Effekte einer Sauerstoffsonde mit Reservoir (Oxymizer) im Vergleich zu einer konventionellen Sauerstoffbrille bei Patienten mit COPD, Stadium III und IV unter körperlicher Belastung

,,The Oxymizer® is a special oxygen cannula that provides a higher luminal diameter in combination with an incorporated oxygen reservoir‘‘ [Gloeckl et al, 2014]. So far, the impact of an Oxymizer® on performance and oxygenation of patients with severe chronic obstructive pulmonary disease is little explored. Therefore the aim of this study was to close this gap in existing research by investigating the effects of the Oxymizer® on endurance time in comparison to a conventional nasal cannula (CNC). During a three week pulmonary rehabilitation forty three patients with severe chronic obstructive pulmonary disease (age=60,1±8,9 a, FEV1=35,7 (23,1; 47,1) %pred, DLCO=29±13,7 %pred) and indication for LTOT performed four cycling endurance time tests at 70 % of their peak work rate in addition to the actual pulmonary rehabilitation program. Endurance tests were performed twice with Oxymizer® and with a CNC while reversing the treatment order after one week. During the measurement of the endurance time SpO2, tcpCO2 and pulse frequency were monitored using a SenTec Digital Monitoring System (SDMS). This system noninvasively and continuously records the ventilation (tcpCO2), the oxygen supply (SpO2) and the pulse frequency in real time in a clinical environment. Additionally, before and after the endurance time tests a capillary blood sample was taken for blood gas analysis. Furthermore, capillary blood samples were taken for blood gas analysis during rest to enable a complete comparison of the Oxymizer® to a conventional nasal cannula. Using these samples it was investigated whether the O2 flow rate could be lowered under the application of the Oxymizer® while achieving equal blood gas results. The results show that the endurance time was significantly higher when patients cycled while using the Oxymizer® in comparison to cycling while using the CNC (Oxymizer® 575 (330; 1278,5) seconds versus CNC 644 (281; 1053,5) seconds; p=0,004) [Gloeckl et al, 2014]. The difference between the two groups was 91,3±194,8 seconds. Furthermore, at the end of the endurance time the oxygen partial pressure was significantly higher when using the Oxymizer® (64,8±11,4 mmHg versus 61,5±10 mmHg; p<0,001) at comparable carbon dioxide partial pressure (45,1 (36,5; 53,4) mmHg versus 43 (37,3; 53,5) mmHg; p=0,405). However at the end of the endurance time the subjective perceived dyspnea and leg fatigue between both oxygen applications were similar (Oxymizer® Borg dyspnea 7 (5,5; 8), Borg leg fatigue 6,5 (5; 8,5) versus conventional nasal cannula Borg dyspnea 7,5 (5,9; 8), Borg leg fatigue 7 (5,5; 8); p=0,304 und p=0,243). Nevertheless overall results reveal a positive correlation between improvements in endurance time and O2 flow rate (CNC ρ=0,248, p=0,109, Oxymizer® ρ=0,348, p=0,022). A difference between the improvements in the constant work rate test between patients with a lower demand for O2 (2-3 liters/ min) and patients with a higher demand for O2 (4- 6 liters/ min) was shown. Patients with a higher demand for O2 (4-6 liters/ min) were able to improve endurance time significantly more (p=0,009) than patients with a lower demand for O2 (2-3 liters/ min) (161,2±225,4 seconds versus 18,1±123,9 seconds). On equal terms during resting periods paO2 with Oxymizer® showed a significant superiority to CNC (76,9±11,6 mmHg versus 73,8±10,3 mmHg, p=0,009). But as soon as the flow rate with Oxymizer® was decreased, the observed effect disappeared. On the contrary the Oxymizer® now was significantly inferior to the utilization of CNC (x-1l O2 with Oxymizer® p=0,003, x-2l O2 with Oxymizer® p<0,001). The collected data of the endurance time indicates that O2 delivery via the Oxymizer® is superior to a CNC with regard to endurance capacity and oxygenation during exercise for patients with severe COPD. Especially patients with a higher demand for O2 (≥4 liters/ min) could achieve a clinical relevant benefit [Gloeckl et al, 2014]. But the findings during resting periods demonstrate that even under the application of the Oxymizer® the O2 flow rate cannot be lowered to achieve equal blood gas results. Nevertheless the Oxymizer® is superior to CNC when compared under an identical flow rate.