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Table 2 Investigative workup for etiology of chronic cough and sleep-apnea specific workup in patients with chronic cough

From: Chronic cough and obstructive sleep apnea in a community-based pulmonary practice

INVESTIGATIONS PERFORMED N (%)
Pulmonary Function Tests  
Spirometry 70/75 (93%)
Diffusion capacity 60/75 (80%)
Lung volumes 44/75 (59%)
Methacholine challenge testing 2/75 (3%)
Six-minute walk test 1/75 (1%)
Radiologic studies  
Chest X-ray 54/75 (72%)
Chest CT scan 10/75 (13%)
Sinus imaging 10/75 (13%)
Endoscopic studies  
Bronchoscopy 0/75
Upper GI endoscopy 2/75 (3%)
24 hour pH monitoring 1/75 (1%)
(Bravo* pH probe)  
Laboratory studies 5/75 (7%)
SLEEP APNEA RELATED WORKUP  
Sleep history obtained 41/75 (55%)
Abnormal 36/75 (48%)
Screening overnight oximetry 6/75 (8%)
Abnormal 6/75 (8%)
Polysomnography 38/75 (51%)
   Sleep disordered breathing 33/75 (44%)
No OSA (AHI < 5) 4/75 (5%)
Mild OSA (AHI 6-15) 6/75 (8%)
Moderate OSA (AHI 16-30) 6/75 (8%)
Severe OSA (AHI >31) 14/75 (19%)
   Periodic limb movement disorder 1/75 (1%)
   Sleep efficiency (mean) 89%
   Arousal index (mean) 17
   Oxygen saturation (mean) 91%
   Lowest oxygen saturation (mean) 78%
  1. Abbreviations: OSA - Obstructive sleep apnea; AHI - Apnea hypopnea index.
  2. * Bravo pH capsule with delivery system (Medtronic, Inc. Minneapolis, MN, USA)