226 | Chapter 9 Discussion Cardiopulmonary exercise testing with gas exchange analysis is possible in laryngectomy patients wearing an HME. There was no air leakage during testing, all patients were comfortable wearing the connector during their CPETs, and there were no (serious) adverse events. However, less than half (4/10) of the patients reached an RER>1.1 in at least one test, and only one subject reached 95% of his predicted heart rate during one test. Thus, although this setup of CPET is technically feasible and appears to be safe, it could be questioned whether the used ramp protocol is suitable for reaching maximum exercise capacity in this population. The subjects’ reasons for terminating the CPET before reaching predicted maximum levels were mainly exhaustion, feeling out of breath, and leg fatigue, without signs of cardiopulmonary problems. Instead, early stopping was related to a low subjective exercise tolerance30. It is common that inactive patients do not tolerate normal acute physical responses induced by exercising. This can be trained and has proven to be effective in terms of properly performing CPET31. Although we purposefully sampled our participants based on regular physical activity of at least moderate intensity, most participants habitually participated in predominantly low-intensity activities such as cycling (some with electric assistance), moderate strength training, and walking. For selection of participants and determining the steps of the ramp protocol, we relied on self-reported levels of physical activity. However, in survivors of HNC, perceived levels of activity and fitness may not accurately reflect their actual levels32. This should be considered when determining the ramp steps in future testing. Another explanation for patients stopping due to feelings of exhaustion and leg fatigue, could be that exercise capacity was limited by muscle strength, rather than aerobic capacity. Low skeletal muscle mass, sarcopenia, is relatively common (30-50%) in patients undergoing a laryngectomy33,34. Sarcopenia results in less muscle strength, affects gait, endurance and mobility, and may lead to inactivity which further impacts muscle mass and strength35. Limited muscle strength after laryngectomy could be a problem when using the current CPET protocols, which also calls for smaller increments. Only one participant reached their maximum predicted heartrate once. Although this could be due to peripheral fatigue limiting the test, overestimation of maximum predicted heartrate is also common in low-fit subjects, and might be an alternative explanation for this finding36,37.
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