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Biomedical subjects

P W Francis

Publications and source records attributed to P W Francis.

15 recordsLinked to original sources
PubMed2005

Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope.

BACKGROUND: Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object. METHODS: Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived. RESULTS: Magnification changes as a linear function between 100 mm (x1) and 10 mm (x9.55) and then as an exponential function between 10 mm and 3 mm (x40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis. CONCLUSION: We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements.

Artifacts↗
PubMed2005

A new method for objective identification and measurement of airway lumen in paediatric flexible videobronchoscopy.

BACKGROUND: Accurate measurements of airway and lesion dimensions are important to the developmental progress of paediatric bronchoscopy. The malacia disorders are an important cause of respiratory morbidity in children, but no methods are currently available to measure these lesions or the airway lumen accurately. A new measurement technique is described here. METHODS: The magnification power of a paediatric videobronchoscope was defined and a simple and user friendly computer based program (Image J) was used to develop an objective technique (colour histogram mode technique, CHMT) for measurement of the airway lumen. RESULTS: In vivo intra-observer and inter-observer repeatability coefficients for repeated area measurements from 28 images using the Bland-Altman method were 0.9 mm2 and 1.6 mm2, respectively. The average intraclass correlation coefficient for repeated measurements of area was 0.93. In vitro validation measurements using a 2 mm diameter tube resolved radii measurements to within 0.1 mm (coefficient of variability 8%). An "acceptable result" was defined in 92% of 734 images completed with the CHMT alone and 8% with its modification. The success rate for two of three images being within 10% of each other's area was 100%. Measurements of cricoid cross sectional areas from 116 patients compared with expected airway areas for age derived from endotracheal tube sizes were comparable. CONCLUSIONS: The CHMT method of identifying and measuring airway dimensions is objective, accurate, and versatile and, as such, is important to the future development of flexible videobronchoscopy.

Bronchi↗
PubMed2002

Series of laryngomalacia, tracheomalacia, and bronchomalacia disorders and their associations with other conditions in children.

Laryngomalacia, bronchomalacia, and tracheomalacia are commonly seen in pediatric respiratory medicine, yet their patterns and associations with other conditions are not well-understood. We prospectively video-recorded bronchoscopic data and clinical information from referred patients over a 10-year period and defined aspects of interrelationships and associations. Two hundred and ninety-nine cases of malacia disorders (34%) were observed in 885 bronchoscopic procedures. Cough, wheeze, stridor, and radiological changes were the most common symptoms and signs. The lesions were most often found in males (2:1) and on the left side (1.6:1). Concomitant malacia lesions ranged from 24% for laryngotracheobronchomalacia to 47% for tracheobronchomalacia. The lesions were found in association with other disorders such as congenital heart disorders (13.7%), tracheo-esophageal fistula (9.6%), and various syndromes (8%). Even though the understanding of these disorders is in its infancy, pediatricians should maintain a level of awareness for malacia lesions and consider the possibility of multiple lesions being present, even when one symptom predominates or occurs alone.

Adolescent↗
PubMed1999

Growth failure in cystic fibrosis.

