Modeling And Evaluation Of Reference Equations For Lung Function Of Infants And Young Children In Southwest China

PART 1PREDICTIVE MODELING AND EVALUATION OF REFERENCE EQUATIONS FOR LUNG FUNCTION IN TIDAL BREATHING MEASUREMENT OF INFANTS AND YOUNG CHILDRENObjective: To develop reference equations for tidal breathing parameters for Chinese infants during the first 3 years of life.Methods: Pulmonary function tests were measured in 166 infants using the Jaeger BabyBody system with standardized protocols.Tidal breathing measurement includes 12 paramaters such as tidal breathing parameters(respiratory rate,tidal volume,peak expiratory flow,tidal expiratory flow when 75% of tidal volume remains in the lung,tidal expiratory flow when 50% of tidal volume remains in the lung,tidal expiratory flow when 25% of tidal volume remains in the lung)and descriptive parameters of tidal breathing flow-volume loop(TBFVL)including: time to peak tidal expiratory flow as a percentage of expiratory time,volume until peak expiratory flow to expiratory volume,tidal expiratory flow when 25% of tidal volume remains in the lung as a ratio of peak tidal expiratory flow,peak tidal expiratory flow to tidal volume,tidal expiratory flow when 50% of tidal volume remains in the lung to tidal inspiratory flow when 50% of tidal volume remains in the lung,ratio of inspiratory time to expiratory time.All statistical analyses were performed using SPSS Statistics version 18.0.Association between each outcome and likely explanatory continuous variables(body length,weight,age,head circumference,birth weight,gestational age and age of the mother when pregnant)were quantified using Pearson correlations.Independent-samples t test was used to analysis the association between lung function results and various dichotomous variables including gender,ethnicity,postnatal tobacco smoke exposure,parental atopic disease,Caesarean section and living address.Reference equations adjusted for body size,age and gender were built using stepwise regression model.Additionally,raw data were also used to build new predictive equations in the form of various published lung function predictive models.Comparison between our estimates and those published reference equations was done via relative prediction error(RPE%),which was defined as RPE%=Σ(absolute value(predicted value-observed value)*100/ predicted value%)/n.Results: The following equations describe our tidal breathing results in relation to body size,age and gender: VT=20.80+0.34×A+4.38×W+4.91×S;RR=30.30-0.06×A;PTEF/VT=130.72-0.27×A-8.98×S;PEF=25.62+6.88×W;TEF75=20.33+6.99×W;TEF50=23.07+6.39×W;TEF25=0.07+2.57×W+0.55×L.Comparison between various predictive equations show that the current equations derived from our raw data is applicable to our population.Conclusion: The current equations are applicable in Southwest China to infants and young children up to 3 years old,using the same commercially available equipment.Various tidal breathing parameters are linear related to age and/or weight.PART 2 PREDICTIVE MODELING AND EVALUATION FOR PLETHYSMOGRAPHIC MEASUREMENTS OF FUNCTIONAL RESIDUAL CAPACITY IN INFANTS AND YOUNG CHILDRENObjective: To develop reference equations for plethysmographic function residual capacity(FRCp)in Chinese infants and young children during the first 2.5 years of life.Methods: FRCp were measured using the Jaeger Baby Body system with standardized protocols.73 Chinese infants(age: 11.61-125.13w)were recruited from plastic surgical department and urology surgical department of pediatrics at Children’s Hospital of Chongqing Medical University.Reference equation of FRCp was built using multiple regression model.Comparison of application among various foreign equations in our data was assessed.Results: Reference equations adjusted for age and sex were built,shown as FRCp=91.37+1.29*A+22.03*S;the Comparison results suggested that our predictive equation as well as the equation reported by Nguyen TT are applicable to our subjects.Conclusion: The current equation in our study and equation reported by Nguyen TT are applicable in Southwest China to children up to 2.5 years old,using the same commercially available equipment.