Respiratory muscle strength (RMS) is related to fitness, post-surgical morbidity .. Maximal respiratory pressures: normal values and relationship to age and sex . Download Citation on ResearchGate | Maximal respiratory pressures: Normal values and relationship to age and sex | A method for determining maximal. Black, L.F. and Hyatt, R.E. () Maximal respiratory pressures Normal values and relationship to age and sex. American Review of Respiratory Disease,
This research project was based on the physiological concept of maximal strength of respiratory muscles and their determinants such as age, gender, anthropometric characteristics, barometric pressure or restrictive6 or obstructive pathology.
Measuring MIP and MEP is a simple, rapid, noninvasive, validated, and widely used in evaluating respiratory muscle function. Given the importance of measuring maximal respiratory pressures, especially in cardiopulmonary and neuromuscular areas, several studies have attempted to establish predictive values of MIP and MEP. Black and Hyatt5 described a method of the assessment of respiratory muscle strength in healthy subjects of both sexes aged between 20 and This determined the values of maximal respiratory pressures and reference equations for healthy population.
Using variables such as age, sex and, after that first study, several authors evaluated the MIP and MEP in healthy people of different races7, ages and published the results of the reference values of the predictive equations for the calculation of maximal respiratory pressures.
They concluded that differences in lung function among these ethnic groups are found in the respiratory muscle strength, lung elastic recoil, alveolar and airway growth and compliance of the thoracic cavity and the dimensions of the chest wall.
Neder et al3 evaluated healthy subjects of both sexes aged between 20 and 80 years. These authors proposed a regression analysis, pioneered the development of predictive equations for MIP and MEP dependent on sex and age based on a Brazilian population sample. Parreira et al2 concluded that the equations predicted by Neder et al were not able to predict values of MIP and MEP for specific populations.
For that reason, every specific application must be carefully made in the clinical context. As a consequence, the American Thoracic Society state that the reference values of this important measure as well as of other biological variables should ideally be derived from a random selection, geographically related to the population to ensure greater accuracy and predictive power.
If these cannot be met, the test results can cause interpretation errors12 In this sense, MIP and MEP values as found in research in the international context may be inappropriate for using them in the Colombian population, leading to little objective diagnosis of lung function.
This implies taking into account morphophysiological differences such as race, gender, weight, height, BMI, which differ from one population to another and therefore can modify the results of these measures13 The objective of this study was to obtain MIP and MEP values in healthy subjects older than 20 years in the urban area of Manizales, Colombia, and to correlate them with anthropometric and sociodemographic variables.
It is important to have predictive formulas of maximal respiratory pressures validated in the Colombian context, because of the different anthropometric, environmental and cultural characteristics that can be used in the clinical practice and in the field of research in Colombia.
The population consisted ofsubjects from the urban area of Manizales Colombiaa city located at 2, meters above sea level.
The initial sample size was people. The final sample size was subjects. The inclusion criteria were: The exclusion criteria were: The calibration of the measuring equipment for the study variables was carried out.
Weight was recorded in light clothing and without shoes. For the height variable, the measuring rod was located in the laboratory where measurements were made. This variable was recorded without shoes in the inspiration phase. The numerical value was recorded and classified according to WHO standards Additionally, to prevent leakages and increased pressure within the oral cavity, a Speedo nose clip with a standard pressure for adults and a mouthpiece made of silicone attached to the plastic tube of the manometer were used part of Micro Medical Limited, gauge manufacturer.
Researchers were trained with the purpose of undertaking the test to measure maximal respiratory pressures. For this reason, all subjects were instructed about the appropriate way to do it. Besides, a demonstration of the procedure was also carried out. The presence of leakages was prevented by checking that lips were firmly sealed around the mouthpiece and by using a nose clip to control the disturbance of the inspiratory and expiratory measurements by assisting the facial muscles.
For the measurement of maximal respiratory pressures, important variables such as the endurance of the inspiratory and expiratory muscles and their variation according to body position should be considered. Thus, the participant was placed in a sitting position, with the hip at an angle of 90 degrees and feet flat on the floor. The developed procedure began with a pilot test in which 30 people were included. The data collection instruments were adjusted. Three reviewers collected the data.
