Obesity worsens impact of asthma

May 01, 2008

Obesity can worsen the impact of asthma and may also mask its severity in standard tests, according to researchers in New Zealand, who studied lung function in asthmatic women with a range of body mass indexes (BMIs).

This is the first prospective study to reveal a significant comparative difference in how the airways and lungs respond to a simulated asthma attack in obese and non-obese individuals.

The research is reported in the first issue for May of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society. It establishes a direct link between obesity and the development of a phenomenon known as "dynamic hyperinflation"--when air breathed into the lungs cannot be exhaled. This often occurs with acute asthma, but is more frequent in obese individuals.

"We have demonstrated significant differences in the changes in respiratory function that occur with asthmatic bronchoconstriction in relation to obesity," said principal investigator, D. Robin Taylor, M.D., of the University of Otago in New Zealand.

The researchers recruited 30 asthmatic women and divided them into three groups by BMI: normal weight, overweight and obese. Each woman breathed nebulized methacholine to artificially induce an asthma-like attack, and was then assessed for changes in lung function on several measures, including how much air remained in her lungs after exhalation (functional residual capacity, or FRC) and how much air she could breathe in on her next breath (inspiratory capacity, or IC).

"After the methacholine challenge, the amount of bronchoconstriction was identical for each of the three groups, but the changes in FRC and IC were greatest in the obese group. This indicated to us that greater dynamic hyperinflation was occurring among obese individuals," said Dr. Taylor.

With increasing BMI, FRC was higher, whereas IC was significantly decreased. "This means that among women with greater BMI, an asthma-like episode has the potential to cause greater breathing difficulties than in non-obese women," said Dr. Taylor. "The greater dynamic hyperinflation means that obese individuals lose the ability to inhale as deeply or exhale as fully as normal weight individuals."

Curiously, the group of obese individuals with asthma differed from their non-asthmatic counterparts in having a lower FRC before the methacholine challenge than the non-obese group, yet still recorded a greater increase in FRC after the methacholine challenge. "This is the surprising finding in our study. It is quite counterintuitive. You would expect individuals with a heavier chest wall not to develop hyperinflation quite so readily as those who are lighter. But that is not what happened," said Dr. Taylor.

Perhaps most importantly, these findings point to fundamental differences in the way that obese individuals might experience shortness of breath if they have asthma. "We know that asthma in obese subjects is more likely to persist and is more likely to be perceived to be severe. These individuals often require more treatment to achieve asthma control. Our study provides an insight into why this might be happening-the same asthma "trigger" produces a greater effect in obese individuals."

The study also showed that simple spirometry was inadequate to determine the level of pulmonary dysfunction which was occurring in obese individuals.

"Our findings need to be explored further. We need to confirm that the differences in dynamic hyperinflation between obese and non-obese asthmatics are sufficient to explain the differences in symptoms between the two groups. Our study was not large enough to do this," said Dr. Taylor.
-end-


American Thoracic Society

Related Obesity Articles from Brightsurf:

11 years of data add to the evidence for using testosterone therapy to treat obesity, including as an alternative to obesity surgery
New research covering 11 years of data presented at this year's European and International Congress on Obesity (ECOICO 2020) show that, in obese men suffering from hypogonadism (low testosterone), treatment with testosterone injections lowers their weight and improves a wide range of other metabolic parameters.

Overlap between immunology of COVID-19 and obesity could explain the increased risk of death in people living with obesity, and also older patients
Data presented in a special COVID-19 session at the European and International Congress on Obesity (ECOICO 2020) suggests that there are overlaps between the immunological disturbances found in both COVID-19 disease and patients with obesity, which could explain the increased disease severity and mortality risk faced by obese patients, and also elderly patients, who are infected by the SARS-CoV-2 virus that causes COVID-19 disease.

New obesity guideline: Address root causes as foundation of obesity management
besity management should focus on outcomes that patients consider to be important, not weight loss alone, and include a holistic approach that addresses the root causes of obesity, according to a new clinical practice guideline published in CMAJ (Canadian Medical Association Journal) http://www.cmaj.ca/lookup/doi/10.1503/cmaj.191707.

Changing the debate around obesity
The UK's National Health Service (NHS) needs to do more to address the ingrained stigma and discrimination faced by people with obesity, says a leading health psychologist.

Study links longer exposure to obesity and earlier development of obesity to increased risk of type 2 diabetes
Cumulative exposure to obesity could be at least as important as actually being obese in terms of risk of developing type 2 diabetes (T2D), concludes new research published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]).

How much do obesity and addictions overlap?
A large analysis of personality studies has found that people with obesity behave somewhat like people with addictions to alcohol or drugs.

Should obesity be recognized as a disease?
With obesity now affecting almost a third (29%) of the population in England, and expected to rise to 35% by 2030, should we now recognize it as a disease?

Is obesity associated with risk of pediatric MS?
A single-center study of 453 children in Germany with multiple sclerosis (MS) investigated the association of obesity with pediatric MS risk and with the response of first-line therapy in children with MS.

Women with obesity prior to conception are more likely to have children with obesity
A systematic review and meta-analysis identified significantly increased odds of child obesity when mothers have obesity before conception, according to a study published June 11, 2019 in the open-access journal PLOS Medicine by Nicola Heslehurst of Newcastle University in the UK, and colleagues.

Obesity medicine association announces major updates to its adult obesity algorithm
The Obesity Medicine Association (OMA) announced the immediate availability of the 2019 OMA Adult Obesity Algorithm, with new information for clinicians including the relationship between Obesity and Cardiovascular Disease, Diabetes Mellitus, Dyslipidemia, and Cancer; information on investigational Anti-Obesity Pharmacotherapy; treatments for Lipodystrophy; and Pharmacokinetics and Obesity.

Read More: Obesity News and Obesity Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.