Limits...
Relationships between specific airway resistance and forced expiratory flows in asthmatic children.

Mahut B, Trinquart L, Bokov P, Le Bourgeois M, Waernessyckle S, Peiffer C, Delclaux C - PLoS ONE (2009)

Bottom Line: The earliest changes associated with airflow obstruction in asthmatic children are a proportionally greater reduction in FEF(50%) than in FEV(1) using spirometry, and an increase in specific airway resistance (sRaw) using body plethysmography.These results were further explained by a simple one-compartment lung model, which justified the shape of the observed relationships.Specific Raw is more strongly related to FEF(50%) than to FEV(1) and could be used in preschool children to predict subsequent mild airflow limitation.

View Article: PubMed Central - PubMed

Affiliation: Cabinet La Berma, Antony, France.

ABSTRACT

Background: The earliest changes associated with airflow obstruction in asthmatic children are a proportionally greater reduction in FEF(50%) than in FEV(1) using spirometry, and an increase in specific airway resistance (sRaw) using body plethysmography. Consequently, we hypothesized that sRaw could be better linked to FEF(50%) than to FEV(1). The first aim was to assess the relationships between forced expiratory flows and sRaw in a large group of asthmatic children in a transversal study. We then performed a longitudinal study in order to determine whether sRaw of preschool children could predict subsequent impairment of forced expiratory flows at school age.

Methodology: Pulmonary function tests (sRaw and forced expiratory flows) of 2193 asthmatic children were selected for a transversal analysis, while 365 children were retrospectively selected for longitudinal assessment from preschool to school age.

Principal findings: The transversal data showed that sRaw is differently related to FEF(50%) (-1/sRaw) and to FEV(1) (near linearly). These results were further explained by a simple one-compartment lung model, which justified the shape of the observed relationships. As hypothesized, sRaw correlated more strongly to FEF(50%) than to FEV(1) (r = -0.64 versus -0.39, respectively; p<0.001). In the longitudinal part of the study, sRaw at preschool age correlated with subsequent FEF(50%) (% predicted) (-0.31, 95% CI, -0.40 to -0.22), but weakly with subsequent FEV(1) (% predicted) (-0.09, 95% CI, -0.20 to 0).

Conclusion: Specific Raw is more strongly related to FEF(50%) than to FEV(1) and could be used in preschool children to predict subsequent mild airflow limitation.

Show MeSH

Related in: MedlinePlus

Relationships between sRaw and forced expiratory flows: observed data and non-linear regression modelling.Non-linear regression modelling showed that the curves based on our model equations (1') and (2') (see equations in the Methods) fitted well the scatter plots sRaw0.5 for both FEV1 (upper panel) and FEF50% (lower panel), respectively.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2667212&req=5

pone-0005270-g001: Relationships between sRaw and forced expiratory flows: observed data and non-linear regression modelling.Non-linear regression modelling showed that the curves based on our model equations (1') and (2') (see equations in the Methods) fitted well the scatter plots sRaw0.5 for both FEV1 (upper panel) and FEF50% (lower panel), respectively.

Mentions: Non-linear regression modelling showed that the curves based on our model equations (1') and (2') fitted the scatter plots, despite the wide range of expiratory flows for a given sRaw0.5 (Figure 1). The mathematical function relating sRaw0.5 to FEF50% was different from that relating sRaw0.5 to FEV1 (1/R and near linear, respectively). As shown in Figure 1 and 2, there was a large scatter of FEF50% and FEV1 values for each given value of sRaw0.5. However, the latter was similar over the whole range of sRaw0.5 values and the mathematical relationships equally fitted the subgroups of centiles when analysed separately (Figure 2). These results were confirmed when analysing LFTs from both centers separately.


Relationships between specific airway resistance and forced expiratory flows in asthmatic children.

Mahut B, Trinquart L, Bokov P, Le Bourgeois M, Waernessyckle S, Peiffer C, Delclaux C - PLoS ONE (2009)

Relationships between sRaw and forced expiratory flows: observed data and non-linear regression modelling.Non-linear regression modelling showed that the curves based on our model equations (1') and (2') (see equations in the Methods) fitted well the scatter plots sRaw0.5 for both FEV1 (upper panel) and FEF50% (lower panel), respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2667212&req=5

pone-0005270-g001: Relationships between sRaw and forced expiratory flows: observed data and non-linear regression modelling.Non-linear regression modelling showed that the curves based on our model equations (1') and (2') (see equations in the Methods) fitted well the scatter plots sRaw0.5 for both FEV1 (upper panel) and FEF50% (lower panel), respectively.
Mentions: Non-linear regression modelling showed that the curves based on our model equations (1') and (2') fitted the scatter plots, despite the wide range of expiratory flows for a given sRaw0.5 (Figure 1). The mathematical function relating sRaw0.5 to FEF50% was different from that relating sRaw0.5 to FEV1 (1/R and near linear, respectively). As shown in Figure 1 and 2, there was a large scatter of FEF50% and FEV1 values for each given value of sRaw0.5. However, the latter was similar over the whole range of sRaw0.5 values and the mathematical relationships equally fitted the subgroups of centiles when analysed separately (Figure 2). These results were confirmed when analysing LFTs from both centers separately.

Bottom Line: The earliest changes associated with airflow obstruction in asthmatic children are a proportionally greater reduction in FEF(50%) than in FEV(1) using spirometry, and an increase in specific airway resistance (sRaw) using body plethysmography.These results were further explained by a simple one-compartment lung model, which justified the shape of the observed relationships.Specific Raw is more strongly related to FEF(50%) than to FEV(1) and could be used in preschool children to predict subsequent mild airflow limitation.

View Article: PubMed Central - PubMed

Affiliation: Cabinet La Berma, Antony, France.

ABSTRACT

Background: The earliest changes associated with airflow obstruction in asthmatic children are a proportionally greater reduction in FEF(50%) than in FEV(1) using spirometry, and an increase in specific airway resistance (sRaw) using body plethysmography. Consequently, we hypothesized that sRaw could be better linked to FEF(50%) than to FEV(1). The first aim was to assess the relationships between forced expiratory flows and sRaw in a large group of asthmatic children in a transversal study. We then performed a longitudinal study in order to determine whether sRaw of preschool children could predict subsequent impairment of forced expiratory flows at school age.

Methodology: Pulmonary function tests (sRaw and forced expiratory flows) of 2193 asthmatic children were selected for a transversal analysis, while 365 children were retrospectively selected for longitudinal assessment from preschool to school age.

Principal findings: The transversal data showed that sRaw is differently related to FEF(50%) (-1/sRaw) and to FEV(1) (near linearly). These results were further explained by a simple one-compartment lung model, which justified the shape of the observed relationships. As hypothesized, sRaw correlated more strongly to FEF(50%) than to FEV(1) (r = -0.64 versus -0.39, respectively; p<0.001). In the longitudinal part of the study, sRaw at preschool age correlated with subsequent FEF(50%) (% predicted) (-0.31, 95% CI, -0.40 to -0.22), but weakly with subsequent FEV(1) (% predicted) (-0.09, 95% CI, -0.20 to 0).

Conclusion: Specific Raw is more strongly related to FEF(50%) than to FEV(1) and could be used in preschool children to predict subsequent mild airflow limitation.

Show MeSH
Related in: MedlinePlus