OBJECTIVE: The aim of this study was to describe and compare the nutritional status of children aged 0-18 years attending the cystic fibrosis (CF) clinic at the Royal Children's Hospital, Brisbane, Australia, as outpatients in 1986 and 1996. METHODOLOGY: The heights, weights and pulmonary function of children attending the CF clinic as outpatients in 1986 (n = 97) and 1996 (n = 227) were retrospectively analysed using a computerized database maintained by the CF clinic. The heights and weights were analysed in terms of z scores for height for age (HAZ), weight for age (WAZ) and weight for height (WHZ). Pulmonary function data is not available for all children. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and forced mid expiratory flows (FEF) were expressed as a percentage of predicted and are presented here. RESULTS: The 1986 sample consisted of 41 males (age range 0.18-14.59 years, mean age 6.52 (4.33)) and 56 females (age range 0.15-14.97 years, mean age 7.75 (3.70)). The 1996 sample consisted of 111 males (age range 0.09-17.97 years, mean age 8.80 (5.49)) and 114 females (age range 0.12-17.98 years, mean age 8.49 (5.26)). In 1986, males were shorter than females (P = 0.0096) and females had a lower mean FVC than males (P = 0.0438). In 1996, males were shorter, lighter and more wasted than females (P = 0.0357, P = 0.0034 and P = 0.0273, respectively) and females had a lower mean FEV1 and mean FVC than males (P = 0.0176 and P = 0.0079, respectively). Males in 1996 were lighter and more wasted than males in 1986 (P = 0.0023 and P = 0.0139, respectively) and had a lower mean FEV1, mean FVC and mean FEF (P < 0.0001, P = 0.0012 and P = 0.0069, respectively). Females in 1996 were shorter and lighter than females in 1986 (P = 0.0273 and P = 0.0405, respectively) and had a lower mean FEV1, mean FVC and mean FEF (P < 0.0001, P < 0.0001 and P < 0.0001, respectively). When subjects were classified according to FEV1 (FEV1 > or = 75% or FEV1 < 75%), there were no significant differences in z scores between the 1986 group and 1996 group. Similarly, when the 1986 group were matched for gender and FEV1 with the 1996 group, there were no significant differences in z scores for males or females. CONCLUSIONS: It is suggested that the apparent worsening of nutritional status among the 1996 group of CF patients is in fact due to an effect of increased survival of patients with more severe clinical symptoms. The findings from this study highlight the continuing, and in fact, worsening problem of growth failure in children with CF.

Adolescent↗
PubMed1998

Atypical mycobacterial pulmonary disease and bronchial obstruction in HIV-negative children.

Atypical mycobacterial infection in HIV-negative children usually presents with cervical lymphadenopathy. We report on 10 children who are HIV-negative and who presented with pulmonary disease, in whom either culture-proven atypical mycobacterium infection (four), positive avian Mantoux test (five), or lack of response to human tuberculosis treatment (one) had been observed. One case was subsequently diagnosed as chronic granulomatous disease and illustrates that children with atypical mycobacterial pulmonary infection should have their immune status fully investigated. Bronchial obstruction was observed in eight cases, and of these, endobronchial disease was found in six children. The diagnosis of atypical mycobacterial disease is difficult, and a negative avian Mantoux test does not exclude the diagnosis. The availability of clarithromycin and rifabutin has offered new therapeutic options in treating atypical mycobacterial pulmonary infection, but management of these cases can be prolonged and difficult.

Bronchial Diseases↗
PubMed1998

Treatment of acute asthma: salbutamol via jet nebuliser vs spacer and metered dose inhaler.

OBJECTIVE: To compare the efficacy of salbutamol delivered by jet nebuliser (JN) with salbutamol via a pressurised metered dose inhaler (PMDI) and a large volume spacer (Volumatic) for management of acute asthma. STUDY POPULATION: A total of 160 children aged from 4 to 12 years presenting to an Emergency Department with acute asthma. METHODS: The study was of multicentre (n=5) randomised, double blind, parallel design. Children weighing less than 25 kg received salbutamol 2.5 mg via the JN or 600 microg (six puffs) from the PMDI. Children over 25 kg received salbutamol 5 mg via the JN or 1200 microg (12 puffs) via the PMDI. Clinical score (range 0-12) and PEF (over 7 years) were recorded at baseline and 15, 30, 45 and 60 mins post administration. RESULTS: The improvement from baseline at 30 min in the clinical score was 1.87 for JN and 1.43 for PMDI (P=0.09) and at 60 min was 2.15 for JN and 1.12 for PMDI (P=0.0001). The improvement in PEF at 30 min was 51 L min(-1) for JN and 27 L min(-1) for PMDI (P=0.0007) and at 60 min was 57 L min(-1) for JN and 31.5 L min(-1) for PMDI (P=0.001). CONCLUSION: Administration of salbutamol via a PMDI and a large volume spacer device provides effective relief in the management of acute asthma in children, but to a lesser extent than a jet nebuliser. This difference may represent a dose response effect.

Acute Disease↗
PubMed1997

Asthma in children.

