Biomedical subjects
G M Stokes
Publications and source records attributed to G M Stokes.
Lung function after acute bronchiolitis.
We performed 211 lung function measurements on 93 children in the first year after they had been admitted with acute bronchiolitis. During the convalescent phase of the illness, 77% of the infants were hyperinflated with a thoracic gas volume greater than 40 ml/kg and 3 months later 43% were hyperinflated. Twelve months after the initial illness, 17% still had lung function abnormalities and most of these children have had lower respiratory tract symptoms. For the group as a whole about 60% have had at least one episode of wheezing. Specific conductances were significantly lower in children from atopic families, indicating worse lung function, but the significance of this finding is unclear.
Ineffectiveness of ipratropium bromide in acute bronchiolitis.
In a double blind randomised trial, we found no evidence that nebulised ipratropium bromide was of clinical benefit in acute bronchiolitis.
Nebulised therapy in acute severe bronchiolitis in infancy.
We have measured total work of breathing before and after the inhalation of water, salbutamol, and ipratropium bromide, given as nebulised solutions, in 39 studies on 25 infants with acute, severe bronchiolitis. Twenty minutes after nebulised water, mean work of breathing per minute was increased by 4% and work per litre by 10% with 2 infants having significant improvement and 2 others showing deterioration. After salbutamol, mean work of breathing per minute showed a 22% increase and work per litre a 0.5% rise. The condition of only one child improved by greater than 25% after this drug. Ipratropium bromide led to significant improvement in 6 out of 15 studies and no corresponding deterioration. The group results showed a fall in work of breathing, 18% in work per minute and 16% in work per litre.
Bronchodilator effects of the H1 receptor antagonist--clemastine.
We investigated the specific H1 receptor antagonist, clemastine, in 15 children with asthma. In the respiratory unit, clemastine was an effective bronchodilator but in a clinical trial we could not show any significant benefit compared with placebo.
Respiratory problems 2 years after acute bronchiolitis in infancy.
We assessed the clinical progress of 55 children 2 years after admission to hospital with acute bronchiolitis and performed lung function tests on 40. During the 2 year follow up period 75% of the children had wheezed, 36% had 2 or more lower respiratory symptoms lasting more than 2 weeks, 33% had more than 100 days of lower respiratory symptoms, and 13% were readmitted to hospital with acute respiratory disease. In addition 60% of the children were hyperinflated on lung function tests. Many of the children with hyperinflation at the 2 year assessment had not been hyperinflated 1 year earlier, suggesting variable airways obstruction. Reversibility of airways obstruction was also assessed by response to nebulised salbutamol. Nine children had a fall greater than 15% in airways resistance after salbutamol and these children had the highest baseline airways resistances. Airways resistance was higher in the children with a family history of atopy.
Nebulised ipratropium bromide in wheezy infants and young children.
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Bronchodilator effect of two inhaled H1-receptor antagonists, clemastine and chlorpheniramine, in wheezy school-children.
Chlorpheniramine, clemastine and a placebo have been compared for their ability to relieve bronchoconstriction in 14 childhood asthmatics between the ages of 6 and 14 years. Each attended on three separate occasions, inhaling a 2 ml solution containing either 4 mg of chlorpheniramine, 1 mg of clemastine or placebo under double-blind conditions. Lung function was assessed before and at intervals for 30 minutes after the inhalation by peak expiratory flow and spirometry. Each child then inhaled 5 mg of salbutamol in 2 ml of water and the lung function tests were repeated. A significant degree of bronchodilatation was seen 30 minutes after all three inhalations, but considerable coughing occurred after inhaling chlorpheniramine. Actual changes in raw data showed a significant improvement after clemastine between the 20 and 30 minute recordings and that at 30 minutes clemastine produced significantly greater bronchodilatation than placebo. Inhaled H1-receptor antagonists merit further investigation to delineate their role in childhood asthma.
Causes and management of bronchiolitis with chronic obstructive features.
During the last 4 years we have seen 13 children with a severe bronchiolitis. The children have had prolonged respiratory illnesses waxing and waning over many months, often requiring oxygen therapy for long periods. The diagnosis is based on a clinical picture similar to acute bronchiolitis, but persisting for months, frequently associated with failure to thrive, coupled with lung function evidence of hyperinflation and airways obstruction but normal static compliance. Confusion with other chronic lung conditions can be clarified by straightforward observations and investigations. We believe that chronic bronchiolitis is fairly common and often misdiagnosed. The short- and medium-term prognosis appears good although small airways disease may persist into adult life.
Lung function abnormalities after acute bronchiolitis.
