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C Beardsmore

Publications and source records attributed to C Beardsmore.

10 recordsLinked to original sources
PubMed2001

Plethysmographic measurements of lung volume and airway resistance. ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. European Respiratory Society/ American Thoracic Society.

Functional residual capacity (FRC) is the only static lung volume that can be measured routinely in infants. It is important for interpreting volume-dependent pulmonary mechanics such as airway resistance or forced expiratory flows, and for defining normal lung growth. Despite requiring complex equipment, the plethysmographic method for measuring FRC is very simple to apply and, unlike the gas dilution techniques, enables repeat measures of lung volume to be obtained within a few minutes. This method has the further advantage that with suitable adaptations to the equipment, simultaneous measurements of airway resistance can also be obtained. The aim of this paper is to provide recommendations pertaining to equipment requirements, study procedures and reporting of data for plethysmographic measurements in infants. Implementation of these recommendations should help to ensure that such measurements are as accurate as possible and that meaningful comparisons can be made between data collected in different centres or with different equipment. These guidelines cover numerous aspects including terminology and definitions, equipment, data acquisition and analysis and reporting of results and also highlight areas where further research is needed before consensus can be reached.

Airway Resistance↗
PubMed2000

No objective benefit from steroids inhaled via a spacer in infants recovering from bronchiolitis.

A double-blind randomized placebo-controlled trial was conducted to investigate the efficacy of 3 months' inhaled steroids delivered via a spacer device with face mask attachment to infants recovering from bronchiolitis. Forty-eight previously healthy infants recovering from their first documented episode of acute bronchiolitis were randomized to receive 150 microg fluticasone propionate (FP) b.i.d. or placebo delivered via the Babyhaler spacer. Longitudinal assessments were performed on seven occasions over 1 yr based on symptom diaries and health records, clinical examinations, overnight cough recordings and oxygen saturation readings. Lung function was measured 6 months after hospital discharge. Forty-three infants completed the trial (FP 21, placebo 22). There were no significant differences in the three objective end-points measured, recorded night cough, oxygen saturation and lung function test results. Symptom scores were low in both the FP and placebo groups with the absence of (0) or mild (1) symptoms > or =90% of the trial days. No statistical differences in symptom frequency, use of rescue respiratory medications or hospital admissions between treatment groups were found throughout the trial or follow-up periods. In conclusion, the use of inhaled fluticasone propionate in infants recovering from acute bronchiolitis cannot be recommended.

Administration, Inhalation↗
PubMed2000

Respiratory function in survivors of the United Kingdom Extracorporeal Membrane Oxygenation Trial.

Extracorporeal membrane oxygenation (ECMO) improves survival in mature neonates with reversible lung disease. However, ECMO could result in survival of infants with severe respiratory dysfunction who would otherwise have died. Alternatively, infants receiving ECMO might be spared prolonged ventilation and consequent barotrauma, resulting in improved respiratory function. Our aim was to compare respiratory function at 1 yr of age in infants assigned to receive either ECMO or conventional management (CM). Seventy-eight surviving infants of the United Kingdom (UK) ECMO trial (51 in the ECMO group) were studied at 1 yr of age. Questionnaires provided details of respiratory symptoms, and laboratory measurements of respiratory function were made for respiratory rate, tidal volume, lung volume, airway conductance, specific airway conductance, and maximal expiratory flow at FRC (Vmax (FRC)). Data were exchanged on floppy disk for cross-analysis and to ensure that investigators were blinded to the status of the infants. There was a wide spectrum of respiratory function, from normal to markedly abnormal. There were few differences between the groups, but in the CM group lung volume was increased (95% confidence intervals [CIs] of the difference in ECMO versus CM subjects: -67; -4 ml), and inspiratory specific conductance was lower (95% CI: 0.03; 0.98 s(-)(1). kPa(-)(1)). There was a trend toward a lower V max(FRC) (95% CI: -2; 67 ml/s(-)(1) in the CM group. In addition to providing a survival advantage, ECMO did not worsen lung function in infants assigned to receive it. Indeed, their lung function appeared slightly better than that of infants treated conventionally.

Child Development↗
PubMed2000

Alterations in airway wall properties in infants with a history of wheezing disorders.