Explore the source record for details and available documents.

Administration, Inhalation↗
PubMed1994

Aerosol deposition in cystic fibrosis using an aerosol conservation device and a conventional jet nebulizer.

The deposition of technetium radiolabelled aerosol within the lungs of 12 stable cystic fibrosis patients (mean age 12.7 years) was compared using the Acorn nebulizer and mouthpiece alone, and the Acorn nebulizer attached to the Mizer Aerosol Conservation Device (MACD). The total activity delivered to the patient using the MACD was 11.1% (+/- 7.8% s.d.) of the initial dose, compared to 5.8% (+/- 4.2% s.d.) with the nebulizer and mouthpiece alone (P < 0.05). With the MACD, 84% of the intrapulmonary dose was delivered to the peripheral regions, compared to 76.5% with the nebulizer and mouthpiece (P < 0.05). No significant correlation was found between aerosol deposition and pulmonary function. The Mizer Aerosol Conservation Device significantly increases both total intrapulmonary aerosol deposition and peripheral aerosol distribution.

Adolescent↗
PubMed1992

Nebuhaler versus wet aerosol for domiciliary bronchodilator therapy. A multi-centre clinical comparison.

OBJECTIVE: To compare the clinical effectiveness and patient acceptance of a large spacer device (Nebuhaler) for delivery of metered dose aerosol (MDI) terbutaline with nebulised wet aerosol terbutaline. DESIGN: Randomised open crossover study over two sequential four week treatment periods, following a two week run-in. SETTING: Multi-centre including five adult thoracic units and three paediatric centres throughout Australia. PATIENTS: Thirty-eight adults and 23 children with clinical asthma and reversible airflow obstruction (increase in forced expiratory volume in one second [FEV1] of greater than or equal to 15% in response to inhaled bronchodilator) entered the study proper. Six adults and one child withdrew. INTERVENTIONS: Terbutaline was administered four times daily via Nebuhaler/MDI or nebuliser. Clinical assessment with spirometry and peak flow readings was made after run-in and at the end of each treatment period. Patients recorded on diary cards daily peak expiratory flow rates and symptom scores and comparisons of these results for each treatment period were made. At the completion of the study patients answered a treatment preference questionnaire. RESULTS: No differences were found between the two treatment periods in diary card peak flow recordings and symptom score data, and in clinical assessment of spirometry and peak expiratory flow rates. There were also no differences between spirometry and peak flow values recorded at the clinic at randomisation and at the end of each treatment period, suggesting stable basal airflow obstruction over the period of the study. Thirty-two per cent of adults and 52% of children preferred the Nebuhaler/MDI combination, mainly because of convenience of use. Treatment preference was not related to any measured index of lung function. CONCLUSIONS: MDI terbutaline delivered via Nebuhaler provides clinical benefit similar to that of wet aerosol terbutaline in the long-term domiciliary management of patients with stable airflow obstruction.

Adult↗
PubMed1992

Mycobacterium haemophilum causing perihilar or cervical lymphadenitis in healthy children.

We describe five apparently immunologically normal children with infection caused by Mycobacterium haemophilum and resulting in perihilar or cervical lymphadenitis. Clinical distinction from Mycobacterium tuberculosis infection could be made by culture only, because differential Mantoux test results suggested tuberculosis. Treatment of these children involved chemotherapy or surgery or both, and outcome in all cases has been excellent. We believe that M. haemophilum should be added to the list of non-tuberculosis mycobacteria known to cause lymphadenitis in otherwise healthy children.

Antitubercular Agents↗
PubMed1983

Comparison of salbutamol powder with terbutaline aerosol administered with a tube spacer in asthmatic children.

The bronchodilator effect of 400 micrograms of salbutamol powder (2 capsules) administered by a rota-haler was compared with that of 500 micrograms of terbutaline (2 metered doses) administered as an aerosol via a tube-spacer in a group of ten stable asthmatic children (mean age 12 years). The salbutamol powder produced significantly greater bronchodilatation compared with the terbutaline. Forty-five minutes after the administration of each preparation, nebulised salbutamol was given to determine if further bronchodilatation was possible. Additional bronchodilatation was seen in both groups, the greater additional change being after terbutaline. It is concluded that 400 micrograms of salbutamol powder was more effective than 500 micrograms of terbutaline via tube-spacer but following both preparations, nebulised salbutamol produced significant additional bronchodilatation.

