Lung function in teenage Bangladeshi boys and girls

Association between different indexations of extravascular lung water (EVLW) and PaO2/FiO2: a two-center study in 231 patients

Background

Variability of body weight (BW) and height calls for indexation of volumetric hemodynamic parameters. Extravascular lung water (EVLW) has formerly been indexed to actual BW (BW_act) termed EVLW-index (EVLWI). In overweight patients indexation to BW_act might inappropriately lower indexed EVLWI_act. Several studies suggest indexation of EVLWI to predicted BW (EVLWI_pred). However, data regarding association of EVLWI_act and EVLW_pred to mortality and PaO₂/FiO₂ are inconsistent. Two recent studies based on biometric database-analyses suggest indexation of EVLWI to height (EVLWI_height). Therefore, our study compared the association of un-indexed EVLW, EVLWI_height, EVLW_pred and EVLWI_act to PaO₂/FiO₂ and Oxygenation index (OI = mean airway pressure*FiO₂*/PaO₂).

Methods

A total of 2119 triplicate transpulmonary thermodilutions (TPTDs; PiCCO; Pulsion Medical-Systems, Germany) were performed in 50 patients from the evaluation, and 181 patients from the validation groups. Correlations of EVLW and EVLWI to PaO₂/FiO₂, OI and ROC-AUC-analyses regarding PaO₂/FiO₂<200 mmHg (primary endpoint) and OI>10 were performed.

Results

In the evaluation group, un-indexed EVLW (AUC 0.758; 95%-CI: 0.637-0.880) and EVLWI_height (AUC 0.746; 95%-CI: 0.622-0.869) provided the largest ROC-AUCs regarding PaO₂/FiO₂<200 mmHg. The AUC for EVLWI_pred was smaller (0.713). EVLWI_act provided the smallest AUC (0.685). This was confirmed in the validation group: EVLWI_height provided the largest AUC (0.735), EVLWI_act (0.710) the smallest. In the merged data-pool, AUC was significantly greater for EVLWI_height (0.729; 95%-CI: 0.674–0.784) compared to all other indexations including EVLWI_act (ROC-AUC 0.683, p = 0.007) and EVLWI_pred (ROC-AUC 0.707, p = 0.015). The association of EVLW(I) was even stronger to OI compared to PaO₂/FiO₂. In the merged data-pool, EVLWI_height provided the largest AUC regarding “OI>10” (0.778; 95%-CI: 0.713–0.842) compared to 0.739 (95%-CI: 0.669–0.810) for EVLWI_act and 0.756 (95%-CI: 0.688–0.824) for EVLWI_pred.

Conclusions

Indexation of EVLW to height (EVLWI_height) improves the association of EVLW(I) to PaO₂/FiO₂ and OI compared to all other indexations including EVLWI_pred and EVLWI_act. Also considering two recent biometric database analyses, EVLWI should be indexed to height.

Spirometric reference values in Estonian schoolchildren

This study was conducted to describe the relationship between anthropometric parameters and lung function in Estonian children, to determine the reference values for spirometry, and to compare these results with other data sets. The results are based on 1170 healthy non-smoking children (643 girls and 527 boys), aged 6-18 years. The spiroanalyser Pneumoscreen II (Jaeger) was used to register dynamic lung parameters. Natural logarithmic values of lung volumes, standing or sitting height and age were used in the final regression model. Prediction equations for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow, forced expiratory flows when 50 and 75% of FVC has been exhaled, and mean forced expiratory flow over the middle 50% of the FVC for both sexes are presented. In comparison with recent data from European children the reference values were close for FVC, the differences were bigger for FEV1 and forced expiratory flows, especially in taller children.

Ventilatory function of healthy, urban, non smoking, Pakistani young adults aged 18-24 years

Age may have a different contribution to normal lung function values in those aged less than 25 years, as compared to older individuals. We report regression equations predicting ventilatory parameters in this age group, as none have been reported from Pakistan. The study was conducted on students of King Edward Medical College Lahore, Pakistan. Participants had never smoked and reported no respiratory symptoms. In addition to anthropometric data, forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and forced expiratory flow at 50% of FVC (FEF50) were measured. Equations predicting normal values of these parameters were derived using SPSS (Chicago, Illinois, U.S.A.) P < or = 0.05 was treated as statistically significant. Of the students, 519 took part in the study. All four parameters correlated significantly (P < 0.001) and positively with height. FEF50 had a negative correlation with age in both sexes (P < 0.05). The correlation of other parameters with age was variable and not statistically significant. On multiple regression, height featured as an independent predictor in equations for all parameters. The contribution of age as an independent predictor of ventilatory function was, once again, variable. Independent variables were retained in the raw form as their transformation did not improve the goodness of fit of the derived equations. Only height and age emerged as independent predictors of ventilatory function. Values derived from the equations presented in this study were less than those for height and age matched white Caucasians. Such differences were greater than the 'Asian correction factors'.

