gms | German Medical Science

Introduction: Adjustment of sufficient nasal CPAP-therapy in patients with OSAS can be time-consuming and so a parameter, which can predict the adequate pressure would be desirable. The goal of our study was to find out if the esophageal pressure as a measure of the breathing effort during polysomnography is helpful for the prediction of the effective CPAP-pressure.

Methods: 20 patients with OSAS received diagnostic polysomnography with measurement of the esophageal pressure during the whole night. After introduction of nasal CPAP-therapy the connection between esophageal pressure and the effective nCPAP-pressure was examined.

Results: Mean nCPAP-pressure was 8,6 (+/- 2,4) mbar with an pretherapeutic apnea-hypopnea-index (AHI) of 44,7 (+/- 15,7). There was a poor correlation between the mean esophageal pressure (7200-9800 breaths per patient) on the one hand and the effective nCPAP-pressure on the other hand (Spearman correlation: r = 0,42; p < 0,05). This was similar to the poor correlation of the nCPAP-pressure and the AHI (r = 0,48; p < 0,05). A better correlation was seen between the maximum esophageal pressure and the nCPAP-pressure with r = 0,57 (p < 0,01).The best correlation in this small subgroup was seen between the body mass index and the nCPAP-pressure with r = 0,82 (p < 0,01). This correlation was not found in a larger collective. There was no influence of age of the patients to the required nCPAP-pressure.

Conclusion: Polysomnographic parameters as for example the AHI and the mean esophageal pressure are only of limited value for the prediction of the effective nCPAP-pressure in patients with OSAS. Maximum esophageal pressure perhaps in combination with other anatomical factors may be helpful for enclosing a certain pressure area.