Airway diameter and airway wall mechanics (compliance) are important determinants of flow limitation and wheezing. We have previously used the high-speed interrupter technique (HIT) to measure input impedance (Zin) in infants at frequencies up to 900 Hz, including antiresonance phenomena, which are known to be related to wave propagation velocity, and have shown that the frequency at which the first antiresonance occurs (f(ar,1)) is a function of airway wall compliance. We aimed to determine whether f(ar,1) (and thus airway wall compliance) was different in infants with a history of wheezing disorders. We compared 23 asymptomatic infants (aged 36 to 81 wk) with a history of wheezing with an age-matched group of 19 healthy control infants. We found that f(ar,1) was significantly lower in infants with wheezing disorders than in the control group (p < 0. 005), implying differences in airway wall compliance, even when they were clinically asymptomatic. Developmental differences in airway wall mechanics may be important in the pathogenesis of wheezing disorders or, alternatively, alterations in airway wall mechanics might be a consequence of postinflammatory remodeling.

Airway Resistance↗
PubMed1998

A collaborative study of infant respiratory function testing.

The aims of this study were to compare inter-observer variability within and between two specialized infant lung function testing centres and to develop a strategy for performing and analysing infant respiratory function tests to facilitate future collaborative trials. A protocol for data collection and analysis was developed using similar equipment and identical software. All raw data were exchanged on disk and analysed, blind to infant status. All data were cross-analysed by both centres to assess inter-observer variability. Outcome measures were functional residual capacity (FRCpleth), airway resistance (Raw) and maximal expiratory flow at FRC (V'max,FRC). Subjects were recruited from the multicentre UK extracorporeal membrane oxygenation (ECMO) Trial and measured at around 1 yr of age. Forty-two infants attended the Institute of Child Health, London and 36 attended the Leicester Royal Infirmary. The proportion of infants treated with ECMO or conventional management at each centre was similar. There were no significant differences between any of the outcome measures for infants tested at either centre. During a cross-analysis, the agreement between the two centres, within infant, was closer for V'max,FRC and FRCpleth (within 10%) than for the more variable measurements of Raw (within 20%). A collaborative approach to trials with infant respiratory function as an outcome measure appears feasible, providing that close attention is paid to study design, and participants in such trials maintain a standard approach to data collection and analysis.

Airway Resistance↗
PubMed1987

Determinants of end expiratory volume in young children during ketamine or halothane anesthesia.

The expiratory time (Te) and the rate of lung emptying in expiration are important determinants of functional residual capacity (FRC) in infants. In order to determine whether these factors also influence FRC in children during anesthesia, 20 preschool children were studied, 10 while receiving ketamine, and 10 during halothane anesthesia. Te was measured during quiet breathing and the passive expiratory time constant (tau) was determined from the passive expiratory flow volume (V/V) curve following a brief end inspiratory airway occlusion. The number of time constants available for expiration, Te/tau, was then calculated. The difference between FRC and the relaxation volume of the respiratory system (Vrs) (FRC-Vrs) was measured by extrapolating the linear segment of the V/V curve to zero flow, and measuring FRC-Vrs. During ketamine anesthesia, tau was markedly prolonged (1.15 s, range 0.73-2.29 s), with the result that Te/tau was, in all subjects, less than 2. Children anesthetized with halothane had shorter tau (0.38 s, range 0.24-0.65 s), and Te/tau was more than 2 in most subjects. FRC-Vrs was significantly greater in the subjects from the ketamine group (203 ml, range 115-392 ml) than in those from the halothane group (32 ml, range 1-71 ml). For the 20 subjects, there was a significant relationship between FRC-Vrs (ml) and Te/tau described by the equation. FRC-Vrs = 845.0e-1.28(Te/tau) The authors conclude that, in children during ketamine anesthesia, tau is prolonged and, in these children, the relationship of Te to tau is an important determinant of FRC-Vrs. Te/tau was not related causally to FRC-Vrs in the halothane group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1983

Postural variations in pulmonary resistance, dynamic compliance, and esophageal pressure in neonates.

In order to determine effect of posture and to assess the reliability of the esophageal balloon method for measuring esophageal pressure changes (delta Pes) under clinical conditions, lung mechanics were measured in 13 term and preterm babies in each of 3 postures: supine, right, and left lateral. The pulmonary resistance (Rp) was significantly lower and the dynamic compliance (Cdyn) higher in the right lateral than in the supine position. Judged by the occlusion test, delta Pes was recorded accurately in each posture. The mean end-expiratory esophageal balloon pressure (PesEE) was higher in preterm infants and in the supine posture. It is concluded that the (right) lateral posture is mechanically less demanding than the supine posture and that delta Pes can be measured accurately in the supine posture. Absolute values of PesEE have no physiologic meaning and should not be used for patient management or for the calculation of lung mechanics.

Airway Resistance↗