Is forced oscillation technique the next respiratory function test of choice in childhood asthma

Respiratory diseases, especially asthma, are common in children. While spirometry contributes to asthma diagnosis and management in older children, it has a limited role in younger children whom are often unable to perform forced expiratory manoeuvre. The development of novel diagnostic methods which require minimal effort, such as forced oscillation technique(FOT) is, therefore, a welcome and promising addition. FOT involves applying external, small amplitude oscillations to the respiratory system during tidal breathing. Therefore, it requires minimal effort and cooperation. The FOT has the potential to facilitate asthma diagnosis and management in preschool children by faciliting the objective measurement of baseline lung function and airway reactivity in children unable to successfully perform spirometry. Traditionally the use of FOT was limited to specialised centres. However, the availability of commercial equipment resulted in its use both in research and in clinical practice. In this article, we review the available literature on the use of FOT in childhood asthma. The technical aspects of FOT are described followed by a discussion of its practical aspects in the clinical field including the measurement of baseline lung function and associated reference ranges, bronchodilator responsiveness and bronchial hyperresponsiveness. We also highlight the difficulties and limitations that might be encountered and future research directions.

Comparison of airway resistance measurements by the forced oscillation technique and the interrupter technique for detecting chronic obstructive pulmonary disease in elderly patients

Rulmonary function tests provide an objective means to verify ventilatory dysfunction and to estimate its severity in respiratory disorders. Measurement of forced expiratory volume in 1 second （FEV1） and forced vital capacity （FVC） is considered to be the basic tests for the assessment of airway obstruction. Although they are useful diagnostically and prognostically, the results of FEV1 and FVC are strongly dependent on the cooperation of the patient. Lack of collaboration is particularly present in elderly patients because of mood alterations, fatigability or cognitive impairment. The forced oscillation technique （FOT） and the interrupter resistance technique are the two methods of measuring respiratory resistance during tidal breathing, they are of special interest because both of them are noninvasive, requires minimal cooperation, takes little time and can be easily repeated, especially in children and elderly subjects who cannot accomplish forced expiratory maneuvers in a reproducible manner.

Isothermal coarsening of primary particles during rheocasting

The isothermal coarsening behavior of primary solid particles in A356 aluminum alloy semi-solid slurry produced by angular oscillation (AO) technique was investigated.The comparison between the calculation and experimental results shows good quantitative agreement with Lifshitz-Slyozov-Wagner theory.The results show that the variation in shape factor and solid fraction is not significant,the average particle size increases with increasing holding time at the expense of the particle density.Ostwald repining is most likely the predominant growth mechanism in the AO-treated semi-solid slurry during rheocasting.The differences of coarsening occurred in rheocasting and partial re-melting process were also discussed.

Validity and reliability of three methods of stiffness assessment

Background：Stiffness is commonly assessed in relation to injury and athletic performance.The purpose of this research was to compare the validity and reliability of 3 in vivo methods of stiffness assessment using 1 cohort of participants.Methods：To determine inter-day reliability,15 female netballers were assessed for stiffness twice within 1 week using unilateral hopping（vertical stiffness）,free oscillations of the calf,and myometry of various muscles of the triceps surae.To establish convergent construct validity,stiffness was compared to static and dynamic strength measurements.Results：Test–retest stiffness results revealed that vertical stiffness produced moderate to high reliability results and myometry presented moderate to very high reliability.In contrast,the free oscillation technique displayed low to moderate reliability.Vertical stiffness demonstrated a significa t correlation with rate of force development during a squat jump,whilst myometer stiffness measurements from 3 sites in the lower limb revealed significan correlations with isometric rate of force development.Further,significan negative correlations were evident between the eccentric utilisation ratio and various myometer stiffness results.No relationships were established between the free oscillation technique and any of the performance measurements.Conclusion：These results suggest that vertical stiffness and myometry are valid and reliable methods for assessing stiffness.