Expiratory Flow Limitation and Orthopnea in Massively Obese Subjects

doi:10.1378/chest.119.5.1401

Chest

Volume 119, Issue 5, May 2001, Pages 1401-1408

https://doi.org/10.1378/chest.119.5.1401 Get rights and content

Background:

Morbidly obese subjects, who often complain about breathlessness when lying down, breathe at low lung volume with a reduced expiratory reserve volume (ERV). Therefore, during tidal breathing the expiratory flow reserve is decreased, promoting expiratory flow limitation (EFL), which is more likely to occur in the supine position, when the relaxation volume of the respiratory system, and hence the functional residual capacity (FRC), decrease because of the gravitational effect of the abdominal contents.

Purpose:

The aim of the study was to assess EFL and orthopnea in massively obese subjects and to evaluate whether orthopnea was associated with the development of supine EFL.

Methods:

In 46 healthy obese subjects (18 men) with a mean (± SD) age of 44 ± 11 years and a mean body mass index (BMI) of 51 ± 9 kg/m², we assessed EFL in both the seated and the supine positions by the negative expiratory pressure method and assessed postural changes in FRC by measuring the variations in the inspiratory capacity (IC) with recumbency. Simultaneously, dyspnea was evaluated in either position using the Borg scale dyspnea index (BSDI) to determine the presence of orthopnea, which was defined as any increase of the BSDI in the supine position.

Results:

Partial EFL was detected in 22% and 59%, respectively, of the overall population in seated and supine position. The mean increase in the supine IC amounted to 120 ± 200 mL (4.1 ± 6.4%), indicating a limited decrease in FRC with recumbency in these subjects. Orthopnea, although mild (mean BSDI, 1.7 ± 1.3), was claimed by 20 subjects, and in 15 of them EFL occurred or worsened in the supine position. Orthopnea was associated with lower values of seated ERV (p < 0.05) and was marginally related to supine EFL values (p = 0.07). No significant effect of age, BMI, obstructive sleep apnea-hypopnea syndrome, FEV₁, and forced expiratory flow at 75% of vital capacity was found on either orthopnea or EFL.

Conclusion:

In morbidly obese subjects, EFL and dyspnea frequently occur with the subject in the supine position, and both supine EFL and low-seated ERV values are related to orthopnea, suggesting that dynamic pulmonary hyperinflation and intrinsic positive end-expiratory pressure may be partly responsible for orthopnea in massively obese subjects.

Section snippets

Subjects

Forty-six obese subjects (18 men) with a mean body mass index (BMI) of > 40 kg/m² were investigated in a prospective open study at the respiratory division of Sant'Orsola-Malpighi Hospital in Bologna, Italy. The mean (± SD) age and BMI were 42 ± 11 years and 50 ± 8 kg/m², respectively, for men and 45 ± 10 years and 51 ± 9 kg/m², respectively, for women. Five men and eight women were current smokers, while four men and five women were previous smokers. None of the subjects had acute or chronic

Results

The anthropometric characteristics and lung function parameters of the subjects are given in Table 1. According to the MRC dyspnea scale, the chronic dyspnea score as reported by our subjects was mild, amounting to 1.1 ± 0.1. Twenty-one subjects (14 men) had OSAHS, with a markedly higher prevalence in men (78%) than in women (25%).

None of the subjects exhibited complete EFL in either position. Partial EFL was detected in 10 subjects (4 men) when seated, and in 27 subjects (10 men) when supine,

Discussion

The main findings of this study of healthy, massively obese subjects are the following: (1) partial EFL is common when subjects are supine, while it is seldom observed when they are seated; (2) almost half of these subjects experienced orthopnea, although to a mild degree; and (3) in most subjects orthopnea was associated with the occurrence or worsening of EFL in the supine position.

Before discussing these results, some aspects inherent in the NEP method chosen to detect EFL need to be

References (36)

JK Alexander et al.
Observations on some clinical features of extreme obesity, with particular reference to cardiorespiratory effects
Am J Med
(1962)
JH Cullen et al.
The respiratory effects in extreme obesity
Am J Med
(1962)
JM Luce
Respiratory complication of obesity
Chest
(1980)
H Sahebjami et al.
Pulmonary function in obese subjects with a normal FEV₁/FVC ratio
Chest
(1996)
F Zerah et al.
Effects of obesity on respiratory resistance
Chest
(1993)
H Sahebjami
Dyspnea in obese healthy men
Chest
(1998)
A Duguet et al.
Expiratory flow limitation as a determinant of orthopnea in patients with acute left heart failure
J Am Coll Cardiol
(2000)
DF Rochester et al.
Current concepts in the pathogenesis of the obesity-hypoventilation syndrome: mechanical and circulatory factors
Am J Med
(1974)
GN Bedell et al.
Pulmonary function in obese persons
J Clin Invest
(1958)
A Naimark et al.
Compliance of the respiratory system and its component in health and obesity
J Appl Physiol
(1960)

F Barrera et al.

Pulmonary function in the obese patient

Am J Med Sci

(1967)

PM Suratt et al.

Compliance of chest wall in obese subjects

J Appl Physiol

(1984)

DH Tucker et al.

The effect of change in body position on lung volumes and intrapulmonary gas mixing in patients with obesity, heart failure and emphysema

Am Rev Respir Dis

(1960)

CS Ray et al.

Effect of obesity on respiratory function

Am Rev Respir Dis

(1983)

PS Thomas et al.

Respiratory function in the morbidly obese before and after weight loss

Thorax

(1989)

DE Leith et al.

Mechanisms determining residual volume of the lungs in normal subjects

J Appl Physiol

(1967)

RO Crapo et al.

Spirometry as a preoperative screening test in morbidly obese patients

Surgery

(1986)

I Rubinstein et al.

Airflow limitation in morbidly obese, nonsmoking men

Ann Intern Med

(1990)

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Chest

Clinical InvestigationsOBESITYExpiratory Flow Limitation and Orthopnea in Massively Obese Subjects

Background:

Purpose:

Methods:

Results:

Conclusion:

Section snippets

Subjects

Results

Discussion

Am J Med

Am J Med

Chest

Chest

Chest

Chest

J Am Coll Cardiol

Am J Med

Pulmonary function in obese persons

J Clin Invest

Compliance of the respiratory system and its component in health and obesity

J Appl Physiol

Pulmonary function in the obese patient

Am J Med Sci

Compliance of chest wall in obese subjects

J Appl Physiol

The effect of change in body position on lung volumes and intrapulmonary gas mixing in patients with obesity, heart failure and emphysema

Am Rev Respir Dis

Effect of obesity on respiratory function

Am Rev Respir Dis

Respiratory function in the morbidly obese before and after weight loss

Thorax

Mechanisms determining residual volume of the lungs in normal subjects

J Appl Physiol

Spirometry as a preoperative screening test in morbidly obese patients

Surgery

Airflow limitation in morbidly obese, nonsmoking men

Ann Intern Med

Clinical Investigations
OBESITY
Expiratory Flow Limitation and Orthopnea in Massively Obese Subjects