Table 1.
Anthropometric data of the study infants.
Table 2.
Clinical data of preterm infants.
Figure 1.
Box plots of the respective lung function values by subject groups.
Subjects were grouped according to post-conceptional age at birth (term-born and preterm) and according to disease state based on ATS definition of BPD (healthy preterm, mild, moderate and severe BPD) [6]. The boxes indicate the median and the 25th and 75th percentile, the whiskers the upper and lower adjacent values. Outside values are shown as separate dots. Box plots are shown for FRC at airway opening per weight in mL/kg.
Table 3.
Comparison of lung function parameters between groups.
Figure 2.
Box plots of the respective lung function values by subject groups.
Subjects were grouped according to post-conceptional age at birth (term-born and preterm) and according to disease state based on ATS definition of BPD (healthy preterm, mild, moderate and severe BPD) [6]. The boxes indicate the median and the 25th and 75th percentile, the whiskers the upper and lower adjacent values. Outside values are shown as separate dots. Box plots are shown for lung clearance index (LCI).
Figure 3.
Box plots of the respective lung function values by subject groups.
Subjects were grouped according to post-conceptional age at birth (term-born and preterm) and according to disease state based on ATS definition of BPD (healthy preterm, mild, moderate and severe BPD) [6]. The boxes indicate the median and the 25th and 75th percentile, the whiskers the upper and lower adjacent values. Outside values are shown as separate dots. Box plots are shown for tPTEF/tE. The p-value for trend obtained by regression analysis was <0.001.
Figure 4.
Receiver-operator characteristic (ROC) curves comparing tPTEF/tE (dark gray symbols with black outline), respiratory rate (black symbols), FRC per weight (light gray symbols without outline) and LCI (white symbols) between groups.
a) ROC curve comparing the ability of above mentioned lung function parameters to discriminate between healthy infants (term-born and preterm) and BPD infants using data of 221 healthy and 103 preterm infants. The resulting area under the curve is 0.58 for FRCao, 0.52 for LCI, 0.67 for respiratory rate and 0.76 for tPTEF/tE. b) ROC curve comparing the ability of above mentioned lung function parameters to discriminate between 179 term-born and 43 preterm healthy infants; BPD infants were not considered for this analysis. The resulting area under the curve is 0.43 for FRCao, 0.50 for LCI, 0.60 for respiratory rate and 0.64 for tPTEF/tE.
Table 4.
Association of clinical variables and lung function parameters in 185 preterm infants.
Figure 5.
a) Tidal volume versus weight for term and preterm infants. The black line indicates the regression line with a coefficient of correlation of 0.31 for the term-born infants and a coefficient of correlation of 0.65 for the preterm infants and the respective R2 values given in the figure. b) Variability in lung volume determined by weight depending on disease severity. The graph shows 1−R2 value of the regression model between weight and FRC. The R2 value indicates how much of the variability in lung volume can be explained by the weight, and thus the 1−R2 is a measure of how much infants are able to change their lung volumes given their body size.