Submitted: 13 March Accepted: 23 September Correspondence to: Carlos Alberto de Castro Pereira. E-mail: pereirac uol.
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Submitted: 13 March Accepted: 23 September Correspondence to: Carlos Alberto de Castro Pereira. E-mail: pereirac uol. Abstract Objective: To derive reference values for healthy white Brazilian adults who have never smoked and to compare the obtained values with reference values derived by Crapo and by Neder.
Methods: Reference equations by quantile regressions were derived in men and women, non-obese, living in seven cities in Brazil. Age ranged from 21 to 92 years in women and from 25 to 88 years in men. Lower and upper limits were derived by specific equations for 5 and 95 percentiles. The results were compared to those suggested by Crapo in , and Neder in Results: Median values for total lung capacity TLC were influenced only by stature in men, and by stature and age in women.
Residual volume was influenced by age and stature in both genders. Weight was directly related to inspiratory capacity and inversely with functional residual capacity and expiratory reserve volume in both genders. A comparison of observed TLC data with values predicted by Neder equations showed significant lower values by the present data. Mean values were similar between data from present study and those derived by Crapo. Conclusion: New predicted values for lung volumes were obtained in a sample of white Brazilians.
The values differ from those derived by Neder, but are similar to those derived by Crapo. A idade variou entre 21 e 92 anos nas mulheres e de 25 a 88 anos nos homens. Os resultados foram comparados aos sugeridos por Crapo em e Neder em Resultados: Os valores medianos para a capacidade pulmonar total CPT foram influenciados apenas pela estatura nos homens, e pela estatura e idade nas mulheres.
O volume residual foi influenciado pela idade e estatura em ambos os sexos. Capacities include: Functional Residual Capacity FRC - the volume of air present in the lungs at the end of Tidal Volume TV expiration; Total Lung Capacity TLC - total volume of air in the lungs at the end of a maximal inspiration; Vital Capacity VC - Total expired air volume after maximum inspiration or maximum inspiration after maximum expiration; Inspiratory Capacity IC -volume of air inspired from the end of a normal expiration.
The TLC reduction establishes the presence of restriction. This combination is called nonspecific pattern and is commonly observed in obstructive diseases with airway closure, obesity and neuromuscular diseases. In many cases, the reduction of RV is observed to a greater degree than the changes observed in spirometry. In sample selection, ideally more than adults of each gender for each ethnic group with a similar frequency distribution in the various age ranges should be included.
The individuals were selected by verbal invitation, and were more commonly companions or family members of patients or staffs of the study institutions. The project has not been submitted for approval in all centers; however, the complete documentation of all the centers involved was added to the project approved. Women, whom cooked in wood stoves, as well as those exposed to cigarette smoke in the bedroom, were excluded; Color self-declared white as confirmed by the individual and by observers.
The exams were performed by technicians or medical certificates in pulmonary function by Brazilian Thoracic Society. The mouth pressure transducer and pressures and flows in the plethysmograph were calibrated daily. The functional parameters were expressed as BTPS. After detailed instructions regarding the test, the plethysmograph door was closed and the time to temperature equilibrium expected. The patient was then instructed to place the mouthpiece and breathe quietly until a plateau at the endo-expiratory level was reached out.
When the breathing was at the Functional Residual Capacity FRC level, the shutter was closed and the patient instructed to pant softly, at a frequency between 0.
The pressure-flow plots were recorded for airway resistance calculation not included in the present study. The pressure-volume charts for determination of FRC were obtained by closing shutter at the end of a normal expiration. After opening the obturator, ERV and inspiratory vital capacity were determined. The system registers four loops by each maneuver, and at least three maneuvers were performed on all tested, therefore, with 12 loops. When the acceptance criteria were not met, more loops were performed.
The final value noted was the average value. The data from these individuals were not compared to those included. Initially, the numerical data variables were analyzed descriptively, and expressed by summary measures as median and quartiles 1st quartile, 3rd quartile and the values of these variables were compared according gender by the non-parametric Mann -Whitney test.
Quantile regressions were used to derive the reference values. Initially, all predictor variables were included in the model. The spirometry values were compared to those expected for the Brazilian population.
The differences between the TLC values provided by Crapo and Neder and observed in this sample were expressed in graphs and differences calculated by paired t-test. The distribution for anthropometric data is shown in Table 1. Age in males varied from years and from 21 to 92 years in females. The median stature in males was cm cm and cm cm in females. The median values and the dispersion for the main functional data, expressed by quartiles 1 and 3, are shown in Table 2.
