The Etiologies, Pathophysiology, and Alternative/Complementary Treatment of Asthma

Alternative Medicine Review, Feb, 2001 by Alan L. Miller

Animal and human studies have provided evidence for the microaspiration theory of GER, although overall the evidence looks less convincing than the "reflex theory." Inhalation of a dilute acid solution in cats caused significantly greater bronchoconstriction than infusion of acid into the esophagus.[83] Ambulatory esophageal pH monitoring and scintigraphic technetium monitoring have provided documentation of esophageal acid reflux and microaspiration of gastric acid in humans.[84,85] It might be that asthma related to GER is a multifactorial problem, with components of microaspiration and gastroesophageal reflux.

If indeed GER causes asthma or exacerbates hypersensitive respiratory tissue, the true test should be that anti-reflux or antacid therapy significantly improves asthma symptoms. However, antacid therapy, which has consisted mostly of H2 blockers (cimetidine, ranitidine) or a proton pump inhibitor (omeprazole), has not been consistently effective, showing mixed results.[74]

A small study (n=5) of asthma patients with noctumal symptoms and GER determined that treating asthma with ephedrine improved asthma symptoms as well as reflux symptoms. The authors stated the bronchodilation provided by the ephedrine and the subsequent improvement in GER symptoms suggests GER might be a result of asthma symptomatology, not the opposite.[86]

The most common GER therapy is a pharmacological reduction in gastric acid output. However, Wright found a substantial number of children with asthma actually have a reduction in gastric acid output. He theorizes that reduced gastric output results in inadequate protein digestion and an increase in allergenicity of foods, as well as a reduction in nutrient absorption. Treatment with hydrochloric acid supplementation is part of his integrated treatment protocol, and is claimed to provide symptomatic improvement.[87,88]

The Possible Role of Dehydration in Asthma

It is important to ensure the asthma patient is well hydrated; however, good data does not exist showing a firm association between dehydration and asthma, except in exercise-induced asthma (EIA). In EIA, dehydration of airway epithelial cells may contribute to epithelial damage, edema, and hyper-responsiveness.[89-93] This does not rule out the possibility that chronic sub-clinical dehydration may contribute to asthma-related symptoms; in fact, it lends credibility to the theory.

Aspirin-induced Asthmatic Exacerbation

A subset of individuals with asthma experience symptoms after ingestion of aspirin or other similar non-steroidal anti-inflammatory drugs (NSAIDs). Since most NSAIDs block the enzyme cyclooxygenase, it is thought this leaves more arachidonic acid to react with the other arm of the eicosanoid pathway, regulated by activity of lipoxygenase. Downstream metabolites of this pathway include the leukotrienes, very potent stimulators of inflammation and bronchial constriction. Avoidance of NSAIDs is imperative in these individuals. Some asthmatics also react to sulfites present in some foods and wines. This reaction is more common in people who experience symptoms following ingestion of NSAIDs.[95]