Postural changes in lung volumes and respiratory resistance in subjects with obesity

Watson, R. A.; Pride, N. B.

doi:10.1152/japplphysiol.00430.2004

Cited by 175 publications

(156 citation statements)

References 36 publications

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“…Our results confirm others in showing that TLC and RV are not significantly affected by weight loss or postural changes, 15,16,22 although modifications in TLC have been reported in some obese subjects. 5,[23][24][25] Other spirometric variables, such as VC and FEV 1 , increased significantly with weight loss induced by gastroplasty.…”

Section: Discussionsupporting

confidence: 91%

“…This longitudinal study confirms the sparse evidence in the literature of the different effects of body position on lung volumes depending on BMI range, as shown separately in the morbidly obese 15,16 and mildly to severely obese groups. 13,14,21 In non-obese subjects, the decrease in FRC upon adopting the supine position is essentially attributed to the gravitational effects of the abdominal contents.…”

Section: Discussionsupporting

confidence: 89%

“…[12][13][14] Although a significant supine reduction in FRC has also been reported in mild to moderate obesity, its absence has been shown in morbid obesity. 15,16 However, most studies have compared obese subjects to normal weight controls. Data from longitudinal evaluation of postural changes in lung volumes in morbidly obese individuals following weight loss is scarce.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Weight Loss on Postural Changes in Pulmonary Function in Obese Subjects: A Longitudinal Study

et al. 2015

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BACKGROUND: Postural changes are known to affect normal lung volumes. A reduction in sitting to supine functional residual capacity (FRC) is well-described in non-obese subjects adopting a supine position. However, postural changes in lung volumes in the obese require further exploration. We aimed to longitudinally address the effects of weight loss on postural changes in lung volumes and pulmonary function in obese subjects. We tested the hypothesis that supine reduction in FRC would be absent in morbid obesity and recovered upon weight loss. METHODS: This was a prospective, observational, longitudinal study. Consecutive morbidly obese adults (N ‫؍‬ 12, age: 44 ؎ 14 y, body mass index: 45 ؎ 5 kg/m 2 ) enrolled in a bariatric surgery program were included. Standard pulmonary function tests and blood gas analysis were performed both before and 1 y after surgery. Pulmonary function was assessed in both the sitting and supine position using spirometry and multi-breath helium dilution. Parameters recorded before and after weight loss were compared. The main outcome measure was FRC. RESULTS: Ten subjects were retested 1 y after surgery (body mass index: 31 ؎ 5 kg/m 2 ). FRC was not affected by change in posture before surgery. Supine reduction in FRC was observed after weight loss (⌬FRC: ؊0.6 ؎ 0.4 L, sitting vs supine, P ‫؍‬ .002). Pulmonary gas exchange improved (alveolar-to-arterial oxygen partial pressure difference: ؊8 ؎ 11 mm Hg, P ‫؍‬ .035). CONCLUSIONS: Although postural change in FRC is absent when the morbidly obese adopt a supine position, supine reduction in FRC can be recovered following gastroplasty-induced weight loss, despite residual mild to moderate obesity. This also shows that mild to moderate obesity may affect supine FRC more than morbid obesity. (ClinicalTrials.gov registration NCT02207192.) Key words: lung function; obesity; weight loss; postural change; pulmonary function test; functional residual capacity; bariatric surgery. [Respir Care 2015;60(7):992-999.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Weight Loss on Postural Changes in Pulmonary Function in Obese Subjects: A Longitudinal Study

et al. 2015

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“…The effects of obesity on the lung function values have not been found to be consistent in earlier studies [58]. Other studies (other than from India) have reported effects of obesity on asthma [53], reduced FRC and expiratory reserve volume detected even at modest increase in weight [25], significant inverse relation between BMI and values of VC and TLC and the values of FRC and ERV decreasing exponentially with BMI [54], reduced FRC in obese subjects [55] and extreme obesity associated with a reduction in ERV, FVC, FEV 1 , FRC, FEF %, and MVV [56]. Several studies reported no significant differences in FEV 1 , FVC, FEV 1 /FVC ratio and FEF between obese and non-obese subjects [1,57,58].…”

Section: Discussionmentioning

confidence: 78%

Alterations in lung functions based on BMI and Body fat % among obese Indian population at National Capital Region

