Correlation of spirometry with the six-minute walk test in eutrophic and obese individuals

Abstracts

OBJECTIVE: To assess the distance covered by both eutrophic individuals and individuals with different grades of obesity and correlate the data obtained with spirometric values. This study is justified by the existing difficulty in assessing the functional capacity in obese individuals, and by the low cost and good specificity of six-minute walk test (6MWT) in predicting reduced capacity for activities of daily living for any individual. METHODS: One hundred fifty-four individuals of both genders were assessed after being divided into two groups: G1, obese individuals (n = 93, BMI ≥ 30 kg/m²) and G2, eutrophic individuals (n = 61, BMI 18.5 to 24.99 kg/m²). The 6MWT was performed using the methodology described by the American Thoracic Society (ATS-2002). Spirometry was performed both before and after the application of a bronchodilator agent (BDA) in accordance with the Guidelines for Pulmonary Function Tests by the Brazilian Society of Pneumology and Phthisiology (SBPT-2002). The statistical analysis, consisting of mean, standard deviation, Pearson's correlation, Student's t test and Spearman's correlation, considered p < 0.05. RESULTS: The 6MWT analysis with spirometry for G1 was positively correlated only with pre- and post-BDA peak expiratory flow rate (PEFR). CONCLUSION: The present study showed a positive correlation between pre- and post-BDA PEFR and the distance covered in the 6MWT in obese subjects, that is, the higher the PEFR, the higher the physico-functional capacity of the individual, and consequently, the greater the distance covered

Walk; spirometry; obesity; exercise test; pulmonary function tests

OBJETIVO: Avaliar a distância percorrida por indivíduos eutróficos e com diferentes graus de obesidade e correlacionar com parâmetros espirométricos. A justificativa para o estudo se faz pela dificuldade de avaliar a capacidade funcional de obesos, e devido ao baixo custo do teste de caminhada de seis minutos (TC6') e sua boa especificidade em predizer reduzida capacidade de atividades de vida diária para todo e qualquer indivíduo. MÉTODOS: Avaliados 154 indivíduos, de ambos os sexos, divididos em dois grupos: G1 obesos (n = 93, IMC ≥ 30 kg/m²) e G2 eutróficos (n = 61, IMC de 18,5 a 24,99 kg/m²). O TC6' foi realizado com metodologia descrita pela ATS (2002). A espirometria foi realizada antes e após a aplicação do broncodilatador (BD) conforme as Diretrizes para Testes de Função Pulmonar da Sociedade Brasileira de Pneumologia e Tisiologia: SBPT-2002. Análise estatística composta por média, desvio-padrão, correlação de Pearson, Teste t de Student e de Spearman, considerando p < 0,05. RESULTADOS: A análise do TC6' com a espirometria para o G1 apresentou correlação positiva apenas para o pico de fluxo expiratório (PFE) pré- e pós-BD. CONCLUSÃO: O presente estudo apresentou correlação positiva entre o PFE pré- e pós-BD e a distância percorrida no TC6' em obesos, ou seja, quanto maior o PFE, maior a capacidade físico-funcional do indivíduo e consequentemente maior a distância percorrida

Caminhada; espirometria; obesidade; teste de esforço; testes de função respiratória

ORIGINAL ARTICLE

^IPost-graduation Student; Physical Therapist, Universidade Católica de Brasília (UCB), Brasília, DF, Brazil

^IIPost-graduation Student in Physical Therapy in Intensive Care; Physical Therapist, UCB, Brasília, DF, Brazil

^IIIGraduated in Physical Therapy, UCB; Physical Therapist, Brasília, DF, Brazil

^IVPhysical Therapist; Doctorate Student in Physical Education, UCB; Professor in the Graduation Course and Post-graduation Coordinator in Physical Therapy in Intensive Care, UCB, Brasília, DF, Brazil

^VPost-Doctoral Fellow at Duke Medical Center (USA) and the World Health Organization (WHO), Switzerland; M.Sc. Supervisor and Ph.D. Advisor, UCB and Universidade de Brasília (UnB); Assistant Secretary of Health/SES, Brasília, DF, Brazil

Correspondence to

SUMMARY

OBJECTIVE: To assess the distance covered by both eutrophic individuals and individuals with different grades of obesity and correlate the data obtained with spirometric values. This study is justified by the existing difficulty in assessing the functional capacity in obese individuals, and by the low cost and good specificity of six-minute walk test (6MWT) in predicting reduced capacity for activities of daily living for any individual.

