[The preliminary report of investigation: Using mask for cardiopulmonary exercise testing in Chinese children may result misinterpretation and misdiagnosis].

Objective: Observe the increased anatomical dead space of the mask, summarize the law of exercise induced oscillatory breathing (EIOB) in the results of CPET's new 9 figure, and analyze its incidence and age groups that are prone to oscillatory breathing. Methods: After signed the informed consent form by guardian, 501 children from pre-school to middle-school, aged 3~14 year, performed Harbor-UCLA standard protocol CPET with strict quality control in the CPET laboratory of Liaocheng Children's Hospital since 2014. CPET data was interpreted second by second from the breath by breath collection, averaged by 10s and then display by 9 plots. We analyzed the trends, pattern, incidence and age difference for EIOB and gas leakage. Results: The incidence of EIOB was the highest in the 3 to 6-year-old group, which was 42%. The 7 to 10-year-old group was 29.4% and the 11- to 14-year-old group was 29.9%. The three groups were tested by chi-square (x2=7.512), and the difference was statistically significant (P<0.05). 14 out of 508 children had air leakage during CPET, the incidence rate was 2.7%. Conclusion: The phenomenon of oscillatory breathing (OB) in children may be caused by the increased anatomical dead space of the mask, and it is not caused by disease. To improve the quality of CPET and to reduce clinical misdiagnosis, it is recommended to use a mouthpiece to decrease the dead space rather than the musk.