhaler, containing 100 micrograms fenoterol and 40 micrograms ipratropium bromide per puff, administered according to a randomization schedule, on four non-consecutive days. Before, and at intervals up to eight hours after inhalation FEV1, FVC, pulse and blood pressure were measured. Immediate and prolonged bronchodilatation followed each dose. The overall analysis of the FEV1, and FVC showed little difference between 2, 4 and 6 puffs. The highest dose, 8 puffs, was more effective, but associated with an increased incidence of side effects.

Adult↗
PubMed1984

Quantitative lung scintigrams and lung function in the selection of patients for pneumonectomy.

A method for predicting postoperative respiratory function following lung resection has been used in 11 patients with both histologically proven bronchial carcinoma and chronic obstructive airways disease, in order to assess their fitness for surgical treatment. Quantitative ventilation and perfusion scintigrams were used to measure the amount of functioning tissue in each lung. These data were used in conjunction with spirometric measurements to calculate the likely functional effect of pneumonectomy. There was a high degree of correlation (r) between predicted and measured lung function for both FEV1 (r = 0.75, P less than 0.01) and FVC (r = 0.88, P less than 0.01). The postoperative FEV1 was within 150 ml of the predicted value in 45% of the patients. In the remaining patients the actual volumes were greater than predicted by 210-540 ml. For FVC the results were within 150 ml of predicted in 45% of patients and in the remainder actual volumes were greater by 160-650 ml. Both sets of calculations underestimated lung volumes by an average of 200 ml. The method is shown to be accurate, simple, non-invasive, and readily available and brings a degree of objectivity to an important decision that is often based mainly on clinical assessment.

Aged↗
PubMed1984

Therapeutic advantages of twice-daily over four-times daily inhalation budesonide in the treatment of chronic asthma.

Topical steroid therapy is now widely used in the treatment of chronic asthma, but few controlled studies have been conducted to evaluate the most efficient dosage regimen. The present study was designed to assess, in a double-blind fashion, the relative efficacy of a new topical steroid, budesonide (Pulmicort) in controlling pulmonary function and asthma symptoms during twice-and 4-times daily dosing. Both active and placebo drug were administered via the tube spacer inhaler. Objective lung function measurements indicate that twice-daily dosing is at least as effective as 4-times daily dosing, and it is suggested that the twice-daily dosage regimen may lead to better patient compliance.

Aerosols↗
PubMed1983

Dysphonia caused by inhaled steroids: recognition of a characteristic laryngeal abnormality.

Nine of 14 asthmatic patients who presented with persistent dysphonia while taking inhaled corticosteroids had a bilateral adductor vocal cord deformity with bowing of the cords on phonation. This causes the dysphonia and usually occurs without candidiasis. It was seen with beclomethasone dipropionate (in both pressurised aerosol and dry powder preparations), betamethasone valerate, and budesonide. It was related to the dose and potency of inhaled steroid and may represent a local steroid myopathy. It was reversed when the inhaled steroid was stopped, although resolution sometimes took weeks. Laryngeal candidiasis may have contributed to the vocal cord abnormality in two of these nine patients. Of the five patients without vocal cord deformity, laryngeal candidiasis was the sole cause of dysphonia in three. In the remaining two dysphonia was thought to be psychogenic. The vocal cord deformity may exist subclinically. Of nine patients who started to take aerosol steroid and who were examined monthly for one year, three developed vocal cord deformity but only one had persistent dysphonia. Vocal abuse did not appear to contribute to dysphonia.

Adult↗
PubMed1982

Recovery of hypothalamo-pituitary-adrenal function in asthmatics whose oral steroids have been stopped or reduced.

Hypothalamo-pituitary--adrenal (HPA) function was studied using tetracosactrin and insulin hypoglycemia tests in eleven asthmatic patients who were receiving or had taken oral steroids. The patients had been on prednisone, 5--20 mg/day for 2--17 years. As the dose was reduced they used beclomethasone inhalation, up to 800 micrograms/day. Seven insulin hypoglycemia tests were performed when the patients had been off oral steroids for 15--37 months. Plasma cortisol responses were normal in all seven, three had subnormal responses of ACTH. In five patients serial tetracosactrin and insulin hypoglycaemia tests were performed during reduction of steroid dose. Two patterns of recovery of HPA function were observed. In one, both hypothalamo--pituitary and adrenal function seemed to return simultaneously, in the other normal response to tetracosactrin appeared before that to insulin hypoglycaemia. One patient had normal ACTH and cortisol responses to the stress of a vasovagal attack, but failed to respond to subsequent hypoglycaemia. We conclude that a normal response to tetracosactrin does not indicate recovery of the HPA axis after stopping prolonged oral steroid therapy for asthma, and that patients should continue to carry steroid therapy cards for at least 5 years after such treatment has been discontinued.

Adrenocorticotropic Hormone↗
PubMed1982

Morbidity from chronic asthma.

Seventy asthmatic patients newly referred to a hospital outpatient clinic have been studied. In one-third of the patients the diagnosis of asthma had not been considered. Eight patients presented with an FEV1 of one litre or less. Acute severe asthma is commonly believed to precede death from asthma, but patients with more chronic symptoms may have equally severe airways obstruction without appearing acutely ill. Failure to diagnose and treat such patients may be contributing to our present inability to reduce the death rate from asthma.

Adult↗
PubMed1980

The straight back syndrome.

The straight back syndrome, consisting of loss of normal upper thoracic spinal curvature associated with cardiac murmurs and radiographic cardiomegaly is considered a form of 'pseudoheart disease' which has been attributed to squashing of the heart in the reduced AP diameter of the chest. During an 18-month period 31 patients referred to a cardiologist were found to have a straight back. Forty-five relatives were subsequently examined and 27 were found also to have a straight back. Palpitations and chest pain were the commonest symptoms. On the lateral chest radiograph the distance from the middle of the anterior border T8 to a vertical line connecting T4 and T12 was found to be significantly reduced compared to controls, and a value less 1.2 cm is indicative of a straight back. Of the 58 subjects with the syndrome, 39 (67 per cent) had clinical and/or echocardiographic evidence of mitral valve prolapse. Respiratory function testing revealed no significant abnormality. HLA typing showed no association with an particular HLA antigen but indicates that the straight back syndrome is inherited as an autosomal dominant condition and suggested that the antigenic determinants may be located on chromosome 6. We conclude that the straight back syndrome should no longer be considered a form of pseudoheart disease and patients should be investigated for associated mitral valve prolapse and their relatives screened.

Adolescent↗