METHODS: One hundred fifty-four individuals of both genders were assessed after being divided into two groups: G1, obese individuals (n = 93, BMI > 30 kg/m²) and G2, eutrophic individuals (n = 61, BMI 18.5 to 24.99 kg/m²). The 6MWT was performed using the methodology described by the American Thoracic Society (ATS-2002). Spirometry was performed both before and after the application of a bronchodilator agent (BDA) in accordance with the Guidelines for Pulmonary Function Tests by the Brazilian Society of Pneumology and Phthisiology (SBPT-2002). The statistical analysis, consisting of mean, standard deviation, Pearson's correlation, Student's t test and Spearman's correlation, considered p < 0.05.

RESULTS: The 6MWT analysis with spirometry for G1 was positively correlated only with pre- and post-BDA peak expiratory flow rate (PEFR).

CONCLUSION: The present study showed a positive correlation between preand post-BDA PEFR and the distance covered in the 6MWT in obese subjects, that is, the higher the PEFR, the higher the physico-functional capacity of the individual, and consequently, the greater the distance covered.

Keywords: Walk; spirometry; obesity; exercise test; pulmonary function tests.

Introduction

Obesity is a worldwide epidemical disease of fat accumulation in the body, caused by excessive and chronic intake of caloric foods linked to a low energy expenditure mainly related to a sedentary lifestyle^1-3.

Etiology and risk factors for the development of obesity are multiple, including genetic and psychological aspects, low metabolic rate, bad dietary habits, endocrine diseases, side effects of drugs and sedentary behavior².

The World Health Organization (WHO)⁴ indicates that approximately 1.6 billion adults were overweight in 2005 worldwide, and at least 400 million were obese. Projections for 2015 show that 2.3 billion adults will be overweight and over 700 million will be obese.

The second phase of the 2002-2003 Family Budget Survey by the Instituto Brasileiro de Geografia e Estatistica (IBGE)⁵ demonstrated that out of 95.5 million people > 20 years of age, 38.8 million (40.6%) were overweight, with 10.5 million being considered obese.

The classification of overweight and obesity in adults is expressed by the body mass index (BMI -kg/m²). This index is defined by the weight in kilograms (kg) divided by the squared stature in meters (m²). Individuals with a BMI < 18.5 kg/m² are underweight; between 18.5 and 24.9 kg/m² they are considered normal; between 25 and 29.9 kg/m² they are overweight. BMI classifications for obesity are: grade I, a BMI from 30 to 34.9 kg/m²; grade II, between 35 and 39.9 kg/m²; grade III or extreme obesity for BMI > 40 kg/m^2,4,6.

Five decades ago, obesity was recognized to affect lung function, producing mechanical effects reflected on the pulmonary mechanics, possibly leading to a reduced complacency, which may result in a restrictive ventilatory disorder^7-10.

The simple spirometry is a pulmonary function test measuring the air inhaled and exhaled by the lungs and the following pulmonary volumes and capacities: forced vital capacity (FVC); forced expiratory volume in one second (FEV₁); forced expiratory flow between 25% and 75% of the FVC (FEF_25-75%); VEF1/FVC ratio and peak expiratory flow rate (PEFR)^7,11.

Spirometry is indicated to detect whether a pulmonary dysfunction is present or not; to rate the severity of a known pulmonary disease; to follow-up the pulmonary function under therapy and the disease course; to assess the effects from environmental and occupational exposure; and others¹².

Spirometry is a safe procedure, but increased intracranial pressure, syncope, dizziness, chest pain, paroxysmal cough, risk for infections, bronchospasm, and pneumothorax can occur¹².