The first one was responsible for the reading and signing of the informed consent approved by the Ethics Committee of the Autonoma University of Manizales and for the registration of the sociodemographic variables, the second one assessed the anthropometric variables, and the third one was in charge of the procedure and the recording of respiratory pressures.
For the MIP determination, the participant was asked to introduce and adjust the mouthpiece and nose clip based on the residual volume and also to perform a maximal inspiration during 3 or 4 seconds. For the MEP determination from the total lung capacity, the subject was asked to introduce the mouthpiece and nose clip and perform a maximal exhalation for 3 or 4 seconds.
Three MIP maneuvers and three MEP maneuvers were performed in a sitting position, recording the highest value in each of the three cases. From the ethical point of view, this study was considered itself as a ''minimal risk research,'' according to Act 11 of resolution of of the Health Ministry of Colombia because of the noninvasive clinical tests that did not risk the physical and moral integrity of the participants.
Additionally, this research project met the principles set forth in the Declaration of Helsinki issued in by the World Medical Association.
Its interest is scientific, and at all times the integrity of the participants was protected. All cautions to respect their privacy and to minimize the impact of the study on their physical and mental integrity were taken.
For qualitative variables proportions were calculated and for quantitative variables mean, range and standard deviation were calculated. The bivariate analysis assessed the relationship of independence and homogeneity of the anthropometric variables with the values of maximal respiratory pressures. They used correlation coefficients according to the measuring level of the variable and to their normal or abnormal behavior Kolmogorov -Smirnov.
Maximal respiratory pressures: normal values and relationship to age and sex.
Additionally, homogeneity tests were carried out by using student's t-tests and Mann-Whitney U tests according to normal or abnormal behavior of the variables.
A multiple linear regression model from the model evaluation tests was constructed. The gender variable showed Differentiating the variable subcategories, it was found that MIP average values in females The MEP average value among respondents was It was found that those with an age range of 20 to 39 years in both males and females, the MIP and MEP values were higher compared to those over 40 years.
A multiple linear regression model was estimated in order to predict MIP and MEP values based on variables such as age, gender The highest coefficients of determination r2 were taken for both MIP to MEP values; and the best model was tested for normality and homoscedasticity of waste, using the Kolmogorov-Smirnov and White tests respectively, it was also verified that the errors were normally distributed K-Sequal to 0 and to be independent Durbin Watson near 2.
Finally, a multiple regression model was proposed to predict the dependence of the values obtained for maximal respiratory pressures respect to the independent variables with better r2 by a linear combination of the parameters used and the theoretical and practical formulation of the model obtained for values of maximum inspiratory and expiratory pressure was exposed. The model used was as follows MIP: Overall test of the model: This means it is important to assess them using spirometric tests since there are dysfunctions that affect the respiratory muscles but not the bronchus itself.
The results of this study show lower respiratory pressure values than those found in international studies, presenting averages of 75 cm H20 for MIP and In contrast, other studies such as Black and Hyatt5 exhibited average values of The maneuvers for maximal respiratory pressures were performed on a voluntary basis, therefore the patient's mood, cooperation and understanding of how to carry out the tests could have influenced results.
Another important aspect to consider is that all of the research studies mentioned, including this one, have not only used different measuring equipment but have also calibrated them under different conditions. This could be due to anatomical, structural and hormonal differences. Results show that the greater the weight and the higher the body mass index BMI classification mild obesitythe higher the respiratory pressure values.
This makes muscle performance better in men than in women A BMI above 35 moderate and severe obesity does not mean greater muscle strength probably because these individuals present pulmonary restriction and mechanical disadvantage During infancy, bone growth is accompanied by an increase in muscle length in which multiplication of sarcomeres takes place and this in turn can generate more muscle strength in this respiratory case The variables in Costa1 study showed a positive correlation with weight and height in men, but with height only in women.
Wilson8 and Harik-Khan's23 studies demonstrated that height was a negative predictor only in women and one of their studies 23 showed that weight was a positive predictor for both men and women.
Correlations were made between the variables of gender, age, weight, height, BMI and BMI Classification and maximum respiratory pressures in order to obtain prediction formulas. To determine the reference values for MIP the variables of age, gender and BMI classification were used while gender, weight and height were used to determine reference values for MEP.