Measurements of thoracic gas volume, airways resistance, and total respiratory resistance were measured in a group of babies with acute severe bronchiolitis. Assessments were made at convalescence, three to four months later, and after 12 months. Clinical histories were also taken 12 months after the acute episode. Results at this time showed that 35% of the infants had coughing attacks, 50% episodes of wheezing, 50% had dry skin or eczema, and that over 75% had lung function abnormality.
Work of breathing, intra-thoracic pressure and clinical findings in a group of babies with bronchiolitis.
Total work of breathing was measured on 55 occasions on 26 babies with acute bronchiolitis using a respiratory jacket to measure tidal volume and a naso-gastric tube to record oesophageal pressure. Work of breathing was increased six-fold on average and on one occasion exceeded forty times the expected. Approximately 40% of the intra-thoracic pressure swing was positive relative to atmospheric. It was not possible to correlate the work of breathing measurements with detailed clinical assessments.
Assessment of a new device for delivering aerosol drugs to asthmatic children.
A new device, known as the aero-chamber, for delivering aerosol drugs was compared with a standard aerosol inhaler in asthmatic children aged between 5 years 3 months and 13 years 10 months. The study was conducted under double-blind conditions using fenoterol, a beta 2 stimulant, as the active agent and a placebo. Response to treatment was assessed by measuring the peak expiratory flow rate before and after each inhaler. Seven of 10 children had greater mean improvements in peak expiratory flow rates when receiving the active drug from the aerochamber. The aerochamber offers a method for administering a whole range of canistered packaged drugs to children unable to use the standard inhalers.
Ketotifen in the prophylaxis of childhood asthma.
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Bronchodilator effects of clemastine, ipratropium, bromide, and salbutamol in preschool children with asthma.
The bronchodilator activity in nebulised salbutamol, ipratropium bromide, clemastine, and a placebo was studied in 14 asthmatic children aged between 3 and 5 years. Changes in lung function were monitored by measuring peak expiratory flow rate and total respiratory resistance using a modification of the forced oscillation technique. Ipratropium bromide produced a degree of bronchodilation similar to that of salbutamol, but the bronchodilatory activity of clemastine was not appreciably better than for the placebo.
Bronchodilator effect of inhaled ipratropium bromide in wheezy toddlers.
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Measurement of work of breathing in infancy.
Assessment of lung function in young children is extremely difficult unless sedation is given. If tidal exchange and intrathoracic pressure swings can be recorded, the severity of the respiratory problem can be measured by construction pressure-volume loops and calculating the work of breathing. The system we have used to measure tidal thoracic volumes is that of a soft, rubber, inflatable jacket with pressure-volume characteristics linear from inflation pressure of 2.5 to 7 cm H2O. Oesophageal (intrathoracic) pressures are measured using water-filled nasogastric tubes (FG6). Frequency responses showed that 63% rise times for the jacket and water-filled nasogastric tube assessed together to be 10.5 msec. Recordings were traced onto a computer digitizing tablet and print-outs were obtained with the following information: respiratory rate, tidal thoracic volume, minute thoracic volume, oesophageal pressure, resistive work per min, elastic work per min, and total work per min. Comparisons were made between volumes measured using the respiratory jacket (VJ) and by pneumotachograph and integrator (VInt) in six infants. Hysteresis arising from the jacket produces some change in resistive work of breathing, but the total work of breathing is only increased by a maximum of 10.5%. Studies on healthy newborn babies showed that the jacket system tends to underrecord the resistive work of breathing, but that total work of breathing values are very similar. Reproducibility of analysis showed the following coefficients of variation from the mean: tidal thoracic volume, 1.6%; minute thoracic volume, 1.7%; resistive work, 5%; elastic work, 2%; and total work, 2.5%. The extent of breath-to-breath variation is much larger. This system makes it possible to obtain serial measurements of work of breathing without the need for sedation in infants who may be acutely ill and in respiratory failure.
Efficacy of orally administered salbutamol and theophylline in pre-schoolchildren with asthma.
Oral administration of salbutamol and theophylline has been shown to be effective in relieving bronchoconstriction in asthmatic children aged between 3 and 5 years. Changes in respiratory function were monitored using a Wright's low range peak flow meter and a modification of the forced oscillation technique. A combination of both drugs in half doses was as effective as either alone. Nebulised salbutamol produced considerable further improvement in lung function.
The bronchodilator effects of chlorpheniramine in childhood asthma.
Significant improvement in lung function has been demonstrated following the inhalation of chlorpheniramine. The doses which were used caused local irritation and are probably unsuitable for routine clinical use. Nevertheless, we believe that antihistamines deserve further investigation in the treatment of childhood asthma.