Evaluation of cardio-respiratory parameters during the stair climbing test and the six minutes walking test

Background: The stair climbing test (SCT) could be used as an alternative to the six minutes walking test (6MWT) to assess exercise tolerance in COPD patients. Objective: To compare the relationship between evolution of dyspnoea, oxygen saturation and heart rate during the stair climbing test and the 6MWT. Material and method: A self-paced 2-minutes SCT and a 6MWT were performed on a separate day in 36 stable COPD patients (Age = 65.1 ± 12.7 y.o.; FEV1 = 54 ± 17.5 % pred.val.; BMI = 25.3 ± 4.3kg.m-2) without encouragement. Arterial oxygen saturation (SpO2), heart rate (HR), and dyspnoea (VAS) were measured before, during and immediately after both tests. Climbed and walked distances were measured at the end of the tests. Results: Delta HR and maximum HR measured during exercise were significantly different for each test (38 ±17 bpm and 109 ±11 bpm vs 25 ±12 bpm and 104 ±16 bpm, p<0.001 and p=0.01 for SCT and 6MWT respectively). Difference between pre- and post-exercise saturation tended to be different between both tests (3 ±3% and 4 ±2% for SCT and 6MWT respectively, p=0.056). Difference between pre- and post-exercise dyspnoea was significantly greater with SCT than with 6MWT (6 ±2 vs 4 ±2, p<0.001). There was a significant correlation between FEV1 and climbed distance (r=0.44, p<0.01) and walked distance (r=0.34, p<0.05). Conclusion: These results highlight that HR and dyspnoea increase to a greater extent during the SCT compared to the 6MWT despite similar changes in SpO2

Non-invasive ventilation: Evaluation of CO<inf>2</inf> washout by intentional leaking in three recent oronasal masks. A pilot study

Background. Many types of interfaces with intentional leaks exist for Non Invasive Ventilation. The purpose of intentional leaks is to remove CO2 from the interface, however the calibration does not allow a sufficiently large flow and rebreathing of CO2 can occur. The aim of this study was to compare the CO2 rinsing capacities of three new generation oronasal masks with intentional leaks (A: Quattro®, [Resmed]; B: Amara® [Respironics]; C: Forma® [Fisher&Paykel]) in healthy subjects. Methods. Seventeen healthy volunteers were included in this prospective cross-sectional, randomized, double-blinded trial. Each subject underwent ventilation with a home ventilator (IPAP: 14 cmH2O; EPAP: 4 cmH2O) with each mask consecutively. Transcutaneous capnography (PtcCO2) recordings were carried out throughout the trial and ventilator data (tidal volume, respiratory rate, minute ventilation and unintentional leaks) were also analyzed. Mask comfort was assessed using a visual analog scale (0 to 10). Results. The results showed no differences in PtcCO2 between masks (P=0.82). There were no significant differences in respiratory parameters (tidal volume, P=0.79; respiratory rate, P=0.65; minute ventilation, P=0.12) between masks. The rate of unintentional leaks were significantly lower for Mask A (P=0.016). Subjects rated Mask A and Mask C as more comfortable than Mask B (P=0.041). Conclusion. There was no effect of mask on PtcCO2 in healthy subjects. The mask with the highest comfort rating had not the lowest rate of unintentional leaks