Obstructive Sleep Apnea and Asthma Share Common Risk Factors
such as obesity and allergic rhinitis (a stuffy or runny nose). In fact, Several studies have shown that asthmatic patients are more likely to develop obstructive sleep apnea syndrome symptoms than patients in the general population. Symptoms of Obstructive Sleep Apnea Syndrome (OSAS), such as:
- witnessed apneas
- daytime sleepiness
are common in the asthmatic population, suggesting a possible association between OSA and asthma. Recent studies even suggest that obstructive sleep apnea syndrome is an independent risk factor for asthma exacerbations.
There is also mounting evidence that implicates obesity as a major risk factor for asthma. Asthma is more prevalent in obese individuals and obesity appears to predispose individuals to airway hyperresponsiveness as well as contribute to severe asthma. Obesity is also a known risk factor for obstructive sleep apnea syndrome.
Asthmatic patients also have increased incidence of nasal obstruction; and nasal obstruction contributes to sleep disordered breathing in predisposed individuals. Clinical studies have shown that the majority of individuals with asthma have rhinitis. Rhinitis and chronic sinusitis are common conditions that cause nasal congestion. The increased nasal obstruction in asthmatic patients causes an increase in nasal resistance that in turn increases the negative pressure in the upper airway during inspiration which is a key factor for developing OSAS. Asthmatic patients also have a reduction in their upper airway patency due to chronic airway mucosal inflammation which causes a reduction in airway cross-sectional area. Likewise, repeated nocturnal asthma symptoms cause chronic sleep deprivation and sleep fragmentation which increases upper airway collapsibility and in turn upper airway resistance. These factors further increase the risk for the development of obstructive sleep apnea symptoms in asthmatic individuals. Also, gastroesophageal reflux is a well-known trigger for nocturnal asthma and the prevalence of gastroesophageal reflux is increased in patients with sleep apnea syndrome.
Several studies have shown improvement in asthma symptoms after treatment for OSAS with CPAP.Therefore, it is important that clinicians consider, identify and treat obstructive sleep apnea in patients with asthma, especially unstable, poorly controlled asthmatic patients. This recommendation is supported by the National Asthma Education and Prevention Program.
Written by Dr. Nisbet