The Table 3 presents the final model estimates. The comparisons between the values observed for the TLC and those predicted by the Crapo and Neder equations are shown in Table 4 and Figure 1. The values predicted by Neder were higher than those found in the present study. For males, the average difference was 0. The measurement of TLC is essential for the diagnosis of restrictive lung disease. The VC may be reduced in both, restrictive and obstructive lung disease, in the later due to increased residual volume.
The elevated TLC indicates, in general, loss of lung elastic recoil, as occurs in emphysema and in some cases of asthma. Factors that determine normal lung size include stature, age, gender, body mass, altitude, ethnic group, and physical activity pattern.
Great swimmers, divers and rowers may have increased TLC by increased muscle strength. With advancing age, the pulmonary elastic retraction decreases.
In addition to the loss of elastic recoil, the accumulation of fat and the decrease in the strength of the respiratory muscles lead to the reduction of VC, which is therefore multifactorial. In the present study, IC correlated directly with weight, which can be explained by the correlation of muscle mass with weight, and FRC and ERV correlated negatively with weight, probably due to the effect of deposition of higher central fat, even with the inclusion in the study of individuals with BMI in the normal range.
The derived values in the present study were compared to the values suggested by Neder and Crapo. The pulmonary volumes may be higher in inhabitants born at sites with more than m high, presumably due to increased pulmonary growth due to hypoxemia. Therefore, this factor should not have influenced the values observed in the present study and that of Crapo et al.
Only two male individuals were over 85 years of age. The technique used was the single breath by helium dilution, used to measure of CO diffusion, which may underestimate TLC.
As TLC can range more or less for the respiratory diseases, two-tailed tests 2x SEE were used by Crapo to establish reference limits, which resulted in wide variation around the predicted value. The TLC limits would be calculated by adding or subtracting 1.
However, common pulmonary diseases have a tendency to increase or decrease TLC data, and the calculation of limits by the 5th and 95th percentiles is accepted. Therefore, in the present study, the lower limits are closer to the expected value, increasing the sensitivity for the detection of restrictive disorder. Neder et al. The racial profile was variable, with inclusion of 34 non-white individuals. Race has a significant effect on lung volumes.
The method used to determine FRC was the N2 washout by multiple breaths. The tests were performed in a Medical Graphics system, which provides greater results compared to other large systems, which may explain the high values found.
The values were derived by linear equations. As shown in Table 4 and Figure 1, the values of Neder et al. Quantile regressions were used in the present study, as in other studies on reference values for pulmonary function.
However, the covariates may affect the distribution of residuals in several ways. One advantage of using the quantile regression to estimate the median instead of the usual least squares regression to estimate the average is that the result of quantile regression is more stable in response to outliers.
Additional data that should be considered are the type of equipment and the methods used, besides that, the selection criteria and the sample size. A careful revaluation of acceptance criteria of maneuver was applied in the present study by review of all cases. The present study has limitations.
The most obvious is the uncertain extrapolation of data to black race, which is important in Brazil. In this study, volunteers were invited. For the derivation of reference values for pulmonary function, only non-smokers with no symptoms or cardiorespiratory diseases should be included.
For this, a validated respiratory epidemiological questionnaire should be applied. Fulfilled these conditions, the use of volunteers to establish reference values is valid. The values differ from those expected by Neder and are close to those derived by Crapo. J Bras Pneumol. Lung volumes and airway resistance in patients with a possible restrictive pattern on spirometry.
The "complex restrictive" pulmonary function pattern: clinical and radiologic analysis of a common but previously undescribed restrictive pattern. Mild chronic obstructive pulmonary disease: why spirometry is not sufficient! Expert Rev Respir Med.
Lung mechanics in subjects showing increased residual volume without bronchial obstruction. Response of lung volumes to inhaled salbutamol in a large population of patients with severe hyperinflation. The effects of body mass index on lung volumes. Improvement of dyspnea after bariatric surgery is associated with increased Expiratory Reserve Volume: a prospective follow-up study of 45 patients.
Correspondence to: Carlos Alberto de Castro Pereira. E-mail: rb. Methods: Reference equations by quantile regressions were derived in men and women, non-obese, living in seven cities in Brazil. Age ranged from 21 to 92 years in women and from 25 to 88 years in men. Lower and upper limits were derived by specific equations for 5 and 95 percentiles. The results were compared to those suggested by Crapo in , and Neder in
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