Grade III obesity can impair the respiratory system because of perithoracic and abdominal fat accumulation, reducing the expiratory reserve volume (ERV) and the functional residual capacity (FRC), also promoting ventilation/ perfusion (V/Q) ratio changes from hypoxemia rest and supine hypoxemia, likely because of small airway closure¹³.

The six-minute walk test (6MWT) is a practical and simple assessment of the submaximal level of functional exercise capacity for activities of daily living¹⁴. It measures the distance a person can walk fast on a flat and hard surface over six minutes. The test assesses and integrates responses from all systems involved during the exercise (cardiovascular, respiratory, neuromuscular, and metabolic systems), but it does not provide specific and isolated information¹⁵.

The 6MWT is mainly indicated for: comparing pre- and post-treatment phases; measuring the functional status; and predicting the morbidity and mortality from cardiopulmonary diseases. The primary measurement is the total distance covered. The secondary measurement includes muscle fatigue and dyspnea, assessed by the modified Borg Scale or a Visual Analogue Scale. The last measurement would be the saturation of peripheral oxygen (SpO₂), measured by a pulse oximeter¹⁶. Absolute contraindications are: stable and unstable angina, recent acute myocardial infarction; relative contraindications are: heart rate at rest higher than 120 bpm; systolic blood pressure (SBP) higher than 180 mmHg, and diastolic blood pressure (DBP) over 100 mmHg¹⁵.

From the literature review, no specific studies of reference values for physical-functional and pulmonary capacity in obese individuals compared to eutrophic individuals were found. The correlation of these capacities has a considerable clinical relevance, as it can contribute to setting strategies for preventive treatment and complication treatment in obesity in order to offer better respiratory conditions with an appropriate choice of the therapeutic method to help individuals to be embedded into a treatment group.

The rationale for this study was the difficulty in assessing functional capacity in obese individuals. The 6MWT has a low cost, is easily applied, and its good specificity in predicting reduced capacity for the activities of daily living in any individual has also influenced the choice.

The present study aimed to assess the influence of excess body weight on pulmonary and physical-functional capacity, correlating variables of spirometry testing and the sixminute walk test in different grades of obesity and in eutrophic individuals.

Methods

The sample consisted of 154 sedentary volunteers of both genders between 20 and 59 years of age, non-smokers and divided into two groups: study group (G1) formed by 93 obese subjects (BMI > 30 kg/m²) and control group (G2), consisting of 61 eutrophic subjects (BMI 18.5 to 24.99 kg/m²). G2 should have a normal spirometry and all volunteers signed an informed consent and concluded the tests proposed.

Volunteers with physical-mental changes who might not understand the test performance, such as in behavior disorders, with associated and decompensated diseases (heart, metabolic, pulmonary, neuromuscular, and musculoskeletal diseases) significantly limiting the walk, or disagreement about any procedure proposed were excluded.

The present study was approved by the Ethics Committee of the Universidade Católica de Brasília (CEP/UCB 052/2009).

Volunteers were instructed to wear comfortable clothes, appropriate sneakers for a walk, to use their medication normally and not to exercise vigorously over the two hours preceding the tests. An evaluation form containing personal data, vital signs, anthropometric measurements, diseases associated, dyspnea grade, life habits, spirometric parameters and 6MWT was designed.

Initially, volunteers were weighed on a digital scale (Filizola) with 100 g increments and their weight was noted. Stature was checked by a stadiometer (Cardiomed) affixed to the laboratory wall. Heart rate (HR) and saturation of peripheral oxygen (SpO₂) were collected from the pulse oxymeter (Moriya^®); blood pressure (BP) was measured by a sphygmomanometer (Missouri) and a stethoscope (Littman) on the left upper limb. Waist circumference (WC) was measured at the midpoint between the last costal border and the iliac crest; hip circumference (HC) was measured at the femur major trochanter level, in an orthostatic position. WC and HC were measured by a 13 mm wide long flexible measure tape (Kapor) with one-millimeter accuracy. Waist/ hip-ratio (WHR) was calculated following the circumference measurement.

