Featured Research

from universities, journals, and other organizations

Why hot, humid air triggers symptoms in patients with mild asthma

Date:
June 6, 2012
Source:
Nationwide Children's Hospital
Summary:
Patients who inhaled an asthma drug before breathing in hot, humid air were able to prevent airway constriction that volunteers without asthma did not experience in the same environment.

May is asthma awareness month, and with summer right around the corner, a study shows that doctors may be closer to understanding why patients with mild asthma have such difficulty breathing during hot, humid weather. The study, appearing in the June print issue of the American Journal of Respiratory and Critical Care Medicine, found that patients who inhaled an asthma drug before breathing in hot, humid air were able to prevent airway constriction that volunteers without asthma did not experience in the same environment.

Ipratropium, a drug occasionally used for asthma, prevents airway muscle contraction and increases airflow to the lungs. Its success in combating the air temperature response suggests that hot, humid air triggers asthma symptoms by activating airway sensory nerves that are sensitive to an increase in temperature.

"We know that breathing cold, dry air induces airway constriction in asthmatics," said Don Hayes, MD, medical director of the Lung and Heart-Lung Transplant Program at Nationwide Children's Hospital. "But the effects that temperature increases have on airway function in these patients are generally overlooked. We know very little about the mechanisms that cause symptoms when asthmatic patients are exposed to hot, humid air."

Dr. Hayes and his colleagues at the University of Kentucky Medical Center (where Dr. Hayes was on staff prior to joining Nationwide Children's late last year) enrolled patients with mild asthma and healthy controls in a study to assess their pulmonary reaction to hot, humid air. Six asthmatic patients (ranging from 21 years of age to 26) and six healthy subjects (between 19 and 46) were asked to breathe into a device designed to deliver air at certain desired temperatures and humidity levels. The device produced a humidified gas mixture of air either hot or room temperature. Subjects breathed via a mouthpiece into this free stream of air for four minutes and were asked to pant. Investigators measured participants' airway resistance before and for 16 minutes immediately following the challenge. They also measured body temperature, heart rate, arterial blood pressure and oxygen saturation before and afterward.

Results showed that breathing of hot, humid air triggered an immediate increase in airway resistance in patients with mild asthma, but caused either only a very small or no response in healthy subjects. Breathing hot, humid air also triggered consistent coughs in those with asthma. When the asthmatic participants used an ipratropium aerosol before the challenge, they did not experience airway constriction.

"We don't fully understand the mechanisms underlying these responses," said Dr. Hayes, who is the study's primary author.

A recent study by the same research group found that airway sensory nerves called C-fiber nerves were activated with the temperature within the chest was elevated to about 102 degrees Fahrenheit. These data were developed in Lu-Yuan Lee's, MD, laboratory at the University of Kentucky using animal models. Dr. Lee's laboratory has a 20-year history of National Institutes of Health funding to study C-fiber sensory nerves in the lung.

"When C-fiber sensory nerves are stimulated, a number of pulmonary defense reflex responses can occur, including cough and bronchoconstriction," said Dr. Hayes, also a faculty member at The Ohio State University College of Medicine.

"This study is a good example of how we can translate findings from a research laboratory into a better understanding and more in-depth knowledge about how to prevent and treat diseases in patients," said Dr. Lee.

Dr. Hayes says further research is needed to completely understand how patients' bodies react to hot and humid air and is planning such studies at Nationwide Children's. Overall, he says that this data provides evidence to support that ambient air temperatures and humidity levels are very important in asthma and this research introduces potential new drug targets for the treatment of asthma.


Story Source:

The above story is based on materials provided by Nationwide Children's Hospital. Note: Materials may be edited for content and length.


Journal Reference:

  1. D. Hayes, P. B. Collins, M. Khosravi, R.-L. Lin, L.-Y. Lee. Bronchoconstriction Triggered by Breathing Hot Humid Air in Patients with Asthma: Role of Cholinergic Reflex. American Journal of Respiratory and Critical Care Medicine, 2012; 185 (11): 1190 DOI: 10.1164/rccm.201201-0088OC

Cite This Page:

Nationwide Children's Hospital. "Why hot, humid air triggers symptoms in patients with mild asthma." ScienceDaily. ScienceDaily, 6 June 2012. <www.sciencedaily.com/releases/2012/06/120606164934.htm>.
Nationwide Children's Hospital. (2012, June 6). Why hot, humid air triggers symptoms in patients with mild asthma. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2012/06/120606164934.htm
Nationwide Children's Hospital. "Why hot, humid air triggers symptoms in patients with mild asthma." ScienceDaily. www.sciencedaily.com/releases/2012/06/120606164934.htm (accessed September 17, 2014).

Share This



More Health & Medicine News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

President To Send 3,000 Military Personnel To Fight Ebola

President To Send 3,000 Military Personnel To Fight Ebola

Newsy (Sep. 16, 2014) President Obama is expected to send 3,000 troops to West Africa as part of the effort to contain Ebola's spread. Video provided by Newsy
Powered by NewsLook.com
Obama Orders Military Response to Ebola

Obama Orders Military Response to Ebola

AP (Sep. 16, 2014) Calling the Ebola outbreak in West Africa a potential threat to global security, President Barack Obama is ordering 3,000 U.S. military personnel to the stricken region amid worries that the outbreak is spiraling out of control. (Sept. 16) Video provided by AP
Powered by NewsLook.com
UN: 20,000 Could Be Infected With Ebola by Year End

UN: 20,000 Could Be Infected With Ebola by Year End

AFP (Sep. 16, 2014) Nearly $1.0 billion dollars is needed to fight the Ebola outbreak raging in west Africa, the United Nations say, warning that 20,000 could be infected by year end. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Obama: Ebola Outbreak Threat to Global Security

Obama: Ebola Outbreak Threat to Global Security

AP (Sep. 16, 2014) President Obama is ordering U.S. military personnel to West Africa to deal with the Ebola outbreak, which is he calls a potential threat to global security. (Sept. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins