Biomedical subjects

D Filbrun

Publications and source records attributed to D Filbrun.

4 recordsLinked to original sources

PubMed2000

Adult-type pulmonary function tests in infants without respiratory disease.

A new method that permits the measurement of adult-type maximal expiratory flow-volume curves and fractional lung volumes in sedated infants was recently described. The purpose of this study was to define the normal range for these new measures of pulmonary function in infants and young children. Measurements of forced expiratory flows and fractional lung volume were made on 35 occasions in 22 children (ages 3-120 weeks) without respiratory disease. Maximal expiratory flow-volume curves were measured by the raised lung volume, thoracoabdominal compression technique. Functional residual capacity (FRC) was measured plethysmographically. Measurements of total lung capacity (TLC), residual volume (RV), FRC, forced vital capacity (FVC), and forced expiratory flows at 25, 50, 75, 85, and between 25% and 75% of expired FVC (FEF(25), FEF(50), FEF(75), FEF(85), and FEF(25-75), respectively) all increased in relation to infant length (P<0.001). RV/TLC, FRC/TLC, and FEF(25-75)/FVC declined in relation to increasing length (P<0.001). The forced expiratory flow and fractional lung volume measurements using this method were similar to previously reported estimates using other methods. These estimates represent a reasonable reference standard for infants and young children with respiratory problems.

Anesthesia, General↗

PubMed2000

Tidal breath analysis for infant pulmonary function testing. ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. European Respiratory Society/American Thoracic Society.

The aim of this position paper is to provide recommendations pertaining to software and equipment requirements when analysing tidal breathing measurements in infants. These guidelines cover numerous aspects including terminology and definitions, equipment, data acquisition and analysis, and reporting of results, and highlight areas in which further research is needed before consensus can be reached. When collecting tidal breathing data in infants and children, equipment dead space and resistance must be minimized, all sources of leak eliminated, and a flowmeter with appropriate frequency response and linearity employed. Inspired gases should be corrected to body temperature, barometric pressure and saturated with water vapour conditions and efforts made to eliminate the various sources of drift in volume that can occur. In addition, the analogue-to-digital converter used to sample data must be capable of adequately resolving the highest and lowest flows required by the study. An adequate sampling rate must be used; 50-100 Hz may be sufficient for the determination of timing and volume parameters, especially in older infants, but rates of 200 Hz are recommended for analysis of the tidal breathing flow/volume loop and other sensitive parameters such as time to peak tidal expiratory flow/expiratory time. The potentially most troublesome aspect of tidal breath analysis from the computational point of view is the identification of the beginning and end of inspiration and expiration. Once methods and equipment for the measurement and analysis of tidal breathing in infants have been standardized, there is an urgent need to establish appropriate reference ranges for various key parameters so that they may be used more effectively in the clinical setting. Implementation of these recommendations should help to ensure that such measurements are as accurate as possible and that more meaningful comparisons can be made between data collected in different centres or with different equipment.

Child↗

PubMed2000

Forced expiratory flows and volumes in infants. Normative data and lung growth.

Forced expiratory flows (FEF) can be measured in infants from lung volumes initiated near total lung capacity. In order to establish reference values and to evaluate lung growth, we obtained measurements in 155 healthy subjects between 3 and 149 wk of age. Forced vital capacity (FVC) was highly correlated with body length; however, after accounting for length, age was also significant. When subjects were divided at the median age (40 wk) younger compared with older subjects had a significantly larger slope for length (3.7 versus 2.8; p = 0.002). The flow parameters (FEF(50), FEF(75), FEF(85), and FEF(25-75)) were highly correlated with length, and those infants whose mothers smoked had lower flows. For FEF(75), male subjects had lower flows than female subjects. The relationship between FEF and volume was assessed using FEV(0.5)/FVC, which decreased with increasing length. Smaller subjects emptied their lung volume proportionately faster. We conclude that our study provides reference values for this age group and demonstrates that smoke-exposed infants and male subjects have decreased FEF. In addition, our findings indicate that lung volume increases most rapidly during the first year of life and that airways are large relative to lung volume very early in life.

Anthropometry↗

PubMed1996

Flow limitation in normal infants: a new method for forced expiratory maneuvers from raised lung volumes.

Forced expiratory maneuvers generated by rapid thoracic compression have been used to assess airway function in infants. It remains unclear whether flow limitation can be achieved in healthy infants because low pressure transmission across the chest wall and inspiratory effort may limit the maximum transpulmonary pressure developed during the maneuver. We have found that several rapid inflations to a lung volume set at an airway pressure of 30 cmH2O (V80) briefly inhibit respiratory effort and allow forced expiration to proceed from V80 to residual volume. We used a water-filled esophageal catheter to measure isovolume pressure-flow curves in seven healthy infants (3-88 mo). Forced vital capacity (FVC) was defined as the volume between V80 and residual volume. Pressure transmission between the compression jacket and the esophagus decreased with decreasing lung volume and averaged 60 and 37% at 50 and 75% of expired FVC, respectively. Subjects demonstrated plateaus in their isovolume pressure-flow curves at 50% of expired FVC and lower lung volumes. We conclude that this new methodology enables forced expiratory maneuvers to achieve flow limitation in healthy infants over at least the lower portion of their lung volume.

Child Development↗