The 6MWT was performed using the methodology specified by the American Thoracic Society (ATS-2002)¹⁵ in a hard surface, covered, long, flat and walled corridor which was 30 m long; meter-by-meter marks were done and two cones signaled the walk turn. Parameters such as BP, HR, SpO₂, and the modified Borg scale (it assesses subjectively the degree of effort, assigning a grade from 0 to 10) were collected early and late over the walk. When the test was terminated, the distance covered was calculated through notes of the number of turns performed by the volunteer.

The volunteer was instructed to undergo the test as fast as possible without running for six minutes, walking from one cone to another during the stipulated time and the test could be interrupted at any time.

Every minute the investigator approached the volunteer and said encouragement phrases, such as: "You are doing well!" and "Only a few minutes left!". At these points, SpO₂ and HR were verified in the oxymeter connected to the volunteer through an elastic belt to avoid many displacements and swings and keep the safety of the equipment use.

As soon as the 6MWT was finished, the volunteer should sit down and rest for approximately 30 minutes to undergo the spirometry pre- and post-bronchodilator agent (Spirometer: V Max 229 Sensor Medics), performed by a trained technician, that is, the volunteer underwent spirometry and after the bronchodilator agent (BDA) administration, he/she waited for 15 minutes to undergo a new spirometry so that the response to the bronchodilator agent could be evaluated.

The spirometry was performed with the volunteer sitting and using disposable mouthpieces for individual use with nose clip, in accordance with the recommendations in the Guidelines for Pulmonary Function Tests (Brazilian Society of Pneumology and Phthisiology: SBPT-2002)¹¹. Spirometry report was made by a pneumologist in charge of the Cardiopulmonary Rehabilitation Laboratory of Universidade Católica de Brasília.

In the statistical treatment by SPSS 17.0 data exploratory analyses were made to identify possible misconduct cases or extreme values, normality test for variables, and descriptive statistics with mean and standard deviation for age, BMI and the other pre- and post-BDA spirometric values.

Pearson coefficient of correlation was used to verify a possible association between BMI and the distance covered the WC, and the distance covered by the 6MWT. The same test was used to verify the association between distance covered and spirometric parameters.

Student's t test was used to compare the spirometry variables among the groups for independent samples. This test was also used to compare HR, SpO₂, respiratory rate (RR), BP, WC, WHR and distance covered with the 6MWT in different groups. HR in early 6MWT was compared with end HR by the paired t test.

Spearman test was used to correlate the obesity grade with the distance covered and the spirometry. All analyses were performed with a 5% significance level adopted.

Results

The study included 154 subjects, with 93 in G1 and 61 in G2. In the obese group, mean age was 37.6 ± 10.5 years and BMI was 36.73 ± 5.35 kg/m²; in the eutrophic group, mean age was 29.6 ± 9.0 years and BMI was 22.5 ± 2.05 kg/m². In G1, 64.5% were females and 35.5% were males; in G2, 73.8% were females and 26.2% were males. Regarding the obesity grade, the sample included 42 grade I obesity subjects (45.2%), 28 grade II obesity subjects (30.1%), and 23 grade III obesity subjects (24.7%).

As the groups were compared concerning WC, WHR and distance covered over the 6MWT measurements, significant differences were observed for all variables across the groups. Obese subjects had a WC 114.7 ± 16.7 cm versus 75.8 ± 9.3 cm in the eutrophic group. As for WHR, the mean was 0.93 ± 0.07 cm for obese subjects and 0.79 ± 0.07 cm for eutrophic group. In the 6MWT, obese subjects covered a mean of 531.5 ± 57.2 m, and eutrophic subjects, 589 ± 45.1 m.

Regarding HR, SpO₂ and RR at rest, the groups are statistically equal, with means and standard deviation shown in Table 1.

Pearson coefficient of correlation identified a negative and moderate correlation (p = 0.001) between BMI and the distance covered over the 6MWT; a negative and slight association (p = 0.001) was demonstrated between the distance covered and WC in G1 and, in G2, there was no significant correlation between both variables.

