Abstract
Problem: Due to methodical problems concerning data analysis and interpretation, esophago-pharyngeal pressure (EPP) monitoring is not routinely performed in sleep laboratories. It was investigated whether automatic analysis of EPP is a helpful tool for a more precise characterization of the OSAS (ie, breathing effort and the site of obstruction).
Methods: 20 patients with suspected OSAS underwent polysomnography including EPP measurement (probe: 1.8 mm diameter, 5 pharyngeal, 1 esophageal transducers) during the second night. The pressure was measured during obstructive apneas and normal breathing in S1-4 and REM sleep for every breath during the whole night. The site of the maximal pressure reduction between 2 transducers was assumed the site of obstruction during apnea.
Results: The mean AHI was 33. The mean esophageal pressure amplitude (mm Hg) during normal breathing was 6.5 in S1, 10.2 in S2, 16.5 in S3, 12.7 in S4, and 9.0 in REM sleep. Patients with an AHI <20 versus >20 had a mean pressure amplitude in S3 of 7.4 versus 28.9. 12 patients had maximal reduction of pharyngeal pressure between the nasopharyngeal and the oropharyngeal transducer, 2 patients at the tonsils, and 6 patients between the oropharyngeal and hypopharyngeal transducer.
Conclusion: During normal breathing, OSAS patients have an elevated breathing effort which is not reflected in the AHI. Obstruction during an apnea most often occurred at the velum.
Significance: EPP with automatic analysis can improve the characterization of the OSAS and seems to be a helpful tool for the detection of the site of obstruction during an apnea. Further investigations have to show whether EPP also facilitates a distinctive surgical therapy of the OSAS and improves the outcome.
Support: None reported.