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Biomedical subjects

Simon Godfrey

Publications and source records attributed to Simon Godfrey.

15 recordsLinked to original sources
PubMed2006

Non-invasive measurement of total respiratory compliance and resistance in cats.

We adapted non-invasive techniques developed for human infants to measure total respiratory system compliance (Crs) and resistance (Rrs) in 21 healthy cats. The animals breathed through a face mask attached to a respiratory circuit and measurements were taken of changes in lung volume and airway pressure during brief occlusions of the airway at different lung volumes. The slope of the plot of change in volume against airway pressure yielded the multiple occlusion Crs with a mean (+/-95%CI) value of 6.8 (6.3-7.3) ml/cm H2O. In 12 animals measurements were made by the single breath technique in which occlusion was made early in expiration and on release, a plot of the subsequent relaxed expiratory flow and volume yielded the time constant (taurs), Crs and Rrs with mean (+/-95%CI) values of 0.27 (0.22-0.31) s, 7.0 (6.1-7.8) ml/cm H2O, and 38.7 (33.7-43.6) cm H2O/l/s, respectively. Rrs was significantly correlated inversely with forced expiratory flow at resting lung volume (V'maxFRC).

Airway Resistance↗
PubMed2006

Non-invasive forced expiratory flow-volume curves to measure lung function in cats.

Forced expiratory flow-volume curves were performed in 15 cats using the non-invasive thoracic compression techniques developed for use in human infants. Cats breathed through a face mask and pneumotachygraph from which flow and volume were obtained. Thoracic compression was applied from an inflatable bag in a non-expandable jacket surrounding the animal. Bag inflation at end inspiration was initiated by a computer pulse to a pressurized chamber. Processed signals from the pneumotachygraph determined maximum-forced expiratory flow at lung volume equivalent to functional residual capacity (FRC), termed V'maxFRC. Different compression pressures were used, and the highest value from a technically satisfactory flow-volume loop was taken as the result. Mean (+/- 95% CI) V'maxFRC was 422 (369-475) ml/s. Compared with infants of similar weight (V'maxFRC approximately 180 ml/s), cats had a much higher V'maxFRC. Tests repeated another day showed a mean (+/-95% CI) percentage difference between paired tests to be 2.8 (-12.6, +18.3)%. Non-invasive forced expiratory flow-volume measurements can be reliably obtained in sedated cats.

Air Pressure↗
PubMed2005

Timing and nature of wheezing at the endpoint of a bronchial challenge in preschool children.

Bronchial reactivity to inhaled agents in preschool children can be undertaken by auscultating the lungs to detect wheezing, but there is a lack of information on when wheeze first appears at the endpoint of the challenge and on the acoustic characteristics of the wheeze. We recorded breath sounds continuously during tidal breathing inhalation challenges with adenosine 5'-monophosphate, using sensors attached over each upper lobe in 80 preschool children. In 35 children, the challenge was considered positive by a pediatrician who determined the endpoint by detecting wheeze on auscultation after an inhalation. Using acoustic analysis, we determined that the first wheeze appeared during the 2-min period of nebulization in 31% of positive challenges; it was unilateral in 37%, and only inspiratory in 46%. A running window of 6 sec was used to detect at least two wheezes without reference to phase of breathing, and this index had a sensitivity of 97.6% and specificity of 99.7% for determining the endpoint of a challenge. Detecting wheeze acoustically adds safety to the technique by enabling the challenge to be stopped earlier, while the lack of a need to document the phase of breathing simplifies the technique.

Acoustics↗
PubMed2004

Development of pediatric pulmonology in the United Kingdom, Europe, and Australasia.

The organization of medicine in Europe, the UK and the Commonwealth countries was always much less formal than in the USA for many years and pediatricians interested in pediatric lung disease and asthma often started off as adult internists or specialists in adult pulmonary medicine. The early leaders in developing a special interest in the breathing of children during the 1940s and 1950s were predominantly physiologists and clinicians who began to apply physiological techniques to the study lung function in healthy and sick infants and children. A major contribution to our understanding of the epidemiology of wheezing in children was the early establishment of a cohort study in Australia which is still yielding important information. It was during the early 1970s that pediatric pulmonary "politics" began to emerge in the UK when pediatricians interested in lung diseases began to arrange an informal society and meet regularly under the auspices of the British Paediatric Association. In fairly characteristic fashion, pulmonology in Europe was represented for a while by several different societies but due to the efforts of some dedicated enthusiasts there finally emerged the Paediatric Assembly of the European Respiratory Society (ERS) and its first Head, Max Zach, went to become President of the ERS itself. Despite some early doubts abut the future for pediatric pulmonology as a specialty in Europe and Australasia it is clearly flourishing as shown by the rising membership of the professional societies and the constant stream of high quality basic science and clinical publications.

Australasia↗
PubMed2004

Is clinical wheezing reliable as the endpoint for bronchial challenges in preschool children?

The present study was designed to compare the clinical finding of wheeze by auscultation with an objective evaluation by acoustic means at the endpoint of a bronchial challenge in preschool children. Challenges were undertaken using a tidal breathing method in 51 preschool children as part of the investigation of possible asthma. An electronic stethoscope was used for auscultation of each lung and for the simultaneous recording of the acoustic sonogram for analysis. In 24 children, the pediatrician determined that the challenge was positive, and in 22 of these, he heard wheezing at the endpoint of the challenge. In 2 children the challenge was considered positive, based on a modest fall in saturation. The acoustic record was scanned manually for presence of wheeze defined in terms of duration, and power spectrum without reference to auscultatory findings. In positive challenges, the mean wheeze rate was 28.1% (95% CI, 19.5-36.8%), while no wheeze was detected acoustically in negative challenges. Using a cutoff wheeze rate (duration of wheeze/duration of breath phase x100) of 10% for the whole group, clinical wheezing detected by the pediatrician had a sensitivity of 100% (no false negatives) and a specificity of 91%. In conclusion, the clinical observation of wheeze agrees very well with its detection by acoustic measurement at the endpoint of a bronchial challenge in preschool children.