Analysis of HR and SpO₂ evolution in both groups every minute in the 6MWT demonstrated significant correlation for HR at the third (p = 0.014), fifth (p = 0.016), and sixth (0.031) minutes. G1 had a lower HR than G2 all over the test. However, SpO₂ had no difference between both groups.

Systolic (SBP) and diastolic (DBP) BP compared between the groups showed differences for all initial and end variables (p = 0.001) in 6MWT, with G1 having the highest variable values.

As HR was compared before and at the end of the 6MWT in each group, a statistical significance was observed (p = 0.001), with G1 showing a mean initial and end HR in the 6MWT 84.5 ± 10.7 bpm and 133 ± 17.4 bpm, respectively, lower than G2, which had a mean initial 84.6 ± 13.1 bpm and 139.1 ± 16.8 bpm for the end-of-the test HR.

Before the 6MWT, the exertion perception on the modified Borg scale was chosen. In G1, 57 volunteers initiated the walk with no exertion (Borg 0), 11 with minimal exertion (Borg 0.5), 7 with very little exertion (Borg 1), 12 with little exertion (Borg 2) and 6 with moderate exertion (Borg 3). In G2: 46 volunteers initiated the walk at Borg 0, 9 at Borg 0.5, 2 at Borg 1, 3 at Borg 2, and only one at Borg 3.

At the end of the 6MWT, the exertion perception for G1 was: 2 obese subjects ended the walk at Borg 0; 6 at Borg 0.5; 8 at Borg 1; 24 at Borg 2; 33 at Borg 3; 8 had a nearly severe exertion (Borg 4); 6 had severe exertion (Borg 5); 4 had profound exertion (Borg 7); and 2 maximum exertion (Bort 10). In G2: 4 eutrophic subjects had Borg 1; 4 had Borg 0.5; 15, Borg 2; 26, Borg 3; two, Borg 4; seven, Borg 5; and 3 Borg 7.

As the association between obesity grade and distance covered over the 6MWT was verified, Spearman coefficient demonstrated a negative and moderate correlation between the variables (p = 0.001), i.e., subjects with grade I obesity covered a longer distance than the other obese subjects.

The spirometric parameters pre- and post-BDA FEV₁/ FVC (p = 0.0001) and post-BDA FEF_25-75% (p = 0.04) showed a negative correlation compared with all the spirometric parameters in both groups, with G1 showing reduced values related to G2.

When the obesity grade was correlated with the spirometry parameters by Spearman test, a negative association of the peak expiratory flow rate was found. For pre-BDA PEFR the p-value was 0.007, whereas for post-BDA PEFR p = 0.02, i.e., the higher the obesity grade, the lower the peak flow reached. For the other parameters, there was no significant correlation.

The mean spirometric parameters for pre-BDA FVC and post-BDA FEV₁ were lower in grade II obese subjects related to grade III obese subjects, differing from the other parameters which had decreasing means as obesity increased (Table 2).

The spirometry had five different spirometric reports for G1, with 84 revealing a normal spirometry (90.3%); five had a slight reversible post-BDA obstructive ventilatory disorder (5.4%); three had a slight restrictive ventilatory disorder (3.2%) and only one subject had a mixed ventilatory disorder with a moderate nonreversible post-BDA obstructive component (1.1%).

As the association between 6MWT and the sample spirometry variables was analyzed, a slight positive correlation was found for pre-and post-BDA FEV₁/FVC, post-BDA FEF_25-75%, pre- and post-BDA PEFR, indicating the longer the distance covered, the higher these spirometry parameters, as shown in Table 3.

As the same analysis of 6MWT with the spirometric parameters only for G1 is performed, a weak positive correlation was observed only for pre-(p = 0.007) and post-BDA (p = 0.005) PEFR, i.e., the longer the distance covered, the higher the PEFR value in the obese group, whereas for G2 there was no significant correlation.

Discussion

According to Enright and Sherril¹⁷, there are formulas predicting the distance covered over the 6MWT regarding age, weight and stature. In the study by Barata et al.¹⁸, the attempted establishment of specific formulas for Brazilian healthy elderly individuals was frustrated due to small sample. No studies using specific reference values or formulas for obese individuals were found and so predicting equations were not used in the current study.