Adolescent↗
PubMed1980

Hemoglobin desaturation: its occurrence during sleep in patients with cystic fibrosis.

Sleep studies were performed in 20 clinically stable cystic fibrosis (CF) patients (mean age, 18.2 years) to determine the magnitude of fall in hemoglobin saturation (Sao2) during sleep and to relate these changes to pulmonary function and echocardiographic findings. Five healthy young adults served as controls. In both groups, the maximum fall in Sao2 was seen during rapid eye movement (REM) sleep. The mean maximum fall in the control group during REM sleep was 2.0% (range, 1% to 3%), compared with 7.4% (range, 1% to 23%) in the CF group. Of the 11 patients in whom right ventricular systolic time intervals were obtained, eight of the nine patients with falls in Sao2 greater than 3% during REM sleep had echocardiographic evidence of pulmonary hypertension. Repeated episodes of desaturation during sleep may contribute to the development and progression of cor pulmonale in CF patients.

Adolescent↗
PubMed1980

Mechanism of hemoglobin desaturation during rapid-eye-movement sleep in normal subjects and in patients with cystic fibrosis.

To assess the mechanism of the decrease in hemoglobin O2 saturation during rapid-eye-movement sleep, we studied 5 normal subjects 22 to 30 yr of age and 20 patients with cystic fibrosis 9 to 29 yr of age. The largest decrease in arterial O2 saturation, as monitored with an ear oximeter during sleep, occurred during rapid-eye-movement sleep, with a mean +/- SEM decrease of 2 +/- 0.31% in the normal subjects and 7.4 +/- 1.3% in the patients in both groups. Rapid-eye-movement sleep was associated with a significant loss of intercostal and diaphragmatic tonic muscle activity (p < 0.01), as monitored with surface electrodes, and a decrease in the baseline position of the rib cage and abdomen, as recorded by magnetometers (p < 0.01). This suggests a decrease in functional residual capacity, which was accompanied by a consistently lower arterial O2 saturation during rapid-eye-movement sleep. Short periods (< 20 s) of inhibition of phasic respiratory muscle activity during rapid-eye-movement sleep were followed by further decreases in arterial O2 saturation. We conclude that the desaturation during rapid-eye-movement sleep in all subjects was mainly due to a decrease in functional residual capacity, leading to airway closure in the dependent lung regions. The hemoglobin desaturation was further aggravated by transient periods of hypoventilation.

Adolescent↗
PubMed1980

Oral and inhaled salbutamol in the prevention of exercise-induced bronchospasm.

Oral salbutamol in a dose 0.15 mg/kg of body weight was compared to a total dose of 0.2 mg of salbutamol aerosol in its ability to produce bronchodilation and to prevent exercise-induced bronchospasm (EIB) in 16 asthmatic children in a single-blind crossover study. The degree of bronchodilation seen 120 minutes after the oral salbutamol was equal to that seen 40 minutes after the salbutamol aerosol as assessed by peak expiratory flow (PEF), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), forced expiratory flow during the middle half of the FVC (FEF25-75%), and maximum expiratory-flow after 75% of the FVC had been expired (V25). With respect to changes in PEF and FEV1, both active agents were equally effective in blocking EIB following a standardized treadmill exercise test. However, in assessing changes in FEF25-75%, and V25 following exercise, the aerosol was slightly but significantly more effective than the oral preparation in blocking EIB. Oral salbutamol was clinically effective in preventing EIB for 4.9 to 5.8 hours. The aerosol route has the advantages of a faster onset of action, fewer side effects, and greater protection against EIB with respect ot small airways function. Nevertheless, for patients who are unable to use a metered aerosol, oral salbutamol is a useful alternative both as a bronchodilator and in preventing EIB.

Administration, Intranasal↗