Raised-Volume Forced Expiratory Flow-Volume Curve in Healthy Taiwanese Infants

Distinct lung function and bronchodilator responses between term and preterm young children with recurrent wheezing

BACKGROUND

Recurrent or unresolved wheezing is a common complaint in certain young children populations, especially those born preterm. Using infant lung function testing, we aimed to distinguish the differences between term and preterm young children with recurrent wheezing.

METHODS

Children under 2 years of corrected age were enrolled if they had 3 or more wheezing episodes during the enrollment period. Healthy term controls of comparable age were also recruited for reference. Measurements of lung function were made, including tidal breathing, passive respiratory mechanics, and forced tidal and raised-volume expiration. For children with recurrent wheezing, raised-volume forced expiration was repeated after an adequate delivery of bronchodilator nebulization was achieved.

RESULTS

In total, 68 young children (40 with recurrent wheezing and 28 healthy controls) were recruited. Among children with recurrent wheezing, 23 preterm children (preterm group), and 17 term children (term group) were enrolled. Compared with healthy controls, both the term and preterm groups had lower lung function as measured by absolute values and z scores. The term group performed worse than the preterm group with regard to forced vital capacity, forced expiratory volume at 0.5 s (FEV_0.5), and peak expiratory flow. Following bronchodilator nebulization, the term group had significantly higher increases in FEV_0.5 and forced mid-expiratory flow than the preterm group.

CONCLUSION

Young children with recurrent wheezing, especially term infants, demonstrated lower lung function than healthy controls. Moreover, the term group evidenced greater responsiveness to bronchodilators than the preterm group. The distinct bronchodilator responses may offer further information to guide the diagnosis and treatment of young children with recurrent wheezing.

Evolution and Determinants of Lung Function until Late Infancy among Infants Born Preterm

To investigate the evolution of lung function in preterm infants with and without bronchopulmonary dysplasia (BPD) and to determine the perinatal characteristics associated with indexes of lung function in later infancy. Longitudinal lung function assessments were performed at approximately 6, 12, 18, and 24 months of corrected age in preterm infants. Perinatal characteristics were further analyzed to ascertain the determinants of lung function indexes. Although all preterm infants (n = 121; 61 without BPD and 60 with BPD) exhibited decreased lung function in early infancy (6 months of age), after body length was adjusted for, only infants with BPD exhibited poor performance. Furthermore, the lung function of infants with mild to moderate BPD caught up gradually, but the generally poor lung function performance of infants with severe BPD, especially in forced expiratory flow, persisted until later age (24 months). Regarding perinatal characteristics, the z-score of body length at the time of examination and total number of days on positive-pressure ventilation are the major determinants of lung function in later infancy.

Forced expiratory flows and volumes in a Swedish cohort of healthy term infants

BACKGROUND

The use of pulmonary function tests (PFTs) in infants has increased during the last decades, making the need for equipment- and ethnic-specific reference data mandatory for appropriate interpretation of the results.

AIM

Our aim was to investigate how well the already published reference equations for infant spirometry fit a healthy population of Swedish infants.

METHOD

We performed forced tidal and raised volume expiratory maneuvers in healthy infants using Jaeger BabyBody equipment.

RESULTS

PFT data were collected from 91 healthy infants aged between 3 months to 2 years at 143 occasions. Mean (standard deviation) z-scores were 0.68(1.33) for maximal flow at functional residual capacity (V'_max FRC), -0.15(0.96) for forced vital capacity (FVC), 0.40(1.33) for the forced expired volume in the initial 0.5 seconds (FEV_0.5 ) and 0.52(0.93) for the ratio FEV_0.5 /FVC, respectively. Z-scores for all indices but FEV_0.5 /FVC were highly dependent on length.

CONCLUSIONS

We have shown that the use of previously published reference equations may result in an age-related misinterpretation of lung function measure in a Swedish infant population.

Nebulized step-down budesonide vs. fluticasone in infantile asthma: A retrospective cohort study

The United States Food and Drug Administration has approved budesonide in infantile asthma but nebulization of infants under budesonide has the risk of relapse of asthma. The objective of the present study was to compare the effectiveness and safety of fluticasone step-down treatment with budesonide step-down treatment in infantile asthma. The data of 778 infants with confirmed asthma were included in the analysis. Infants who had received nebulized 500 µg budesonide twice daily for 6 weeks followed by 250 µg budesonide twice daily for 6 weeks were included in the BS group (n=389), while infants who had received nebulized 250 µg fluticasone twice daily for 6 weeks followed by 125 µg fluticasone twice daily for 6 weeks were included in the FC group (n=389). The data of lung function tests and a safety study were collected and analyzed. Budesonide treatment achieved a reduced specific airway resistance (sRaw; 1.28±0.11 vs. 1.21±0.10 kPa/sec; P<0.0001, q=13.45) and improved forced expiratory volume in 1 sec (FEV1; 0.977±0.068 vs. 0.997±0.085 l/sec; P<0.0001, q=5.54). In addition, fluticasone treatment achieved a reduced sRaw (1.27±0.1 vs. 1.23±0.11 kPa/sec, P<0.0001, q=7.39) and improved FEV1 (0.971±0.069 vs. 0.992±0.085 l/sec; P=0.0003, q=5.46). Of note, the efficacy of budesonide to reduce sRaw (P=0.008, q=3.69) and improve FEV1 (P<0.0001, q=6.93) was greater than that of fluticasone. The budesonide treatment group had more post-treatment symptom-free days than the fluticasone treatment group (165.56±23.15 vs. 112.21±9.45 days; P<0.0001). The step-down approach of budesonide nebulization may better support the functional and clinical outcomes with an increased number of post-treatment symptom-free days compared with fluticasone in infantile asthma (level of evidence, 3).