According to ATS¹⁵, the 6MWT should be discontinued if the volunteer have chest pain, unbearable breathlessness, leg cramps, dizziness, excess sweating and pallor. In the study, only an eutrophic female volunteer needed to close the test from severe back pain.

The eutrophic females covered a mean of 583.44 ± 43.75 m versus 522.61 ± 48.54 m for obese females, and eutrophic males obtained a mean covered distance 604.68 ± 46.47m versus 547.81 ± 68.16 m for the obese ones. This data bears out the study by Perecin et al.¹⁹, which concluded eutrophic individuals walk longer distances than obese individuals. In addition, they confirmed what ATS presents¹⁵ -two of the factors reducing the distance in 6MWT would be a high body weight and female gender. Duration of obesity, on average 10 years for G1, can also have contributed to the reduced distance covered, as complications and changes are known to arise over the time.

The current study shows a negative and moderate association between the distance covered in the 6MWT and BMI, which was not observed by Pelegrino et al.²⁰ in a study conducted with patients presenting a chronic obstructive pulmonary disease, with no significant association between distance and BMI.

A slight negative association was observed when the obesity grade and the distance covered overt the 6MWT were correlated, in which the lower the obesity grade, the longer the distance covered. The same result was found by Pires et al.²¹ with different BMI grades.

The oxygen desaturation peak over the 6MWT, in this study, was maintained over the first minute for obese subjects and over the first three minutes for eutrophic subjects, unlike the study by Brunetto et al.²² with COPD patients, who reached the peak at the third and sixth minutes of the test, demonstrating a lack of physical functional fitness in obese individuals.

In obesity, the function of respiratory muscles is impaired from the increased resistance they must overcome and from the reduced capacity of these muscles²³. Increased body fat can affect pulmonary function tests, with a slight decrease in pulmonary volumes being associated. As shown by Collins et al.²⁴, FVC, VEF1 and total pulmonary capacity (TPC) are significantly decreased in patients with elevated body fat. This was also observed in the present study, in which the mean predicted percentage of spirometric parameters decreased as the obesity grade rose.

The present study results bear out data by Domingos-Benicio et al.²⁵, who found no significant differences between FVC and FEV₁ values in both eutrophic and obese subjects. However, the results contradict these autriors' statement that there would be a difference in the FEV₁/FVC ratio between both groups.

According to Teixeira et al.¹⁰, the higher the excess weight, the lower the FEV₁/FVC ratio and FEF_25-75%. There is a controversy in the study by Jones and Nzekwu²⁶, which showed obesity is associated with a high FEV₁/FVC ratio. The present study found a negative correlation for post-BDA FEF_25-75% between both groups, indicating this value is reduced in the obese group.

Obese people often complain of dyspnea, even though they do not have a demonstrable lung disease²⁷. Obesity can cause a limited airway flow, with reduced VEF1 and FVC. Unlike asthma, these reductions are typically symmetrical and result in a preserved FEV₁/FVC ratio. A number of authors demonstrate the FEV₁/FVC ratio is increased in obesity, consistently with the restrictive physiology^9,28.

It is noteworthy that out of 93 obese subjects, only three had a mild restrictive ventilatory disorder diagnosed by spirometry, i.e., 3.2%. In the study by Silva et al.¹³, over 10% of the 50-patient-sample were found with a mild to moderate restriction grade, and Faintuch et al.²⁹ diagnosed 20.9% of mild restrictive grade in 46 candidates for bariatric surgery.

Airway narrowing from obstructive phenomena associated with weight gain could explain the other diagnoses in the study, as Teixeira et al.¹⁰ believed in a study of grade II and III obese subjects.

According to Pereira¹¹, airway obstruction is a feature in asthma, emphysema, chronic bronchitis, bronchiolitis, and bronchiectasis. However, in the present study, no volunteer had any of these diseases previously diagnosed.

The 6MWT reproducibility seems to be higher than that for FEV₁ in patients with COPD¹⁵. A number of studies show significant associations between the distance over the 6MWT and FEV₁^20,30. However, Pereira¹¹ states FEV₁ is weakly correlated with exercise capacity and symptom improvement in patients with COPD.

