Biomedical subjects
S G Spiro
Publications and source records attributed to S G Spiro.
Slow-release oral salbutamol and aminophylline in nocturnal asthma: relation of overnight changes in lung function and plasma drug levels.
In a double-blind controlled trial 14 chronic asthmatic patients with regular nocturnal exacerbations took 16 mg slow-release oral salbutamol (two Ventolin spandets), 450 mg slow-release aminophylline (two Phyllocontin Continus tablets), or placebo at midnight. Mean peak expiratory flow rates on waking were significantly higher on the active drugs than on placebo (p < 0.01 for salbutamol; p < 0.05 for aminophylline) but neither drug abolished the overnight fall in PEFR. Plasma drug levels at 0600 hr were 17.3 ng/ml (+/- 5.3 ng/ml SD) for salbutamol, and 7.1 micrograms/ml (+/- 3.1 micrograms/ml SD) for theophylline. Steady-state derived from plasma levels of salbutamol during intravenous infusion indicated that the morning salbutamol levels were probably in a therapeutic range for asthma. The morning theophylline levels, however, were suboptimal when aminophylline was given only at night.
Intravenous infusion of salbutamol in severe acute asthma.
Out of 62 asthmatic patients admitted to hospital with an acute exacerbation of their disease, those whose symptoms had not sufficiently improved 15 minutes after an initial intensive regimen were randomly allocated to receive an intravenous infusion of either salbutamol 10 microgram/min (20 patients) or aminophylline 1 mg/min (19 patients). During the infusions, which lasted 36 hours, peak expiratory flow rates and spirometric values improved in both groups, but differences between the groups did not achieve statistical significance. Although salbutamol may be infused safely for a prolonged period to patients with acute asthma, it has no particular advantage over aminophylline. Furthermore, in patients who respond poorly to initial intensive treatment the subsequent infusion of a bronchodilator may not increase the rate of recovery from the rate that would occur naturally.
The metabolic effects of inhaled salbutamol.
1 The metabolic effects of salbutamol (5 mg) given by intermittent positive pressure breathing have been studied in eight patients with airflow obstruction. 2 No changes in plasma nonesterified fatty acids, triglyceride, glucose, insulin or cortisol were seen 1 and 4 h after administration. 3 It is concluded that inhaled salbutamol does not cause the unwanted metabolic effects reported with oral or parenteral administration, and that this is a further indication for this route of administration.
Pressure outside the extrapulmonary airway in dogs.
We have measured the static and dynamic transmural pressures of extrapulmonary airways during positive pressure lung inflation in anesthetized dogs suspended in the standing position. Thin, fluid-filled catheters measured pressures within and on the anterior surface of the airways in the mediastinum and neck. The change from mediastinal to cervical static extra-airway pressures (Pea) was not abrupt but occurred through the thoracic outlet and the root of the neck. The static Pea in the mediastinum was more positive than pleural pressure when lung volume was increased with positive pressures. During forced deflation equal pressure points (EPP) were in labor bronchi from which airway narrowing extended towards the mouth. Under these conditions, the dynamic mediastinal Pea mouthward of the EPP remained close to pleural pressures even at high volumes. This suggested that forces of restitution generated in the surrounding tissues by the narrowing of the airways did have a small effect in reducing the pressure affecting their anterior surface.
Endobronchial lipoma: a review with four cases.
Endobronchial lipomas are rare benign tumours which can cause irreversible pulmonary damage unless removed early. The clinical features and treatment of four cases are reviewed in the light of the previous literature. The histogenesis of these tumours and their relationship to hamartomas are discussed. The treatment of choice in most cases is bronchoscopic excision.
Exercise testing in clinical medicine.
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A case of pulmonary veno-occlusive disease respondong to treatment with azathioprine.
Histological features of a lung biopsy specimen from a 46-year-old woman showed all the characteristics described in veno-occlusive disease. The clinical features, however, were distinctive in that in addition to the lung involvement there was alopecia, digital vasculitic ulcers, Raynaud's phenomenon, polyarthritis, and muscle weakness. Treatment with azathioprine resulted in a progressive improvement in her condition. It is suggested that pulmonary small vein occlusion may occur as a pattern of tissue response in more than one situation and that is sometimes more amenable to therapy than has been previously reported.
Metabolic response to intravenous salbutamol therapy in acute asthma.
In patients suffering from an acute attack of asthma the effects of salbutamol infusion (10 microng/min) on their plasma concentrations of non-esterified fatty acids (NEFA), triglyceride, insulin, and glucose were compared with those in a group of asthmatics not requiring infusion. Salbutamol was found significantly to increase the plasma concentrations of glucose and insulin while having little effect on NEFA or triglyceride. However, NEFA concentrations were found to be significantly increased in patients with an acute attack of asthma at the time of their admission to hospital. This increase is attributed to the stress of the asthmatic attack itself.
Exercise tests before and after heart valve replacement.
