Approximately seventy-five percent (75%) of asthma patients also experience symptoms of gastroesophagel reflux disease (GERD), but until recently the relationship between these two diseases remained largely ambiguous. A series of recent studies by Dr. Vikram Khoshoo and other scientists now indicate that not only can GERD cause or exacerbate asthma, but that asthma and asthma medications may in return cause or aggravate GERD. Notably, the Khoshoo study, which focused on asthmatic children, strongly indicates that treating the existing GERD may drastically lower the need for asthma medications.
The past difficulty in pinpointing the exact relationship between GERD and asthma is unsurprising given their seemingly separate areas of influence in the human body. Symptoms of GERD result from improper functioning of the lower esophageal sphincter (LES), which acts as a door between the stomach and lower esophagus. When this door is loose, or functioning incorrectly, the acidic contents of the stomach flow back into the esophagus and up towards the throat. The resulting discomfort is commonly called ‘heartburn.’ Asthma, on the other hand, is characterized by a chronic inflammation of the lungs and air passages that impairs an individual’s ability to breathe. Incidence of asthma has long been correlated to allergies and a generally overactive immune system, which results in the constriction of air passages.
From a group of 46 children with asthma, Dr. Khoshoo’s team identified 27 who also had symptoms of GERD. These 27 either received acid-suppressing drugs and made lifestyle changes or underwent surgery to tighten the LES. After an observation period of 12 months, the children who had received some form of GERD treatment were found to have achieved a 50% reduction in total required asthma medications. Notably, there was a 50% reduction in bronchodilator use and 89% of the children with GERD did not require corticosteroids. Khoshoo’s findings, which strongly implicate GERD as an inducer or aggravator of asthma in children, are significant both pathologically and because they identify a new means of alleviating asthma through GERD treatments.
Although the exact mechanism by which GERD induces asthma is uncertain, scientists have identified several likely explanations. One such theory is that as acid reaches the throat, there is significant potential for it to aggravate the air passages and lungs, which would cause the characteristic constriction associated with asthma. Additionally, the findings of Dr. Susan Harding of the University of Alabama at Birmingham suggest a common nerve source for the base of the esophagus and the bronchial tree. In this scenario, the entrance of acid into the esophagus would trigger responses in both systems – an explanation which would account for the observed constriction of airways when acid enters the esophagus.
Intriguingly, in addition to the evidence identifying GERD as a causative or aggravating agent of asthma, several studies have also indicated that asthma and asthma medications can in fact induce or enhance GERD. Dr. Harding notes that anti-asthma medications such as albuterol and prednisone have the effect of decreasing the pressure and contractive abilities of the LES, thus increasing incidence of acid reflux. Moreover, several studies have indicated that beta-adrenergic bronchodilators relax the smooth muscle of the esophagus, also promoting reflux events. Specifically, one South Birmingham, UK study found that asthmatics treated with Beta2-agonists were twice as likely to experience GER symptoms as their untreated counterparts. The authors
of this study also postulated that hyperinflation of the chest associated with asthma could lead to mechanical failure of the LES.
Physicians advise that individuals suffering from asthma often also have GERD if: symptoms worsen after meals, exercise, or during the night; they experience frequent coughing or hoarseness; there is recurrent pneumonia or pulmonary fibrosis; or if there is no response to standard asthma treatment.