Asthma↗
PubMed2004

Pulmonary hemorrhage/hemoptysis in children.

Pulmonary hemorrhage and hemoptysis are uncommon in childhood, and the frequency with which they are encountered by the pediatric pulmonologist depends largely on the special interests of the center to which the child is referred. In those centers caring for children with cystic fibrosis or congenital heart disease, these will be by far the most common causes of hemoptysis. Other causes of hemoptysis are far less common, such as bleeding from localized lesions in the upper airway or tracheobronchial tree. Even less common is bleeding into the lungs as part of a systemic disease, usually with renal involvement (pulmonary-renal syndromes), such as systemic lupus erythematosis or Goodpasture's syndrome. Bleeding into the lungs in children with a bleeding diathesis probably only occurs in immunosuppressed children after transplantation. When no other cause is found for pulmonary hemorrhage, the presumed diagnosis is idiopathic pulmonary hemosiderosis. This review discusses the various causes of hemoptysis and pulmonary hemorrhage, and the appropriate investigations to aid in determining the correct diagnosis. The management and prognosis of idiopathic pulmonary hemosiderosis, based on cumulative experience from published reports, are considered in more detail.

Child↗
PubMed2004

Hemoptysis in children.

Explore the source record for details and available documents.

Anti-Glomerular Basement Membrane Disease↗
PubMed2004

Relapsing polychondritis: reversible airway obstruction is not always asthma.

Relapsing polychondritis (RP) is a rare disease characterized by recurrent inflammation of cartilaginous and other proteoglycan-rich tissues. Respiratory tract involvement is a common cause of morbidity and mortality in RP. We describe a patient whose clinical features at onset of disease were typical of asthma. Later, the patient developed symptoms and signs characteristic of RP. Tracheobronchomalacia necessitated airway support by stenting. The possibility that airway obstruction in the initial stages of RP is due to airway inflammation and that early, aggressive immunosuppressive treatment of RP may delay or prevent irreversible cartilaginous destruction and airway collapse are discussed.

Airway Obstruction↗
PubMed2003

Exhaled nitric oxide is age-dependent in asthma.

We determined whether the exhaled nitric oxide (eNO) level in asthmatics is age-dependent. Eighty-seven asthmatic patients aged 2-41 years were studied. Hyperreactivity to adenosine 5'-monophosphate (AMP) was used to confirm asthma (</= 200 mg/ml). In the younger group of children (2-5 years), AMP challenge was performed by the provocation concentration causing wheeze (PCW) method, while in the older groups of patients (6-41 years), regular spirometry was used. Exhaled NO was measured in the younger group by the tidal breathing method (TBm) and in the older subjects by the slow vital capacity method (SVCm). TBm and SVCm were compared in 21 other subjects, and there was a significant correlation between the two values (r = 0.96, P < 0.0001). The equation of correlation between the two methods was eNOTBm = 0.78eNOSVCm - 0.51. Within asthmatic patients, we found a significant increase in eNO with age (P < 0.0001), while there was no significant difference in AMP reactivity (P = 0.35). We conclude that eNO in asthmatic patients is age-dependent, with lower values in young children.

Adenosine Monophosphate↗
PubMed2003

The effect of montelukast on bronchial provocation tests and exhaled nitric oxide levels in asthmatic patients.

BACKGROUND: Leukotriene antagonist therapy in asthmatic patients alleviates symptoms and improves exercise tolerance, however the effect of these drugs on bronchial provocation tests and exhaled nitric oxide levels are less clearly established. OBJECTIVE: To determine the effect of montelukast treatment on airway hyperresponsiveness to exercise, methacholine and adenosine-5'-monophosphate and on exhaled nitric oxide levels in steroid-naive asthmatics. METHODS: Following a 2 week run-in period, 20 mild to moderate asthmatics were enrolled in an open label 6 week trial of oral montelukast-sodium therapy. Bronchial hyperreactivity (exercise, methacholine and adenosine-5'-monophosphate challenges) and exhaled nitric oxide levels were measured before and after the 6 week period. RESULTS: Montelukast treatment resulted in a significant improvement in exercise tolerance: median delta FEV1 20.0% (range 0-50) prior to treatment vs. 15.0% (range 0-50) post-treatment (P = 0.029). A significant difference was also observed for exhaled NO following therapy: median NO 16.0 ppb (range 7-41) vs. 13.0 (range 4.8-26) (P = 0.016). No change was seen in baseline lung function tests (FEV1, MEF50) or in the bronchial responsiveness (PC20) for methacholine and adenosine-5'-monophosphate. CONCLUSIONS: This study demonstrates that the leukotriene antagonist montelukast-sodium reduces bronchial hyperreactivity in response to exercise and reduces exhaled nitric oxide levels but has little effect on bronchial responsiveness to methacholine and adenosine challenges.

Acetates↗
PubMed2002

Gavaging the infant lung.

An 8-month-old female infant was hospitalized for persistent bilateral infiltrates, failure to thrive, and tachypnea. An extensive diagnostic workup was negative, except for strong oil-red O staining of the white-turbid bronchoalveolar lavage fluid and borderline esophageal pH monitoring. Conservative treatment failed, and she was scheduled for gastrostomy and Nissen-fundoplication until the family physician found that the anxious mother was feeding the child forcibly, which caused chronic aspiration pneumonitis. The mother was given psychological support and was supervised, and the child recovered completely.

Anxiety Disorders↗