The present study showed a positive correlation between pre- and post-BDA PEFR and the distance covered over the T6WT in obese subjects. PEFR is an exertiondependent expiratory parameter, reflecting the airway caliber. Therefore, when airways are narrow and have a reduced PEFR, the distance covered over the 6MWT will also be reduced, enabling a cause and consequence hypothesis.

A positive correlation between the pre- and post-bronchodilator agent peak expiratory flow rate and the distance covered over the 6MWT can be found in obese individuals, i.e., the higher the PEFR, the higher the individual physicalfunctional capacity and the longer the distance covered.

A relevant point in the study was obese group covered a shorter distance over the 6MWT compared with the eutrophic group, with a significant difference. This shows the interference a number of years of obesity settlement can cause on the individual and demonstrates the clinical importance of this finding for further studies.

Another important finding was the higher the obesity grade, the bigger the repercussions these individuals could show in spirometric parameters, which were reduced in this group.

Acknowledgements

The authors wish to thank the assistance and contribution of the Universidade Católica de Brasília, Dr. João Daniel, the coordinator Renata Nóbrega, and Otacilio Reis.

References

• 1. Kane AB, Kumar V. Patologia nutricional e ambiental. In: Abbas AK, Fausto N, Kumar V, coordenadores. Robbins e Cotran: patologia: bases patológicas das doenças. 7. ed. Rio de Janeiro: Elsevier; 2005. p. 482-6.
• 2. Pedroso ERP, Oliveira RG. Blackbook: clínica médica. Belo Horizonte: Blackbook Editora; 2007. p. 536-58.
• 3. Wanderley EM, Ferreira VA. Obesidade: uma perspectiva plural. Ciênc Saúde Coletiva 2010;15(1):185-94.
• 4. World Health Organization. Obesity and over weight. N. 311. Atua-lizado September; 2006. [citado 2009 feb. 14]. Disponível em: http://www.who.int/mediacentre/factsheets/fs311/en/index.html
• 5. IBGE. Pesquisa de Orçamentos Familiares (POF), 2002-2003. [citado 9 fev 2009]. Disponível em: http://www.ibge.gov.br
• 6. Jensen MD. Obesidade. In: Andreoli TE, Cecil RL, coordenadores. Cecil: medicina interna básica. 6. ed. Rio de Janeiro: Elsevier; 2005. p. 1552-62.
• 7. Barreto SSM. Volumes pulmonares. J Pneumol 2002;28 (Supl 3):83-94.
• 8. Rasslan Z, Saad Junior R, Stirbulov R, Fabbri RMA, Lima CAD. Avaliação da função pulmonar na obesidade graus I e II. J Bras Pneumol 2004;30(6):508-14.
• 9. Beuther DA, Weiss ST, Sutherland ER. Obesity and asthma. Am J Respir Crit Care Med 2006;174(2):112-9.
• 10. Teixeira CA, Santos JE, Silva GA, Souza EST, Martinez JAB. Prevalência de dispneia e possíveis mecanismos fisiopatológicos envolvidos em indivíduos com obesidade graus 2 e 3. J Bras Pneumol 2007;33(1):28-35.
• 11. Pereira CAC. Espirometria. J Pneumol. 2002;28(Supl 3):1-82.
• 12. Douce FH. Provas de função pulmonar. In: Scanlan CL, Wilkins RL, Stoller JK. Fundamentos da terapia respiratória de Egan. 7. ed. São Paulo: Manole; 2000. p. 394-401.
• 13. Silva AMO, Boin IFS, Pareja JC, Magna LA. Análise da função respiratória em pacientes obesos submetidos à operação Fobi-Capella. Rev Col Bras Cir 2007;34(5):314-20.
• 14. Gibson GJ. Obesity, respiratory function and breathlessness. Thorax 2000;55(Suppl 1):41-4.