Reference values for lung function tests. I. Static volumes

Static lung volume (LV) measurements have a number of clinical and research applications; however, no previous studies have provided reference values for such tests using a healthy sample of the adult Brazilian population. With this as our main purpose, we prospectively evaluated 100 non-smoking subjects (50 males and 50 females), 20 to 80 years old, randomly selected from more than 8,000 individuals. Gender-specific linear prediction equations were developed by multiple regression analysis with total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), RV/TLC ratio and inspiratory capacity (IC) as dependent variables, and with age, height, weight, lean body mass and indexes of physical fitness as independent ones. Simpler demographic and anthropometric variables were as useful as more complex measurements in predicting LV values, independent of gender and age (R2 values ranging from 0.49 to 0.78, P < 0.001). Interestingly, prediction equations from North American and European studies overestimated the LV at low volumes and underestimated them at high volumes (P < 0.05). Our results, therefore, provide a more appropriate frame of reference to evaluate the normalcy of static lung volume values in Brazilian males and females aged 20 to 80 years.

Lung function in Estonian children: effect of sitting height

The present analysis formed part of the population study of Estonian school-children and was undertaken in order to examine the relationships between lung function variables, standing and sitting height. We measured forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow and forced expiratory flows when 50 and 75% of FVC had been exhaled, and anthropometric indices in 645 healthy schoolchildren, aged 6-18 years. The growth spurt in standing and sitting height occurred between the ages of 11 and 13 years in girls, and 13 and 15 years in boys. Growth spurts of lung parameters occurred during the same periods. FVC and FEV1 showed close correlations (r = 0.89-0.94) with all anthropometric parameters and age, whereas correlation coefficients for the flows were less close (r = 0.65-0.88). In boys, correlations between sitting height and lung function variables were greater than those with standing height. Using stepwise regression analysis, in boys sitting height was selected in all lung function parameters, and in girls sitting height was never selected. We conclude that there is a very close correlation between sitting height and lung function variables. The use of sitting height in parallel with standing height in predicted values for Estonian schoolchildren would make the values more exact.

Peak expiratory flow rate in Sri Lankan schoolchildren of Sinhalese ethnic origin

Normal values for lung function indices are not available for Sri Lankan children. Reference standards for peak expiratory flow rate (PEFR) in non-smoking Sri Lankan schoolchildren belonging to the Sinhalese ethnic group have been derived. A total of 1206 schoolchildren of age range 5-19 years was studied. The mini-Wright peak flow meter was used to measure peak expiratory flow rates. The highest of three readings was taken as the correct value. The results were correlated with age, standing height, weight and surface area. The flow rate was only marginally higher in pre-pubertal boys than in girls. Girls reached a maximum at 15 years of age. The boys continued to show an increase in the PEFR until, at the age of 19 years, they had values about 150 l min-1 higher than females of the same age. Up to a height of 150 cm, a weight of 35 kg and l.1 m2 surface area, the two sexes showed similar gradients of increase of PEFR. Beyond these limits, the relationships changed abruptly, the boys showing an increase and the girls, a decrease in the gradient. There was a high correlation between PEFR and the anthropometric measurements studied. The peak flow rates compared favourably with those of other ethnic groups. Prediction formulae were developed with age and height as the independent variables. A nomogram based on these equations was constructed. These results would be useful in obtaining predicted normal values in Sinhalese school children with respiratory dysfunction.

Peak expiratory flow in rural residents of Tamil Nadu, India

BACKGROUND

In a country such as India that covers several latitudes, climatic zones, ethnic groups, and dietary habits lung function within the normal population would be expected to vary. Several studies have looked at normal values of peak expiratory flow (PEF) in different regions of urban India but none has looked at rural South India. A study of PEF has now been carried out in a rural population of Tamil Nadu.

METHODS

All subjects were of Dravidian stock and lived at sea level with rice as their staple food. Ten five year age groups from 10 to 59 years with 100 males and 100 females in each were studied. Peak flow was measured by mini-Wright peak flow meter, and height was also measured. Regression equations for predicting normal PEF were calculated.

RESULTS

Peak flow ranged from 150 to 680 l/min in males and from 150 to 500 l/min in females. Maximum values of PEF were attained at the age of 32.5 years in men and 35.6 years in women. There was a significant linear correlation between height and PEF and a curvilinear relation between age and PEF in both sexes.

CONCLUSION

Regression equations are now available for PEF values in normal subjects from rural South India. PEF was related to age and height and values were greatest in the fourth decade.