OBJECTIVEBody plethysmography is a typical method to measure functional residual capacity (FRC) and airway resistance (Raw). The aim of the study was to test the feasibility of measuring lung function with the body plethysmography in young children with acute lower respiratory tract infection (ALRI) by evaluating changes and prognosis of lung function for infants with ALRI with or without wheezing via body plethysmograph.

METHODPulmonary function tests (PFTs) were performed by using body plethysmography in 444 children with ALRI, aged 1-36 months, to assess their tidal breathing parameters such as ratio of time to peak tidal expiratory flow to total expiratory time (TPTEF/TE), ratio of volume to peak tidal expiratory flow to total expiratory volume (VPTEF/VE), plethysmographic functional residual capacity (FRCP), FRCP per kilogram (FRCP/kg), specific effective airway resistance (sReff), effective airway resistance (Reff), Reff per kilogram (Reff/kg), etc. According to whether there was wheezing or not, children who had ALRI with wheezing were classified as Group-W, or without wheezing as Group-N. Changes or correlations of tidal breathing parameters and plethysmographic parameters were compared.One hundred and three contemporaneous healthy controls aged 1-36 months underwent the same tests for comparison. And 36 wheezing children accepted PFTs at follow-up in recovery phase.

RESULTMean values of TPTEF/TE in Group-W,Group-N and the Control respectively were (20.5 ± 6.7)%,(22.8 ± 6.5)%,(34.6 ± 5.0)% (F = 110.500, P < 0.001), while VPTEF/VE respectively were (23.0 ± 6.3)%,(25.2 ± 6.8)%,(34.5 ± 4.2)% (F = 107.800, P < 0.001). Compared to the Control,Group-W and Group-N had significantly higher values of FRCP (226 vs. 176 vs. 172 ml, χ(2) = 64.870, P < 0.001), FRCP/kg(24.40 vs.17.80 vs.17.60 ml/kg,χ(2) = 68.890, P < 0.001), sReff(1.00 vs. 0.52 vs. 0.46 kPa·s,χ(2) = 75.240, P < 0.001), Reff (3.90 vs.2.74 vs.2.20 kPa·s/L, χ(2) = 36.480, P < 0.001) and Reff/kg [0.42 vs. 0.29 vs.0.22 kPa·s/(L·kg), χ(2) = 29.460, P < 0.001]. Although 25 (12.8%) wheezing children with ALRI had normal values of tidal breathing parameters, they already had increased FRCP, FRCP /kg, sReff, Reff and Reff/kg (t = 2.221, 1.997, 2.502, 2.587, 2.539, all P < 0.05). Values of FRCP and Reff in infants caught ALRI were inversely correlated to that of TPTEF/TE and VPTEF/VE (P < 0.05); 36 children with wheezing who accepted PFTs at follow-up had shown significant decline in the specific parameters of plethysmography such as FRCP, FRCP/kg, sReff, Reff and Reff/kg (Z = -1.999, -2.195, -2.038, -1.823, -2.054, all P < 0.05), while no improvement in the main parameters of tidal breathing such as TPTEF/TE.

CONCLUSIONMeasuring lung function with the body plethysmography in young children with ALRI is feasible. FRC and Raw, as special lung function testing parameters of body plethysmography, were sensitive indicators reflecting impairment of lung function in infants with ALRI (especially for children caught ALRI with wheezing) and shows significant correlation with parameters from lung function testing via tidal breathing. Therefore plethysmography is worthy of clinical promotion.

Airway Resistance ; physiology ; Case-Control Studies ; Child, Preschool ; Female ; Functional Residual Capacity ; physiology ; Humans ; Infant ; Lung ; physiopathology ; Male ; Plethysmography, Whole Body ; Respiratory Function Tests ; Respiratory Sounds ; diagnosis ; physiopathology ; Respiratory Tract Diseases ; diagnosis ; physiopathology ; Tidal Volume

BACKGROUNDThe respiratory system changes with age and a better understanding of the changes contribute to detect and prevent respiratory dysfunctions in old population. The purpose of this study was to observe age-associated changes of pulmonary function parameters in healthy young adults and the elderly.

