Atemarbeit bei druckentlastendem PAP im Vergleich zur konventionellen CPAP-Therapie

Within the conventional CPAP-therapy, which continues to be the gold-standard therapy for treatment of obstructive sleep apnea, relevant compliance problems caused by an increased expiration pressure frequently occur (Hill, 2000). Against this background, Philips-Respironics (Murriville, USA) has developed a pressure-relieving CPAP-therapy, which automatically reduces pressure during expiration via controlling respiratory flow in three pressure-relief phases (C-Flex 1-3). The effect of a pressure-relieving CPAP-therapy with respect to inspiratory flow limitations was examined, as previously studied by Canisius et al. (Canisius et al., 2009), whose data was used for this post-hoc analysis. Here, no relevant discrepancies were observed in the appearance of flow limitations between CPAP and C-Flex. However a significant increase in the inspiration time ratio/expiration time ratio (Ti7Te) and the inspiratory breath cycle (Ti/Ttot), as well as a significantly increased respiratory rate in C-Flex2 and C-Flex 3 (REM sleep) could be observed. Taking into account changes in the breathing parameters, particularly the extension of the inspiratory time and the simultaneous consecutive reduction of the expiration time, the question arose as to what extent the breathing effort changes under the pressure relieving PAP therapy. Scientific studies from Schneider et al. (Schneider et al., 2009) have led to the presumption that the C-Flex therapy increases the respiratory effort due to the increase of the inspiration time and the change of the inspiration/expiration time ratio in favour of the inspiration to reach the tidal volume. On the basis of the data from Canisius et al. (Canisius et al., 2009), an alternative theory was put forward, i.e. that an extension of the inspiratory time together with a consecutive reduction of the expiration time under C-Flex could lead to the decrease of the exhalation effort. A precise analysis of the respiratory effort under C-Flex has to date not been possible due to technical limitations. This should now be clarified in the presented post-hoc analysis. 51 The bases of the analysis were the waveforms of 24 patients from Canisius et al. (Canisius et al., 2009). The majority of the patients were already treated sufficiently with the CPAP-therapy, the rest were newly treated. 22 patients passed through all ventilation modes (CPAP and C-Flex 1-3) during NREM- a REM-sleep for 15 minutes each. In only two patients could the modi not be measured in all sleep stages. With the help of computer assisted automated respiratory effort analysis, the respiratory effort of a single breath could be determined. The result of this analysis could not demonstrate any increase of the respiratory work under C-Flex in comparison to CPAP. Instead an average linear decrease of the respiratory effort between CPAP and C-Flex of 1.22 joule was shown. These differences occurred because of the large variation of values as well as the insufficient numbers of patients and are therefore not statistically significant. This applies for REM- as well as NREM-stages. A significant difference in the respiratory effort could be detected by correlation between the respiratory effort under C-Flex and BMI. A significant reduction of the respiratory effort under CFlex- 3 and a decreasing BMI could be shown. To verify the existing hypothesis, further studies with higher case numbers are necessary. Should a reduction of the breathing effort be traceable, the C-Flex therapy could be applied to disorders, which are accompanied by an enhanced respiratory effort such as amyotrophic lateral sclerosis or chronic obstructive lung disease.