A simple progressive exercise test was performed before and after operation on five subjects undergoing mitral valve replacement and on five subjects undergoing aortic valve replacement. The responses of heart rate and ventilation were related to work rate )kilopond metres/min). The patients were also assessed clinically by the New York Heart Association grading and radiologically before each exercise test. The clinical grading was shown to be a poor guide to observed exercise tolerance, as the improvement noted in symptoms was not matched by the objective measurement of working capacity. Only two patients had normal exercise tolerance after surgery, although six of the ten patients claimed that they had no exertional dyspnoea after operation. The changes in simple ventilatory function tests before and after operation were generally small. We suggest that measurements of exercise tolerance before and after operation should be an essential part of heart valve replacement surgery.
Arterialized ear lobe blood samples for blood gas tensions.
The accuracy of arterialized blood samples both at rest and during exercise is described in comparison to simultaneous arterial blood samples. The technique was found to be reliable and sufficiently accurate for clinical exercise testing, with no significant differences for Po2 or Pco2 between the two methods.
Nocturnal asthma and sudden death.
Asthmatics may develop a considerable increase in airways obstruction during the night or early hours of the morning. In most patients, this causes only mild symptoms. In others, the effects may be severe, resulting in sudden death. Greater awareness of the potential severity of nocturnal asthma, together with actual measurement of airways obstruction at the time of symptoms, might prevent some of these catastrophes. If patients are not getting relief with their regular therapy, they should be admitted to the hospital for organized management.
Effect of intravenous injection of salbutamol in asthma.
The effect of i.v. salbutamol was compared with aerosol salbutamol in ten asthmatic patients. 2 A cumulative dose of salbutamol (300 mug) given in three separate injections over 45 min resulted in a mean increase in peak expiratory flow rate (PEFR) of 38.3% and FEV1 of 36%. 3 There was no significant difference in degree of bronchodilatation to the same dose of salbutamol administered intravenously or by aerosol. 4 Palpitations, tremor, and postural hypotension were common when the drug was injected intravenously over one minute, but did not occur after aerosol administration. 5 It is suggested that sulbutamol by intravenous injection is a useful addition to the treatment of acute asthma.
Intravenous infusion of salbutamol in the treatment of asthma.
The effects of i.v. infusion of increasing rates of salbutamol for up to 4 h were documented in ten convalescent asthmatic patients. 2 The major bronchodilator effect was seen at 4.16 mug/minute. A small further improvement occurred at infusion rates up to 25.0 mug/min but was not significantly better than that seen at the lower infusion rate. 3 Cardiovascular effects were minimal after 60 min at the lower rate and even at 25.0 mug/min mean heart rate rose by only 17.1 beats/minute. All patients tolerated the 4 h infusion well. 4 It is concluded that i.v. infusion of salbutamol may be a useful addition to the treatment of the patient with a severe attack of asthma.
Bronchorrhoea in a case of alveolar cell carcinoma.
In a case of bronchorrhoea associated with alveolar cell carcinoma thf rheological and chemical features of the sputum indicated that it was bronchial fluid and not saliva and part bronchial secretion, partly serum transudate. The viscosity and chemical constituents were similar to those found in bronchorrhoea when associated with chronic bronchitis, asthma, or bronchiectasis. The surfactant studies suggested an alveolar origin for most of thf fluid, while the failure of fluid restriction, corticosteroids, atropine, or cytotoxic drugs to influence the sputum volume and properties indicated that the cells responsible are "autonomous".
An analysis of the physiological strain of submaximal exercise in patients with chronic obstructive bronchitis.
An increasing work rate was performed by 40 patients with chronic obstructive bronchitis, split into two groups according to FEV1 (group M, mean FEV1 1-451. and group S, mean FEV1 0-621.), and by 20 normal, non-athletic men of similar age to the patients. Values for cardiac frequency and ventilation were interpolated to standard oxygen uptakes of 0-75, 1-0, and, where possible, 1-5 min-1. The tidal volume at a ventilation of 20 and 30 1 min-1 was also determined. The cardiac frequencies at oxygen uptake of 0-75 and 1-01 min-1 were significantly higher in the patient groups than in the normal men, and were highest in patient group S. The cardiac output when related to the oxygen uptake was in the normal range in all three groups of subjects, so that the patients had smaller stroke volumes than the normal men. Ventilation at oxygen uptakes of 0-75 and 1-01 min-1 was significantly higher in both patient groups than in the normal subjects; there were no significant differences between the two patient groups, Values for dead space/tidal volume ration, alveolar-arterial oxygen gradient, and the percent venous admixture measured during a constant work rate test were significantly greater than normal in the patient groups. Possible factors limiting exercise tolerance in these patients were assessed by extending the increasing work rate test from submaximum to maximum exercise. Changes in blood gas tensions and blood lactate concentrations from resting levels were small, and probably did not limit exercise performance. Measurements at maximum exercise did not add appreciably to the analysis of the disturbed cardiopulmonary function. This study has shown that major disturbances in cardiopulmonary function can be demonstrated without the need for stressing a patient to the limit of his effort tolerance.
A new technique for recording respiratory transients at the start of exercise.
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An increasing work rate test for assessing the physiological strain of submaximal exercise.
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