The goal of the study is to examine the possible underlying causes of sleep apnea (a disorder in which there are problems with breathing during sleep) in World Trade Center Responders. The study will look at the relationship between sleep apnea and various nose and throat conditions. Specifically, the study will look at upper airway disease (problems with the nose and throat), nasal inflammation, and nasal resistance (the amount of airflow through the nose). Subjects will have a physical exam and answer questions about nasal symptoms and sleeping problems. Nasal lavage (washing the inner nasal passages) will be performed on the subjects and markers of inflammation will be measured in the lavage fluid. Rhinomanometry (measuring the airflow through the nose) will also be performed to measure the degree of airflow obstruction. All subjects will be asked to perform in-home sleep apnea monitoring. Those subjects who are diagnosed with sleep apnea will test two treatment methods. Sleep apnea is treated by using a CPAP (continuous positive airway pressure) device. This device blows air into a mask worn by the patient during sleep. The two treatment methods that will be tested are the fixed pressure CPAP (pressure is constant during use) and CPAP-flex (pressure decreases when the subject exhales). Patients will be randomly assigned to one treatment method for one month then crossed to the other treatment method for the next month. The investigators will determine if patients with certain nasal conditions (high nasal resistance) are more likely to use CPAP-flex rather than CPAP.

Following the World Trade Center (WTC) disaster, an estimated 40,000 individuals were exposed to significant amounts of dust while working in rescue, recovery and debris removal. A significant number of these responders have reported least one new or worsened upper airway respiratory symptom when examined in 2004 with 50% of responders continuing to have symptoms of chronic rhino-sinusitis or upper airway disease (UAD) in 2007. In addition, about 50% of those with UAD referred to our sleep center reported new onset snoring on their questionnaires immediately following their exposure and had unusually high prevalence of obstructive sleep apnea (OSA) that did not appear to be related to obesity, which is the usual risk factor for OSA. This suggests to us that mechanisms other than obesity may be important in the pathogenesis of OSA in these subjects. Given their chronic nasal symptoms they also provide a unique opportunity to examine the relationship between nasal pathology and OSA and test if nasal symptoms reported by the subjects in the WTC Health Program (WTCHP) are an indicator of increased nasal resistance due to nasal inflammation resulting from exposure to the WTC dust. Positive Airway Pressure (CPAP) is the standard therapy for OSA but despite its efficacy has poor adherence. Subjects with high nasal resistance (such as responders with UAD and OSA) may experience additional pressure during expiration at the upper airway resulting in greater difficulty in tolerating CPAP therapy than those who do not have high nasal resistance. Reduction of excess expiratory positive pressure by the modality known as Cflex™ during CPAP therapy (CPAPFlex) may improve comfort and adherence in these subjects without compromising CPAP efficacy. In the present proposal we will study responders enrolled at the Environmental and Occupational Health Sciences Institute of Robert Wood Johnson Medical School (RWJMS) and the NYU School of Medicine Clinical Center of Excellence at Bellevue Hospital

Inclusion Criteria:

• Member of the World Trade Center Health Program at either the Environmental and Occupational Healthy Sciences Institute at Robert Wood Johnson Medical School in Piscataway, NJ, the New York University School of Medicine Clinical Center of Excellence at Bellevue Hospital in New York, NY, or the Icahn School of Medicine at Mount Sinai.

Exclusion Criteria:

• Gross skeletal alterations affecting the upper airway (nose and throat)
• Unstable chronic medical conditions known to affect Obstructive Sleep Apnea (congestive heart failure, stroke)
• Pregnancy or intent to become pregnant
• Habitual snoring or diagnosis of obstructive sleep apnea prior to 9/11/2001.

Participants assigned to the treatment arm.

Adverse event data were collected for 2 months after the start of the trial.