The use of esophageal manometry in the diagnosis of sleep-related breathing disorders

Relative prolongation of inspiratory time predicts high versus low resistance categorization of hypopneas

STUDY OBJECTIVES

Sleep disordered breathing events conceptually separate into "obstructive" and "central" events. Esophageal manometry is the definitive but invasive means of classifying hypopneas. The purpose of this project was to identify noninvasive markers for discriminating high vs. low resistance hypopneas.

METHODS

Forty subjects with obstructive or central sleep apnea underwent diagnostic polysomnography with nasal cannula airflow and esophageal manometry; 200% resistance relative to reference breaths was used to define "high" resistance. Noninvasive parameters from 292 randomly selected hypopneas in 20 subjects were analyzed and correlated to resistance. The best parameter and cutoff for predicting high relative resistance was determined and tested prospectively in 2 test sets in the 20 remaining subjects. Test Set A: 15 randomly selected hypopneas in each subject; Test Set B: all hypopneas in 7 subjects.

RESULTS

In the development set, prolongation of inspiratory time during the 2 smallest breaths of a hypopnea (T(i)) relative to baseline had the best correlation to high relative resistance. In the Test Set A, relative T(i) > 110% classified obstructive events with sensitivity = 72%, specificity = 77%, PPV = 64%, NPV = 83%. Similar numbers were obtained for classification of hypopneas based on presence of flow limitation (FL) alone. When either relative T(i) or presence of FL were used to define high resistance, sensitivity = 84%, specificity = 74%, PPV = 65%, NPV = 89%. Similar results were obtained for Test Set B.

CONCLUSIONS

Relative prolongation of T(i) is a good noninvasive predictor of high/low resistance in a dataset with both FL and NFL hypopneas. Combination of FL and relative T(i) improves this classification. The use of T(i) to separate obstructive and central hypopneas needs to be further tested for clinical utility (outcomes and treatment effects).

Pneumothorax as an initial manifestation of obstructive sleep apnea syndrome

CASE REPORT

A sixty-five-year-old man with bullous lung disease was admitted to emergency service with chest pain and dyspnea that developed during sleep. Pneumothorax was diagnosed both clinically and radiologically. After the chest drainage, the patient presented with a prolonged air leak that required thoracotomy. Further history and occurrence of pneumothorax during sleep suggested that obstructive sleep apnea might play a role in the development of pneumothorax. Nocturnal polysomnography later confirmed the diagnosis of severe obstructive sleep apnea syndrome.

DISCUSSION

We hypothesized that obstructive sleep apnea may be a risk factor for pneumothorax especially in patients with bullous lung disease, and pneumothorax may be listed in the complications of obstructive sleep apnea syndrome.