CO2 rebreathing caused by a defectively designed mask can lead to hypercapnia. APEX’s masks can affectively solve these problems.


Noninvasive ventilation (NIV) is widely used to treat a variety of respiratory diseases, such as acute respiratory failure (ARF), chronic obstructive pulmonary disease (COPD), and obstructive sleep apnea (OSA). NIV provides respiratory support via an interface to patients’ respiratory system without invading into human bodies.  Interfaces for NIV include nasal pillow mask, nasal mask, full-face mask, total face mask, and helmet mask. Each type of interface has its own characteristics to optimize the wide range of needs from different users. However, nasal mask, full face mask, total face mask and helmet mask have higher risk of carbon dioxide (CO2) rebreathing because their higher internal volumes [1] create extra anatomical dead space to human bodies. Dead space is the volume of air which is inhaled but does not take part in the gas exchange. There is around 4~5% CO2 contained in humans' exhaled air. The CO2 accumulated inside of the interfaces' dead space of NIV has the risk of CO2 rebreathing. The volume of interfaces [2], the breathing frequency [3], the ventilation mode [4], and the exhalation port position [5] can affect the CO2 removal efficacy of masks. COrebreathing caused by a defectively designed mask can lead to hypercapnia, which describes the arterial blood CO2 level (PaCO2) above 46 mmHg (6.1 kPa)[6], and it may cause the symptoms of headache, dizziness, difficulty in breathing, and abnormal tiredness[7]. These conditions may affect the users’ daily life dramatically.


 OSA patients use CPAP therapy to alleviate sleep apnea caused by the collapsed upper airway. A CPAP mask is designed to provide adequate ventilation and expel CO2 efficiently through exhalation ports. Otherwise, the sleepiness and dizziness derived from both OSA and CO2 rebreathing will decrease the therapeutic effects and lower the quality of life of users[8][9]. Clinically, when the OSA patient shows the symptoms of hypercapnia, the SpO2 should be examined. The caregiver should adjust the therapeutic range of CPAP or change the interface to eliminate the risk of consistent CO2 rebreathing.


We value the importance of quality of life and effective therapeutic effects for OSA patients. Taking CO2 wash-out into consideration when designing a CPAP mask, “Tranquil Fresh Tech” in WiZARD CPAP Masks features decreasing turbulent flow and separating inhaled and exhaled flows. Thus, the CO2 exhaled by the patient can be expelled smoothly and efficiently from the CPAP mask. Furthermore, the sound level of WiZARD CPAP mask can be decreased due to the smoothly-expelled airflow technology. “Tranquil Fresh Tech” can significantly reduce expiratory resistance and lower noise level during sleep, thus it is able to provide a quiet and relaxing sleep experience for the users of WiZARD CPAP Mask.

[1] Cortegiani, A., Misseri, G., Accurso, G., Gregoretti, C., & Ball, L. (2019). Reducing Rebreathing During Noninvasive Ventilation: Bias Flow or No Bias Flow?. Respiratory Care, 64(11), 1453-1453. doi: 10.4187/respcare.07185
[2] Taccone, P., Hess, D., Caironi, P., & Bigatello, L. (2004). Continuous positive airway pressure delivered with a “helmet”: Effects on carbon dioxide rebreathing*. Critical Care Medicine, 32(10), 2090-2096. doi:10.1097/01.ccm.0000142577.63316.c0
[3] Signori D, Bellani G, Calcinati S, Grassi A, Patroniti N, Foti G. Effect of face mask design and bias flow on rebreathing during noninvasive ventilation. Respir Care 2019; 64(7):793-800
[4] Saatci, E., Miller, D., Stell, I., Lee, K., & Moxham, J. (2004). Dynamic dead space in face masks used with noninvasive ventilators: a lung model study. European Respiratory Journal, 23(1), 129-135. doi: 10.1183/09031936.03.00039503
[5] Schettino, G., Chatmongkolchart, S., Hess, D., & Kacmarek, R. (2003). Position of exhalation port and mask design affect CO2 rebreathing during noninvasive positive pressure ventilation*. Critical Care Medicine, 31(8), 2178-2182. doi: 10.1097/01.ccm.0000081309.71887.e9
[6] Prabhakar, H. (2016). Chapter 20 - Hypercapnia, Complications in neuroanesthesia (pp. 157-168). Academic Press.
[7] Schaefer, K., Hastings, B., Carey, C. and Nichols, G., 1963. Respiratory acclimatization to carbon dioxide. Journal of Applied Physiology, 18(6), pp.1071-1078.
[8] Kawata, N., Tatsumi, K., Terada, J., Tada, Y., Tanabe, N., Takiguchi, Y., & Kuriyama, T. (2007). Daytime Hypercapnia in Obstructive Sleep Apnea Syndrome. Chest, 132(6), 1832-1838. doi: 10.1378/chest.07-0673
[9] Batool-Anwar S, Goodwin JL, Kushida CA, Walsh JA, Simon RD, Nichols DA, Quan SF. Impact of continuous positive airway pressure (CPAP) on quality of life in patients with obstructive sleep apnea (OSA). J Sleep Res. 2016 Dec;25(6):731-738. doi: 10.1111/jsr.12430. Epub 2016 May 30. PMID: 27242272; PMCID: PMC5436801.

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