Table 2.
Investigative workup for etiology of chronic cough and sleep-apnea specific workup in patients with chronic cough
| 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% |
Abbreviations: OSA - Obstructive sleep apnea; AHI - Apnea hypopnea index.
* Bravo pH capsule with delivery system (Medtronic, Inc. Minneapolis, MN, USA)