METHODSA cross-sectional study was conducted among 600 male and female subjects aged 19 to 92 years. The subjects were divided into three groups by age: young adult (19 - 39 years), middle-aged adult (40 - 59 years), and the elderly (≥ 60 years). The pulmonary function was measured with routine examination methods and 13 parameters including vital capacity (VC), residual volume (RV), functional residual capacity (FRC), total lung capacity (TLC), RV/TLC, forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), FEV(1)/FVC, peak expiratory flow (PEF), forced expiratory flow at 25% of FVC exhaled (FEF(25)), forced expiratory flow at 50% of FVC exhaled (FEF(50)), diffusion capacity of the lung for carbon monoxide (D(L)CO), and specific diffusion capacity of CO (KCO) were collected and analyzed. Changes in pulmonary function parameters among the pre-elderly and elderly subjects, especially the aging influence on FEV(1)/FVC and RV were studied further.

RESULTSTen pulmonary function parameters including VC, FVC, FEV(1), FEV(1)/FVC, PEF, FEF(25), FEF(50), TLC, D(L)CO and KCO decreased significantly with age in both male and female subjects (P < 0.01). RV and RV/TLC were increased with age (P < 0.01). FRC remained stable during aging. Except FRC, the linear relationship was significant between age and other pulmonary function parameters. In the pre-elderly and elderly subjects, RV had a non-significantly increasing tendency with age (P > 0.05), and FEV(1)/FVC did not change significantly with age (P > 0.05).

CONCLUSIONTotal pulmonary function was declined with advancing age, but FRC was stable, and the increasing tendency of RV and decreasing tendency of FEV(1)/FVC obviously slowed down in the pre-elderly and elderly subjects.

Adult ; Age Factors ; Aged ; Aged, 80 and over ; Aging ; physiology ; Cross-Sectional Studies ; Female ; Forced Expiratory Volume ; Functional Residual Capacity ; Humans ; Lung ; physiology ; Male ; Middle Aged ; Vital Capacity ; Young Adult

The prognostic role of resting pulmonary hyperinflation as measured by residual volume (RV)/total lung capacity (TLC) in chronic obstructive pulmonary disease (COPD) remains poorly understood. Therefore, this study aimed to identify the factors related to resting pulmonary hyperinflation in COPD and to determine whether resting pulmonary hyperinflation is a prognostic factor in COPD. In total, 353 patients with COPD in the Korean Obstructive Lung Disease cohort recruited from 16 hospitals were enrolled. Resting pulmonary hyperinflation was defined as RV/TLC > or = 40%. Multivariate logistic regression analysis demonstrated that older age (P = 0.001), lower forced expiratory volume in 1 second (FEV1) (P < 0.001), higher St. George Respiratory Questionnaire (SGRQ) score (P = 0.019), and higher emphysema index (P = 0.010) were associated independently with resting hyperinflation. Multivariate Cox regression model that included age, gender, dyspnea scale, SGRQ, RV/TLC, and 6-min walking distance revealed that an older age (HR = 1.07, P = 0.027), a higher RV/TLC (HR = 1.04, P = 0.025), and a shorter 6-min walking distance (HR = 0.99, P < 0.001) were independent predictors of all-cause mortality. Our data showed that older age, higher emphysema index, higher SGRQ score, and lower FEV1 were associated independently with resting pulmonary hyperinflation in COPD. RV/TLC is an independent risk factor for all-cause mortality in COPD.
Aged ; Dyspnea/diagnosis/physiopathology ; Exercise Test ; Exercise Tolerance ; Female ; Forced Expiratory Flow Rates/physiology ; Forced Expiratory Volume ; Humans ; Lung/*physiopathology ; Male ; Middle Aged ; Prognosis ; Pulmonary Disease, Chronic Obstructive/*diagnosis/mortality/physiopathology ; Pulmonary Emphysema/*diagnosis/mortality/physiopathology ; Republic of Korea ; Residual Volume/*physiology ; Respiratory Function Tests ; Surveys and Questionnaires ; Total Lung Capacity/*physiology ; Vital Capacity ; Walking/physiology