• 15. Solway S, Brooks, D, Lacasse Y, Thomas S. A qualitative systematic overview of the measurement properties of functional walk tests used in cardiorespiratory domain. Chest 2001;119(1):256-70.
• 16. American Thoracic Society. ATS Statement: Guidelines for the Six-Minute Walk Test. This Official Statement of The American Thoracic Society Was Approved buy the ATS Board of Directors, March 2002. Am J Respir Crit Care Med 2002;166(1):111-7.
• 17. Enright P L. The six minute walk test. Respir Care 2003;48(8):783-5.
• 18. Enright PL, Sherril DL. Reference equations for the six-minute walk in healthy adults. Am J Respir Crit Care Med 1998;158(5 Pt 1):1384-7.
• 19. Barata VF, Gastaldi AC, Mayer AF, Sologuren MJJ. Avaliação das equações de referência para predição da distância percorrida no teste de caminhada de seis minutos em idosos saudáveis brasileiros. Rev Bras Fisioter 2005;9(2):165-71.
• 20. Perecin JC, Domingos NC, Gastaldi AC, Souza TC, Cravo SLD, Sologuren MJJ. Teste de caminhada de seis minutos em adultos eutróficos e obesos. Rev Bras Fisioter 2003;7(3):245-51.
• 21. Pelegrino NRG, Lucheta PA, Sanchez FF, Faganello MM, Ferrari R, Godoy I. Influência da massa magra corporal nas repercussões cardiopulmonares durante o teste de caminhada de seis minutos em pacientes com DPOC. J Bras Pneumol 2009;35(1):20-6.
• 22. Pires SR, Oliveira AC, Parreira VF, Britto RR. Teste de caminhada de seis minutos em diferentes faixas etárias e índices de massa corporal. Rev Bras Fisioter 2007;11(2):147-51.
• 23. Brunetto AF, Pitta FO, Probst VS, Paulin E, Yamaguti WPS, Ferreira L. F. Influência da saturação de O₂ na velocidade do teste de distância percorrida em 6 minutos, em pacientes com DPOC grave. Rev Bras Fisioter 2003;7(2):123-9.
• 24. Collins CL, Hoberty PD, Walker JF, Fletcher EC, Peiris AN. The effects of body fat distribution on pulmonary function tests. Chest 1995;107(5):1298-302.
• 25. Domingos-Benício NC, Gastaldi AC, Perecin JC, Avena KM, Guimarães RC, Sologuren MJJ et al. Medidas espirométricas em pessoas eutróficas e obesas nas posições ortostática, sentada e deitada. Rev Assoc Med Bras 2004;50(2):142-7.
• 26. Jones RL, Nzekwu MU. The effects of body mass index on lung volumes. Chest 2006;130(3):827-33.
• 27. El-Gamal H, Khayat A, Shikora S, Unterborn JN. Relationship of dyspnea to respiratory drive and pulmonary function tests in obese patients before and after weight loss. Chest 2005;128(6):3870-4.
• 28. Sin DD, Jones RL, Man SF. Obesity is a risk factor for dyspnea but not for airflow obstruction. Arch Intern Med 2002;162(13):1477-81.
• 29. Faintuch J, Souza SAF, Valezi AC, Sant' Anna AF, Gama-Rodrigues JJ. Pulmonary function and aerobic capacity in asymptomatic bariatric candidates with very severe morbid obesity. Rev Hosp Clin Fac Med Univ São Paulo 2004;59(4):181-6.
• 30. Rodrigues SL, Viegas CAA. Estudo de correlação entre provas funcionais respiratórias e o teste de caminhada de seis minutos em pacientes portadores de doença pulmonar obstrutiva crônica. J Pneumol 2002;28(6):324-8.

Correlation of spirometry with the six-minute walk test in eutrophic and obese individuals

Patrícia Lúcia Gontijo^I; Tiago Pessoa Lima^II; Thais Ribeiro Costa^II; Ederson Paulo Dos Reis^III; Flavia Perassa de Faria Cardoso^IV; Florêncio Figueiredo Cavalcanti Neto^V

Publication Dates

• Publication in this collection
  25 Aug 2011
• Date of issue
  Aug 2011

History

• Received
  16 Dec 2010
• Accepted
  12 Apr 2011