This regression formula differs from that proposed by Black and Hyatt5 in which the best correlation was found when they used the age variable. Bruschi et al24 established equations for the Italian population, considering age and gender as well as body surface area as significant variables of their prediction equations. In Brazil, there have been few studies regarding reference values for maximal respiratory pressures, although a few have been of note: It is important to note that when the equations proposed by Neder et al.
Therefore, in view of the scarcity of reference tables for the Brazilian population, the objective of this study was to compare MIP and MEP values obtained from healthy adult subjects with those of the equations proposed by Neder et al. The hypothesis of this study was that there are differences among studies for certain variables, and that new equations should therefore be drawn up. Each of the six ten-year age brackets used in the study included 10 male and 10 female subjects.
The volunteers were selected according to the criteria of having a BMI between Subjects with a history of respiratory or cardiovascular disease were excluded, as were those with any neuromuscular disease that would prevent the tests from being performed. After the anamnesis, during which an evaluation record, containing questions about smoking, practice of regular physical activity, presence of cardiovascular and respiratory dysfunction, family history and medications in use, was filled out, the anthropometric measures were collected.
Weight and height were measured with a calibrated scale Welmy S. The manometer was equipped with a mouthpiece adapter containing an orifice of approximately 2 mm in diameter in order to prevent a rise in the intraoral pressure generated by the contraction of the buccinator muscles, thereby hindering interference in the results, in accordance with the recommendations given in two studies.
We compared the values measured in this study with those predicted using the equations proposed by Neder et al. Initially, to compare the measured values with those predicted using the equations proposed by Neder et al. Student's t-test was used for variables with normal distribution, whereas the Wilcoxon test was used for those with non-normal distribution. The variables that presented statistically significant correlations were placed in linear regression models in order to establish the predictive equations for the respiratory pressures.
Finally, the percentage variability for MIP and MEP values measured in the sample was calculated with the predicted values, together with the confidence interval for each age bracket, separated by gender, in order to determine to which age brackets the new proposed equations would be more adequate.
Results The anthropometric data of the study sample are presented in Table 1. The measures of maximal respiratory pressures found in this study were compared with the predicted values using the equations by Neder et al. However, no significant differences were found between measured and predicted MEP values for males and females Table 2.
Since age was the variable with the best predictive power regarding maximal respiratory pressures, this variable was considered in a simple regression analysis model in order to establish the equations for MIP and MEP. On the basis of the linear regression model, considering gender and age as predictive variables, the following equations for MIP and MEP are proposed for the Brazilian population: Considering the variability for the predicted values, it was shown that the fluctuation was greater for MIP than for MEP, especially for males in the year age bracket.
For females, the fluctuation was greater for MIP, but with the greatest variability in the year age bracket. Discussion The search for reference values for respiratory muscle strength has encouraged researchers in several countries to establish equations.
According to the results obtained in the present study, MIP was shown to be significantly lower than the predicted values using the equations proposed by Neder et al.
Maximal respiratory pressures: normal values and relationship to age and sex.
Therefore, our results showed that the predicted values using the equations by Neder et al. Considering that the methodology used in the present study was similar to that employed in the study conducted by Neder et al. This might have resulted in overestimated values, due to undesired contraction of the buccinator muscles, since the activation of these muscles can generate a pressure that interferes with that produced by the respiratory muscles.
One group of authors 7 recently measured MIP and MEP in a population of healthy subjects from three Brazilian cities and compared the values obtained with those predicted by Neder et al. Few of the values found were within the range predicted for the age bracket, and the authors concluded that the Neder et al. Our measurements were lower than those previously reported for adults 1,5,13 and for elderly subjects over the age of 65 years.
In two studies, 13,15 height was shown to be a negative predictor only for females, and, in two studies, 15,16 weight was shown to be a positive predictor for both genders. From this aspect, MIP correlated positively with weight for males in the study conducted by Neder et al.
One group of authors 18 studied individuals of both genders in the year age bracket in Australia and observed that respiratory muscle strength was significantly lower in those in the year age bracket group than in those in the year age bracket. The primary mechanism for this decrease, according to the authors, was the sarcopenia associated with the aging process.
Other authors 13 measured the same parameters in White individuals adults and childrenusing age, height and weight to consider equations in order to determine predicted values. Similarly to Neder et al. Using gender and age as variables, we proposed new equations for the determination of respiratory muscle strength in the Brazilian population.