Kamal¹,

Kesavachandran²,

Bihari³

et al. 2015

Nepal J Epidemiology

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Abstract:Background:In India, non-asthmatic hospital admission case study has been conducted to find out the relationship between obesity and lung functions. The main objective of the present study was to find out the alterations in lung functions due to obesity among Indian population living at National Capital Region (NCR). Materials and Methods:We examined 609 non obese and 211 obese subjects in a cross sectional study from National Capital Region, India with age group ranges between 18-70 years. BMI and body fat % was determined using body fat analyzer. Obese and non-obese subjects were classified based on criteria for BMI and Body fat %. Lung function test viz., FEV 1 and PEFR were conducted using portable spirometer (PIKO-1). Results:A significant correlation (p<0.05) was observed between BMI and PEFR among non-obese male and female subjects. Decline in PEFR and FEV 1 values for corresponding increase in body fat % was observed among study subjects. A significant (p<0.01) decline in mean FEV 1 and PEFR was observed among non-obese and obese subjects, compared to their Indian reference standards for lung functions. A significant negative correlation (p<0.01) was observed between body fat % and lung functions (FEV 1, PEFR). Conclusion: It is concluded that obese subjects are at a risk of lung function impairment, based on the criteria followed for BMI and body fat %. The study also demonstrate that body fat% classification as a better index for determination of obese subjects compared to BMI classification, with respect to lung function impairments.

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“…A better understanding of the effects on obese patients of changing position from sitting to supine is important because the supine position is standard for sleep. The findings regarding the change in FRC and position vary between studies, with some investigators finding no change 9,10 and others 11 finding a decrease in the supine compared with the sitting position. One reason for these discrepancies between studies may relate to whether closing volume is taken into account.…”

Section: Introductionmentioning

confidence: 97%

Mechanisms of Orthopnea in Stable Obese Subjects

Perino¹,

Nesme²,

Germain³

et al. 2016

Respir Care

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BACKGROUND: The present study explored the role of closing volume as a determinant of orthopnea in stable obese subjects. We hypothesized that: (1) increase in closing volume in supine position would be greater in orthopneic than in non-orthopneic subjects, and (2) the relationship of change in closing volume to change in dyspnea with position would be dependent on expiratory flow limitation in the sitting position. METHODS: In stable obese subjects, in sitting and supine positions, we measured the Borg dyspnea score, static lung volumes, expiratory flow limitation during tidal breathing, and single-breath nitrogen expiration test. From the latter, we determined closing volume and closing capacity, slope of phase III, and opening capacity. Orthopnea was defined as any increase in the Borg score in the supine position from its value in the sitting position. RESULTS: Twenty-one subjects (13 women), median age (interquartile range) 55 (49 -57) y and with body mass index of 39 (38 -42) kg/m 2 were included, of whom 12 were orthopneic and 11 had expiratory flow limitation while seated. In the sitting position, orthopneic and non-orthopneic subjects were similar for age, body mass index, and pulmonary function tests, including single-breath nitrogen expiration test-derived variables. In the orthopneic subjects, there were no changes in any respiratory variable between positions. In the non-orthopneic subjects, there was a significant decrease in slope of phase III in the supine position from 1.67 (1.33-3.60) to 1.40 (1.25-1.66)%/L (P ‫؍‬ .008). Overall, the subjects' Borg score significantly correlated with the slope of phase III (r ‫؍‬ 0.63, P ‫؍‬ .002) and opening capacity (r ‫؍‬ ؊0.47, P ‫؍‬ .03). In 10 subjects without expiratory flow limitation, it correlated with slope of phase III (r ‫؍‬ 0.68, P ‫؍‬ .03). CONCLUSIONS: In stable obese subjects, magnitude of orthopnea correlated with an increase in the slope of phase III in subjects without expiratory flow limitation. Expiratory flow limitation should be taken into account in obese patients.

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Postural changes in lung volumes and respiratory resistance in subjects with obesity

Cited by 175 publications

References 36 publications

Effect of Weight Loss on Postural Changes in Pulmonary Function in Obese Subjects: A Longitudinal Study

Effect of Weight Loss on Postural Changes in Pulmonary Function in Obese Subjects: A Longitudinal Study

Alterations in lung functions based on BMI and Body fat % among obese Indian population at National Capital Region

Mechanisms of Orthopnea in Stable Obese Subjects

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